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Micromachines
Volume 17
Issue 8
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Micromachines, Volume 17, Issue 8 (August 2026) – 116 articles

Cover Story (view full-size image): This cover presents a temperature-dependent equivalent circuit model for SAW devices with spurious modes, offering a reliable solution for RF filter design under extreme temperatures. When spurious modes are close to the main mode, isolation capacitances are proposed to flexibly adjust the resonance frequencies. The motional resistance Rm and inductance Lm are treated as temperature-dependent. Using these parameters, the RF characteristics are modeled and verified with measurements. The consistent results confirm the model is accurate. The background PCB layout was generated using ChatGPT (OpenAI, GPT-4) and refined manually. The resonator structure, equivalent circuit, and labels were manually designed. AI was not used to generate any scientific data or results. View this paper
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50 pages, 13022 KB  
Review
A Framework for Short-Range Wireless Power and Data Transfer in Miniaturized High-Power, High-Bandwidth Implants
by Lyssa Ramaut, Pieterjan Polfliet, Gilles Callebaut and Liesbet Van der Perre
Micromachines 2026, 17(8), 989; https://doi.org/10.3390/mi17080989 - 21 Aug 2026
Viewed by 370
Abstract
As implantable medical devices become increasingly miniaturized while demanding higher power levels, longer lifetimes, and larger data throughput, conventional powering and communication approaches are reaching their practical limits. Consequently, wireless power and data transfer have emerged as key enabling technologies for next-generation implantable [...] Read more.
As implantable medical devices become increasingly miniaturized while demanding higher power levels, longer lifetimes, and larger data throughput, conventional powering and communication approaches are reaching their practical limits. Consequently, wireless power and data transfer have emerged as key enabling technologies for next-generation implantable systems. However, designing wireless links that simultaneously satisfy these requirements while remaining compact, efficient, and safe remains a significant challenge. To address this, this paper introduces an exploration and evaluation framework for selecting and co-designing short-range wireless power and data transfer technologies in medical devices such as cochlear and retinal implants. Guided by application requirements and relevant safety standards, the framework evaluates candidate technologies based on their operating principles, performance, and integration complexity. Based on this analysis, resonant inductive coupling is identified as the preferred approach for wireless power transfer, while both coil-based and antenna-based solutions are considered for wireless data transfer. Additionally, the paper compares architectures for integrated wireless power and data transfer, including both single- and multiple-link designs, and reviews strategies for uplink communication. The framework aims to guide the development of future sensory neuroprostheses that are smaller, safer, and capable of higher performance through optimized wireless link design. Full article
(This article belongs to the Special Issue Miniaturized Implantable Devices for Wireless Applications)
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13 pages, 2555 KB  
Perspective
Red-Ox Energy Partitioning of Light-Driven Electrons: From Laser Ablation to Plasmonics
by Haoran Mu, Hsin-Hui Huang, Tomas Katkus, Nguyen Hoai An Le, Jurga Juodkazytė, Yoshiaki Nishijima and Saulius Juodkazis
Micromachines 2026, 17(8), 988; https://doi.org/10.3390/mi17080988 - 21 Aug 2026
Viewed by 217
Abstract
In femtosecond-laser processing of titania in water, light can induce reduction and oxidation simultaneously. We follow this redox energy partitioning, in this perspective, from colloidal titania synthesis to hot-electron devices. Femtosecond ablation/fragmentation of an aqueous anatase suspension (515 nm, 230 fs, 5μ [...] Read more.
In femtosecond-laser processing of titania in water, light can induce reduction and oxidation simultaneously. We follow this redox energy partitioning, in this perspective, from colloidal titania synthesis to hot-electron devices. Femtosecond ablation/fragmentation of an aqueous anatase suspension (515 nm, 230 fs, 5μJ, fluence F≈25.5 J cm−2/pulse at clamped intensity ∼1013 W cm−2) yields surface-reduced, Ti3+-rich bluish TiO2−x, while the same optical breakdown generates reactive oxygen species (ROS), among them H2O2 and HO• radicals, which compete by re-oxidising Ti3+. When the reduced titania is decorated with plasmonic nanoparticles (e.g., Au), an n-type plasmonic photo-electrode is realised: sp hot electrons are injected over the Schottky barrier, while the deep d-band supplies oxidising holes. The oxygen evolution reaction (OER) proceeds in stages at potentials well above the formal 1.23 V via the two-electron peroxide route (∼1.77 V) or, for sufficiently energetic holes, via the one-electron HO• route (∼2.7 V). In a biased cell, H2 evolves on Pt through the adsorbed (H2+)ad intermediate. The same Au/semiconductor physics on silicon enables sub-band-gap hot-electron photo-detection. Energy-level diagrams (flat-band and in-contact) and the sp- vs. d-band origin of the injected carriers are discussed. Full article
(This article belongs to the Section E: Engineering and Technology)
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28 pages, 35935 KB  
Article
Efficient Automatic Design of a 2D TMD FET via Machine Learning-Assisted TCAD Simulation
by Na Shi, Zi-Jun Wei and Tong Wu
Micromachines 2026, 17(8), 987; https://doi.org/10.3390/mi17080987 - 21 Aug 2026
Viewed by 257
Abstract
As the scaling of silicon-based devices approaches physical limits, two-dimensional transition-metal dichalcogenide field-effect transistors (2D TMD FETs) have emerged as promising candidates for logic devices in the post-Moore era. However, their design optimization relies heavily on computationally intensive TCAD simulations, thereby limiting efficient [...] Read more.
As the scaling of silicon-based devices approaches physical limits, two-dimensional transition-metal dichalcogenide field-effect transistors (2D TMD FETs) have emerged as promising candidates for logic devices in the post-Moore era. However, their design optimization relies heavily on computationally intensive TCAD simulations, thereby limiting efficient exploration of multidimensional parameter spaces. This paper proposes an efficient automated design framework for 2D TMD FETs under small-sample conditions and validates it using a monolayer MoS2 FET as a case study. The framework integrates device design, physics-based simulation, performance prediction, and inverse design, establishing a bidirectional mapping between device parameters and electrical performance. Target-driven closed-loop optimization is achieved through TCAD-based feedback validation. Results demonstrate that, using a dataset comprising 300 TCAD samples, the forward model achieves an average coefficient of determination (R2) of 0.9503. TCAD revalidation of the inverse-designed devices yields an average mean absolute error (MAE) of 0.0464 and an average mean absolute percentage error (MAPE) of 5.46% for performance metrics. Regarding computational efficiency, while a single TCAD simulation takes approximately 25 to 50 min, the trained model performs inference in under 50 ms, achieving a speedup of at least 3×104 during the inference phase. Accounting for the generation of the 300 TCAD samples and the training of both forward and inverse models, the framework’s one-time computational cost ranges from 160.27 to 285.27 h. Once the cumulative number of design tasks exceeds approximately 342 to 385, the total computational cost falls below that of direct TCAD simulation, with the computational advantage becoming increasingly significant as the number of tasks grows. Consequently, this method is highly suitable for large-scale parameter sweeps, device screening, and multi-objective, high-frequency design iterations. It drastically reduces repetitive TCAD calls, offering a scalable solution for the efficient, automated design of 2D TMD FETs. Full article
(This article belongs to the Special Issue Emerging Technologies and Applications for Semiconductor Industry)
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12 pages, 5731 KB  
Article
Tunable Optical Bistability Within the Bandgap in One-Dimensional Photonic Crystal Multilayer Structures Containing Weyl Semimetal
by Liuxin Qian, Zhiheng Li, Zean Shen, Jiao Tang and Leyong Jiang
Micromachines 2026, 17(8), 986; https://doi.org/10.3390/mi17080986 - 21 Aug 2026
Viewed by 207
Abstract
In this paper, we propose a layered structure composed of Weyl semimetal (WSM) and one-dimensional photonic crystal (1D-PhC) to achieve low-threshold and tunable optical bistability (OB). By exploiting the bandgap characteristics of the photonic crystal and the strong third-order nonlinearity of WSM in [...] Read more.
In this paper, we propose a layered structure composed of Weyl semimetal (WSM) and one-dimensional photonic crystal (1D-PhC) to achieve low-threshold and tunable optical bistability (OB). By exploiting the bandgap characteristics of the photonic crystal and the strong third-order nonlinearity of WSM in the terahertz regime, reflective OB is realized within the photonic bandgap. It is shown that at certain frequencies inside the bandgap, the reflectance exhibits a jump with an increasing incident electric field, manifesting a clear hysteresis loop. The bistable threshold and hysteresis width can be effectively tailored by adjusting the Fermi energy and the thickness of the WSM layer. In addition, the influence of the incident angle and the parameters of the spacer layer on the OB threshold has also been elucidated. After parameter optimization, the incident electric field threshold is reduced to the order of 106 V/m. We believe that this structure can provide a reference for constructing optical bistable schemes with simple structures and low thresholds. Full article
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12 pages, 5231 KB  
Article
Effects of Ga and Si Incorporation on Oxygen-Related Defects and Bias-Temperature Stability of ZnSnO Thin-Film Transistors
by Sang Ji Kim, Jaehong Park, Wonjun Shin and Sang Yeol Lee
Micromachines 2026, 17(8), 985; https://doi.org/10.3390/mi17080985 - 21 Aug 2026
Viewed by 304
Abstract
Zn–Sn–O (ZTO) thin-film transistors (TFTs) are promising indium-free oxide semiconductor devices, but their electrical stability is limited by oxygen-related defect states. In this study, Ga and Si incorporated ZTO TFTs were systematically compared using an identical bottom-gate top-contact device architecture to investigate dopant-dependent [...] Read more.
Zn–Sn–O (ZTO) thin-film transistors (TFTs) are promising indium-free oxide semiconductor devices, but their electrical stability is limited by oxygen-related defect states. In this study, Ga and Si incorporated ZTO TFTs were systematically compared using an identical bottom-gate top-contact device architecture to investigate dopant-dependent defect modulation and bias-temperature stability. Both Ga and Si incorporation induced a positive threshold-voltage shift and reduced the relative contribution of oxygen-deficient bonding components, suggesting modification of oxygen-related defect environments in the ZTO channel. Optical analysis further showed reduced Urbach energies after dopant incorporation, suggesting a decrease in localized band tail states and reduced structural disorder. Under negative bias temperature stress (NBTS), SZTO exhibited the smallest threshold-voltage shift, demonstrating the most effective stability enhancement. These results indicate that Ga incorporation preserves high field-effect mobility while improving stability, whereas Si incorporation more effectively reduces oxygen-related defect features and provides enhanced NBTS stability. This study provides insight into the dopant-dependent defect engineering for the improved reliability of indium free oxide TFTS. Full article
(This article belongs to the Special Issue Next-Generation Functional Thin Films for Smart and Sustainable Electronics)
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16 pages, 2070 KB  
Article
Device-Level Modeling, Cross-Axis Analysis, and Optical Characterization of a Symmetric Triple-Layer MOEMS Accelerometer
by Pengfei Li, Shuang Wu, Wenhui Yan, Yujie Xiong, Jiaxin Sun, Chaoyue Shi, Haiyan Wang, Xiaoxu Wang and Qianbo Lu
Micromachines 2026, 17(8), 984; https://doi.org/10.3390/mi17080984 - 20 Aug 2026
Viewed by 289
Abstract
Enhancing the proof mass without enlarging the chip area or introducing structural asymmetry is a central challenge in the development of low-noise microelectromechanical system (MEMS) accelerometers. Here, we present a symmetric triple-layer MOEMS accelerometer and analyze its device-level sensitivity trade-off, cross-axis coupling behavior, [...] Read more.
Enhancing the proof mass without enlarging the chip area or introducing structural asymmetry is a central challenge in the development of low-noise microelectromechanical system (MEMS) accelerometers. Here, we present a symmetric triple-layer MOEMS accelerometer and analyze its device-level sensitivity trade-off, cross-axis coupling behavior, and dynamic consistency between measurement and finite-element simulations. The proposed sensing element sandwiches one without-beam mass layer between two identical with-beam layers, thereby increasing the effective proof mass while preserving mirror symmetry. A lumped-parameter model is developed to explain the sensitivity trade-off among single-layer, asymmetric double-layer, and symmetric triple-layer configurations. Finite-element simulations are used to distinguish translational cross-axis coupling from rotational cross-axis coupling. The experimental characterization of one packaged triple-layer prototype demonstrates a mechanical sensitivity of 193.91 µm/(m/s2), a 10 min output RMS fluctuation of 1.81 µg, and a measured first-order resonant frequency of 11.23 Hz, in close agreement with the tolerance-included finite-element prediction of 11.40 Hz. The resonance bandwidth further yields an apparent package-level quality factor of approximately 374 under ambient pressure, providing additional characterization of the packaged device dynamics. Full article
(This article belongs to the Section A: Physics)
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15 pages, 4558 KB  
Article
A Flexible Capacitive Pressure Sensor with Broad-Range High Sensitivity Based on 3D Porous Ionogel for Wearable Health Monitoring
by Yi Chen, Xuedan Xie, Yonghua Wang and Dan Liu
Micromachines 2026, 17(8), 983; https://doi.org/10.3390/mi17080983 - 20 Aug 2026
Viewed by 265
Abstract
Flexible pressure sensors featuring high sensitivity, a broad detection range, and excellent stability are pivotal components for high-precision electronic skins and human health monitoring. To circumvent the limitations of existing sensors in maintaining high responsiveness across extensive pressure ranges, herein, a novel flexible [...] Read more.
Flexible pressure sensors featuring high sensitivity, a broad detection range, and excellent stability are pivotal components for high-precision electronic skins and human health monitoring. To circumvent the limitations of existing sensors in maintaining high responsiveness across extensive pressure ranges, herein, a novel flexible capacitive pressure sensor is developed based on a 3D porous ionogel foam composite (IL/EG/PVA@MF) coupled with a planar electrode array. This device leverages the synergistic structural engineering of the 3D hyperelastic melamine foam (MF) skeleton and the pressure-regulated fringe-field distribution and iontronic interfacial polarization of the porous ionogel. Experimental evaluations demonstrate that the sensor achieves a high normalized sensitivity of 62.45 kPa−1 (2–10 kPa) and maintains reliable piecewise linear sensing performance across a broad working range of 0–50 kPa, accompanied by a rapid response time of within 8 ms. Furthermore, the sensor exhibits outstanding performance consistency after 6000 compression-release cycles at 50 kPa, verifying its good mechanical durability. In practical applications, the device can monitor diverse physiological signals with high fidelity, ranging from subtle radial artery pulses to large-scale joint movements and specific coughing patterns, underscoring its broad potential for integrated wearable systems and intelligent healthcare. Full article
(This article belongs to the Topic Advanced Materials for Flexible and Wearable Electronics)
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12 pages, 15456 KB  
Article
Rational In Situ Fabrication of ZnMoO4 Shielding Layers to Mitigate Zinc Degradation and Extend Battery Lifespan
by Xiaodong Zhang, Yan Zhang, Yingbin Liu, Kai Li and Changdong Chen
Micromachines 2026, 17(8), 982; https://doi.org/10.3390/mi17080982 - 20 Aug 2026
Viewed by 291
Abstract
Aqueous zinc-ion batteries (AZIBs) have garnered extensive attention owing to their high theoretical capacity, cost-effectiveness, and intrinsic safety. However, the practical deployment of AZIBs is severely hindered by deleterious side reactions, including surface corrosion, hydrogen evolution, and uncontrollable dendrite growth on the metallic [...] Read more.
Aqueous zinc-ion batteries (AZIBs) have garnered extensive attention owing to their high theoretical capacity, cost-effectiveness, and intrinsic safety. However, the practical deployment of AZIBs is severely hindered by deleterious side reactions, including surface corrosion, hydrogen evolution, and uncontrollable dendrite growth on the metallic Zn anode. In this work, we propose a simple one-step immersion strategy to in situ construct a ZnMoO4 (ZMO) protective coating on the Zn electrode. Mechanistically, the ZMO layer with polar surfaces exhibits a preferential adsorption affinity towards water molecules and Zn2+ ions. This synergistic adsorption behavior serves a dual function: it effectively excludes active water from the electrode surface to suppress hydrogen evolution, and simultaneously, the strong interaction with Zn2+ lowers the desolvation energy barrier, facilitating rapid Zn2+ desolvation at the interface. Furthermore, the resulting ZMO coating promotes a homogenized surface electric field and provides abundant nucleation sites, thereby guiding uniform Zn deposition and effectively mitigating dendrite formation. Consequently, the ZMO-modified Zn anode delivers significantly enhanced electrochemical reversibility and long-term cycling stability. This work provides a cost-effective and industrially viable surface engineering strategy to tackle the fundamental challenges of Zn anodes, paving the way for the commercialization of high-performance AZIBs. Full article
(This article belongs to the Special Issue Next-Generation Functional Thin Films for Smart and Sustainable Electronics)
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28 pages, 3122 KB  
Article
Transport Characteristics and Parametric Sensitivity of a Single-Stage Circular-Channel Knudsen Pump
by Dingdong Zhang, Tongchao Zhao, Laixi Zhang, Marcos Rojas-Cárdenas and Stéphane Colin
Micromachines 2026, 17(8), 981; https://doi.org/10.3390/mi17080981 - 20 Aug 2026
Viewed by 342
Abstract
Thermal transpiration enables a Knudsen pump to transport gas without moving components. An axial-integration formulation based on pre-computed transport coefficients from the linearized Shakhov kinetic model is applied to a single-stage unit comprising a circular microchannel and a circular macrochannel in series, with [...] Read more.
Thermal transpiration enables a Knudsen pump to transport gas without moving components. An axial-integration formulation based on pre-computed transport coefficients from the linearized Shakhov kinetic model is applied to a single-stage unit comprising a circular microchannel and a circular macrochannel in series, with opposite wall-temperature gradients. The pressure-generation and gas-transport capabilities are characterized by the maximum pressure difference or thermomolecular pressure difference (TPD), the maximum mass flow rate, the equivalent TPD, the equivalent flow resistance, and the complete mass-flow-rate–pressure-difference characteristics. The principal quantitative calculations cover temperature differences ranging from 10 to 50 K, while the 75 and 100 K cases are retained only to assess the persistence of the calculated trends. The formulation reproduces benchmark experimental TPD data with a maximum absolute relative deviation of 12.5% and a mean absolute relative deviation of 6.7%, and shows excellent agreement with numerical data from the literature, with deviation below 1%. A decomposition of the microchannel and macrochannel contributions shows that a macrochannel contributing little to the total equivalent flow resistance may nevertheless produce appreciable reverse thermal transpiration. At the baseline condition of the study and for an inlet pressure Pi=10 kPa, the macrochannel contributes only 0.37% of the total equivalent flow resistance but cancels 15.2% of the microchannel equivalent TPD. Over Pi=1–50 kPa, the temperature-difference sensitivity of the TPD ranges from 0.93 to 1.05, whereas the microchannel-radius sensitivity varies from −0.41 to −1.62. For the maximum mass flow rate, the microchannel-radius sensitivity ranges from 2.06 to 2.56 and the microchannel-length sensitivity remains close to −1, while the macrochannel-length effect is negligible. Increasing the macrochannel radius improves both limiting outputs, i.e., TPD and maximum mass flow rate, but with progressively diminishing benefits from further enlargement of the macrochannel. These results provide a quantitative basis for preliminary dimension selection while explicitly identifying the limitations associated with linearization, finite channel length, fully developed flow, and neglected interface losses. Full article
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15 pages, 5498 KB  
Article
Wind Bell-Inspired Polymeric Triboelectric Nanogenerator for Efficient Omnidirectional Wind Energy Harvesting at Extremely Low Wind Speeds
by Xichun Zheng, Haojie Li, Xue Liu, Wei Zhong, Jiwen Fang, Chong Li, Xiaohong Dong and Jiang Shao
Micromachines 2026, 17(8), 980; https://doi.org/10.3390/mi17080980 - 20 Aug 2026
Viewed by 323
Abstract
Wind energy, an abundant renewable resource, remains difficult to harness efficiently due to fluctuating speeds and unpredictable directions. In this work, we present a wind bell-inspired triboelectric nanogenerator (WB-TENG) designed for omnidirectional, variable-speed wind harvesting, utilizing layered triboelectric polymers such as polytetrafluoroethylene (PTFE), [...] Read more.
Wind energy, an abundant renewable resource, remains difficult to harness efficiently due to fluctuating speeds and unpredictable directions. In this work, we present a wind bell-inspired triboelectric nanogenerator (WB-TENG) designed for omnidirectional, variable-speed wind harvesting, utilizing layered triboelectric polymers such as polytetrafluoroethylene (PTFE), polyethylene terephthalate (PET), and polyamide (PA) to enhance energy capture performance. The developed device demonstrates the ability to generate electrical output even under extremely low wind speeds as low as 0.5 m/s. Additionally, it successfully captures wind energy from all directions within a full 360° range. Through structural optimization, the WB-TENG achieves a peak output voltage of 25.1 V and a maximum power of 3.5 μW, representing substantial improvements of 170% and 1232%, respectively, over the performance of our previous prototype. To verify its practical capability, the optimized WB-TENG is employed to power several electronic devices, including a digital watch and 50 commercial LEDs, confirming its potential for real-world energy harvesting applications. This work presents a novel and effective strategy for harnessing wind energy under dynamic environmental conditions, offering a sustainable approach for decentralized energy collection in low-speed and omnidirectional wind settings. Full article
(This article belongs to the Topic Advanced Energy Harvesting Technology, 2nd Edition)
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15 pages, 11340 KB  
Article
Electrochemical Microstructuring of Columnar Cu2O Layers Through Preferential Grain Boundary Dissolution
by Pei Loon Khoo, Mizuki Kono, Katsutoshi Sakai, Masakazu Kobayashi and Masanobu Izaki
Micromachines 2026, 17(8), 979; https://doi.org/10.3390/mi17080979 - 19 Aug 2026
Viewed by 232
Abstract
Crystalline oxide microfeatures offer optical, electronic, catalytic, and interfacial functions, but their fabrication often requires templates, patterned scaffolds, or serial machining. A template-free route converted an electrodeposited Cu2O coating on Au(111)/Si into substrate-supported vertical microfeatures by anodization at a nominal cell [...] Read more.
Crystalline oxide microfeatures offer optical, electronic, catalytic, and interfacial functions, but their fabrication often requires templates, patterned scaffolds, or serial machining. A template-free route converted an electrodeposited Cu2O coating on Au(111)/Si into substrate-supported vertical microfeatures by anodization at a nominal cell voltage of 10 V in 0.002 mol L−1 Na2S2O8 at 277 K. FE-SEM showed progressive widening of the pre-existing intercolumnar network and narrowing of the retained features. This spatially non-uniform removal identifies preferential dissolution along the intercolumnar network as the principal removal pathway at the coating-morphology scale. From 1 to 8 min, the within-image mean and median feature widths decreased by 36.0% and 45.9%, respectively. The dominant out-of-plane Cu2O(111) diffraction signature was retained while mean visible reflectance decreased. The Cu-H2O potential-pH framework provides a qualitative thermodynamic guide to possible oxidative pathways that are evaluated against the experimental evidence. C 1s-referenced XPS provides direct ex situ evidence of an anodization-associated Cu(II)/CuO-like contribution at the outermost surface. Chopped photoelectrochemical measurements showed the largest condition-level light–dark current density contrast after short anodization, providing a secondary functional comparison of the completed coatings. Full article
(This article belongs to the Special Issue Future Trends in Ultra-Precision Machining, Second Edition)
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23 pages, 184943 KB  
Article
Additive Manufacturing of Polyamide-6 Preforms for Scalable Thermal Drawing of Structured Fibers
by Akila Bandara, Ahmed Moustafa Abd-El Nabi, Luka Morita and Dan Sameoto
Micromachines 2026, 17(8), 978; https://doi.org/10.3390/mi17080978 - 19 Aug 2026
Viewed by 443
Abstract
Thermal drawing is a prominent, scalable method for transforming preforms with complex macroscopic morphologies into multifunctional microscopic fibers. With the intent to develop fibers with complex cross-sections for potential integration in soft robotics, smart textile and fabric applications, we explore the potential of [...] Read more.
Thermal drawing is a prominent, scalable method for transforming preforms with complex macroscopic morphologies into multifunctional microscopic fibers. With the intent to develop fibers with complex cross-sections for potential integration in soft robotics, smart textile and fabric applications, we explore the potential of polyamide-6 (PA6) as a base material for thermal drawing. By implementing Fused Deposition Modeling (FDM), we additively manufactured PA6 preforms with solid circular and three-channel cross-sectional architectures. These preforms were then utilized in a series of thermal drawing experiments to identify the best-performing printing layer thickness and channel aspect ratio (AR) that consistently yielded scalable, microscopic fiber diameters over extended durations. Our results demonstrate that a printing layer thickness of 0.3 mm yielded the most consistent drawn fiber diameters for extended durations among the tested values. Additionally, AR experiments indicate that the intermediate ARs of 0.4 and 0.5 between the inner channel diameter and the outer diameter produce the most promising results within the investigated range, based on dimensional trends and qualitative observations of internal channel integrity. Full article
(This article belongs to the Special Issue Emerging Trends in Soft Robotics and Bioinspired Technologies)
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23 pages, 10837 KB  
Article
Milling Stability Prediction Considering Axial Geometric Contact Effects
by Yanlong Zhang, Xiaoru Ren and Junfeng Yang
Micromachines 2026, 17(8), 977; https://doi.org/10.3390/mi17080977 - 19 Aug 2026
Viewed by 262
Abstract
To overcome the limitations of existing three-degree-of-freedom milling stability models in representing axial cutting conditions, this study develops a stability prediction framework that accounts for both axial segmentation and the axial contact angle. A three-degree-of-freedom dynamic model of the milling system is first [...] Read more.
To overcome the limitations of existing three-degree-of-freedom milling stability models in representing axial cutting conditions, this study develops a stability prediction framework that accounts for both axial segmentation and the axial contact angle. A three-degree-of-freedom dynamic model of the milling system is first formulated by introducing the axial contact angle. The tool axis is then discretized, so that the cutting force coefficients can be evaluated in different axial sections and the non-uniform distribution of cutting forces along the tool can be captured more accurately. After incorporating the regenerative mechanism, the milling dynamics are expressed in the form of a linear time-delay differential equation. To enhance the numerical accuracy of the time-delay system solution, a full-discretization scheme using third-order Lagrange–Hermite interpolation is developed for constructing the state transition matrix. The stability boundary is subsequently determined based on Floquet theory, from which the stability lobe diagram is generated. The proposed model and solution procedure are validated by comparison with existing methods and by time-domain simulation. The results show that, when the spindle speed ranges from 5000 to 10,000 rpm and the axial depth of cut ranges from 0 to 8 mm, the overall variation rate of the predicted stability region is 11.19% after incorporating axial discretization and 59.88% after considering the axial contact angle. The stable and unstable cutting responses obtained from time-domain simulations are consistent with the regions predicted by the stability lobe diagram, which supports the validity of the proposed approach. Further investigation shows that, for the established three-degree-of-freedom milling model and the specified cutting parameters, the axial contact angle exerts a pronounced nonlinear effect on the stability boundary. Specifically, as the axial contact angle ε increases within the range 0°<ε≤45°, the stable region gradually shrinks; when ε increases from 45° to 90°, the stable region expands instead. These observations can provide useful guidance for selecting milling parameters and identifying stable machining conditions. Full article
(This article belongs to the Section D: Materials and Processing)
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9 pages, 1815 KB  
Article
Broad Perfect Transparent Band in Asymmetric Photonic Crystals with Graded-Index Films
by Chenming Zhang, Qi Wei, Xinya Zhang, Wufeng Sun, Xiangyu Li, Ang Liu and Guiqiang Du
Micromachines 2026, 17(8), 976; https://doi.org/10.3390/mi17080976 - 19 Aug 2026
Viewed by 317
Abstract
Photonic crystals possessing mirror symmetry have been widely investigated to obtain perfect transmission properties. However, complex asymmetric nanostructures can achieve perfect transmission via phase-matching, while one-dimensional photonic crystals exhibit pronounced angle- and polarization-dependent transmission characteristics under oblique incidence. In this study, we systematically [...] Read more.
Photonic crystals possessing mirror symmetry have been widely investigated to obtain perfect transmission properties. However, complex asymmetric nanostructures can achieve perfect transmission via phase-matching, while one-dimensional photonic crystals exhibit pronounced angle- and polarization-dependent transmission characteristics under oblique incidence. In this study, we systematically investigated the optical properties of one-dimensional asymmetric photonic crystals containing graded-index films, which yielded a broad perfect transparent photonic band that differed from those occurring in one-dimensional asymmetric photonic crystals comprising solid-index films. The transparent band redshifted, and its bandwidth decreased with increasing amplitude of the graded index. Moreover, the broad perfect transparent band obtained over a wide range of incident angles exhibited greater insensitivity to the incident angle for transverse magnetic polarization than for transverse electric polarization. These results provide a theoretical foundation for designing perfect broadband optical devices using photonic crystals with graded-index films. Full article
(This article belongs to the Special Issue Photonic and Optoelectronic Devices and Systems, 5th Edition)
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23 pages, 4725 KB  
Review
Triboelectric Nanogenerators for Vehicle Energy Harvesting and Intelligent Sensing
by Chuanqing Zhu, Yatong Ren, Ziyue Xi and Hengxu Du
Micromachines 2026, 17(8), 975; https://doi.org/10.3390/mi17080975 - 18 Aug 2026
Viewed by 435
Abstract
As vehicle intelligence and automotive electrification advance, the extensive deployment of distributed sensing nodes for comprehensive monitoring has grown rapidly. This poses severe challenges, such as rising onboard power consumption and the inability of conventional centralized power supply systems to sustain these sensors. [...] Read more.
As vehicle intelligence and automotive electrification advance, the extensive deployment of distributed sensing nodes for comprehensive monitoring has grown rapidly. This poses severe challenges, such as rising onboard power consumption and the inability of conventional centralized power supply systems to sustain these sensors. Triboelectric nanogenerators (TENGs), an emerging technology for energy harvesting and self-powered sensing, exhibit great potential to address the above challenges. This review systematically summarizes research on TENGs for vehicle energy harvesting and intelligent sensing, covering their fundamental working principles and applications in diverse vehicle scenarios. First, the basic principle and working modes of TENGs are described, and their suitability for complex and variable vehicle environments is evaluated. Subsequently, existing applications are categorized into three domains: vehicle vibration systems, wheel–road systems, and intelligent vehicle systems. Studies on various topics are reviewed, including vibration energy harvesting and sensing, vehicle collision monitoring, tire energy harvesting, road sensing, smart cockpits, human–machine interaction, and vehicle fluid monitoring. Emphasis is placed on their technical approaches and application prospects. Finally, the state-of-the-art research and prevailing technical bottlenecks are summarized, and potential solutions and future research perspectives are discussed. This review aims to support the reliable practical deployment of TENG technology in vehicle engineering and to provide a technical basis for energy-saving strategies and in situ sensing technologies for future intelligent vehicles. Full article
(This article belongs to the Special Issue Micro Energy Harvesting Systems: From Devices to Self-Powered Applications)
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27 pages, 18242 KB  
Article
Impact of Printed Circuit Board Dielectric Material on the Thermal Behavior of Wafer-Level Packaging GaN Transistors Used in High-Power-Density Converters for Electric Vehicle Applications
by Mohamed Belguith, Sonia Eloued, Moncef Kadi, Jaleleddine Ben Hadj Slama and Mahmoud Hamouda
Micromachines 2026, 17(8), 974; https://doi.org/10.3390/mi17080974 - 18 Aug 2026
Viewed by 367
Abstract
GaN power devices used in high-power-density converters face significant thermal-management challenges because substantial heat is generated within a compact active region and transferred through the device–Printed Circuit Board (PCB) interface. This study investigates the influence of PCB dielectric-material selection on the coupled thermal [...] Read more.
GaN power devices used in high-power-density converters face significant thermal-management challenges because substantial heat is generated within a compact active region and transferred through the device–Printed Circuit Board (PCB) interface. This study investigates the influence of PCB dielectric-material selection on the coupled thermal and electrical behavior of a 48 V/12 V GaN half-bridge converter. Flame Retardant 4 (FR4), Hydrocarbon ceramic laminate material RO4000 series (4003) (RO4003), and polybenzoxazole (PBO) were compared using a reduced steady-state thermal-resistance network, three-dimensional finite-element simulations in Ansys Icepak, parasitic-capacitance extraction in Ansys Q3D, and switching simulations in LTspice. Both analytical and numerical models produced the same thermal-performance ranking, with PBO providing the lowest junction temperature. Under identical geometry, power dissipation, and boundary conditions, the Finite Elements Method (FEM) results showed a reduction in the maximum junction temperature from 225 °C for FR4 to 159 °C for PBO. The extracted layout-associated capacitances were also reduced by approximately 30–38% with PBO relative to FR4. This decrease produced a slight reduction in the switching-node falling time and lowered the calculated transistor loss from 3.118 W to 3.102 W. The results show that PCB dielectric selection is primarily a thermal-design parameter, while its electrical influence remains modest under the investigated operating conditions. Full article
(This article belongs to the Topic Wide Bandgap Semiconductor Electronics and Devices)
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32 pages, 23095 KB  
Review
Microrobots for Precision Diagnosis and Treatment in the Digestive System: A Review of Actuation Mechanisms, Structural Design, Preclinical and Translational Applications
by Yulong Gao, Fei Liu and Gongxin Li
Micromachines 2026, 17(8), 973; https://doi.org/10.3390/mi17080973 - 18 Aug 2026
Viewed by 544
Abstract
Because lesions associated with digestive system diseases are often deeply seated, embedded within complex luminal milieus, and protected by substantial local delivery barriers, conventional diagnostic and therapeutic modalities remain constrained in their targeting capability, minimal invasiveness, and precision. Microrobots, leveraging micro-scale motion, active [...] Read more.
Because lesions associated with digestive system diseases are often deeply seated, embedded within complex luminal milieus, and protected by substantial local delivery barriers, conventional diagnostic and therapeutic modalities remain constrained in their targeting capability, minimal invasiveness, and precision. Microrobots, leveraging micro-scale motion, active navigation, programmable controllability, and theranostic integration, open a new avenue for the precise diagnosis and treatment of digestive system diseases. Here, we review the major actuation modalities and structural designs of microrobots and discuss recent advances in their use across the gastrointestinal and hepatopancreatobiliary systems, focusing on targeted drug delivery, biospecimen harvesting, lesion detection, and interventional treatment. We further discuss the major obstacles to progress in this field, including robust operation in complex in vivo settings, real-time imaging and closed-loop feedback control, biosafety, degradability, and eventual clinical implementation. With continued advances in high-performance materials, multimodal actuation, intelligent control, and convergence with endoscopic and medical imaging technologies, microrobots are poised to accelerate the transition of digestive disease care toward precision, intelligence, and minimally invasive intervention. Full article
(This article belongs to the Section D2: Biomaterial Devices)
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18 pages, 5095 KB  
Article
Linking Surface Wettability to Interfacial Thermal Transport at Ti–Water Interfaces: A Molecular Dynamics Study
by Haoming Huang, Xi Wang, Ming Ma, Shan Qing, Zhumei Luo, Xiaoyan Huang, Jing Zhang and Xiaohui Zhang
Micromachines 2026, 17(8), 972; https://doi.org/10.3390/mi17080972 - 18 Aug 2026
Viewed by 577
Abstract
Solid–liquid interfacial heat transfer plays a key role in microelectronic devices, energy systems, and liquid cooling technologies. However, the vibrational mismatch at solid–liquid interfaces produces an interfacial thermal resistance (ITR) that limits the heat-dissipation efficiency. Herein, molecular dynamics (MD) simulations were used to [...] Read more.
Solid–liquid interfacial heat transfer plays a key role in microelectronic devices, energy systems, and liquid cooling technologies. However, the vibrational mismatch at solid–liquid interfaces produces an interfacial thermal resistance (ITR) that limits the heat-dissipation efficiency. Herein, molecular dynamics (MD) simulations were used to study the regulation of heat transfer at Ti–water interfaces by the Ti-O interaction strength. As the interaction strength increased, the Ti surface changed from strongly hydrophobic to complete wetting, with the contact angle spanning 153° to θ < 5° over the full droplet series. Over the range where the interfacial thermal conductance (ITC) was computed, the contact angle decreased from about 143° to 15°, and the ITC increased from 35.71 ± 4.26 to 231.97 ± 14.17 MW/m2·K. This increase originated from changes in the interfacial water structure, as the stronger interaction led to a denser and more ordered near-wall water structure that became more tightly bound to the surface, which enhanced the solid–liquid vibrational coupling. From the phonon perspective, the spectral overlap increased by only about 2%, from 0.01973 to 0.02008 THz−1, while the ITC increased by a factor of 6.5, indicating that the spectral overlap is not the controlling factor. Instead, the phonon lifetime of the interfacial Ti shortened markedly while the phonon heat capacity remained stable, showing that the enhancement originates from the stronger interfacial coupling rather than from an increase in the spectral overlap. This work clarifies how wettability regulates the microscopic structure of interfacial water and interfacial vibrational coupling, and provides a basis for understanding heat transfer at metal–water interfaces. Full article
(This article belongs to the Section A2: Surfaces and Interfaces)
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21 pages, 15365 KB  
Article
Multifunctional Properties of Nickel Nanoparticles Produced by Laser Ablation in Liquid
by Alexandru-Mihai Iamandi, Daniel-Liviu Ghiculescu, Gabriela Huminic, Angel Huminic, Ioan Mihail Ghițiu and Nicu Doinel Scărișoreanu
Micromachines 2026, 17(8), 971; https://doi.org/10.3390/mi17080971 - 17 Aug 2026
Viewed by 319
Abstract
This study explores the multifunctional properties of Ni nanoparticles obtained by laser ablation in liquid, with emphasis on the potential use of these nanoparticles in different applications such as cooling fluids or photoelectrochemical ones. The Ni nanoparticles were synthesized by the laser ablation [...] Read more.
This study explores the multifunctional properties of Ni nanoparticles obtained by laser ablation in liquid, with emphasis on the potential use of these nanoparticles in different applications such as cooling fluids or photoelectrochemical ones. The Ni nanoparticles were synthesized by the laser ablation in liquid technique using an Nd-YAG laser and ultrapure water as liquid. The structural, dimensional, morphologic, and stoichiometric characterizations of the nanoparticles were performed using different techniques such as transmission electron microscopy (TEM), energy dispersive X-ray (EDS) and dynamic light scattering spectroscopy (DLS). Nickel nanoparticles with sizes ranging from 5 to 15 nm in diameter were obtained. The experimental measurements were performed to determine the thermal conductivity and viscosity of the obtained nanofluids, essential parameters in the evaluation of the cooling fluid performances. Loading TiO2 thin films with Ni nanoparticles led to the enhancement of the photoelectrochemical water splitting properties of TiO2 thin films, the Ni nanoparticles acting on the collecting, transferring and separating the photogenerated charges and ultimately improving the overall anodic and cathodic efficiencies. The results obtained can contribute to the development of innovative, multifunctional solutions based on non-precious metals for cooling and water splitting systems used in industrial, electronics and other applications. Full article
(This article belongs to the Special Issue Recent Advances in Micro/Nanofabrication, 3rd Edition)
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87 pages, 32041 KB  
Review
Multifunctional MXene-Based Nanomaterials in Optoelectronics: From Interfacial Engineering to Device
by Seongeun Byeon, Seonhu Jung, Junseo Lee, Seongheon Jeon and Seokyeong Lee
Micromachines 2026, 17(8), 970; https://doi.org/10.3390/mi17080970 - 17 Aug 2026
Viewed by 404
Abstract
Two-dimensional transition-metal carbides and nitrides (MXenes) are increasingly adopted in advanced electronic devices, where their metallic conductivity, optical tunability, and chemically addressable surfaces support next-generation multifunctional optoelectronics. Their practical performance, however, depends not only on their intrinsic properties but also on the heterogeneous [...] Read more.
Two-dimensional transition-metal carbides and nitrides (MXenes) are increasingly adopted in advanced electronic devices, where their metallic conductivity, optical tunability, and chemically addressable surfaces support next-generation multifunctional optoelectronics. Their practical performance, however, depends not only on their intrinsic properties but also on the heterogeneous interfaces where charges, photons, and ions interact. Unlike earlier reviews organized around synthesis routes or separate device categories, this review takes interfacial chemistry as a single organizing principle and follows it from surface terminations through to integrated systems. The structural and surface-chemical characteristics of MXenes are described first, showing how dynamic terminations and interfacial dipoles regulate work functions and energy-level alignment. We then discuss molecular functionalization, defect passivation, and heterojunction formation as strategies for reducing Schottky barriers and improving charge-transfer kinetics. Optoelectronic platforms built on these engineered interfaces, including high-efficiency photovoltaics, broadband photodetectors, and stretchable wearable systems, are subsequently detailed, together with emerging architectures that merge self-powered sensing with neuromorphic visual functions, a scope seldom treated alongside conventional devices in previous surveys. By connecting surface chemistry with device integration, this review outlines a materials-to-systems pathway toward more reliable and scalable MXene-based optoelectronic technologies. Full article
(This article belongs to the Special Issue Photonic and Optoelectronic Devices and Systems, 5th Edition)
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24 pages, 5489 KB  
Article
Performance Analysis of Typical Data Fusion Algorithms for Inertial Measurement Arrays
by Ting Zhu, Zhenzhen Guan, Qiwen Wang, Wei Wu and Jingbei Tian
Micromachines 2026, 17(8), 969; https://doi.org/10.3390/mi17080969 - 17 Aug 2026
Viewed by 287
Abstract
This paper investigates data fusion for multi-MEMS gyroscope arrays by comparing four methods: numerical averaging, weighted least squares, direct estimation Kalman filtering, and indirect estimation Kalman filtering. The state-estimation characteristics and observability of the two Kalman-filter models are also analyzed. The performance of [...] Read more.
This paper investigates data fusion for multi-MEMS gyroscope arrays by comparing four methods: numerical averaging, weighted least squares, direct estimation Kalman filtering, and indirect estimation Kalman filtering. The state-estimation characteristics and observability of the two Kalman-filter models are also analyzed. The performance of the four methods is evaluated through controlled simulations, static experiments, dynamic turntable experiments, and array-size analysis. The simulation and static experimental results show that when the IMUs exhibit similar Allan bias-instability characteristics, the four methods yield relatively similar results in terms of bias instability. When the Allan bias-instability characteristics of the IMUs differ, numerical averaging provides poorer performance, whereas the other three methods yield comparable results in terms of bias instability. When different error components are present and exhibit conflicting trends, fixed weighting based on a single statistical indicator may lead to weight mismatch. In the dynamic experiment, the three-axis gyroscope and three-axis accelerometer measurements are separately processed using the same fusion method, and the resulting six-axis fused data are used as inputs to the PSINS inertial navigation system, with the final horizontal position drift adopted as a system-level performance metric. Under the tested dynamic conditions, the direct estimation Kalman filter achieves the smallest final horizontal position drift, followed by the indirect estimation Kalman filter, while both outperform numerical averaging and fixed-weight fusion. The array-size analysis shows that the performance gain gradually diminishes as the number of IMUs increases. The geometric knee point is located at approximately 21 IMUs, and the main performance-transition range is approximately 21–30 IMUs. Under the simulation and experimental conditions considered in this study, this range provides a favorable trade-off among fusion performance, computational burden, and array complexity. Full article
(This article belongs to the Special Issue Micro/Nanostructures in Sensors and Actuators, 2nd Edition)
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14 pages, 9850 KB  
Article
Development of Piezoresistive Micropressure Sensor Based on Grooved Diaphragm with Back Peninsulas and Trenches
by Peicang Chen, Lei Guo, Jiahao Feng, Chenxi Li, Yan Liu and Weidong Wang
Micromachines 2026, 17(8), 968; https://doi.org/10.3390/mi17080968 - 16 Aug 2026
Viewed by 399
Abstract
To validate the effectiveness of the grooved diaphragm with back peninsulas and trenches (GDPT) and the radial basis function neural network (RBFNN)-based dimension generator in the development of a 1 kPa piezoresistive micropressure sensor, this paper presents a comprehensive investigation into the design, [...] Read more.
To validate the effectiveness of the grooved diaphragm with back peninsulas and trenches (GDPT) and the radial basis function neural network (RBFNN)-based dimension generator in the development of a 1 kPa piezoresistive micropressure sensor, this paper presents a comprehensive investigation into the design, fabrication, and characterization of the anticipative sensor prototype. The GDPT achieves favorable sensing stress and reduced deflection, enabling a favorable trade-off between sensitivity and nonlinearity; the RBFNN-based generator efficiently determines practicable dimensions for the complex structure, offering a significant improvement over the conventional trial-and-error process. Characterization results demonstrate that the fabricated sensor achieves sensitivity of 13.01 mV/(V·kPa) and nonlinearity of 0.26% FS within the pressure range of 0–1 kPa, in good agreement with the preset design target. This work verifies the validity of the proposed approach and offers a holistic methodology for developing high-performance piezoresistive sensors. Full article
(This article belongs to the Special Issue Recent Advances in Silicon-Based MEMS Sensors and Actuators)
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12 pages, 11933 KB  
Article
Electrical Characterization of Mesh-Structured Floating-Gate Neuromorphic Transistors with Varying Mesh Sizes
by Taehwan Koo, Hyeongjin Chae, Kangmin Yoo, Hyeonseok Jeong, Juyeong Chae, Dongyeop Kim, Jineui Park and Moongyu Jang
Micromachines 2026, 17(8), 967; https://doi.org/10.3390/mi17080967 - 16 Aug 2026
Viewed by 454
Abstract
This study investigates the influence of mesh-structured floating-gate (FG) geometry on the electrical and DC synaptic characteristics of flash-memory-based neuromorphic transistors. Devices with mesh sizes of 3 µm × 3 µm, 1 µm × 1 µm, 500 nm × 500 nm, and 200 [...] Read more.
This study investigates the influence of mesh-structured floating-gate (FG) geometry on the electrical and DC synaptic characteristics of flash-memory-based neuromorphic transistors. Devices with mesh sizes of 3 µm × 3 µm, 1 µm × 1 µm, 500 nm × 500 nm, and 200 nm × 200 nm were comparatively evaluated while maintaining the same channel dimensions. As the mesh size decreased, the perimeter-to-area (P/A) ratio increased from 1.33 to 20.0 µm−1, and the cycle-averaged memory window increased from 0.86 to 1.68 V under the same DC program/erase sequence. The 200 nm device also exhibited a read-current modulation range exceeding six orders of magnitude, compared with approximately three orders of magnitude for the 3 µm device. These trends are consistent with a greater contribution of mesh-edge regions to local electrostatic conditions and charge injection. At the same time, smaller mesh sizes produced more abrupt threshold-voltage and read-current changes during the initial program/erase steps, indicating a trade-off between response sensitivity and gradual state modulation. These results show that mesh-size scaling provides an effective geometrical design variable for tuning the memory window and readout characteristics of mesh-structured floating-gate synaptic transistors. Full article
(This article belongs to the Special Issue Functional Materials for Energy and Electronic Applications)
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13 pages, 7410 KB  
Article
AC Electrokinetics-Enhanced Capacitive Aptasensor for Point-of-Care Testing of Acrylamide in Coffee
by Ke Wang, Mingna Xie, Yuyang Zhao, Jiuyi Wang, Leilei Zeng, Xiaogang Lin and Jie Jayne Wu
Micromachines 2026, 17(8), 966; https://doi.org/10.3390/mi17080966 - 16 Aug 2026
Viewed by 296
Abstract
Acrylamide (AA) is a common contaminant in foods processed at high temperatures and has attracted significant attention due to its potential neurotoxicity and carcinogenicity. Therefore, the development of a highly sensitive, highly selective sensing technology suitable for on-site detection is of great importance [...] Read more.
Acrylamide (AA) is a common contaminant in foods processed at high temperatures and has attracted significant attention due to its potential neurotoxicity and carcinogenicity. Therefore, the development of a highly sensitive, highly selective sensing technology suitable for on-site detection is of great importance for ensuring food safety. In this study, an aptamer (Apt)-based capacitive AA sensor was developed based on the alternating current electrokinetics (ACEK) effect. The sensor utilizes an aptamer as the biomimetic recognition element, which can specifically recognize AA, thereby enabling quantitative detection. Additionally, a detachable detection fixture and data acquisition system were designed to enhance the detection stability and convenience of sensor. Within the linear range of 1 nmol/L to 10 µmol/L, the sensor response (dC/dt) exhibited a good linear relationship with AA concentration, with a detection limit as low as 0.4235 nmol/L. The sensor exhibits good selectivity toward structural analogs of AA, with a recovery relative standard deviations (RSDs) of less than 5.42% in spiked coffee samples. This portable detection system provides a sensitive and user-friendly tool for the analysis of acrylamide in food and holds great potential for application in food safety. Full article
(This article belongs to the Special Issue Microsensors for Early Disease Diagnosis and Rapid Food Safety Testing)
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18 pages, 5421 KB  
Article
Selective Plasma Mode Modulation in HfO2 Charge Trap Layers via RP/DP/RP Atomic Layer Deposition for Enhanced Memory Performance and Interface Quality
by Byungwook Kim, Yongwoon Jang, Hyeonwu Nam, Changyun Hong, Minkyun Kang, Wookyung Lee and Changbun Yoon
Micromachines 2026, 17(8), 965; https://doi.org/10.3390/mi17080965 - 15 Aug 2026
Viewed by 312
Abstract
Hafnium oxide (HfO2) has emerged as a promising charge trap layer (CTL) for nonvolatile memory devices; however, its long-term reliability remains challenging due to leakage current through grain boundary pathways and interface defect formation. Within plasma-enhanced atomic layer deposition (PEALD), direct [...] Read more.
Hafnium oxide (HfO2) has emerged as a promising charge trap layer (CTL) for nonvolatile memory devices; however, its long-term reliability remains challenging due to leakage current through grain boundary pathways and interface defect formation. Within plasma-enhanced atomic layer deposition (PEALD), direct plasma ALD (DPALD) forms crystalline HfO2 with deeper trap sites, while its ion-assisted nature may contribute to interface damage, resulting in a lower net trap density than remote plasma ALD (RPALD), which better preserves interfacial quality. We propose an interface–bulk–interface (RP/DP/RP) process design that places RPALD at the interfaces and DPALD in the bulk, aiming to combine bulk trap sites with interfacial protection. Charge trap memory (CTM) devices were fabricated across RP/DP/RP thickness combinations. Within the tested range, the optimized structure exhibited the widest memory window and the highest effective trapped charge density among the measured devices, improving upon DPALD and comparable to RPALD, together with the lowest near-interface trap density at the Si/Al2O3 interface. The device also maintained a stable memory window up to 104 program/erase cycles, and short-term retention data suggest potentially stable program and erase states, requiring longer-term validation. These results indicate that spatial modulation of plasma modes offers a process-level strategy for improving HfO2-based CTM devices. Full article
(This article belongs to the Special Issue Manufacturing and Application of Advanced Thin-Film-Based Device, Second Edition)
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16 pages, 10652 KB  
Article
Laser-Enhanced Machine Vision for Edge Profile Measurement of Thin Film Printed Electronics
by Mothana A. Hassan and Ali Abdulkhaleq Alwahib
Micromachines 2026, 17(8), 964; https://doi.org/10.3390/mi17080964 - 15 Aug 2026
Viewed by 253
Abstract
Thin film printed electronics, such as flexible circuits and sensor sheets, require non-contact inspection to detect defects and edge degradation. The present paper presents a laser-enhanced machine vision framework for detecting and analyzing the edges of printed conductive tracks using Canny edge detection [...] Read more.
Thin film printed electronics, such as flexible circuits and sensor sheets, require non-contact inspection to detect defects and edge degradation. The present paper presents a laser-enhanced machine vision framework for detecting and analyzing the edges of printed conductive tracks using Canny edge detection and Otsu thresholding. Using a coherent laser source, Otsu’s method enhances contrast at the ink–substrate interface, enabling robust segmentation of edge lines. Canny operator is applied to thresholded images to extract precise edge profiles. Multiple printed tracks are analyzed to calculate four lateral edge roughness values (Ra). As a result, the values are 40.43 µm, 40.09 µm, 50.26 µm and 40.94 µm. The results show that the suggested method can detect and qualify variations in edge parameters. Printed electronics are produced using an inline inspection and quality control system based on non-contact, high-resolution, and scalable technologies. Full article
(This article belongs to the Section A2: Surfaces and Interfaces)
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44 pages, 9955 KB  
Review
A Review on Micromixers, Microdroplet Generators and Their Integration
by Wang He, Ling Zhang, Lei Wu, Yushan Chen and Tingting Chen
Micromachines 2026, 17(8), 963; https://doi.org/10.3390/mi17080963 - 15 Aug 2026
Viewed by 622
Abstract
High-efficiency mixing and precise droplet generation are essential for the broad application of microfluidic chips in biology, chemistry, and medicine, with integrated micromixer and microdroplet generator systems playing an increasingly important role in diagnostics and drug detection. This review offers a comprehensive and [...] Read more.
High-efficiency mixing and precise droplet generation are essential for the broad application of microfluidic chips in biology, chemistry, and medicine, with integrated micromixer and microdroplet generator systems playing an increasingly important role in diagnostics and drug detection. This review offers a comprehensive and systematic overview of micromixers and microdroplet generators, covering their classification, working principles, performance characterization, and integration strategies. Passive and active micromixers, the latter employing pressure, electric, acoustic, magnetic, and thermal fields to enhance mixing, are summarized with a critical discussion of their advantages, limitations, and structural optimization. Various droplet generation methods, including crossflow, flow focusing, coflow, step emulsification, and active techniques, are examined alongside key parameters affecting droplet size, monodispersity, and generation frequency. Performance characterization metrics for both components, including mixing efficiency, mixing time, pressure drop, droplet size distribution, generation frequency, and stability, are also discussed. The review then focuses on integration, emphasizing two primary architectural strategies: mixing reagents before encapsulation and inducing mixing within droplets after formation. Synergistic applications in single cell analysis, materials synthesis, and drug screening are presented. Notably, unlike previous reviews that treat micromixers or droplet generators separately, this review uniquely emphasizes architectural integration and critically evaluates the associated trade-offs. Current challenges and future directions, including material selection, fabrication techniques, and practical application-oriented considerations, are also addressed. Full article
(This article belongs to the Special Issue Advanced Biosensors: Nanomaterials, Micro/Nano Devices and Applications)
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16 pages, 3363 KB  
Article
A 67–110 GHz Multi-Carrier Communication Front End Based on Broadband Diplexer and Filtering Waveguide-to-Microstrip Transitions
by Yujie Zhi, Yulong Zhong, Bo Zhang, Yibo Fan, Zuqiang Ou and Jincai Qiao
Micromachines 2026, 17(8), 962; https://doi.org/10.3390/mi17080962 - 15 Aug 2026
Viewed by 564
Abstract
This paper presents a 67–110 GHz millimeter-wave RF front end for 6G high-speed wireless communications. A broadband diplexer based on a staggered branch-waveguide structure is first proposed to achieve low insertion loss and high isolation simultaneously. The fabricated diplexer exhibits better than 12 [...] Read more.
This paper presents a 67–110 GHz millimeter-wave RF front end for 6G high-speed wireless communications. A broadband diplexer based on a staggered branch-waveguide structure is first proposed to achieve low insertion loss and high isolation simultaneously. The fabricated diplexer exhibits better than 12 dB return loss, 48.6% fractional bandwidth, and less than 1.5 dB insertion loss. A filtering waveguide-to-microstrip transition is then developed to suppress harmonics and spurious signals while maintaining efficient mode conversion. Back-to-back measurements demonstrate over 50 dB out-of-band suppression at 99.5 GHz with a center frequency of 89 GHz. Finally, the proposed components are integrated with broadband amplifiers, filters, and a local oscillator to realize a 67–110 GHz RF front end with 4–26 GHz IF output. Experimental results show harmonic suppression better than 60 dBc, demonstrating excellent spectral purity and validating the proposed architecture as a compact, broadband, and highly integrated solution for future millimeter-wave and terahertz communication systems. Full article
(This article belongs to the Special Issue Novel RF Nano- and Microsystems)
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22 pages, 14722 KB  
Article
Five-Axis Micro Ball-End Milling Force Prediction for Micro Curved-Surface Parts
by Zhenghu Yan, Yicheng Yang, Shuai Wang, Chenxi Yang and Ruisi Qin
Micromachines 2026, 17(8), 961; https://doi.org/10.3390/mi17080961 - 15 Aug 2026
Viewed by 292
Abstract
Micro curved-surface parts are widely used in the aerospace, defense, biomedical, and automotive industries, and their growing adoption imposes increasingly stringent performance requirements. Five-axis micro-milling can achieve precision machining of parts with complex shapes. In the micro-milling process, the cutting force is a [...] Read more.
Micro curved-surface parts are widely used in the aerospace, defense, biomedical, and automotive industries, and their growing adoption imposes increasingly stringent performance requirements. Five-axis micro-milling can achieve precision machining of parts with complex shapes. In the micro-milling process, the cutting force is a critical parameter, as it is the main factor causing machining deformation, vibration, and tool wear. Therefore, this study develops a prediction model for five-axis micro-milling forces in the machining of micro complex curved-surface parts. First, four coordinate systems were established for the five-axis milling process, and the transformation relationships among them were derived. A cutter–workpiece engagement (CWE) extraction method based on solid modeling was also introduced. Then, an instantaneous undeformed chip thickness (IUCT) model was established, taking into account tool runout, elastic recovery of the machined surface, minimum chip thickness, and the local radius of the micro ball-end mill. On this basis, a five-axis micro-milling force prediction model was developed. Finally, five-axis micro-milling experiments were conducted on a micro-impeller and a micro-spherical part, and the cutting forces at different cutter location (CL) points were measured. For the micro-impeller blade, the average percentage errors in the X, Y, and Z directions at all selected CL points were below 11.2%; for the micro-spherical part, the corresponding errors were below 14.4%. These results show good agreement between the predicted and measured values, verifying the effectiveness of the proposed model. Full article
(This article belongs to the Section D: Materials and Processing)
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17 pages, 3163 KB  
Article
Tolerance Inversion for Lens Support Loads Based on Feature-Enhanced Active-Learning Gaussian Process Regression
by Jingteng Liu, Shiyu Li, Xia Kang, Songmao Xian, Ji Zhou and Junbo Liu
Micromachines 2026, 17(8), 960; https://doi.org/10.3390/mi17080960 - 14 Aug 2026
Viewed by 277
Abstract
Support load fluctuations in lithographic objectives can induce additional surface figure errors in lenses. Conventional Monte Carlo-based tolerance analysis is computationally expensive in high-dimensional load spaces, and surrogate models based only on raw load inputs often fail to accurately capture local-extremum responses such [...] Read more.
Support load fluctuations in lithographic objectives can induce additional surface figure errors in lenses. Conventional Monte Carlo-based tolerance analysis is computationally expensive in high-dimensional load spaces, and surrogate models based only on raw load inputs often fail to accurately capture local-extremum responses such as peak-to-valley (PV). To address the load tolerance inversion problem under prescribed PV and root mean square (RMS) constraints, a tolerance inversion framework integrating Regional Peak-to-Valley Fluctuation Features, Active-Learning Gaussian Process Regression, and dual-metric tolerance boundary search (RPVF-ALGPR) is proposed. The framework transforms the local fluctuation information in low-order Zernike-reconstructed wavefronts into regional peak-to-valley fluctuation features and combines them with the original support loads as inputs to the GPR surrogate models. It further combines posterior-uncertainty-driven active learning to construct surrogate models for both metrics, thereby enabling the inverse determination of the critical load fluctuation boundary. One set of training results from a biconvex lens case study shows that the proposed method effectively improves PV and RMS prediction accuracy and reduces the number of samples required to reach the prescribed accuracy threshold by 35.7% compared with random sampling. The results provide a reference for support-load tolerance allocation and optomechanical stability evaluation of high-precision lenses. Full article
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