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Editor’s Choice Articles

Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to readers, or important in the respective research area. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

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30 pages, 10883 KB  
Review
MXene- and MOF-Based Hydrogels: Emerging Platforms for Electrochemical Biosensing and Health Monitoring
by Kandaswamy Theyagarajan, Sairaman Saikrithika and Young-Joon Kim
Micromachines 2026, 17(2), 267; https://doi.org/10.3390/mi17020267 - 20 Feb 2026
Viewed by 305
Abstract
Smart healthcare is rapidly emerging as a transformative paradigm, enabling simultaneous health monitoring, therapeutic intervention, and early prediction of disease onset. In this context, electrochemical monitoring systems have attracted growing interest due to their cost-effectiveness, ease of operation, miniaturization and compatibility with wearable [...] Read more.
Smart healthcare is rapidly emerging as a transformative paradigm, enabling simultaneous health monitoring, therapeutic intervention, and early prediction of disease onset. In this context, electrochemical monitoring systems have attracted growing interest due to their cost-effectiveness, ease of operation, miniaturization and compatibility with wearable platforms. Accordingly, conductive hydrogel-based electrochemical (bio)sensors have gained significant attention for health monitoring owing to their soft mechanical properties, high water content, excellent biocompatibility, and ability to form intimate, conformal interfaces with biological tissues. Their three-dimensional polymeric networks facilitate efficient ion transport and mechanical flexibility, making them particularly suitable for wearable and noninvasive sensing and monitoring applications. However, the intrinsically limited conductivity and catalytic activity of pristine hydrogels often constrain their electrochemical performance. To overcome these limitations, functional nanomaterials such as metal–organic frameworks (MOFs) and MXene (MX) nanosheets have been increasingly integrated into hydrogel matrices to enhance conductivity and electrochemical activity. This review provides a comprehensive and critical comparison of recent advances in MOF- and MX-integrated conductive hydrogels for electrochemical health monitoring. In addition to material design strategies and sensing performance, emerging trends in data-driven sensing aimed at improving signal interpretation and multi-analyte discrimination are systematically discussed. Key challenges related to long-term stability, biocompatibility, scalability, and intelligent system integration are critically assessed, and the future potential of these platforms within closed-loop architectures is highlighted, paving the way for next-generation conductive hydrogel-based electrochemical sensors in smart healthcare applications. Full article
(This article belongs to the Special Issue Bioelectronics and Its Limitless Possibilities)
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38 pages, 7875 KB  
Review
The Evolution of Lithography: From Resolution Scaling to Manufacturing Constraints
by Heejoon Chae, Hyunje Park and Dae Joon Kang
Micromachines 2026, 17(2), 261; https://doi.org/10.3390/mi17020261 - 18 Feb 2026
Viewed by 706
Abstract
Lithographic patterning continues to evolve under the dual pressure of ever-finer features and manufacturable, cost-effective integration. Beyond headline resolution, industrial adoption is increasingly determined by a small set of coupled metrics: throughput, overlay (registration), defectivity, and cost, as well as by how these [...] Read more.
Lithographic patterning continues to evolve under the dual pressure of ever-finer features and manufacturable, cost-effective integration. Beyond headline resolution, industrial adoption is increasingly determined by a small set of coupled metrics: throughput, overlay (registration), defectivity, and cost, as well as by how these trade-offs shift with materials, substrate form factors, and integration flows. Here, we review lithographic techniques across three eras: traditional methods (pre-1990s), non-conventional innovations (1990s), and contemporary advancements (post-2000s), with an explicit goal that goes beyond compilation. Specifically, we provide a decision framework for interpreting each method using the same manufacturing-relevant criteria. For each class of technique, we summarize the operating principle and representative process routes, then map the dominant bottlenecks to the metric that ultimately limits scale-up. This cross-cutting lens clarifies why many emerging methods are compelling at the physics level yet remain constrained at the system level, where process windows, in-line control, and compatibility with existing fabrication ecosystems govern viability. By connecting mechanism-level innovation to manufacturing-level constraints, this review offers practical guidance for researchers and engineers seeking to position nanolithography options for applications ranging from high-volume semiconductor production to agile prototyping and materials- or substrate-limited devices. Full article
(This article belongs to the Special Issue Nanoscale Lithography—Pressing Miniaturization towards Ever Smaller Sizes)
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20 pages, 4253 KB  
Article
Construction of Highly Active Interfaces on Screen-Printed Carbon Electrodes via Controllable Electrochemical Exfoliation for High-Performance Flexible Enzyme-Free Glucose Sensing
by Wenjing Xue, Ziyan Chen, Xiao Peng, Haocheng Yin, Yimeng Zhang and Yuming Zhang
Micromachines 2026, 17(2), 251; https://doi.org/10.3390/mi17020251 - 16 Feb 2026
Viewed by 224
Abstract
Enzyme-free flexible glucose sensors hold great promise in the field of wearable health monitoring. However, their performance is limited by the balance between the catalytic interface activity and stability. This paper reports a strategy for interface gradient roughening of screen-printed carbon electrodes (SPCE) [...] Read more.
Enzyme-free flexible glucose sensors hold great promise in the field of wearable health monitoring. However, their performance is limited by the balance between the catalytic interface activity and stability. This paper reports a strategy for interface gradient roughening of screen-printed carbon electrodes (SPCE) via controllable electrochemical exfoliation (EE). It systematically reveals the inherent relationships among the degree of EE treatment, electrode morphology, surface chemistry, and electrochemical performance. On this basis, the deposition of gold nanoparticles (AuNPs) with high density and uniform distribution is achieved, and a high-performance flexible enzyme-free glucose sensor is constructed. The study finds that EE treatment can significantly increase the true surface area of the electrode and introduce abundant oxygen-containing functional groups, thus effectively reducing the charge transfer resistance. Nevertheless, excessive exfoliation leads to the degradation of the conductive network, indicating the existence of a critical “performance window”. The EE-SPCE optimized with 150 cycles has both a high active area and good electrical conductivity, providing an ideal deposition substrate for AuNPs, increasing their distribution density by approximately 158% and reducing the average particle size to 125 nm. The fabricated AuNPs/EE-SPCE sensor exhibits excellent performance in glucose detection: it has a high sensitivity of 550.766 μA·mM−1·cm−2 in the range of 0.1–3 mM, a detection limit of 0.0998 mM, a wide linear range, excellent selectivity, long-term stability, and good mechanical flexibility. This research not only develops an efficient and scalable method for constructing flexible sensing interfaces but also clarifies the trade-off relationship among “roughening–conductivity–catalytic performance” at the mechanistic level, providing an important theoretical basis and a general strategy for rationally designing high-performance flexible electrochemical devices. Full article
(This article belongs to the Special Issue Microdevices and Electrode Materials for Electrochemical Applications)
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14 pages, 5315 KB  
Article
A Triboelectricity-Driven Self-Sustainable System for Removing Heavy Metal from Water
by Jonghyeon Yun, Hyunwoo Cho, Geunchul Kim, Inkyum Kim and Daewon Kim
Micromachines 2026, 17(2), 229; https://doi.org/10.3390/mi17020229 - 11 Feb 2026
Viewed by 352
Abstract
As the demand for clean water grows, the strategic management of water resources has become increasingly critical. However, the depletion of these resources is being accelerated by anthropogenic pollutants and resultant internal pipe corrosion within distribution networks. Conventional water treatment methods are characterized [...] Read more.
As the demand for clean water grows, the strategic management of water resources has become increasingly critical. However, the depletion of these resources is being accelerated by anthropogenic pollutants and resultant internal pipe corrosion within distribution networks. Conventional water treatment methods are characterized by high energy consumption, rendering them impractical in environments lacking a continuous external power supply. Consequently, innovative, self-sustained technologies for simultaneously monitoring fluid conditions and purifying water are a necessity. In this work, we present a water-driven triboelectric nanogenerator (W-TENG) used for energy harvesting and water-quality monitoring within pipe networks. Composed of a silicone rubber tube and aluminum electrodes, the optimized W-TENG achieved an open-circuit voltage of 58 V, short-circuit current of 1.1 µA, and 59.5 mW/m2 at a 10 MΩ load. The W-TENG distinguishes pH levels and liquid types based on electrical outputs. Notably, a parallel connection of two W-TENGs enhanced electrical energy by 214% compared to the sum of two units. As an application, a self-powered electrochemical deposition was conducted and copper ions were successfully removed using energy stored in a 1 mF capacitor. These results indicate that the W-TENG is expected to be utilized as a self-powered platform for simultaneous water purification and real-time infrastructure monitoring. Full article
(This article belongs to the Special Issue Piezoelectric Microdevices for Energy Harvesting)
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21 pages, 7792 KB  
Article
Optimization of Magnetic Filler Loading and Interstitial Dielectric Percolation for Tunable Triboelectric–Electromagnetic Hybrid Generators
by Geunchul Kim, Jonghwan Lee, Yuseob Lee, Jihwon Keum, Inkyum Kim and Daewon Kim
Micromachines 2026, 17(2), 231; https://doi.org/10.3390/mi17020231 - 11 Feb 2026
Cited by 1 | Viewed by 616
Abstract
In this study, a material-driven strategy is presented to realize tunable triboelectric–electromagnetic hybrid generators while overcoming the form-factor limitations of conventional magnet-assisted systems. A magneto-dielectric hybrid generator (MDHG) was constructed using a soft magnetized dielectric composite, where NdFeB microparticles were embedded in an [...] Read more.
In this study, a material-driven strategy is presented to realize tunable triboelectric–electromagnetic hybrid generators while overcoming the form-factor limitations of conventional magnet-assisted systems. A magneto-dielectric hybrid generator (MDHG) was constructed using a soft magnetized dielectric composite, where NdFeB microparticles were embedded in an Ecoflex matrix and activated by pulse magnetization, allowing a single compliant layer to operate simultaneously as a triboelectric contact medium and a magnetic flux source coupled to a coil. The magnetic filler loading was systematically optimized to elucidate the trade-off between enhanced electromagnetic induction and a non-monotonic triboelectric response governed by dielectric polarization, surface potential, and interfacial energetics. To selectively strengthen the triboelectric branch without sacrificing electromagnetic output, nanoscale BaTiO3 was introduced as an interstitial dielectric phase to promote polarization-active pathways and suppress screening-driven charge-utilization loss. Under contact–separation operation, the optimized MDHG produced triboelectric outputs up to a VOC of 400.40 V and ISC of 56.95 μA, while the electromagnetic branch delivered up to a VOC of 260.04 mV and ISC of 0.89 mA, corresponding to 2.87- and 2.62-fold increases in triboelectric VOC and ISC over pristine Ecoflex. Finally, the hybrid signatures enabled a wearable smart-skin interface capable of decoupling touch occurrence, intensity, and counter-material identity. Full article
(This article belongs to the Special Issue Piezoelectric Microdevices for Energy Harvesting)
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44 pages, 5347 KB  
Review
Solution-Processed OLEDs: A Critical Review and Methodology Proposal for Stack Optimization
by Yassine Chiadmi, Paul-Vahe Cicek and Ricardo Izquierdo
Micromachines 2026, 17(2), 217; https://doi.org/10.3390/mi17020217 - 5 Feb 2026
Viewed by 762
Abstract
Solution-processed OLEDs represent a low-cost, scalable alternative to vacuum-deposited devices, particularly for flexible and large-scale applications. However, selecting compatible materials for each layer remains a complex task, further complicated by inconsistent documentation, solvent interactions, and limited reproducibility across the literature. This work presents [...] Read more.
Solution-processed OLEDs represent a low-cost, scalable alternative to vacuum-deposited devices, particularly for flexible and large-scale applications. However, selecting compatible materials for each layer remains a complex task, further complicated by inconsistent documentation, solvent interactions, and limited reproducibility across the literature. This work presents a literature review and critical analysis of materials, solvents, and fabrication methods involved in solution-processed OLEDs, with particular attention to layer formulation, solvent orthogonality, and processing constraints. A Monte Carlo-based optimization framework is introduced as a proof of concept, aiming to formalize stack selection and explore viable combinations based on empirical constraints. The critical analysis highlights recurring issues in the field and advocates for a more structured, reproducibility-oriented approach to OLED design. Full article
(This article belongs to the Special Issue Emerging Trends in Optoelectronic Device Engineering, 2nd Edition)
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15 pages, 2461 KB  
Article
Development of MWCNTs/MXene/PVA Hydrogel Electrochemical Sensor for Multiplex Detection of Wound Infection Biomarkers
by Qihang Li, Jia Han, Ting Xue and Yuyu Bu
Micromachines 2026, 17(2), 209; https://doi.org/10.3390/mi17020209 - 3 Feb 2026
Viewed by 398
Abstract
To address the clinical urgency of simultaneously monitoring multiple biomarkers in chronic wound infections, this study presents the innovative development of an electrochemical sensor based on a MWCNTs/MXene/PVA composite hydrogel. A dual-channel conductive network is constructed via the electrostatic self-assembly of the two-dimensional [...] Read more.
To address the clinical urgency of simultaneously monitoring multiple biomarkers in chronic wound infections, this study presents the innovative development of an electrochemical sensor based on a MWCNTs/MXene/PVA composite hydrogel. A dual-channel conductive network is constructed via the electrostatic self-assembly of the two-dimensional material MXene and multi-walled carbon nanotubes (MWCNTs). This strategy not only enhances the charge transfer efficiency but also effectively suppresses the aggregation of MWCNTs and exposes the electrocatalytic active sites. Additionally, the thermal annealing process is incorporated to facilitate the ordered arrangement of polyvinyl alcohol (PVA) nanocrystalline domains, strengthening the hydrogen bond-mediated interfacial adhesion and resolving the issues of hydrogel swelling and delamination. The detection limit (LOD) of the optimized sensor (MWCNTs0.6/MXene0.4/PVA) for pyocyanin (PCN) within complex biological matrices, including phosphate-buffered saline (PBS), Luria–Bertani (LB) broth, and saliva, was decreased to a range of 0.84~0.98 μM. Leveraging the disparities in the characteristic oxidation potentials (ΔE > 0.3 V) of PCN, uric acid (UA), and histamine (HA) in simulated wound exudate (SWE), the multi-component synchronous detection functionality of the non-specific sensor was expanded for the first time. This study offers a high-precision and multi-parameter integrated approach for point-of-care testing (POCT) of wound infections. Full article
(This article belongs to the Special Issue Flexible and Biodegradable Electronics and Novel Semiconductor Devices)
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17 pages, 2934 KB  
Article
A Microfluidic Platform for Viscosity Testing of Non-Newtonian Fluids in Engineering and Biomedical Applications
by Yii-Nuoh Chang and Da-Jeng Yao
Micromachines 2026, 17(2), 201; https://doi.org/10.3390/mi17020201 - 1 Feb 2026
Viewed by 527
Abstract
This study presents a microfluidic platform for non-Newtonian fluid viscosity sensing, integrating a high-flow-rate flow field stabilizer to mitigate flow uniformity limitations under elevated flow rate conditions. Building upon an established dual-phase laminar flow principle that determines relative viscosity via channel occupancy, this [...] Read more.
This study presents a microfluidic platform for non-Newtonian fluid viscosity sensing, integrating a high-flow-rate flow field stabilizer to mitigate flow uniformity limitations under elevated flow rate conditions. Building upon an established dual-phase laminar flow principle that determines relative viscosity via channel occupancy, this research aimed to extend the measurable viscosity range from 1–10 cP to 1–50 cP, which covers viscosity regimes relevant to biomedical fluids, dairy products during gelation, and low-to-moderate viscosity industrial liquids. A flow stabilizer was developed through computational fluid dynamics simulations, optimizing three key design parameters: blocker position, porosity, and the number of outlet paths. The N5 design proved most effective, providing over 50% reduction in standard deviation for asymmetric velocity distribution in high-flow simulations. The system was validated using simulated blood and dairy samples, achieving over 95% viscosity accuracy with less than 5% sample volume error compared to conventional viscometers. The chip successfully captured viscosity transitions during milk acidification and gelation, demonstrating excellent agreement with standard measurements. This low-volume, high-precision platform offers promising potential for applications in food engineering, biomedical diagnostics, and industrial fluid monitoring, enhancing microfluidic rheometry capabilities. Full article
(This article belongs to the Special Issue Microfluidics in Biomedical Research)
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20 pages, 28708 KB  
Article
Nervous System-on-Chip: Innovative Microfluidic Platform to Compartmentalize hiPSC-Derived Neural Networks
by Rahman Sabahi-Kaviani, Antigoni Gogolou, Celine Souilhol, Mark van der Kroeg, Steven A. Kushner, Femke M. S. de Vrij, Anestis Tsakiridis and Regina Luttge
Micromachines 2026, 17(2), 199; https://doi.org/10.3390/mi17020199 - 1 Feb 2026
Viewed by 823
Abstract
This study presents the development of a Nervous System-on-Chip (NoC) using microfabrication techniques, focusing on the integration of human induced pluripotent stem cell (hiPSC)-derived neurons. We designed and fabricated NoCs based on microtunnel devices (MDs) with radial and linear configurations to facilitate the [...] Read more.
This study presents the development of a Nervous System-on-Chip (NoC) using microfabrication techniques, focusing on the integration of human induced pluripotent stem cell (hiPSC)-derived neurons. We designed and fabricated NoCs based on microtunnel devices (MDs) with radial and linear configurations to facilitate the compartmentalized culture of cortical and enteric neural networks. Our findings demonstrate that these MDs allow axonal growth while restricting migration of somas and dendrites between compartments, thereby promoting the formation of organized neural networks. This creates a microfluidic platform capable of supporting the growth of different culture systems, which could potentially be combined to study interactions between the central and enteric nervous systems. The resulting neuronal networks exhibited viability, expression of key lineage markers, and synapse formation, highlighting the platform’s potential for advanced nervous system modeling. MD-based NoC models provide an innovative microfluidic platform for studying the biology of human neural networks, with implications for the investigation of neurodegenerative diseases such as Parkinson’s Disease and applications in pre-clinical research. Full article
(This article belongs to the Special Issue Microfluidics in Biomedical Research)
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14 pages, 3098 KB  
Article
A High-Accuracy Solid/Liquid Composite Packaging Method for Implantable Pressure Sensors
by Bo Wang, Yubiao Zhang, Yuning Huang, Zhonghua Li, Senran Jiang, Fuji Wang, Qiang Liu and Xing Yang
Micromachines 2026, 17(2), 162; https://doi.org/10.3390/mi17020162 - 27 Jan 2026
Viewed by 795
Abstract
This study addresses the critical packaging requirements of implantable pressure sensors concerning measurement accuracy and environmental stability. We propose a solid/liquid composite packaging technique based on Parylene-C and silicone oil. Utilizing liquid silicone oil as an intermediate medium, this method effectively decouples solid/solid [...] Read more.
This study addresses the critical packaging requirements of implantable pressure sensors concerning measurement accuracy and environmental stability. We propose a solid/liquid composite packaging technique based on Parylene-C and silicone oil. Utilizing liquid silicone oil as an intermediate medium, this method effectively decouples solid/solid interface shear forces, thereby mitigating measurement errors caused by mechanical coupling. Furthermore, the superior hydrophobic properties of silicone oil and its defect-filling capability are employed to slow the infiltration rate of water molecules at the interface, ensuring long-term stability. The influence of the solid/liquid composite layer on the mechanical properties of the sensor’s sensitive element was analyzed through finite element simulation. The experimental results demonstrate the efficacy of this approach: after adding a liquid silicone oil layer between the Parylene coating and the sensitive element, the sensor’s accuracy improved to 0.5 mmHg within the pressure range encountered in clinical human applications. In simulated bodily fluids, it demonstrated exceptional long-term stability, with drift values consistently below 2 mmHg over a 30-day period. This research provides a feasible and straightforward solution for the packaging design of high-performance implantable pressure sensors. Full article
(This article belongs to the Special Issue Flexible and Wearable Sensors, 4th Edition)
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20 pages, 5655 KB  
Article
Structure Design Optimization of a Differential Capacitive MEMS Accelerometer Based on a Multi-Objective Elitist Genetic Algorithm
by Dongda Yang, Yao Chu, Ruitao Liu, Xiwen Zhang, Saifei Yuan, Fan Zhang, Shengjie Xuan, Yunzhang Chi, Jiahui Liu, Zetong Lei and Rui You
Micromachines 2026, 17(1), 129; https://doi.org/10.3390/mi17010129 - 19 Jan 2026
Viewed by 1131
Abstract
This article describes a global structure optimization methodology for microelectromechanical system devices based on a multi-objective elitist genetic algorithm. By integrating a parameterized model with a multi-objective evolutionary framework, the approach can efficiently explore design space and concurrently optimize multiple metrics. A differential [...] Read more.
This article describes a global structure optimization methodology for microelectromechanical system devices based on a multi-objective elitist genetic algorithm. By integrating a parameterized model with a multi-objective evolutionary framework, the approach can efficiently explore design space and concurrently optimize multiple metrics. A differential capacitive MEMS accelerometer is presented to demonstrate the method. Four key objectives, including resonant frequency, static capacitance, dynamic capacitance, and feedback force, are simultaneously optimized to enhance sensitivity, bandwidth, and closed-loop driving capability. After 25 generations, the algorithm converged to a uniformly distributed Pareto front. The experimental results indicate that, compared with the initial design, the sensitivity-oriented design achieves a 56.1% reduction in static capacitance and an 85.5% improvement in sensitivity. The global multi-objective optimization achieves a normalized hypervolume of 35.8%, notably higher than the local structure optimization, demonstrating its superior design space coverage and trade-off capability. Compared to single-objective optimization, the multi-objective approach offers a superior strategy by avoiding the limitation of overemphasizing resonant frequency at the expense of other metrics, thereby enabling a comprehensive exploration of the design space. Full article
(This article belongs to the Special Issue Artificial Intelligence for Micro Inertial Sensors)
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17 pages, 3126 KB  
Article
A Multifunctional Peptide Linker Stably Anchors to Silica Spicules and Enables MMP-Responsive Release of Diverse Bioactive Cargos
by So-Hyung Lee, Suk-Hyun Kwon, Byung-Ho Song, In-Gyeong Yeo, Hyun-Seok Park, A-Ri Kim, Lee-Seul Kim, Ji-Min Noh, Hee-Jung Choi, Da-Jeoung Lim and Young-Wook Jo
Micromachines 2026, 17(1), 127; https://doi.org/10.3390/mi17010127 - 19 Jan 2026
Viewed by 381
Abstract
Silica spicules provide a natural transdermal conduit but require a linker that binds strongly under physiological conditions and releases payloads selectively in response to biological cues. Existing silane chemistries or polydopamine coatings lack enzyme responsiveness and show limited control over release. We created [...] Read more.
Silica spicules provide a natural transdermal conduit but require a linker that binds strongly under physiological conditions and releases payloads selectively in response to biological cues. Existing silane chemistries or polydopamine coatings lack enzyme responsiveness and show limited control over release. We created a 180-member peptide library with the motif L–X1–X2–[Y–F–Y]–A–L–G–P–H–C and screened for silica binding. Biophysical assays (circular dichroism, ζ-potential, quartz crystal microbalance, atomic force microscopy) and molecular dynamics identified high-affinity binders. The lead, P176, was tested for matrix metalloprotease (MMP)-responsive cleavage. Conjugation and release of Vitamin C and Stigmasterol were analyzed by HPLC and Franz diffusion cells. P176 showed high silica affinity (~55 µg mg−1), robust biophysical signals (Δf −35 to −38 Hz; rupture force ~154 pN; ζ shift −22 to−11.5 mV), and favorable adsorption energy (−48.5 kcal mol−1, contact 4.5 nm2, 8.5 H-bonds). The MMP gate displayed efficient kinetics (Vmax 117.9 RFU·min−1, Km 5.0 µM) with >90% cleavage at 60 min, reduced to 26% by inhibitor. Conjugation yields reached 87% (Vitamin C) and 77% (Stigmasterol). Franz diffusion showed MMP-dependent release (24 h: Vitamin C 90–96%, Stigmasterol 80–85%) with minimal basal leakage. Released Vitamin C enhanced collagen I to ~250% in fibroblasts, while Stigmasterol attenuated LPS-induced macrophage morphology; keratinocytes retained normal marker expression. This study demonstrates that a single amphipathic, sequence-programmed peptide can couple strong silica anchoring with protease-responsive release and broad payload compatibility, establishing a versatile platform for spicule-based transdermal and regenerative delivery. Full article
(This article belongs to the Section B5: Drug Delivery System)
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12 pages, 5511 KB  
Article
Low Temperature Effect of Resistance Strain Gauge Based on Double-Layer Composite Film
by Mengqiu Li, Zhiyuan Hu, Fengming Ye, Jiaxiang Wang and Zhuoqing Yang
Micromachines 2026, 17(1), 114; https://doi.org/10.3390/mi17010114 - 15 Jan 2026
Viewed by 313
Abstract
Strain gauges play a crucial role in numerous fields such as bridge and building structural health monitoring. However, traditional strain gauges generate spurious signals due to the temperature effect, which in turn affects their measurement accuracy. Herein, we propose a resistance strain gauge [...] Read more.
Strain gauges play a crucial role in numerous fields such as bridge and building structural health monitoring. However, traditional strain gauges generate spurious signals due to the temperature effect, which in turn affects their measurement accuracy. Herein, we propose a resistance strain gauge based on a double-layer composite film, which is characterized by an adjustable resistance temperature coefficient (TCR), an ultra-near-zero temperature effect, and good TCR repeatability. It is precisely through the combination of materials with positive and negative TCR, leveraging their opposing temperature resistance characteristics, that a low temperature effect has been achieved. Compared with the single-layer alloy-based strain gauge, the developed strain gauge based on double-layer composite film has greatly reduced sensitivity to temperature interference, and its TCR can be reduced to a ultra-near-zero value, approximately 0.8 ppm/°C, while the stability of TCR is excellent. In addition, the gauge factor of the strain gauge is 1.83, and it maintains excellent linearity. This work fully highlights the potential application value of the developed strain gauge in stress monitoring of bridges and building structures. Full article
(This article belongs to the Special Issue Structural Analyses and Designs for Flexible/Stretchable Electronics, 3rd Edition)
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30 pages, 3247 KB  
Article
The Clausius–Mossotti Factor in Dielectrophoresis: A Critical Appraisal of Its Proposed Role as an ‘Electrophysiology Rosetta Stone’
by Ronald Pethig
Micromachines 2026, 17(1), 96; https://doi.org/10.3390/mi17010096 - 11 Jan 2026
Viewed by 720
Abstract
The Clausius–Mossotti (CM) factor underpins the theoretical description of dielectrophoresis (DEP) and is widely used in micro- and nano-scale systems for frequency-dependent particle and cell manipulation. It has further been proposed as an “electrophysiology Rosetta Stone” capable of linking DEP spectra to intrinsic [...] Read more.
The Clausius–Mossotti (CM) factor underpins the theoretical description of dielectrophoresis (DEP) and is widely used in micro- and nano-scale systems for frequency-dependent particle and cell manipulation. It has further been proposed as an “electrophysiology Rosetta Stone” capable of linking DEP spectra to intrinsic cellular electrical properties. In this paper, the mathematical foundations and interpretive limits of this proposal are critically examined. By analyzing contrast factors derived from Laplace’s equation across multiple physical domains, it is shown that the CM functional form is a universal consequence of geometry, material contrast, and boundary conditions in linear Laplacian fields, rather than a feature unique to biological systems. Key modelling assumptions relevant to DEP are reassessed. Deviations from spherical symmetry lead naturally to tensorial contrast factors through geometry-dependent depolarisation coefficients. Complex, frequency-dependent CM factors and associated relaxation times are shown to inevitably arise from the coexistence of dissipative and storage mechanisms under time-varying forcing, independent of particle composition. Membrane surface charge influences DEP response through modified interfacial boundary conditions and effective transport parameters, rather than by introducing an independent driving mechanism. These results indicate that DEP spectra primarily reflect boundary-controlled field–particle coupling. From an inverse-problem perspective, this places fundamental constraints on parameter identifiability in DEP-based characterization. The CM factor remains a powerful and general modelling tool for micromachines and microfluidic systems, but its interpretive scope must be understood within the limits imposed by Laplacian field theory. Full article
(This article belongs to the Special Issue Advances in Electrokinetics for Cell Sorting and Analysis)
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16 pages, 24814 KB  
Article
Inverse Design of Thermal Imaging Metalens Achieving 100° Field of View on a 4 × 4 Microbolometer Array
by Munseong Bae, Eunbi Jang, Chanik Kang and Haejun Chung
Micromachines 2026, 17(1), 65; https://doi.org/10.3390/mi17010065 - 31 Dec 2025
Cited by 1 | Viewed by 1037
Abstract
We present an inverse designed metalens for long-wave infrared (LWIR) imaging tailored to consumer and Internet of Things (IoT) platforms. Conventional LWIR optics either rely on costly specialty materials or suffer from low efficiency and narrow fields of view (FoV), limiting scalability. Our [...] Read more.
We present an inverse designed metalens for long-wave infrared (LWIR) imaging tailored to consumer and Internet of Things (IoT) platforms. Conventional LWIR optics either rely on costly specialty materials or suffer from low efficiency and narrow fields of view (FoV), limiting scalability. Our approach integrates adjoint-based inverse design with fabrication-aware constraints and a cone-shaped source model that efficiently captures oblique incidence during optimization. The resulting multi-level metalens achieves a wide FoV up to 100° while maintaining robust focusing efficiency and stable angle-to-position mapping on low-power 4×4 microbolometer arrays representative of edge devices. We further demonstrate application-level imaging on 4×4 microbolometer arrays, showing that the proposed metalens delivers a substantially wider FoV than a commercial narrow FoV lens while meeting low-resolution, low-cost, and low-power constraints for edge LWIR modules. By eliminating bulky multi-element stacks and reducing cost and form factor, the proposed design provides a practical pathway to compact, energy-efficient LWIR modules for consumer applications such as occupancy analytics, smart-building automation, mobile sensing, and outdoor fire surveillance. Full article
(This article belongs to the Special Issue Recent Advances in Electromagnetic Devices, 2nd Edition)
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30 pages, 16390 KB  
Review
Auger Electron Spectroscopy for Chemical Analysis of Passivated (Al,Ga)N-Based Systems
by Alina Domanowska and Bogusława Adamowicz
Micromachines 2026, 17(1), 47; https://doi.org/10.3390/mi17010047 - 30 Dec 2025
Viewed by 716
Abstract
This review summarizes the use of Auger Electron Spectroscopy (AES) for microchemical analysis of two different types of dielectric/(Al,Ga)N-based systems: (i) extrinsic dielectric PECVD SiO2, ALD Al2O3, and ECR-CVD SiNx films on AlxGa1−x [...] Read more.
This review summarizes the use of Auger Electron Spectroscopy (AES) for microchemical analysis of two different types of dielectric/(Al,Ga)N-based systems: (i) extrinsic dielectric PECVD SiO2, ALD Al2O3, and ECR-CVD SiNx films on AlxGa1−xN/GaN structures in the context of their application in microelectronic power devices and (ii) intrinsic Al2O3 films on AlN epitaxial layers grown by high-temperature oxidation for nanostructured technology of various gas/ion sensors. Particular attention is given to AES depth profiling across complete multilayer cross-sections, combining qualitative analysis of spectral line shape and intensity evolution as well as kinetic energy shifts with quantitative elemental depth distributions. This approach enables identification of chemical states and oxidation-related transformations at dielectric/semiconductor interfaces. Reported results demonstrate that AES provides micro- to nanometer-scale chemical information essential for distinguishing interfacial from the bulk properties. The capabilities and inherent limitations of AES depth profiling, including sputter-induced artifacts are also addressed, highlighting the role of optimized experimental conditions in reliable interface analysis. Full article
(This article belongs to the Special Issue GaN Power Devices: Recent Advances, Applications, and Perspectives)
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13 pages, 7642 KB  
Article
Mid-Wave Infrared Polarization Combiner Based on Reflective Metasurface
by Lulu Yang, Xin Wang, Xuhui Li and Liquan Dong
Micromachines 2026, 17(1), 36; https://doi.org/10.3390/mi17010036 - 28 Dec 2025
Viewed by 403
Abstract
Polarization beam combining (PBC) is an important technology for enhancing laser brightness. The conventional bulk polarization beam combiners are Brewster plates and birefringent polarization prisms. However, in the mid- and long-wave infrared range, the beam combining performance is limited by the transmission and [...] Read more.
Polarization beam combining (PBC) is an important technology for enhancing laser brightness. The conventional bulk polarization beam combiners are Brewster plates and birefringent polarization prisms. However, in the mid- and long-wave infrared range, the beam combining performance is limited by the transmission and birefringent coefficient of the available materials. In this paper, a polarization beam combiner based on a reflection metasurface was proposed. The phases of incident beams with orthogonal linear polarizations were individually manipulated by the side lengths of the rectangular silicon pillar. A metasurface polarization beam combiner operating band was designed and fabricated. When the two beams at 4.6 μm with orthogonal linear polarizations were incident on the metasurface at angles of −13.3° and 13.3°, respectively, they were reflected in the 0°-direction. The overall beam combining efficiency was 88.9%. When both of the quantum cascade lasers used in the experiments were in the fundamental transverse Gaussian mode, the measured beam quality factors M2 of the combined beam were 1.21 and 1.14 along the fast and slow axes, respectively. Both simulation and experimental results demonstrated that the proposed metasurface was an efficient polarization beam combiner with negligible wavefront distortion. It is a promising alternative to traditional bulk optics for the mid- and long-wave infrared. Full article
(This article belongs to the Special Issue Advanced Optoelectronic Materials/Devices and Their Applications)
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26 pages, 88895 KB  
Review
Active Propelled Micro Robots in Drug Delivery for Urologic Diseases
by Chunlian Zhong, Menghuan Tang and Zhaoqing Cong
Micromachines 2026, 17(1), 24; https://doi.org/10.3390/mi17010024 - 25 Dec 2025
Viewed by 1095
Abstract
Active propelled micro robots (MRs) represent a transformative shift in biomedical engineering, engineered to navigate physiological environments by converting chemical, acoustic, or magnetic energy into mechanical propulsion. Unlike passive delivery systems limited by diffusion and systemic clearance, MRs offer autonomous mobility, enabling precise [...] Read more.
Active propelled micro robots (MRs) represent a transformative shift in biomedical engineering, engineered to navigate physiological environments by converting chemical, acoustic, or magnetic energy into mechanical propulsion. Unlike passive delivery systems limited by diffusion and systemic clearance, MRs offer autonomous mobility, enabling precise penetration and retention in hard-to-reach tissues. This review provides comprehensive analysis of MR technologies within urology, a field uniquely suited for microrobotic intervention due to the urinary tract’s anatomical accessibility and fluid-filled nature. We explore how MRs address critical therapeutic limitations, including the high recurrence of kidney stones and the rapid washout of intravesical bladder cancer therapies. The review categorizes propulsion mechanisms optimized for the urinary environment, such as urea-fueled nanomotors and magnetic swarms. Furthermore, we detail emerging applications, including bioresorbable acoustic robots for tumor ablation and magnetic grippers for minimally invasive biopsies. Finally, we critically assess the path toward clinical translation, focusing on challenges in biocompatibility, real-time tracking (MRI, MPI, photoacoustic imaging), and the regulatory landscape for these advanced combination products. Full article
(This article belongs to the Special Issue Active Propelled Micro/Nano Technologies in Drug Delivery: Design, Fabrication and Applications)
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19 pages, 3290 KB  
Article
Magnetically Sculpted Microfluidics for Continuous-Flow Fractionation of Cell Populations by EpCAM Expression Level
by Zhenwei Liang, Xiaolei Guo, Xuanhe Zhang, Yiqing Chen, Chuan Du, Yuan Ma and Jiadao Wang
Micromachines 2026, 17(1), 9; https://doi.org/10.3390/mi17010009 - 22 Dec 2025
Viewed by 481
Abstract
Continuous-flow separation of magnetically labeled cells according to surface-marker expression levels is increasingly needed to study phenotypic heterogeneity and support downstream assays. Here, we present a microfluidic platform that uses spatially engineered soft magnetic strips (SMS) to sculpt lateral magnetic deflection fields for [...] Read more.
Continuous-flow separation of magnetically labeled cells according to surface-marker expression levels is increasingly needed to study phenotypic heterogeneity and support downstream assays. Here, we present a microfluidic platform that uses spatially engineered soft magnetic strips (SMS) to sculpt lateral magnetic deflection fields for quantitative, label-guided cell fractionation. Under a uniform bias field, the SMS generates controllable magnetic gradients within the microchannel, producing distinct lateral velocities among EpCAM-labeled tumor cells that carry different Dynabead loads, which indirectly report membrane protein expression. Multi-outlet collection converts these “race-based” trajectory differences into discrete expression-level-resolved fractions. A COMSOL–MATLAB framework and a force-equivalent metric |(H·∇)H| are used to optimize key structural parameters of the magnetic interface, including strip thickness, width, and vertical spacing from the flow channel. Three journey nodes at 1.5, 3, and 9 mm along the flow path define a three-stage cascade that partitions MDA-MB-231, Caco-2, and A549 cells into four EpCAM-related magnetic subgroups: high (H), medium (M), low (L), and near-negative (N). Experiments show that the sorted fractions follow the expected expression trends reported in the literature, while maintaining high cell recovery (>90%) and viability retention of 98.2 ± 1.3%, indicating compatibility with downstream whole-blood assays and culture. Rather than introducing a new biomarker, this work establishes a quantitative magnetic-field design strategy for continuous microfluidic sorting, in which the spatial configuration of soft magnetic elements is exploited to implement expression-level-dependent fractionation in next-generation magneto-fluidic separation systems. Full article
(This article belongs to the Special Issue Microfluidic Chips for Biomedical Applications)
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45 pages, 4439 KB  
Review
Gallium Nitride for Space Photovoltaics: Properties, Synthesis Methods, Device Architectures and Emerging Market Perspectives
by Anna Drabczyk, Paweł Uss, Katarzyna Bucka, Wojciech Bulowski, Patryk Kasza, Paula Mazur, Edyta Boguta, Marta Mazur, Grzegorz Putynkowski and Robert P. Socha
Micromachines 2025, 16(12), 1421; https://doi.org/10.3390/mi16121421 - 18 Dec 2025
Viewed by 1676
Abstract
Gallium nitride (GaN) has emerged as one of the most promising wide-bandgap semiconductors for next-generation space photovoltaics. In contrast to conventional III–V compounds such as GaAs and InP, which are highly efficient under terrestrial conditions but suffer from radiation-induced degradation and thermal instability, [...] Read more.
Gallium nitride (GaN) has emerged as one of the most promising wide-bandgap semiconductors for next-generation space photovoltaics. In contrast to conventional III–V compounds such as GaAs and InP, which are highly efficient under terrestrial conditions but suffer from radiation-induced degradation and thermal instability, GaN offers an exceptional combination of intrinsic material properties ideally suited for harsh orbital environments. Its wide bandgap, high thermal conductivity, and strong chemical stability contribute to superior resistance against high-energy protons, electrons, and atomic oxygen, while minimizing thermal fatigue under repeated cycling between extreme temperatures. Recent progress in epitaxial growth—spanning metal–organic chemical vapor deposition, molecular beam epitaxy, hydride vapor phase epitaxy, and atomic layer deposition—has enabled unprecedented control over film quality, defect densities, and heterointerface sharpness. At the device level, InGaN/GaN heterostructures, multiple quantum wells, and tandem architectures demonstrate outstanding potential for spectrum-tailored solar energy conversion, with modeling studies predicting efficiencies exceeding 40% under AM0 illumination. In this review article, the current state of knowledge on GaN materials and device architectures for space photovoltaics has been summarized, with emphasis placed on recent progress and persisting challenges. Particular focus has been given to defect management, doping strategies, and bandgap engineering approaches, which define the roadmap toward scalable and radiation-hardened GaN-based solar cells. With sustained interdisciplinary advances, GaN is anticipated to complement or even supersede traditional III–V photovoltaics in space, enabling lighter, more durable, and radiation-hard power systems for long-duration missions beyond Earth’s magnetosphere. Full article
(This article belongs to the Special Issue Thin Film Microelectronic Devices and Circuits, 2nd Edition)
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13 pages, 3501 KB  
Article
Channel-Free Micro-Well–Template-Assisted Magnetic Particle Trapping for Efficient Single-Particle Isolation
by Jin-Yeong Park, Kyeong-Taek Nam, Young-Ho Nam, Yong-Kweon Kim, Seung-Ki Lee and Jae-Hyoung Park
Micromachines 2025, 16(12), 1397; https://doi.org/10.3390/mi16121397 - 11 Dec 2025
Viewed by 805
Abstract
This study presents a channel-free, micro-well–template-assisted magnetic particle trapping method for efficient single-particle isolation without the need for microfluidic channels. Dual-surface silicon micro-well arrays were fabricated using photolithography, PE-CVD, and DRIE processes, featuring hydrophilic well interiors and hydrophobic outer surfaces to enhance trapping [...] Read more.
This study presents a channel-free, micro-well–template-assisted magnetic particle trapping method for efficient single-particle isolation without the need for microfluidic channels. Dual-surface silicon micro-well arrays were fabricated using photolithography, PE-CVD, and DRIE processes, featuring hydrophilic well interiors and hydrophobic outer surfaces to enhance trapping performance. The proposed method combines magnet-assisted sedimentation with rotational sweeping of a glass slide placed above the micro-well array, enabling rapid and uniform particle confinement within a 250 × 250 well array. Experimental results showed that the trapping efficiency increased with the well width and depth, achieving over 93.8% within three trapping cycles for optimized structures. High single-particle occupancy was obtained for wells of comparable size to the particle diameter, while deeper wells enabled stable trapping with minimal loss. The entire trapping process was completed within five minutes per cycle, demonstrating a rapid, simple, and scalable approach applicable to digital immunoassay systems for ultrasensitive biomolecule detection. Full article
(This article belongs to the Special Issue Microfluidics in Biomedical Research)
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24 pages, 3720 KB  
Review
Metallic Particles in Sodium Battery Anodes: A Review
by Rafaela Ruiz, Carlos Pérez-Vicente and Ricardo Alcántara
Micromachines 2025, 16(12), 1391; https://doi.org/10.3390/mi16121391 - 8 Dec 2025
Viewed by 909
Abstract
Sodium-ion batteries have emerged as a promising alternative to lithium-ion systems, due to the abundance and low cost of sodium resources. However, the demand for higher performance is always increasing, and developing new electrode materials and optimizing their behavior in full cells is [...] Read more.
Sodium-ion batteries have emerged as a promising alternative to lithium-ion systems, due to the abundance and low cost of sodium resources. However, the demand for higher performance is always increasing, and developing new electrode materials and optimizing their behavior in full cells is necessary. Their electrochemical performance remains limited by challenges related to the anode materials. A fundamental understanding of electrode materials is essential to advance their practical application, for example, by designing strategies to minimize irreversible processes and enhance the reversible capacity. Thus, the properties of metals, including nanoparticles and clusters, are critical for various types of sodium batteries, such as sodium-ion microbatteries. Additionally, metallic nanoparticles exhibiting special properties are generated in situ at the negative electrode during the electrochemical cycling of certain batteries. This review focuses on their formation mechanisms, structural and electrochemical effects, and strategies to control their distribution and size. Particular attention is given to the interaction between metallic particles and carbon matrices, as well as their influence on capacity. Finally, current limitations and future perspectives for optimizing the properties of the metallic particles in advanced sodium battery anodes are highlighted. Full article
(This article belongs to the Section D：Materials and Processing)
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11 pages, 2440 KB  
Article
Internal Temperature Measurement of Optically Levitated Particles in Vacuum by Raman Thermometry
by Kou Li, Jiaming Liu, Xincai Xu, Zhuangzhuang Wang, Nan Li, Han Cai, Wenqiang Li and Huizhu Hu
Micromachines 2025, 16(12), 1388; https://doi.org/10.3390/mi16121388 - 7 Dec 2025
Viewed by 583
Abstract
An optical levitation system in a vacuum is an efficient system to investigate the dynamics of isolated micro- and nanoparticles. However, the motion and stability of the trapped particles in this system can be affected by the internal temperature, which remains a challenge [...] Read more.
An optical levitation system in a vacuum is an efficient system to investigate the dynamics of isolated micro- and nanoparticles. However, the motion and stability of the trapped particles in this system can be affected by the internal temperature, which remains a challenge to measure. Conventional methods are constrained by material specificity or lack the capability for direct temperature measurement. Here, we demonstrate the application of Raman thermometry for non-contact temperature detection of an optically levitated fused silica sphere in vacuum. In addition, the experimental results reveal a linear increase in particle temperature with laser power, consistent with photothermal theory. The integration of Raman thermometry with the optical levitation system enables high-precision thermal sensing at the microscale, offering significant potential for applications in precision metrology and fundamental physics. Full article
(This article belongs to the Special Issue Optical Tweezers and Their Applications)
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16 pages, 2897 KB  
Article
Self-Powered Microfluidic System Based on Double-Layer Rotational Triboelectric Nanogenerator
by Yiming Zhong, Haofeng Li and Dongping Wu
Micromachines 2025, 16(12), 1386; https://doi.org/10.3390/mi16121386 - 6 Dec 2025
Viewed by 722
Abstract
Self-powered microfluidic systems represent a promising direction toward autonomous and portable lab-on-chip technologies, yet conventional electrowetting platforms remain constrained by bulky high-voltage supplies and intricate control circuitry. In this work, we design a triboelectric nanogenerator (TENG)-based microfluidic system that harvests mechanical energy for [...] Read more.
Self-powered microfluidic systems represent a promising direction toward autonomous and portable lab-on-chip technologies, yet conventional electrowetting platforms remain constrained by bulky high-voltage supplies and intricate control circuitry. In this work, we design a triboelectric nanogenerator (TENG)-based microfluidic system that harvests mechanical energy for droplet manipulation without any external electronics. The TENG integrates two triboelectric units with a 25° phase offset, enabling periodic high-voltage generation. Finite element simulations elucidate the electric field distributions of the TENG and microfluidic chip, validating the operating principle of the integrated microfluidic system. Experimental studies further quantify the effects of electrode geometry and rotational speed on the critical drivable droplet volume, demonstrating stable transport over linear, S-shaped, and circular trajectories. Remarkably, the droplet motion direction can be instantaneously reversed by reversing the TENG rotation direction, achieving bidirectional control without auxiliary circuitry. This work establishes a voltage-optimized, structurally tunable, and fully self-powered platform, offering a new paradigm for portable digital microfluidics. Full article
(This article belongs to the Special Issue Celebration of 60th Anniversary of Moore's Law: The Significant Milestone in Micromachines)
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19 pages, 4754 KB  
Article
Small Object Localization with 90% Annotation Reduction by Positive-Unlabeled Learning
by Xiao Zhou, Shihong Wang, Weiguo Hu, Zhaohao Xie, Zheng Pang, Zhuo Jiang and Zhen Cheng
Micromachines 2025, 16(12), 1379; https://doi.org/10.3390/mi16121379 - 3 Dec 2025
Viewed by 540
Abstract
Small object localization is one of the most challenging tasks owing to the poor visual appearance and noisy representation caused by the intrinsic structure of small targets. Recent advances in localizing small objects are mainly dependent on regression-based counting approaches, which require considerable [...] Read more.
Small object localization is one of the most challenging tasks owing to the poor visual appearance and noisy representation caused by the intrinsic structure of small targets. Recent advances in localizing small objects are mainly dependent on regression-based counting approaches, which require considerable annotations for training. As a contrast, human learners can quickly master labeling skills from only a few annotation examples. In this paper, we attempt to simulate this training mechanism and propose a novel positive-unlabeled (PU) learning based approach that can localize small objects by learning from partial point annotations. We evaluate our approach on five typical datasets of small objects involving a single cell, an animal/insect, and human crowds. Quantitative experimental results show that our approach has achieved inspiring localization performance (F1 score > 0.75) even under the supervision of less than 10% of the overall point annotations. This approach paves the way for low-annotation-cost single-cell analysis within microfluidic droplets. Full article
(This article belongs to the Special Issue Microfluidics for Single Cell Detection and Cell Sorting)
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13 pages, 2824 KB  
Article
Development of Metal-Enhanced Fluorescence Nanorods on Micro Post Arrays for Portable Detection of Human Semen Biomarkers
by Seongmin Lee, Won Il Heo, Kui Young Park, Seong Jun Seo, Xun Lu and Seok-min Kim
Micromachines 2025, 16(12), 1378; https://doi.org/10.3390/mi16121378 - 2 Dec 2025
Viewed by 522
Abstract
Rapid and reliable on-site identification of body fluids is essential in forensic and field diagnostic applications. Commercial kits provide only single results and often suffer from cross-reactivity, while conventional microarrays offer multiplex capability but lack sufficient fluorescence intensity for field-deployable systems. In this [...] Read more.
Rapid and reliable on-site identification of body fluids is essential in forensic and field diagnostic applications. Commercial kits provide only single results and often suffer from cross-reactivity, while conventional microarrays offer multiplex capability but lack sufficient fluorescence intensity for field-deployable systems. In this study, we present a highly sensitive nanorods on micro post array (NMPA) substrate and a smartphone-based portable detection system. The NMPA substrate integrates metal nanorods with UV-imprinted micro post structures to produce metal-enhanced fluorescence and improved signal localization. When evaluated using a microarray scanner, the substrate achieved high sensitivity, detecting semen diluted up to 1/100,000. The portable smartphone system further demonstrated simultaneous detection of three semen biomarkers (PSA, ACPP, and Semenogelin-1) at a 1/1000 dilution, matching the detection limit of commercial kits. Specificity tests using blood, saliva, urine, vaginal fluid, and environmental contaminants showed no false-positive responses. These results highlight the potential of the NMPA system as a portable diagnostic technology capable of rapid (<15 min), multiplex, and highly sensitive detection in field environments. Future work will focus on quantitative calibration, substrate stability assessment, and expansion toward multi biomarker panels for broader forensic and clinical applications. Full article
(This article belongs to the Section B4: Point-of-Care Devices)
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9 pages, 1807 KB  
Article
Enhanced Efficiency and Reliability of AlGaN UVC-LED with Tapered Hole Injection Layer
by Linlin Xu, Yang Peng, Feng Wu, Wei Guo, Jiangnan Dai and Changqing Chen
Micromachines 2025, 16(12), 1376; https://doi.org/10.3390/mi16121376 - 2 Dec 2025
Viewed by 588
Abstract
In this work, the electrical and optical performance of AlGaN-based ultraviolet-C light-emitting diodes (UVC-LEDs) with a tapered Al-content hole injection layer was investigated both theoretically and experimentally. A total of 1000 h of real-time electrical stress was conducted to study the degradation process [...] Read more.
In this work, the electrical and optical performance of AlGaN-based ultraviolet-C light-emitting diodes (UVC-LEDs) with a tapered Al-content hole injection layer was investigated both theoretically and experimentally. A total of 1000 h of real-time electrical stress was conducted to study the degradation process of such devices. UVC-LED incorporating a hole injection layer with a larger gradient was found to significantly suppress the degradation process compared to a sample with a smaller tapering gradient. Marginal efficiency droop of only 4.55% as well as 66% improved light output power, were identified for the proposed design under a current density of approximately 100 A/cm2. It was unambiguously demonstrated that UVC-LED with a greatly tapered hole injection layer facilitates both electron blocking and hole injection, providing a promising pathway towards the development of high-efficiency UV emitters. Full article
(This article belongs to the Section D1: Semiconductor Devices)
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15 pages, 8068 KB  
Article
High-Quality and High-Efficiency Fabrication of Microlens Array by Rotary Profile Cutting Method
by Liheng Gao, Xiuwen Sun, Qian Yu, Yinhui Wang, Md Nasir Uddin, Ruijue Duan, Gang Wang, Zhikang Zhou, Qiuchen Xie, Tao Sun and Tianfeng Zhou
Micromachines 2025, 16(12), 1374; https://doi.org/10.3390/mi16121374 - 1 Dec 2025
Viewed by 562
Abstract
To enhance the fabrication consistency and surface quality of microlens array (MLA) molds, this study presents a high-quality and high-efficiency rotary profile-cutting (RPC) method conducted on a four-axis ultraprecision machining platform. A geometric model is established to define the relationship between tool parameters [...] Read more.
To enhance the fabrication consistency and surface quality of microlens array (MLA) molds, this study presents a high-quality and high-efficiency rotary profile-cutting (RPC) method conducted on a four-axis ultraprecision machining platform. A geometric model is established to define the relationship between tool parameters and microlens structural features, and the toolpath is optimized by refining control points to enhance machining accuracy. In addition, a novel tool-setting error characterization approach is developed, enabling submicron-level positioning of the diamond tool, with errors in the X and Y directions controlled within 1 μm. Experimental validation demonstrates the successful fabrication of a 6 × 6 square-array MLA mold with a curvature radius of 507 μm using the proposed RPC method. Subsequent replication of MLA through precision glass molding (PGM) yielded structures with a peak-to-valley (PV) value below 354 nm and surface roughness (Ra) below 11 nm. Optical performance tests confirm the high consistency and accuracy of the fabricated MLA, highlighting the potential of the proposed RPC technique for advanced optical component manufacturing. Full article
(This article belongs to the Special Issue Ultra-Precision Micro Cutting and Micro Polishing)
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22 pages, 3241 KB  
Article
Exploring Pump–Probe Response in Exciton–Biexciton Quantum Dot–Metal Nanospheroid Hybrids
by Spyridon G. Kosionis, Dimitrios P. Alevizos and Emmanuel Paspalakis
Micromachines 2025, 16(12), 1319; https://doi.org/10.3390/mi16121319 - 25 Nov 2025
Viewed by 722
Abstract
We study the optical susceptibility of a CdSe-based semiconductor quantum dot with a cascade exciton–biexciton configuration, which is coupled via the Coulomb interaction to a gold spheroidal nanoparticle, in the presence of a nearly resonant strong pump field and a weak probe field. [...] Read more.
We study the optical susceptibility of a CdSe-based semiconductor quantum dot with a cascade exciton–biexciton configuration, which is coupled via the Coulomb interaction to a gold spheroidal nanoparticle, in the presence of a nearly resonant strong pump field and a weak probe field. We take both fields’ polarization vectors to be parallel to the interparticle axis, derive the equations of motion for the density matrix, and proceed with a perturbative expansion approach to calculate the components of the density matrix associated with the effective optical susceptibility, which describes processes to first order in the probe field and to all orders in the pump field. We present spectra of the effective susceptibility and examine their dependence on the metal nanoparticle’s geometric characteristics for various interparticle distances and pump field detunings, under both one- and two-photon resonance conditions. The role of the biexciton energy shift is also studied. Lastly, we introduce a dressed-state picture to elucidate the origin of the observed spectral features. Our calculations reveal that reducing the interparticle distance and increasing the metal nanoparticle aspect ratio enhance the exciton–plasmon coupling, leading to pronounced resonance splitting, spectral shifts, and broadened gain regions. Prolate nanoparticles aligned with the field polarization exhibit the strongest coupling and the widest gain bandwidth, whereas oblate geometries produce nearly overlapping resonances. Under exact resonance, the probe displays zero absorption with a negative dispersion slope, indicating slow-light behavior. These results demonstrate the tunability of hybrid CdSe-Au nanostructures for designing nanoscale optimal amplifiers, modulators, and sensors. Full article
(This article belongs to the Special Issue Emerging Trends in Optoelectronic Device Engineering)
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16 pages, 4549 KB  
Article
Miniature Electromagnetic and Mechanical Resonators for Measurements of Acceleration with the Help of Nitrogen-Vacancy Color Centers
by Marina Rezinkina, Oleg Rezinkin, Fedor Jelezko and Claus Braxmaier
Micromachines 2025, 16(12), 1311; https://doi.org/10.3390/mi16121311 - 23 Nov 2025
Viewed by 2498
Abstract
Using mathematical and physical modeling, we investigate the influence of the configuration and parameters of miniature electromagnetic and mechanical resonators on their output characteristics. Such electromagnetic resonators are required for the microwave excitation of nitrogen-vacancy color centers, which are used as sensors for [...] Read more.
Using mathematical and physical modeling, we investigate the influence of the configuration and parameters of miniature electromagnetic and mechanical resonators on their output characteristics. Such electromagnetic resonators are required for the microwave excitation of nitrogen-vacancy color centers, which are used as sensors for various physical quantities, including acceleration, force, and magnetic field induction. The mechanical resonators under consideration are designed for measuring acceleration using nitrogen–vacancy color centers. As a result of these studies, we selected the types of miniature electromagnetic and mechanical resonators that ensure the efficient operation of nitrogen–vacancy color center sensors. Full article
(This article belongs to the Special Issue Advancing MEMS/MOEMS Sensors: AI-Driven Optimization and Emerging Applications)
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18 pages, 3600 KB  
Article
Active–Passive Vibration Control of Cantilever Beam Based on Magnetic Spring with Negative Stiffness and Piezoelectric Actuator
by Min Wang, Zhiwei Jiang, Wei Jiang, Xianghui Feng, Jiheng Ding, Yi Sun, Huayan Pu and Songquan Liao
Micromachines 2025, 16(12), 1307; https://doi.org/10.3390/mi16121307 - 21 Nov 2025
Viewed by 954
Abstract
To enhance the low-frequency vibration suppression capability of cantilever beams, a magnetically tunable piezoelectric cantilever beam structure (MTPCBS) is proposed in this paper. A magnetic spring with negative stiffness (NSMS) is fixed at the free end of a cantilever beam, forming a quasi-zero-stiffness [...] Read more.
To enhance the low-frequency vibration suppression capability of cantilever beams, a magnetically tunable piezoelectric cantilever beam structure (MTPCBS) is proposed in this paper. A magnetic spring with negative stiffness (NSMS) is fixed at the free end of a cantilever beam, forming a quasi-zero-stiffness structure. Meanwhile, a macro-fiber composite (MFC) patch is bonded near the root of the beam to implement active skyhook damping control for active vibration control. A theoretical model of the cantilever beam, NSMS, and MFC is established, and the displacement transmissibility of the MTPCBS is derived. The influences of the magnet distance of the NSMS and the control gain of the controller are investigated via simulation. Experimental results indicate that compared to the single beam, the effective vibration isolation frequency of the proposed MTPCBS shifts from 15.3 Hz to 4.6 Hz. When subjected to random vibration excitation ranging from 1 to 80 Hz, the root mean square (RMS) value of vibration decreases from 0.03 g to 1.77 × 10−3 g, with the vibration attenuation rate improving from −50% to 91%. The proposed MTPCBS and active–passive vibration control method for cantilever beams significantly enhances low-frequency vibration suppression capabilities, providing a feasible strategy for achieving broadband vibration suppression. Full article
(This article belongs to the Special Issue Exploration and Application of Piezoelectric Smart Structures)
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16 pages, 1997 KB  
Article
A 3D-Printed PMMA Microneedle-Based TSA-ELISA Platform for Noninvasive Inflammatory Biomarker Detection
by Minghui Xu, Qingyu Ruan and Yukun Ren
Micromachines 2025, 16(11), 1286; https://doi.org/10.3390/mi16111286 - 14 Nov 2025
Viewed by 827
Abstract
Inflammatory cytokines and proteins are essential indicators of immune status and disease progression; however, conventional assays rely on invasive sampling and complex processing, restricting their use in real-time monitoring. Here, we present a 3D-printed poly(methyl methacrylate) (PMMA) microneedle-based biosensing platform integrated with a [...] Read more.
Inflammatory cytokines and proteins are essential indicators of immune status and disease progression; however, conventional assays rely on invasive sampling and complex processing, restricting their use in real-time monitoring. Here, we present a 3D-printed poly(methyl methacrylate) (PMMA) microneedle-based biosensing platform integrated with a tyramide signal amplification–enhanced enzyme-linked immunosorbent assay (TSA–ELISA) for noninvasive and highly sensitive detection of inflammatory biomarkers in interstitial fluid. The microneedles exhibit precise geometry, adequate mechanical strength, and excellent biocompatibility, facilitating efficient skin penetration and biomarker capture. Stepwise chemical functionalization ensured stable antibody immobilization, while TSA significantly amplified detection signals. The platform achieved reliable, reproducible, and multiplex detection of cytokines and albumin in both healthy individuals and patients with inflammatory skin conditions. Notably, the measured cytokine level in lesional skin of eczema patients was 97.7 pg/mL, showing a significant difference from the 62.8 pg/mL observed in healthy subjects. This MN-based TSA–ELISA system offers a robust and minimally invasive strategy for monitoring inflammation-related biomarkers, holding great potential for clinical diagnostics and personalized healthcare applications. Full article
(This article belongs to the Section B1: Biosensors)
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11 pages, 3075 KB  
Communication
Highly Sensitive Si-Based Electrolyte-Gated Transistor Array for Multiplexed Detection of Arboviruses
by Seonghwan Shin, Jeonghyeon Do, Jongmin Son and Jeong-Soo Lee
Micromachines 2025, 16(11), 1279; https://doi.org/10.3390/mi16111279 - 13 Nov 2025
Viewed by 639
Abstract
Multiplexed detection of arboviruses using a 4 × 4 Si-based electrolyte-gated transistor (EGT) array functionalized with specific aptamers has been investigated. The Si-based EGTs were fabricated using conventional Si microfabrication processes. The EGTs showed excellent intrinsic electrical characteristics, including a low threshold voltage [...] Read more.
Multiplexed detection of arboviruses using a 4 × 4 Si-based electrolyte-gated transistor (EGT) array functionalized with specific aptamers has been investigated. The Si-based EGTs were fabricated using conventional Si microfabrication processes. The EGTs showed excellent intrinsic electrical characteristics, including a low threshold voltage of 0.8 V, a sub-threshold swing of 75 mV/dec, and a gate leakage of <10 pA, ensuring uniform device performance with low device-to-device variation. Aptamers specific to the yellow fever virus nonstructural protein 1 (YF), dengue virus nonstructural protein 1 (DN), and chikungunya virus envelope protein 2 (CHK) were functionalized on EGT arrays to evaluate individual and multiplexed detection. In individual-target detections, concentration-dependent negative shifts in threshold voltage were observed, and relevant limits of detection (LOD) as low as 38.6 pg/mL, 95.2 pg/mL, and 1.6 ng/mL were extracted for YF, DN, and CHK, respectively. In multiplexed detections, sensitivities decreased and variations increased relative to the individual responses, resulting in higher LODs. The extracted LODs were 0.2 ng/mL, 0.6 ng/mL, and 2.8 ng/mL for YF, DN, and CHK, respectively, which are lower than those reported for other methods. These results suggest that Si-based EGT arrays are promising as a scalable, low-cost, and highly sensitive biosensing platform for multiplexed arbovirus detection and point-of-care diagnostics. Full article
(This article belongs to the Special Issue Microsystems for Point-of-Care Testing and Diagnostics)
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12 pages, 2307 KB  
Article
Application of Droplet-Array Sandwiching Technology to Click Reactions for High-Throughput Screening
by Yoshinori Miyata, Shoma Nishimura, Sora Kawakami, Yuriko Higuchi and Satoshi Konishi
Micromachines 2025, 16(11), 1270; https://doi.org/10.3390/mi16111270 - 12 Nov 2025
Viewed by 753
Abstract
High-throughput screening (HTS) is an essential process in drug discovery, requiring platforms that ensure reagent economy, high efficiency, and resistance to cross-contamination. Click chemistry is well suited for HTS because of its biocompatibility, high selectivity, and quantitative fluorescent readout. We focus on droplet-array [...] Read more.
High-throughput screening (HTS) is an essential process in drug discovery, requiring platforms that ensure reagent economy, high efficiency, and resistance to cross-contamination. Click chemistry is well suited for HTS because of its biocompatibility, high selectivity, and quantitative fluorescent readout. We focus on droplet-array sandwiching technology (DAST), in which two droplet microarrays (DMAs) are vertically opposed to achieve solute transport and reagent mixing by controlled contact and separation. Herein, we integrate click chemistry with DAST and evaluate its feasibility as a HTS platform. In DAST, DMAs are formed on wettability-patterned (WP; hydrophilic/hydrophobic) substrates, preserving resistance to cross-contamination. First, we immobilized dibenzocyclooctyne (DBCO) on a WP substrate and verified the occurrence of DBCO–azide reaction using an azide-functional fluorescent dye. The fluorescence intensity increased with concentration and reached a plateau at higher concentrations, indicating saturation behavior in the DBCO–azide click reaction. Second, acoustic mixing with repeated droplet contact–separation was applied to generate concentration gradients on a single substrate while maintaining droplet independence. Third, we qualitatively reproduced the expected concentration dependence of manual handling by combining DAST-based gradient formation with click reaction fluorescence readout. These results reveal that DAST enables a reagent-efficient, cross-contamination-resistant, and low-instrument-dependent HTS foundation for click-chemistry-based assays. Full article
(This article belongs to the Special Issue Advanced Developments in Droplet Microfluidics)
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15 pages, 2988 KB  
Article
Microhand Platform Equipped with Plate-Shaped End-Effectors Enables Precise Probing of Intracellular Structure Contribution to Whole-Cell Mechanical Properties
by Masahiro Kawakami, Masaru Kojima, Toshihiko Ogura, Atsushi Kubo, Tatsuo Arai and Shinji Sakai
Micromachines 2025, 16(11), 1272; https://doi.org/10.3390/mi16111272 - 12 Nov 2025
Cited by 1 | Viewed by 972
Abstract
Cellular mechanical properties are critical indicators of cellular state and promising disease biomarkers. This study introduces a novel microhand system, featuring chopstick-like plate-shaped end-effectors, designed for stable and high-precision single-cell mechanical characterization. First, we automated the force sensor calibration to overcome the inefficiency [...] Read more.
Cellular mechanical properties are critical indicators of cellular state and promising disease biomarkers. This study introduces a novel microhand system, featuring chopstick-like plate-shaped end-effectors, designed for stable and high-precision single-cell mechanical characterization. First, we automated the force sensor calibration to overcome the inefficiency and unreliability of conventional manual methods. To validate the system’s sensitivity, we precisely quantified the mechanical contributions of subcellular components, such as the actin cytoskeleton and chromatin, by measuring stiffness reductions after treatment with Cytochalasin D and Trichostatin A, respectively. Notably, when applied to a cellular model of Hutchinson–Gilford progeria syndrome, we successfully captured disease-induced mechanical alterations. A distinct population of high-stiffness cells was detected in progerin-overexpressing cells, a feature not observed in the control groups. Furthermore, by controlling the indentation speed and depth, the mechanical properties of the cytoplasm and nucleus could be distinctly evaluated. These results demonstrate that our microhand system is a highly sensitive and robust platform, capable of detecting subtle, disease-related changes and elucidating the contributions of specific subcellular structures to cell mechanics. Full article
(This article belongs to the Special Issue Next-Generation Biomedical Devices)
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11 pages, 1931 KB  
Article
A Novel Nano-Scale Biosensor for Measuring Hemoglobin Oxygen Saturation Using Carbon Quantum Dots
by Jeehyun Lee, Xuan Ru Liew, Justin Kok Soon Tan and Sangho Kim
Micromachines 2025, 16(11), 1261; https://doi.org/10.3390/mi16111261 - 6 Nov 2025
Viewed by 3526
Abstract
Hemoglobin oxygen (HbO2) saturation is a critical biomarker in patient care, yet conventional measurement approaches are often costly and require extensive calibration. To address these limitations, the present study proposes a novel biosensor derived from paper-based carbon quantum dots (CQDs) fabricated [...] Read more.
Hemoglobin oxygen (HbO2) saturation is a critical biomarker in patient care, yet conventional measurement approaches are often costly and require extensive calibration. To address these limitations, the present study proposes a novel biosensor derived from paper-based carbon quantum dots (CQDs) fabricated through a one-step thermal treatment. CQDs are carbon-based nanoparticles renowned for their excellent biocompatibility, low toxicity, thermal stability, and remarkable optical properties. To quantify HbO2 saturation, we exploit their photoluminescence, which enables photoinduced electron transfer and fluorescence quenching with hemoglobin. Our results demonstrated that the peak fluorescence intensity of CQDs shows a strong linear correlation with HbO2 saturation. Variations in HbO2 saturation levels were achieved with sodium dithionite and determined using Winterbourn’s equations. Our CQD-based HbO2 saturation measurements closely agreed with those obtained from conventional spectrophotometric analysis. Thus, this investigation highlights the potential of CQDs as a biosensor for effective HbO2 saturation measuring without extensive calibration. Full article
(This article belongs to the Special Issue Advances in Low-Dimensional Materials: Synthesis, Characterization and Device Application, 2nd Edition)
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26 pages, 23199 KB  
Article
Development and Validation of a Multimodal Wearable Belt for Abdominal Biosignal Monitoring with Application to Irritable Bowel Syndrome
by Amir Mohammad Karimi Forood, Sibi M. Pandian, Riley Q. McNaboe, Thuany De Carvalho Lachos, Daniel Octavio Lantigua and Hugo F. Posada-Quintero
Micromachines 2025, 16(11), 1255; https://doi.org/10.3390/mi16111255 - 1 Nov 2025
Viewed by 1153
Abstract
Visceral pain in Irritable Bowel Syndrome (IBS) is difficult to evaluate objectively due to its complex physiological nature and lack of reliable biomarkers. Given the complexity of IBS, a multimodal physiological monitoring approach, combining electrodermal activity (EDA), electrocardiogram (ECG), and surface electromyography (sEMG), [...] Read more.
Visceral pain in Irritable Bowel Syndrome (IBS) is difficult to evaluate objectively due to its complex physiological nature and lack of reliable biomarkers. Given the complexity of IBS, a multimodal physiological monitoring approach, combining electrodermal activity (EDA), electrocardiogram (ECG), and surface electromyography (sEMG), offers a promising approach to capture the autonomic and muscular responses linked to visceral pain. However, no existing wearable device supports simultaneous EDA, ECG, and sEMG acquisition from the abdomen in a format suitable for long-term, real-world use. This study presents the development and validation of a novel wearable belt for concurrent ECG, sEMG, and EDA monitoring, with EDA measured at both the torso and wrist. The system was built using modified BITalino platforms with custom-fabricated reusable electrodes and Bluetooth connectivity for real-time smartphone display. Signal quality was validated against laboratory-grade systems in 20 healthy participants during a four-stage protocol involving cognitive, orthostatic, muscular, and combined stress tasks. Time and frequency-domain analyses showed high correlations and comparable spectral features across all modalities. The belt maintained stable skin contact even during movement-intensive tasks. By enabling anatomically targeted, multimodal data acquisition, this wearable system supports real-world visceral pain assessment in IBS and is ready for deployment in ambulatory and home-based monitoring scenarios. Full article
(This article belongs to the Special Issue Next-Generation Wearable Technologies: Integrating Smart Sensing, Biomedical Innovation, and Sustainable Energy Solutions)
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14 pages, 16744 KB  
Article
Robotic Drop-Coating Graphite–Copper PDMS Soft Pressure Sensor with Fabric-Integrated Electrodes for Wearable Devices
by Zeping Yu, Yunhao Zhang, Lingpu Ge, Daisuke Miyata, Zhongnan Pu, Chenghong Lu and Lei Jing
Micromachines 2025, 16(11), 1247; https://doi.org/10.3390/mi16111247 - 31 Oct 2025
Viewed by 1127
Abstract
Flexible pressure sensors are essential for wearable electronics, human–machine interfaces, and soft robotics. However, conventional Polydimethylsiloxane (PDMS)-based sensors often suffer from limited conductivity, poor filler dispersion, and low structural integration with textile substrates. In this work, we present a robotic drop-coating approach for [...] Read more.
Flexible pressure sensors are essential for wearable electronics, human–machine interfaces, and soft robotics. However, conventional Polydimethylsiloxane (PDMS)-based sensors often suffer from limited conductivity, poor filler dispersion, and low structural integration with textile substrates. In this work, we present a robotic drop-coating approach for fabricating graphite–copper nanoparticle (G-CuNP)/PDMS composite pressure sensors with textile-integrated electrodes. By precisely controlling droplet deposition, a three-layer sandwiched structure was realized that ensures uniformity and scalability while avoiding the drawbacks of conventional full-line coating. The effects of filler loading and graphite nanoparticle (GNP) and copper nanoparticle (CuNP) ratios were systematically investigated, and the optimized sensor was obtained at 40 wt% total fillers with a graphite content of 55 wt%. The fabricated device exhibited high sensitivity in the low-pressure region, stable performance in the medium- and high-pressure ranges, and an exponential saturation fitting with R2 = 0.998. The average hysteresis was 7.42%, with excellent cyclic stability over 1000 loading cycles. Furthermore, a hand-shaped sensor matrix composed of five distributed sensing units successfully distinguished grasping behaviors of lightweight and heavyweight objects, demonstrating multipoint force mapping capability. This study highlights the advantages of robotic drop-coating for scalable fabrication and provides a promising pathway toward low-cost, reliable, and wearable soft pressure sensors. Full article
(This article belongs to the Section A：Physics)
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29 pages, 2301 KB  
Review
Advances in Impedimetric Biosensors: Current Applications and Future Directions
by Ashmit Verma, Mohammad Arqam and Arwa Fraiwan
Micromachines 2025, 16(11), 1244; https://doi.org/10.3390/mi16111244 - 31 Oct 2025
Cited by 1 | Viewed by 2004
Abstract
Impedimetric biosensors have emerged as a versatile class of electrochemical devices, enabling highly sensitive and real-time detection of diverse analytes. Their applications extend across healthcare diagnostics, environmental monitoring, food safety, and agriculture. By virtue of their compact size, high sensitivity, selectivity, portability, and [...] Read more.
Impedimetric biosensors have emerged as a versatile class of electrochemical devices, enabling highly sensitive and real-time detection of diverse analytes. Their applications extend across healthcare diagnostics, environmental monitoring, food safety, and agriculture. By virtue of their compact size, high sensitivity, selectivity, portability, and ease of operation, these sensors have advanced rapidly in both research and practical applications. This review consolidates the wide spectrum of current applications and technological advances reported in the literature. Additionally, it examines the prospects of integrating impedimetric biosensors with emerging technology fields, including artificial intelligence, machine learning, and flexible and wearable devices. By providing an overview of the different categories of impedimetric biosensors, their detection strategies, sensing modalities, and applications, this review presents a comprehensive perspective on the current progress and future opportunities in impedimetric biosensing. Full article
(This article belongs to the Special Issue Biosensors and Their Applications in Disease Characterization and Diagnosis)
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46 pages, 13590 KB  
Review
A Review of Optical Metrology Techniques for Advanced Manufacturing Applications
by Fangyuan Zhao, Hanyao Tang, Xuerong Zou and Xinghui Li
Micromachines 2025, 16(11), 1224; https://doi.org/10.3390/mi16111224 - 28 Oct 2025
Cited by 3 | Viewed by 5981
Abstract
Advanced manufacturing places stringent demands on measurement technologies, requiring ultra-high precision, non-contact operation, high throughput, and real-time adaptability. Optical metrology, with its distinct advantages, has become a key enabler in this context. This paper reviews optical metrology techniques from the perspective of precision [...] Read more.
Advanced manufacturing places stringent demands on measurement technologies, requiring ultra-high precision, non-contact operation, high throughput, and real-time adaptability. Optical metrology, with its distinct advantages, has become a key enabler in this context. This paper reviews optical metrology techniques from the perspective of precision manufacturing applications, emphasizing precision positioning and surface topography measurement while noting the limitations of traditional contact-based methods. For positioning, interferometers, optical encoders, and time-of-flight methods enable accurate linear and angular measurements. For surface characterization, techniques such as interferometry, structured light profilometry, and confocal microscopy provide reliable evaluation across scales, from large structures to micro- and nano-scale features. By integrating these approaches, optical metrology is shown to play a central role in bridging macroscopic and nano-scale characterization, supporting both structural assessment and process optimization. This review highlights its essential contribution to advanced manufacturing, and offers a concise reference for future progress in high-precision and intelligent production. Full article
(This article belongs to the Section A：Physics)
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33 pages, 3868 KB  
Review
Application of Polymer Lubricants in Triboelectric Energy Harvesting: A Review
by Ali Nawaz and Hong-Joon Yoon
Micromachines 2025, 16(11), 1195; https://doi.org/10.3390/mi16111195 - 22 Oct 2025
Cited by 1 | Viewed by 1063
Abstract
The range of lubricant applications has broadened to include multiple sectors, aiming to optimize the operational efficiency of mechanical systems. Given their adaptable friction-reducing properties, lubricants have recently been incorporated into energy harvesting technologies such as triboelectric nanogenerators (TENGs). In such devices, lubricants [...] Read more.
The range of lubricant applications has broadened to include multiple sectors, aiming to optimize the operational efficiency of mechanical systems. Given their adaptable friction-reducing properties, lubricants have recently been incorporated into energy harvesting technologies such as triboelectric nanogenerators (TENGs). In such devices, lubricants are essential for mitigating wear, facilitating heat dissipation, eliminating contaminants, and prolonging the service life of mechanically actuated energy harvesters. Notably, emerging developments in sliding and rotational-mode TENGs leverage lubricants to improve electrical output while reducing interface degradation. However, despite significant potential, TENGs still face inherent challenges, including interface friction and energy losses from air breakdown. Recent research indicates that these drawbacks can be effectively addressed by the intentional use of polymer-based lubricants, which contribute to maintaining micro/nanostructured surfaces and minimizing air breakdown, thereby enhancing charge storage capability and increasing device robustness. This review systematically examines the categories, physicochemical attributes, and operational roles of polymeric lubricants used in TENG technology. It underscores their combined function is both primary and support materials to augment triboelectric efficiency. In addition, the article assesses how different lubricants impact device performance and durability, providing a critical analysis of their suitability based on the operational benchmarks of lubricant-embedded TENG configurations. Full article
(This article belongs to the Special Issue Research Progress in Energy Harvesters and Self-Powered Sensors)
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30 pages, 7417 KB  
Review
Towards Advanced Materials: Functional Perspectives of Co-Doped ZnO Thin Films
by Mariuca Gartner, Mariana Chelu, Anna Szekeres and Peter Petrik
Micromachines 2025, 16(10), 1179; https://doi.org/10.3390/mi16101179 - 18 Oct 2025
Cited by 4 | Viewed by 1942
Abstract
Zinc oxide (ZnO) thin films have attracted increasing attention as promising materials for sensing applications due to their wide band gap, high exciton binding energy, and remarkable chemical stability. However, the inherent limitations of pure ZnO, such as moderate sensitivity, selectivity, and relatively [...] Read more.
Zinc oxide (ZnO) thin films have attracted increasing attention as promising materials for sensing applications due to their wide band gap, high exciton binding energy, and remarkable chemical stability. However, the inherent limitations of pure ZnO, such as moderate sensitivity, selectivity, and relatively high operating temperatures, limit its widespread use in advanced sensing technologies. Co-doping, or dual doping with two distinct elements, has emerged as an effective strategy to overcome these challenges by synergistically tailoring the structural, electronic, and surface properties of ZnO thin films. This review provides a comprehensive overview of recent advances in the development of co-doped ZnO thin films for sensing applications. The focus is on the role of different combinations of dopants, including transition metals, rare earth elements, and non-metals, in modulating the charge carrier concentration, oxygen vacancy density, and adsorption dynamics. These effects collectively enhance the sensing properties and long-term stability and reduce detection limits. The analysis highlights the correlations between synthesis methods, dopant incorporation mechanisms, and resulting sensor performance. Key challenges such as dopant clustering, reproducibility, and scalability are discussed, along with emerging opportunities in flexible room-temperature sensor platforms. Overall, it has been demonstrated that co-doped ZnO thin films represent a versatile and tunable class of sensing materials with strong potential for next-generation environmental and biomedical monitoring. Full article
(This article belongs to the Special Issue Functional Thin Films in Semiconductor Devices and Various Sensing Technologies)
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23 pages, 18716 KB  
Review
Electromagnetic Tracking System for Medical Micro Devices: A Review
by Mingshan He, Aoji Zhu and Lidong Yang
Micromachines 2025, 16(10), 1175; https://doi.org/10.3390/mi16101175 - 16 Oct 2025
Cited by 2 | Viewed by 3155
Abstract
Minimally invasive surgery (MIS) has become increasingly favored by both patients and surgeons owing to its advantages such as shortened recovery times and reduced surgical trauma. To enhance intraoperative feedback from surgical instruments while minimizing harmful radiation exposure, a wide range of electromagnetic [...] Read more.
Minimally invasive surgery (MIS) has become increasingly favored by both patients and surgeons owing to its advantages such as shortened recovery times and reduced surgical trauma. To enhance intraoperative feedback from surgical instruments while minimizing harmful radiation exposure, a wide range of electromagnetic tracking systems (EMTS) has been developed at micro scales for medical applications. This review provides a comprehensive summary of advances in the field over the past five years, with an emphasis on the working principles of EMTS, system architecture, current research progress, and clinical applications. In comparison to other review papers, this article focuses specifically on EMTS for medical micro-devices, such as robotic catheters, endoscopes, and capsule robots. Moreover, Representative research studies and commercial systems are presented along with their clinical implementations, placing greater emphasis on the translation of EMTS into medical applications. Finally, this review outlines and discusses future research directions, highlighting major challenges and potential opportunities for advancing the integration of EMTS into routine clinical workflows. Full article
(This article belongs to the Special Issue Design and Real Time Implementation of Intelligent Control Schemes for Actuators)
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13 pages, 3442 KB  
Article
Patterning Fidelity Enhancement and Aberration Mitigation in EUV Lithography Through Source–Mask Optimization
by Qi Wang, Qiang Wu, Ying Li, Xianhe Liu and Yanli Li
Micromachines 2025, 16(10), 1166; https://doi.org/10.3390/mi16101166 - 14 Oct 2025
Cited by 2 | Viewed by 1764
Abstract
Extreme ultraviolet (EUV) lithography faces critical challenges in aberration control and patterning fidelity as technology nodes shrink below 3 nm. This work demonstrates how Source–Mask Optimization (SMO) simultaneously addresses both illumination and mask design to enhance pattern transfer accuracy and mitigate aberrations. Through [...] Read more.
Extreme ultraviolet (EUV) lithography faces critical challenges in aberration control and patterning fidelity as technology nodes shrink below 3 nm. This work demonstrates how Source–Mask Optimization (SMO) simultaneously addresses both illumination and mask design to enhance pattern transfer accuracy and mitigate aberrations. Through a comprehensive optimization framework incorporating key process metrics, including critical dimension (CD), exposure latitude (EL), and mask error factor (MEF), we achieve significant improvements in imaging quality and process window for 40 nm minimum pitch patterns, representative of 2 nm node back-end-of-line (BEOL) requirements. Our analysis reveals that intelligent SMO implementation not only enables robust patterning solutions but also compensates for inherent EUV aberrations by balancing source characteristics with mask modifications. On average, our results show a 4.02% reduction in CD uniformity variation, concurrent with a 1.48% improvement in exposure latitude and a 5.45% reduction in MEF. The proposed methodology provides actionable insights for aberration-aware SMO strategies, offering a pathway to maintain lithographic performance as feature sizes continue to scale. These results underscore SMO’s indispensable role in advancing EUV lithography capabilities for next-generation semiconductor manufacturing. Full article
(This article belongs to the Special Issue Recent Advances in Lithography)
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14 pages, 4357 KB  
Article
Thermal Gas Flow Sensor Using SiGe HBT Oscillators Based on GaN/Si SAW Resonators
by Wenpu Cui, Jie Cui, Wenchao Zhang, Guofang Yu, Di Zhao, Jingqing Du, Zhen Li, Jun Fu and Tianling Ren
Micromachines 2025, 16(10), 1151; https://doi.org/10.3390/mi16101151 - 10 Oct 2025
Viewed by 759
Abstract
This paper presents a thermal gas flow sensing system, from surface acoustic wave (SAW) temperature sensor to oscillation circuit and multi-module miniaturization integration. A single-port GaN/Si SAW resonator with single resonant mode and excellent characteristics was fabricated. Combined with an in-house-developed SiGe HBT, [...] Read more.
This paper presents a thermal gas flow sensing system, from surface acoustic wave (SAW) temperature sensor to oscillation circuit and multi-module miniaturization integration. A single-port GaN/Si SAW resonator with single resonant mode and excellent characteristics was fabricated. Combined with an in-house-developed SiGe HBT, a temperature-sensitive high-frequency oscillator was constructed. Under constant temperature control, system-level flow measurement was achieved through dual-oscillation configuration and modular integration. The fabricated SAW device shows a temperature coefficient of frequency (TCF) −28.29 ppm/K and temperature linearity 0.998. The oscillator operates at 1.91 GHz with phase noise of −97.72/−118.62 dBc/Hz at 10/100 kHz offsets. The system demonstrates excellent dynamic response and repeatability, directly measuring 0–50 sccm flows. For higher flows (>50 sccm), a shunt technique extends the test range based on the 0–10 sccm linear region, where response time is <1 s with error <0.9%. Non-contact operation ensures high stability and long lifespan. The sensor shows outstanding performance and broad application prospects in flow measurement. Full article
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32 pages, 4265 KB  
Review
A Review on Biomedical, Biomolecular, and Environmental Monitoring Applications of Cysteamine Functionalized Nanomaterials
by Muthaiah Shellaiah
Micromachines 2025, 16(10), 1144; https://doi.org/10.3390/mi16101144 - 8 Oct 2025
Cited by 4 | Viewed by 1489
Abstract
Functionalizing agents enhance the photophysical properties of nanomaterials, thereby broadening their applications. Among these agents, cysteamine (SH-(CH2)2-NH2) is unique because of its free thiol (-SH) and amino (-NH2) groups. The presence of free -SH or [...] Read more.
Functionalizing agents enhance the photophysical properties of nanomaterials, thereby broadening their applications. Among these agents, cysteamine (SH-(CH2)2-NH2) is unique because of its free thiol (-SH) and amino (-NH2) groups. The presence of free -SH or -NH2 groups significantly enhances the functionalization of highly stable nanomaterials. These stable nanomaterials, which contain free -SH or -NH2 groups, can effectively bind with biomedical, biomolecular, and environmental analytes, improving sensor performance and making them valuable materials. In this context, cysteamine-functionalized nanoparticles (NPs), quantum dots (QDs), nanoclusters (NCs), nanocomposites, and other nanostructures have been demonstrated to be useful for quantifying biomedical, biomolecular, and environmental analytes. To date, no review has outlined the functionalizing ability of cysteamine or the application of cysteamine-functionalized nanomaterials in biomedical, biomolecular, and environmental analyte monitoring. This review emphasizes the role of cysteamine in producing stable nanomaterials and detecting specific biomedical, biomolecular, and ecological analytes. It also covers general protocols for functionalizing with cysteamine, the mechanistic basis of analyte detection, and their advantages, limitations, and prospects. Full article
(This article belongs to the Special Issue Nanoparticle-Based (Bio)Sensors for Biomedical and Environmental Monitoring)
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20 pages, 4013 KB  
Review
Bioengineering 3D Pancreatic Cancer Models with Fibrotic Stroma for In Vitro Cancer Modeling
by Xingrun Lan, Keke Chen and Xiaoyun Wei
Micromachines 2025, 16(10), 1140; https://doi.org/10.3390/mi16101140 - 2 Oct 2025
Viewed by 2225
Abstract
Pancreatic ductal adenocarcinoma (PDAC) remains highly lethal due to late diagnosis, high malignancy, and profound resistance to therapy. Traditional two-dimensional (2D) cell cultures fail to recapitulate the complex tumor microenvironment (TME), especially the fibrotic stroma, which is crucial for the progression of PDAC [...] Read more.
Pancreatic ductal adenocarcinoma (PDAC) remains highly lethal due to late diagnosis, high malignancy, and profound resistance to therapy. Traditional two-dimensional (2D) cell cultures fail to recapitulate the complex tumor microenvironment (TME), especially the fibrotic stroma, which is crucial for the progression of PDAC and drug response. In vitro three-dimensional (3D) models, which provide more physiologically relevant features such as tight cell–cell and cell-extracellular matrix (ECM) interactions, as well as 3D architecture, have been regarded as highly promising models in PDAC research. This review summarizes some representative in vitro PDAC models, including 3D spheroids, tumor-on-a-chip, bioprinted constructs, and patient-derived organoids (PDOs), particularly focused on the advances in bioengineering strategies for the integration of the key stomal components for microenvironment recapitulation and their applications. Additionally, we discuss the current challenges facing 3D models and propose potential strategies for constructing in vitro models that more accurately simulate the pathophysiology of the fibrotic stroma, aiming for their application in clinical settings. Full article
(This article belongs to the Special Issue 3D Tissue Engineering Techniques and Their Applications)
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28 pages, 3829 KB  
Review
Automated Platforms in C. elegans Research: Integration of Microfluidics, Robotics, and Artificial Intelligence
by Tasnuva Binte Mahbub, Parsa Safaeian and Salman Sohrabi
Micromachines 2025, 16(10), 1138; https://doi.org/10.3390/mi16101138 - 1 Oct 2025
Cited by 1 | Viewed by 4538
Abstract
Caenorhabditis elegans is one of the most extensively studied model organisms in biology. Its advantageous features, including genetic homology with humans, conservation of disease pathways, transparency, short lifespan, small size and ease of maintenance have established it as a powerful system for research [...] Read more.
Caenorhabditis elegans is one of the most extensively studied model organisms in biology. Its advantageous features, including genetic homology with humans, conservation of disease pathways, transparency, short lifespan, small size and ease of maintenance have established it as a powerful system for research in aging, genetics, molecular biology, disease modeling and drug discovery. However, traditional methods for worm handling, culturing, scoring and imaging are labor-intensive, low throughput, time consuming, susceptible to operator variability and environmental influences. Addressing these challenges, recent years have seen rapid innovation spanning microfluidics, robotics, imaging platforms and AI-driven analysis in C. elegans-based research. Advances include micromanipulation devices, robotic microinjection systems, automated worm assays and high-throughput screening platforms. In this review, we first summarize foundational developments prior to 2020 that shaped the field, then highlight breakthroughs from the past five years that address key limitations in throughput, reproducibility and scalability. Finally, we discuss ongoing challenges and future directions for integrating these technologies into next-generation automated C. elegans research. Full article
(This article belongs to the Special Issue Advances in Microfluidic Chips for Chemical and Biomedical Applications)
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28 pages, 5109 KB  
Review
Advances in Silicon-Based UV Light Detection
by Arif Kamal, Seongin Hong and Heongkyu Ju
Micromachines 2025, 16(10), 1130; https://doi.org/10.3390/mi16101130 - 30 Sep 2025
Cited by 4 | Viewed by 2146
Abstract
Silicon (Si), the cornerstone semiconductor in the micro-electronics industry, can provide a cost-efficient platform with mature technologies for photodetection in visible and near-infrared regions. However, its intrinsic properties, such as a narrow bandgap and the shallow penetration depth of ultraviolet (UV) light into [...] Read more.
Silicon (Si), the cornerstone semiconductor in the micro-electronics industry, can provide a cost-efficient platform with mature technologies for photodetection in visible and near-infrared regions. However, its intrinsic properties, such as a narrow bandgap and the shallow penetration depth of ultraviolet (UV) light into its surface with surface trap states, remain challenges, rendering it unsuitable for effective UV light detection. Various techniques have been reported to circumvent these surface defect-induced difficulties. In addition, wide-bandgap semiconductors that favor UV light absorption in a solar-blind way have been combined with Si for UV light detection in order to retain the device’s compatibility with Si-CMOS processes, though it still faces challenges that need to be overcome. This review starts with concepts of basic parameters of photodetectors and categorizes UV photodetectors according to their detection mechanisms. We also present a review of wide-bandgap semiconductor-based UV light detectors and those based on Si, with a discussion of surface defect minimization. In addition, we review the hybrid structure of the two kinds, i.e., wide-bandgap semiconductors and Si, and discuss their properties that produce synergistic effects. Lastly, we provide conclusions and outlooks for the possible development of next-generation UV light detectors based on Si. Full article
(This article belongs to the Special Issue Photodetectors and Their Applications)
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25 pages, 9895 KB  
Review
Harnessing Microfluidics for the Effective and Precise Synthesis of Advanced Materials
by Xinlei Qi and Guoqing Hu
Micromachines 2025, 16(10), 1106; https://doi.org/10.3390/mi16101106 - 28 Sep 2025
Cited by 1 | Viewed by 2699
Abstract
Microfluidic methods are powerful platforms for synthesizing advanced functional materials because they allow for precise control of microscale reaction environments. Microfluidics manipulates reactants in lab-on-a-chip systems to enable the fabrication of highly uniform materials with tunable properties, which are crucial for drug delivery, [...] Read more.
Microfluidic methods are powerful platforms for synthesizing advanced functional materials because they allow for precise control of microscale reaction environments. Microfluidics manipulates reactants in lab-on-a-chip systems to enable the fabrication of highly uniform materials with tunable properties, which are crucial for drug delivery, diagnostics, catalysis, and nanomaterial design. This review emphasizes recent progress in microfluidic technologies for synthesizing functional materials, with a focus on polymeric, hydrogel, lipid-based, and inorganic particles. Microfluidics provides exceptional control over the size, morphology, composition, and surface chemistry of materials, thereby enhancing their performance through uniformity, tunability, hierarchical structuring, and on-chip functionalization. Our review provides novel insights by linking material design strategies with fabrication methods tailored to biomedical applications. We also discuss emerging trends, such as AI-driven optimization, automation, and sustainable microfluidic practices, offering a practical and forward-looking perspective. As the field advances toward robust, standardized, and user-friendly platforms, microfluidics has the potential to increase industrial adoption and enable on-demand solutions in nanotechnology and personalized medicine. Full article
(This article belongs to the Special Issue Advances in Microfluidic Chips for Chemical and Biomedical Applications)
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