Micromachines

25 pages, 14543 KB

Open AccessArticle

Influence of Inlet Splitter Structure on Flow and Heat Transfer Performance in Microchannel Heat Exchangers

by Yuanyuan Xi, Si Chen, Wenchao Tian, Xiong Xiao, Shuaike Li, Feiyang Li, Yifan Wang and Haojie Dang

Micromachines 2026, 17(2), 275; https://doi.org/10.3390/mi17020275 - 23 Feb 2026

Cited by 1 | Viewed by 473 | Correction

Abstract

Microchannel liquid cooling technology, characterized by high heat-transfer efficiency, represents an effective solution for thermal management in high heat-flux density electronic devices. Existing research has mainly focused on optimizing the structural design of microchannel heat sinks, while neglecting the specific effects of inlet [...] Read more.

Microchannel liquid cooling technology, characterized by high heat-transfer efficiency, represents an effective solution for thermal management in high heat-flux density electronic devices. Existing research has mainly focused on optimizing the structural design of microchannel heat sinks, while neglecting the specific effects of inlet manifold configurations on their heat transfer and flow performance. To obtain more systematic data on microchannel heat transfer performance and internal velocity distribution, this study designed microchannels with single-inlet and triple-inlet configurations. A microchannel cooling performance testing platform was established, and visualization experiments of the internal flow field in straight microchannels were conducted using a particle image velocimetry (PIV) system. The velocity distribution uniformity and heat transfer performance were compared between single-inlet and triple-inlet microchannels with varying channel spacings. The results show that under the same flow conditions, the triple-inlet splitter structure yields a more uniform flow distribution, a lower peak temperature for the heat source chip, and improved heat transfer performance, with its pressure drop reduced to 11.1–26.6% of that of the single-inlet configuration. Furthermore, smaller channel spacings yield improved heat-transfer efficiency in microchannels. Full article

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14 pages, 3076 KB

Open AccessArticle

2D and 3D Interdigital Capacitors and Bias Tees Technologies on MnM Interposer for mmWave Applications

by Gabriel Griep, Robert G. Bovadilla, Leonardo G. Gomes, Luís Q. Cartagena, Gustavo P. Rehder and Ariana L. C. Serrano

Micromachines 2026, 17(2), 274; https://doi.org/10.3390/mi17020274 - 23 Feb 2026

Viewed by 448

Abstract

This paper presents two capacitors fabricated using the metallic nanowire membrane (MnM) interposer technology operating at mmWaves. Standard 2D interdigital capacitors (IDCs) are designed to operate up to 70 GHz, which presents a straightforward and non-complex fabrication. In comparison, this work also proposes [...] Read more.

This paper presents two capacitors fabricated using the metallic nanowire membrane (MnM) interposer technology operating at mmWaves. Standard 2D interdigital capacitors (IDCs) are designed to operate up to 70 GHz, which presents a straightforward and non-complex fabrication. In comparison, this work also proposes an improved device that is more compact and exhibits large capacitance density, as high-performance vias enable the realization of high-depth capacitors. The fabrication process of 3D devices presents advanced maturity and innovation as it takes advantage of the porous nature of the interposer material to overcome the device complexity, and is also described in detail. Both capacitor types are modeled by a numerical lumped-element model that also considers parasitics. The 3D capacitors were successfully fabricated and characterized up to 70 GHz, displaying capacitance values between 30 fF and 160 fF and self-resonant frequencies in good agreement with mmWave applications. The quality factor of these devices, measured at 40 GHz, lies between 16 and 4, and the superficial capacitance density is between 4 pF/mm² and 8 pF/mm², showing that these devices are indeed promising for mmWave applications. These devices present considerably larger capacitance density compared to 2D traditional capacitors fabricated on the high-performance substrate, highlighting the advantage of 3D fabrication using nanowire growth. In addition, thin-film resistances are simulated and fabricated, projecting their functions as an RF-choke in a bias tee configuration using Ti thin film sputtering deposition step that is also part of the capacitors fabrication. Full article

(This article belongs to the Special Issue Recent Advancements in Microwave and Optoelectronics Devices)

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19 pages, 5600 KB

Open AccessArticle

Multi-Objective Optimization and Performance Evaluation of Rhombic Pin-Fin Microchannel Heat Sinks with Diverse Manifold Configurations

by Ruicheng Rong, Xiangqi Liu, Xiao Jin and Ruijin Wang

Micromachines 2026, 17(2), 273; https://doi.org/10.3390/mi17020273 - 23 Feb 2026

Viewed by 343

Abstract

In response to the increasingly severe heat dissipation challenges in electronic devices, three types of manifold microchannel heat sinks (MMC) incorporating rhombic pin-fins were proposed. Under the constraint that the maximum temperature of the heat source surface remains below 343.15 K, numerical comparisons [...] Read more.

In response to the increasingly severe heat dissipation challenges in electronic devices, three types of manifold microchannel heat sinks (MMC) incorporating rhombic pin-fins were proposed. Under the constraint that the maximum temperature of the heat source surface remains below 343.15 K, numerical comparisons with a conventional straight rectangular microchannel heat sinks (MCHS) reveal that the design featuring a trapezoidal manifold exhibits superior comprehensive thermal performance and improved temperature uniformity. Furthermore, the influence of rhombic pin-fin geometry on thermal performance was investigated for both MCHS with and without the trapezoidal manifold under varying mass flow rates. Results show that for the MCHS without a manifold, performance evaluation criterion (PEC) reaches its maximum when the inlet angle of the rhombic pin-fin is 120°, the side length is 0.17 mm, and the pin-fin height is 0.18 mm. In contrast, for the MCHS with the trapezoidal manifold, optimal PEC is achieved at an inlet angle of 110°, a side length of 0.18 mm, and a pin-fin height of 2.2 mm. Additionally, a multi-objective optimization was conducted using the Latin hypercube sampling method. Three objective functions—maximum temperature (

T_{\max}

), thermal performance (PEC), and temperature uniformity (

σ_{T}

)—were considered. A total of 150 sample points were used to train Kriging surrogate models for the rhombic pin-fin MCHS with trapezoidal manifold. The optimization results demonstrate a 34.05% enhancement in thermal performance and an 18.6% improvement in temperature uniformity. Full article

(This article belongs to the Section E：Engineering and Technology)

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20 pages, 3857 KB

Open AccessArticle

Collective Magnetic Mesoporous Silica Nanorobots for Targeted Oral Capsaicin Delivery in Colitis Intervention

by Hongyue Zhang, Yuzhu Di, Lubo Jin, Shuai Yang, Zesheng Li and Bo Qu

Micromachines 2026, 17(2), 272; https://doi.org/10.3390/mi17020272 - 22 Feb 2026

Viewed by 472

Abstract

Magnetic nanoparticles, with their excellent biocompatibility and biodegradability, serve as ideal materials for constructing targeted drug delivery systems. Iron oxide (Fe₃O₄) nanoparticles, controllably prepared via methods such as solvothermal synthesis, can be combined with mesoporous silica to construct magnetically [...] Read more.

Magnetic nanoparticles, with their excellent biocompatibility and biodegradability, serve as ideal materials for constructing targeted drug delivery systems. Iron oxide (Fe₃O₄) nanoparticles, controllably prepared via methods such as solvothermal synthesis, can be combined with mesoporous silica to construct magnetically steerable nanorobots. Such robots enable efficient drug loading and precise delivery. To address challenges in the treatment of Inflammatory Bowel Disease (IBD), including the significant side effects of systemic drugs and the low oral bioavailability and poor colonic targeting of novel food-derived drugs (e.g., capsaicin with anti-inflammatory activity), this study designed capsaicin-loaded iron oxide-mesoporous silica composite nanorobots (Cap-M@mSbots). Driven by a rotating gradient magnetic field of up to 80 mT, Cap-M@mSbots achieve large-scale emergent collective locomotion, with a maximum collective locomotion velocity reaching 180.7 μm/s, and are capable of long-distance movement overcoming millimeter-scale obstacles. This system can be actively propelled to colonic lesion sites under magnetic guidance, achieving targeted drug enrichment and sustained release, thereby offering a novel strategy for the targeted therapy of IBD. Full article

(This article belongs to the Special Issue Recent Study and Progress in Micro/Nanorobots)

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10 pages, 2646 KB

Open AccessArticle

A Low-Noise MEMS Accelerometer Based on a Symmetrical Sandwich Capacitor Structure

by Zihan Wang, Chaowei Si, Jihua Zhang, Zhen Fang, Jinxu Liu, Shuqi Li and Wanli Zhang

Micromachines 2026, 17(2), 271; https://doi.org/10.3390/mi17020271 - 22 Feb 2026

Viewed by 1157

Abstract

This study presents a high-performance MEMS accelerometer employing a symmetrical differential ‘sandwich’ capacitive structure. An orthogonal rectangular compensation method was integrated with wet anisotropic etching to achieve high structural symmetry. An innovative glass–silicon composite cover plate was adopted, and the upper and lower [...] Read more.

This study presents a high-performance MEMS accelerometer employing a symmetrical differential ‘sandwich’ capacitive structure. An orthogonal rectangular compensation method was integrated with wet anisotropic etching to achieve high structural symmetry. An innovative glass–silicon composite cover plate was adopted, and the upper and lower plates were encapsulated by a sensitive structure via anodic bonding, which effectively reduced the parasitic capacitance. Simulations confirmed sufficient separation between the sensitive-axis (Z-axis) resonant frequency and orthogonal/torsional modes, ensuring low cross-axis coupling. The fabricated device exhibits high sensitivity (0.2216 V/g) and excellent linearity (99.842%) within a 0–8 g range. Furthermore, it demonstrates outstanding noise (7.88 µg/√Hz) and bias-instability (6.39 µg) performance, positioning it competitively against commercial counterparts. The proposed design and process offer a viable technical route for high-precision inertial sensing applications. Full article

(This article belongs to the Section D1: Semiconductor Devices)

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16 pages, 2411 KB

Open AccessArticle

Single-Imaging Parasite-Quantification Microfluidic Device for Detection and Analysis of Schistosoma Eggs in Urine

by Heaven D. Chitemo, Vyacheslav R. Misko, Matthieu Briet, Jeffer Bhuko, Filip Legein, Humphrey D. Mazigo and Wim De Malsche

Micromachines 2026, 17(2), 270; https://doi.org/10.3390/mi17020270 - 22 Feb 2026

Viewed by 336

Abstract

The accurate diagnosis of schistosomiasis for effective disease surveillance, treatment, and follow-up is crucial to attain the World Health Organization’s 2030 goal to eliminate schistosomiasis as a public health problem. The current diagnostic tools for urinary schistosomiasis, including the gold standard urine filtration [...] Read more.

The accurate diagnosis of schistosomiasis for effective disease surveillance, treatment, and follow-up is crucial to attain the World Health Organization’s 2030 goal to eliminate schistosomiasis as a public health problem. The current diagnostic tools for urinary schistosomiasis, including the gold standard urine filtration test, have been reported to show low sensitivity in detecting low-intensity infections, which, when missed, act as reservoirs for infections—an evident gap in endemic areas where preventive chemotherapy reduces infection intensities. This study assessed the laboratory-based performance of the newly developed urinary Single Imaging Parasite Quantification chip for Schistosoma haematobium egg detection across different infection intensities. Two designs of the urinary chips were evaluated using polystyrene particles as a model for Schistosoma haematobium eggs, where the prototype design effectively captured the particles in the field of view with 96.00% to 100% efficiency. The second-generation chip, while eliminating the need for the air-drying step that was necessary in the operation of the prototype chip, similarly showed high capture efficiencies (95.20% to 96.00%). Overall, the prototype chip slightly outperformed the second-generation chip, and this difference was statistically significant (unpaired t-test, p = 0.0319). Testing of the prototype chip with spiked goat urine maintained high efficiencies of 99.33% to 100%. Similarly, both chip designs could trap real Schistosoma haematobium eggs in their fields of view, demonstrating their potential as diagnostic platforms that can contribute to improved diagnostics, disease surveillance, and monitoring. Full article

(This article belongs to the Special Issue Microfluidics in Biomedical Research)

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7 pages, 1170 KB

Open AccessArticle

The Transition from the Fowler–Nordheim Regime to the Space-Charge-Limited Current Regime in the Case of a Pointed Nanometric Emitter

by Dimitrios E. Karaoulanis and John P. Xanthakis

Micromachines 2026, 17(2), 269; https://doi.org/10.3390/mi17020269 - 20 Feb 2026

Viewed by 501

Abstract

We examine the transition from the Fowler–Nordheim (FN) field emission regime to the space-charge-limited (SCLC) regime in the case of a pointed nanometric emitter with radius of curvature R ≥ 5 nm, for which the traditional FN equations do not hold. To accomplish [...] Read more.

We examine the transition from the Fowler–Nordheim (FN) field emission regime to the space-charge-limited (SCLC) regime in the case of a pointed nanometric emitter with radius of curvature R ≥ 5 nm, for which the traditional FN equations do not hold. To accomplish this, we use the generalized FN equation for the emission law and the “time of flight” methodology to solve the equations of motion. Taking advantage of the fact that emission from emitters with R = a few nm takes place primarily along the emitter axis, we approximate the paths as linear, provided that the anode is at a far distant position from the cathode. In the approach to the SCLC regime, the calculated currents for emitters with R = a few nm may differ by orders of magnitude, compared to the currents of planar emitters, for the a given fixed anode–cathode separation D. Differences of even greater orders of magnitude are obtained for these currents when R is fixed and D is varied. Furthermore, the variation of currents with D is heavily dependent on R. However, for emitters with R ≥ 25 nm, no appreciable differences in current are observed, compared to the results obtained using the planar theory. An explanation for the observed trends is given. Full article

(This article belongs to the Special Issue Advances in Vacuum Nanoelectronics)

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18 pages, 6107 KB

Open AccessArticle

Design, Modeling, and Fabrication of a High-Q AlN Annular Gyroscope with Sub-10°/h Bias Instability

by Zhenxiang Qi, Jie Gu, Bingchen Zhu, Zhaoyang Zhai, Xiaorui Bie, Wuhao Yang and Xudong Zou

Micromachines 2026, 17(2), 268; https://doi.org/10.3390/mi17020268 - 20 Feb 2026

Viewed by 1453

Abstract

This work presents a high-performance piezoelectric MEMS yaw gyroscope fabricated on a single-crystal silicon platform, which achieves a quality factor of 75 k—the highest reported to date among silicon-based piezoelectric gyroscopes. The device employs a wide annular resonator that operates at 132 kHz [...] Read more.

This work presents a high-performance piezoelectric MEMS yaw gyroscope fabricated on a single-crystal silicon platform, which achieves a quality factor of 75 k—the highest reported to date among silicon-based piezoelectric gyroscopes. The device employs a wide annular resonator that operates at 132 kHz in the in-plane wineglass mode. To maximize transduction efficiency, we develop an analytical model that relates output charge to the area-integrated in-plane stress under modal deformation, and we use this model to guide parametric optimization of the annular width. The resulting geometry simultaneously enhances the mechanical quality factor and the piezoelectric coupling. A back-etching fabrication process is used to eliminate front-side release holes, thereby preserving structural continuity and suppressing thermoelastic damping. In open-loop rate mode operation with a native frequency split of 28 Hz, the gyroscope demonstrates an angle random walk of 0.34°/√h and a bias instability of 8.19°/h. These performance metrics are comparable to those of state-of-the-art lead zirconate titanate (PZT)-based annular gyroscopes, while the use of lead-free aluminum nitride as the transduction material ensures compliance with RoHS environmental regulations. Full article

(This article belongs to the Special Issue Artificial Intelligence for Micro Inertial Sensors)

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30 pages, 10883 KB

Open AccessEditor’s ChoiceReview

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 588

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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16 pages, 5386 KB

Open AccessArticle

Terahertz Wave Absorber Relying on Strontium Titanate and Dirac Semimetal for Dual Adjustability

by Zeng Qu, Mengyuan Zhao, Yuanhao Huang, Yibin Gong, Shishengdian Lu, Xuanqi Zhang, Jiayun Wang, Yuanhui Wang, Yinuo Cheng and Binzhen Zhang

Micromachines 2026, 17(2), 266; https://doi.org/10.3390/mi17020266 - 20 Feb 2026

Viewed by 356

Abstract

Limited by the material response characteristics and structural design, the development of dynamically tunable terahertz absorbers with multi-functional properties remains a major challenge. In this study, a dual-tunable terahertz absorber based on the synergistic integration of strontium titanate (STO) and Dirac semimetal (BDS) [...] Read more.

Limited by the material response characteristics and structural design, the development of dynamically tunable terahertz absorbers with multi-functional properties remains a major challenge. In this study, a dual-tunable terahertz absorber based on the synergistic integration of strontium titanate (STO) and Dirac semimetal (BDS) is proposed. By utilizing the temperature-sensitive dielectric constant of STO and the electrically tunable conductivity of BDS, the device can realize on-demand switching between a broadband absorption mode (absorptivity >90% in the 1.347~2.1271 THz band) and a dual-narrowband absorption mode under external field excitation. Notably, the centrosymmetric cross-patterned structure on the top layer ensures the polarization insensitivity of the device, and this single structure can also serve as a high-sensitivity temperature sensor. Simulation results verify that the device exhibits stable performance under different incident angles and environmental variations. This study constructs a compact multi-functional device platform integrating dynamic absorption regulation and in situ sensing, which provides a new technical route for the development of intelligent terahertz systems in the fields of terahertz imaging, communication, detection and other related areas. Full article

(This article belongs to the Special Issue Flexible Intelligent Sensors: Design, Fabrication and Applications)

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13 pages, 10392 KB

Open AccessArticle

Enhancement of TIRF Imaging of 3D-Cultured Spheroids via Hydrostatic Compression Using a Balloon Actuator

by Maho Kaminaga, Kaisei Nakano, Yuichi Marui, Sota Yamada, Masaki Matsuzaki and Hinata Kametaka

Micromachines 2026, 17(2), 265; https://doi.org/10.3390/mi17020265 - 20 Feb 2026

Viewed by 411

Abstract

Three-dimensional (3D) cultured cells can mimic the in vivo tumor microenvironment more accurately than conventional monolayer cultures. Therefore, they are essential in cancer research and drug discovery. However, high-sensitivity fluorescence imaging of 3D spheroids remains challenging owing to their limited contact with the [...] Read more.

Three-dimensional (3D) cultured cells can mimic the in vivo tumor microenvironment more accurately than conventional monolayer cultures. Therefore, they are essential in cancer research and drug discovery. However, high-sensitivity fluorescence imaging of 3D spheroids remains challenging owing to their limited contact with the observation surface and the low penetration depth of total internal reflection fluorescence microscopy (TIRFM). In this study, we developed a microfluidic device equipped with a water-driven balloon actuator that enables the hydrostatic compression of 3D-cultured spheroids. This system gently presses spheroids against a glass surface, significantly enhancing the contact area and improving TIRFM and epifluorescence imaging quality, with more evident improvement observed in TIRFM. Our results show that hydrostatic compression markedly enhances optical accessibility in spheroids while preserving cell viability and structural integrity. The method is designed to complement volumetric imaging techniques, including confocal and light-sheet microscopy, by enabling high-contrast visualization of cell–surface molecular dynamics. Although the current system focuses on surface accessibility, future studies will incorporate rotational mechanisms and automated pressure control to facilitate multi-angle, high-throughput imaging. This platform offers a promising strategy for the dynamic observation of cell–surface interactions in living 3D systems. Full article

(This article belongs to the Special Issue Microphysiological Systems for Cancer Research)

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22 pages, 2223 KB

Open AccessArticle

Vibration Resistance Optimization of Housing Based on CCD and Multi-Objective PSO

by Lei Cheng, Bingxing Wei, Xuanjun Dai and Yanan Bao

Micromachines 2026, 17(2), 264; https://doi.org/10.3390/mi17020264 - 19 Feb 2026

Viewed by 307

Abstract

To improve the operational reliability of semiconductor laser diode array beam combining systems under vibration conditions, this study introduces an integrated optimization approach combining central composite design (CCD) with multi-objective particle swarm optimization (PSO). The methodology involves establishing a response surface model correlating [...] Read more.

To improve the operational reliability of semiconductor laser diode array beam combining systems under vibration conditions, this study introduces an integrated optimization approach combining central composite design (CCD) with multi-objective particle swarm optimization (PSO). The methodology involves establishing a response surface model correlating housing stiffener parameters with vibration response indicators, subsequently applying multi-objective PSO for Pareto front optimization. This integrated strategy enables balanced multi-objective optimization of the anti-vibration structure. By modifying the original design into a vibration-resistant configuration, the approach delivers substantial performance enhancements: significantly increased first-order natural frequency, effectively suppressed maximum deformation under random vibration, and well-controlled mass addition. Comparative results demonstrate remarkable improvements over the initial design. The optimized parameter set elevates the first-order natural frequency from 356.3 Hz to 1036.1 Hz while reducing maximum deformation at critical positions from 0.2618 mm to 0.055 mm, with a minimal mass increase of merely 165.47 g. Vibration environment simulation verification demonstrates that after optimization, the output laser power decreases by only 3.3%, and the peak irradiance drops by 5.3%. These improvements substantially enhance system reliability under demanding mechanical conditions, confirming the effectiveness and engineering applicability of the CCD-PSO methodology for anti-vibration design in precision opto-mechanical systems. Full article

(This article belongs to the Section E：Engineering and Technology)

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31 pages, 3300 KB

Open AccessReview

Active Wavelength Control of Fiber Bragg Gratings: A Systematic Review of Tuning Mechanisms, Emerging Applications, and Future Frontiers

by Xiaoyan Wang, Erdong Xia, Chunrong Wang and Wen Ren

Micromachines 2026, 17(2), 263; https://doi.org/10.3390/mi17020263 - 19 Feb 2026

Viewed by 1457

Abstract

Fiber Bragg gratings (FBGs) have evolved from passive sensing elements into actively programmable photonic components, enabling dynamic wavelength control across diverse applications. This review provides a comprehensive and systematic overview of active wavelength control technologies for FBGs, deliberately excluding passive sensing applications. We [...] Read more.

Fiber Bragg gratings (FBGs) have evolved from passive sensing elements into actively programmable photonic components, enabling dynamic wavelength control across diverse applications. This review provides a comprehensive and systematic overview of active wavelength control technologies for FBGs, deliberately excluding passive sensing applications. We systematically categorize the fundamental tuning mechanisms—including mechanical, thermal, optothermal, electro-optic, nonlinear optical, and hybrid approaches—and compare their performance characteristics in terms of tuning range, speed, precision, and trade-offs. Key enhancement techniques, such as mechanical amplification, thermal packaging, femtosecond laser fabrication, and FPGA-based interrogation, are examined. The transformative impact of actively controlled FBGs is elucidated across three major application domains: tunable and narrow-linewidth fiber lasers, reconfigurable microwave photonic systems, and emerging fields including quantum information processing and biomedical imaging. A consolidated technology map visualizes the connections between enabling techniques and applications. Finally, we critically analyze core challenges—performance trade-offs, control complexity, and integration bottlenecks—and outline future research directions driven by novel materials, artificial intelligence, and quantum technologies. This review offers a structured framework for understanding active FBGs as programmable photonic primitives, providing actionable insights for researchers and engineers in academia and industry. Full article

(This article belongs to the Section E：Engineering and Technology)

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19 pages, 6537 KB

Open AccessArticle

Design and Study of a PVDF Piezoelectric Film Force Sensor Based on Interface Force Field Reconstruction and Surface Domain Segmentation

by Kaiqiang Yan, Wenge Wu, Xinyi Wu, Yunping Cheng, Lijuan Liu, Yongjuan Zhao, Yicheng Zhang, Pengcheng Liu and Zhi Wang

Micromachines 2026, 17(2), 262; https://doi.org/10.3390/mi17020262 - 19 Feb 2026

Viewed by 443

Abstract

The accurate measurement of dynamic forces is pivotal for advancing manufacturing process monitoring and enhancing equipment intelligence. To address the challenges of contact interface force field nonlinearity in existing PVDF piezoelectric film force sensors and the inability of a monolithic PVDF piezoelectric film [...] Read more.

The accurate measurement of dynamic forces is pivotal for advancing manufacturing process monitoring and enhancing equipment intelligence. To address the challenges of contact interface force field nonlinearity in existing PVDF piezoelectric film force sensors and the inability of a monolithic PVDF piezoelectric film to measure multi-dimensional forces, this study designs a uniform-load double-bossed elastic force-transmitting diaphragm to achieve contact interface force field reconstruction between the sensor’s elastic sensing structure and the sensitive element group. Building upon the load-bearing surface domain segmentation technique, the silver ink electrode on the front surface of a complete circular PVDF piezoelectric film is segmented into four independent sector-shaped rings. Each sector ring, together with its underlying PVDF piezoelectric film, constitutes a sensitive element, and these four sensitive elements are integrated to form the sensitive element group. The three-dimensional force measurement method of this sensitive element group in the Cartesian coordinate system is investigated. The measurement of three-dimensional force is realized by leveraging the tensile-compressive piezoelectric effect of each sensitive element in conjunction with a pre-stressed assembly structure. Quasi-static calibration test results indicate that the charge sensitivities of the force sensor in the X-, Y-, and Z-directions are 52.63 pC/N, 55.96 pC/N, and 9.02 pC/N, respectively, with a linearity ≤4.6%. Dynamic calibration test results reveal that the force measurement module exhibits a natural frequency of 4675.5 Hz. Experimental investigations into the response of triaxial cutting forces to variations in cutting speed, feed rate, and cutting depth were conducted, which verified the sensor’s ability to capture dynamic three-dimensional cutting forces. This study provides an effective solution for the structural design and three-dimensional force measurement methodology of PVDF piezoelectric film force sensors. Full article

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38 pages, 7875 KB

Open AccessEditor’s ChoiceReview

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 1162

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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14 pages, 1797 KB

Open AccessArticle

Development and Characterization of Dissolving Microneedles for the Buccal Delivery of Cannabidiol (CBD)

by Eleni Paganopoulou, Emmanouil Tzimtzimis, Dimitrios Tzetzis, Emmanuel Panteris, Chrysanthi Bekiari, Nikolaos Bouropoulos, Christos Cholevas, Zeeshan Ahmad, Paraskevi Kyriaki Monou and Dimitrios G. Fatouros

Micromachines 2026, 17(2), 260; https://doi.org/10.3390/mi17020260 - 17 Feb 2026

Viewed by 633

Abstract

This study aimed to develop dissolving microneedles (MNs) for the buccal delivery of cannabidiol (CBD). CBD is a non-psychotomimetic phytocannabinoid with anti-inflammatory and anxiolytic properties. The MN arrays were produced using micromolding, which has the ability of scalability. However, this approach lacks the [...] Read more.

This study aimed to develop dissolving microneedles (MNs) for the buccal delivery of cannabidiol (CBD). CBD is a non-psychotomimetic phytocannabinoid with anti-inflammatory and anxiolytic properties. The MN arrays were produced using micromolding, which has the ability of scalability. However, this approach lacks the ability to customize needle geometry; thus, additive manufacturing was implemented in the study. Digital Light Processing (DLP) printing is a promising way to produce molds with customized MN architecture. In the present study, molds were fabricated from 3D-printed MN arrays to prepare dissolving MNs for buccal administration. Polymeric needles based on Eudragit L100-55 and Eudragit RSPO were produced from reverse molds and they were evaluated regarding their physiochemical and mechanical properties, followed by in vitro and ex vivo studies using porcine buccal mucosa. Visualization studies were conducted using confocal scanning laser microscopy, whereas the membrane integrity of the porcine mucosa upon application of the MNs was assessed by histological evaluation. Our results suggest that the needles can be effectively inserted into the buccal tissue and release the active pharmaceutical ingredient (API) in a controlled manner. This approach offers a patient-friendly alternative to oral CBD delivery, bypassing first-pass metabolism. Full article

(This article belongs to the Special Issue Breaking Barriers: Microneedles in Therapeutics and Diagnostics)

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35 pages, 37297 KB

Open AccessArticle

Heterogeneous Acoustofluidic Distributions Induced by Different Radiation Surface Arrangements in Various Pseudo-Sierpiński-Carpet-Shaped Chambers

by Qiang Tang, Boyang Li, Chen Li, Junjie Wang, Huiyu Huang, Yulong Hu, Kan Zhu, Hao Chen, Xu Wang and Songfei Su

Micromachines 2026, 17(2), 259; https://doi.org/10.3390/mi17020259 - 16 Feb 2026

Viewed by 648

Abstract

In this research, an innovative scheme to generate heterogeneous acoustofluidic distributions in various pseudo-Sierpiński-carpet-shaped chambers with different filling fractions and cross-sectional configurations has been proposed and calculated for topographical manipulation of large-scale micro-particles. All of the structural components positioned in the pseudo-fractal chambers [...] Read more.

In this research, an innovative scheme to generate heterogeneous acoustofluidic distributions in various pseudo-Sierpiński-carpet-shaped chambers with different filling fractions and cross-sectional configurations has been proposed and calculated for topographical manipulation of large-scale micro-particles. All of the structural components positioned in the pseudo-fractal chambers are symmetrically distributed in space, and all ultrasonic radiation surfaces hold the unified settings of input frequency point, oscillation amplitude, and initial phase distribution along their respective normal directions. A large number of fascinating acoustofluidic patterns can be generated in the originally-static pseudo-Sierpiński-carpet-shaped chambers at different recursion levels without complicated vibration parameter modulation. The simulation results of acoustofluidic distributions and particle motion trajectories under different radiation surface arrangements further demonstrate the manipulation performance of these specially designed devices, and indicate that controllable spatial partitioning and intensity modulation of the acoustofluidic field can be achieved by adjusting the hierarchical order, cross-sectional configuration and combination mode of the radiation surfaces. Unlike the existing device construction method of miniaturized microfluidic systems, the artificial introduction of fractal elements like Sierpiński carpet/triangle, Koch snowflake, Mandelbrot set, Pythagoras tree, etc., can provide extraordinary perspectives and expand the application range of the acoustofluidic effect, which also makes ultrasonic micro/nano-scale manipulation technology more abundant and diversified. This exploratory research indicates the potential possibility of applying fractal structures as alternative component parts to purposefully customize acoustofluidic distributions for the further research of patterned manipulation of bio-organisms and navigation of micro-robot swarms in brand new ways that cannot be achieved through traditional methods. Full article

(This article belongs to the Special Issue Acoustic-Microfluidic Integration and Biological Applications)

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35 pages, 2729 KB

Open AccessReview

Soft Biomimetic Underwater Vehicles: A Review of Actuation Mechanisms, Structure Designs and Underwater Applications

by Xuejing Liu, Jing Li, Yu Xing, Zhouqiang Zhang, Yong Cao, Yonghui Cao and Bo Li

Micromachines 2026, 17(2), 258; https://doi.org/10.3390/mi17020258 - 16 Feb 2026

Viewed by 1872

Abstract

The growing demand for marine resource development and in-depth exploration of the marine environment has positioned soft biomimetic underwater vehicles (SBUVs) as a research hotspot in the fields of underwater equipment and soft robotics. SBUVs are characterized by bodies made of flexible and [...] Read more.

The growing demand for marine resource development and in-depth exploration of the marine environment has positioned soft biomimetic underwater vehicles (SBUVs) as a research hotspot in the fields of underwater equipment and soft robotics. SBUVs are characterized by bodies made of flexible and extensible materials, integrating the dual advantages of softness and biomimetics. They can achieve muscle-like continuous deformation to efficiently absorb collision energy, while mimicking the propulsion mechanisms of marine organisms—such as fish and jellyfish—through undulating body movements or cavity contraction and relaxation. Such biomimetic propulsion is highly compatible with the flexible actuation of soft materials, enabling excellent environmental adaptability while maintaining favorable propulsion efficiency. Compared with traditional rigid underwater vehicles, SBUVs offer higher degrees of freedom, superior environmental adaptability, enhanced impact resistance and greater motion flexibility. This review systematically summarizes typical actuation methods for SBUVs—including fluid-powered actuation, shape memory alloy actuation, and electroactive polymer actuation—elaborating on their working principles, key technological advances, and representative application cases on SBUVs. These actuation mechanisms each offer distinct advantages. Fluid-powered systems are valued for high power density and precise motion control through direct fluidic force transmission. Shape memory alloys provide high force output and accurate positional recovery via controlled thermal phase changes. Meanwhile, electroactive polymers stand out for their rapid (often millisecond-scale) dynamic response, low hysteresis, and fine, muscle-like deformation under electrical stimuli. Current challenges are also analyzed, such as limited actuation efficiency, material durability issues, and system integration difficulties. Despite these constraints, SBUVs show broad application prospects in marine resource exploration, ecological monitoring, and underwater engineering operations. Future research should prioritize the development of novel materials, coordinated optimization of actuation and control systems, and breakthroughs in core technologies to accelerate the practical implementation and industrialization of SBUVs. Full article

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11 pages, 1802 KB

Open AccessArticle

Design of a Dual-Band Broadband Antenna Based on Structure Reuse

by Huiru Zhang, Junwen Tang and Zhongjun Yu

Micromachines 2026, 17(2), 257; https://doi.org/10.3390/mi17020257 - 16 Feb 2026

Viewed by 402

Abstract

In this paper, a novel dual-band broadband antenna based on structure reuse is proposed. The proposed antenna integrates a slot antenna with a microstrip antenna to achieve dual-band performance. The slot antenna innovatively serves as both a radiating element and a feeding structure [...] Read more.

In this paper, a novel dual-band broadband antenna based on structure reuse is proposed. The proposed antenna integrates a slot antenna with a microstrip antenna to achieve dual-band performance. The slot antenna innovatively serves as both a radiating element and a feeding structure for the microstrip antenna, realizing structure reuse and significantly reducing structural complexity. To enhance the dual-band bandwidth, four symmetrically arranged parasitic strips are introduced, effectively extending the low-frequency bandwidth. Additionally, the high-frequency bandwidth is further improved by the introduction of a U-shaped slot. To analyze its working principle, the characteristics of the current and electric field distributions at each resonant point are given. The measured results indicate that in the low-frequency band, the proposed antenna achieves a relative bandwidth of 22.1% and a peak gain of 6.5 dBi. In the high-frequency band, it realizes a relative bandwidth of 13.6% and a peak gain of 4.6 dBi. Full article

(This article belongs to the Special Issue Design and Characterization of Microwave/Millimeter Wave Devices and Semiconductor Devices)

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18 pages, 2664 KB

Open AccessArticle

Trajectory-Based Identification of Rotary-Axis Position-Independent Geometric Errors Considering Excitation Projection Effects

by Songtao He, Seth Osei, Wei Wang, Jiaying Wang, Kaiyuan You, Qicheng Ding and Jiahao Yu

Micromachines 2026, 17(2), 256; https://doi.org/10.3390/mi17020256 - 16 Feb 2026

Viewed by 368

Abstract

Improving the identification accuracy of geometric errors in five-axis machine tools is a critical requirement in advanced manufacturing. Although rotary axes enhance machining flexibility and productivity, they introduce additional geometric errors, among which position-independent geometric errors (PIGEs) are a dominant source of accuracy [...] Read more.

Improving the identification accuracy of geometric errors in five-axis machine tools is a critical requirement in advanced manufacturing. Although rotary axes enhance machining flexibility and productivity, they introduce additional geometric errors, among which position-independent geometric errors (PIGEs) are a dominant source of accuracy degradation. Existing studies have paid limited attention to how excitation projection associated with test trajectories affects identification accuracy. This study proposes a trajectory-based identification method using a single setup and systematically investigates the influence of excitation projection on the identification accuracy of rotary-axis PIGEs. An error model and a double differential identification scheme are developed and validated through simulation and experimental studies. For the AC-type machine tool, both simulation and experimental results demonstrate that the accurate identification of all rotary-axis PIGEs is achieved after the second differential under a favorable excitation projection. In contrast, the simulation results for a BC-type machine tool indicate that the optimal excitation projection differs due to its kinematic configuration. Compensation results further confirm the effectiveness of the identified PIGEs, showing a significant reduction in trajectory errors. The results reveal that identification accuracy is governed by the relationship between excitation projection and machine tool structural configuration rather than by the physical test trajectory itself. The proposed method, which requires only a single setup, provides an effective and practical approach for improving the identification accuracy of rotary-axis PIGEs in five-axis machine tools. Full article

(This article belongs to the Section E：Engineering and Technology)

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18 pages, 12307 KB

Open AccessArticle

Investigation of a Novel Piezoelectric Harvester for Capturing Rotational Motion

by Junxiang Jiang, Heming Wang and Liang Wang

Micromachines 2026, 17(2), 255; https://doi.org/10.3390/mi17020255 - 16 Feb 2026

Viewed by 1319

Abstract

Piezoelectric energy harvesting technology has received great research interest in recent years. To harvest energy from rotational motion, this work proposes a cantilevered piezoelectric energy harvester based on an adjustable rigid parallel connection. The baffle was designed as a carrier for the rigid [...] Read more.

Piezoelectric energy harvesting technology has received great research interest in recent years. To harvest energy from rotational motion, this work proposes a cantilevered piezoelectric energy harvester based on an adjustable rigid parallel connection. The baffle was designed as a carrier for the rigid connection of the piezoelectric beams A, B and C. The theoretical model of the device was established, and equations for voltage and power were derived. The calculated intrinsic frequencies of the piezoelectric beams are consistent with the experimental results. The baffle size, the distance from the baffle to the free end, and the number of rotor bumps were used as variables in the experiments. The experimental results show that the proposed piezoelectric energy harvester can harvest energy across multiple frequency bands. The maximum average power of the proposed piezoelectric energy harvester is 110.49 mW at a load resistance of 10 kΩ and a rotational speed of 240 r/min. The maximum average power of the harvester is 36.44 mW at a load resistance of 10 kΩ and a rotational speed of 60 r/min. The rigid parallel connection not only broadens the energy harvesting bandwidth but also enhances the output performance of the harvester. Full article

(This article belongs to the Topic AI Sensors and Transducers)

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20 pages, 9096 KB

Open AccessArticle

Beam Drift Mitigation and Wide-Range Measurement in a Miniaturized Ultrasonic Gas Flowmeter

by Shanfeng Hou, Xueying Xiu, Chengguang Liu, Haochen Lyu and Songsong Zhang

Micromachines 2026, 17(2), 254; https://doi.org/10.3390/mi17020254 - 16 Feb 2026

Viewed by 1316

Abstract

To mitigate acoustic beam drift, which degrades the signal-to-noise ratio (SNR) and limits the measurement range in ultrasonic gas flowmeters (USFMs), we present a miniaturized transit-time USFM that integrates a single piezoelectric micromachined ultrasonic transducer (PMUT) with a non-axisymmetric conical cavity. This design [...] Read more.

To mitigate acoustic beam drift, which degrades the signal-to-noise ratio (SNR) and limits the measurement range in ultrasonic gas flowmeters (USFMs), we present a miniaturized transit-time USFM that integrates a single piezoelectric micromachined ultrasonic transducer (PMUT) with a non-axisymmetric conical cavity. This design increases acoustic transmission gain and produces anisotropic directivity across orthogonal radiation planes, thereby broadening acoustic coverage along the flow direction and reducing beam steering. With an optimized cavity angle combination of (50°, 70°), the system achieves a 7.4 dB transmission gain and a half-power beamwidth (HPBW) of 29.1°. Experimental validation demonstrates a sound pressure attenuation of only 0.72 dB at 18.74 m/s. Within the 0.06–12 m³/h flow range, the USFM exhibits indication errors of ±2% (<1 m³/h) and ±1.5% (≥1 m³/h), with repeatability below 0.5%. The performance meets the Class 1.5 accuracy standard specified in CJ/T 477-2015, offering an innovative solution for wide-range miniaturized gas flow measurement. Full article

(This article belongs to the Special Issue Acoustic Transducers and Their Applications, 3rd Edition)

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28 pages, 27017 KB

Open AccessArticle

Electro-Thermal Co-Design and Verification of TGV Transmission Structures for High-Power High-Frequency Applications

by Luming Chen, Zhilin Wei, Shenglin Ma, Yan Chen, Yihan Xie, Chunlei Li, Shuwei He and Hai Yuan

Micromachines 2026, 17(2), 253; https://doi.org/10.3390/mi17020253 - 16 Feb 2026

Viewed by 401

Abstract

Through Glass Via (TGV) technology has emerged as a promising solution for advanced packaging. While glass offers lower dielectric loss than silicon, its lower thermal conductivity raises concerns about electro-thermal coupling effects in high-power, high-frequency applications. Therefore, this study conducted an electro-thermal co-design [...] Read more.

Through Glass Via (TGV) technology has emerged as a promising solution for advanced packaging. While glass offers lower dielectric loss than silicon, its lower thermal conductivity raises concerns about electro-thermal coupling effects in high-power, high-frequency applications. Therefore, this study conducted an electro-thermal co-design of TGV grounded Coplanar Waveguide (CPW) and Radio Frequency (RF) TGV connected CPW structures. A high-power test platform was developed to investigate the electrical and thermal performance of these structures. The temperature distribution mechanism under high-power conditions was revealed. Under high power and high frequency, the decrease in surface conductivity affected by surface state and film layer composition leads to increased loss, triggering temperature rise and forming an electrothermal coupling loop. Under continuous wave operation (5–20 W), the temperature rise reaches 92.4 °C while insertion loss increases by only 0.4 dB. Under pulsed wave operation (25–100 W, 2.5% duty cycle), the temperature rise is merely 2.1 °C with insertion loss increasing by 0.3 dB. The quadruple-redundant design and reduces heat flux density, preventing localized hotspot formation. The pulse intervals suppress thermal accumulation, leading to lower temperature rise. Therefore, continuous wave applications should prioritize thermal management, while pulsed wave applications can focus on electrical performance optimization. Full article

(This article belongs to the Special Issue Microelectronics Assembly and Packaging: Materials and Technologies, 3rd Edition)

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21 pages, 5654 KB

Open AccessReview

Structure Defects in CVD-Grown Silicon Carbide Epitaxial Wafers: From Fundamental Principles to Advanced Reduction Strategies

by Guoliang Zhang, Tiantian Li, Yingbin Liu, Jinfeng Sun and Shaofei Zhang

Micromachines 2026, 17(2), 252; https://doi.org/10.3390/mi17020252 - 16 Feb 2026

Viewed by 616

Abstract

The chemical vapor deposition (CVD) method is a key technology for producing silicon carbide (SiC) epitaxial wafers used in high-performance power devices. Defects in the epitaxial wafers, such as triangular, threading dislocations (TDs); basal plane dislocations (BPDs); and stacking faults (SFs), are considered [...] Read more.

The chemical vapor deposition (CVD) method is a key technology for producing silicon carbide (SiC) epitaxial wafers used in high-performance power devices. Defects in the epitaxial wafers, such as triangular, threading dislocations (TDs); basal plane dislocations (BPDs); and stacking faults (SFs), are considered the critical bottleneck determining device performance and long-term reliability. This review aims to systematically elucidate the fundamental physical and chemical principles underlying defect generation during epitaxial growth of SiC by CVD and provide a comprehensive assessment of corresponding defect reduction strategies. Starting from the essential condition of thermodynamic growth, we analyze the main mechanisms of defect formation, including nonequilibrium kinetics, surface reaction kinetics, and the inheritance of substrate defects. Emphasis is placed on discussing the mechanisms and methods for suppressing defect formation through substrate engineering (off-angle design and surface pretreatment), precise control of the growth parameters (C/Si ratio, temperature, gas composition, and so on), as well as advanced post-treatment techniques. This leads to the proposal of practical strategies focusing on substrate engineering and growth parameter optimization toward practical application. Finally, we summarize the inspection techniques and outline future research directions toward intrinsic low-defect-density SiC epitaxial materials for high-voltage applications. Full article

(This article belongs to the Special Issue Advanced Nano-Semiconductor Devices: Design, Modeling and Next-Generation AI Applications)

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20 pages, 4253 KB

Open AccessFeature PaperEditor’s ChoiceArticle

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 322

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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16 pages, 15607 KB

Open AccessArticle

Ultrathin Microlens Arrays for Dynamic Beam Shaping Based on 3D Lithography

by Ruiqi Cheng, Yue Zhang, Shuo Chen, Yu Shu, Hao Cao and Chengqun Gui

Micromachines 2026, 17(2), 250; https://doi.org/10.3390/mi17020250 - 16 Feb 2026

Viewed by 384

Abstract

Conventional microlens arrays (MLAs) are often constrained by their static focal properties, which limit post-fabrication adaptability in dynamic optical systems. To address this, we demonstrate a tunable beam shaper capable of real-time spot-size modulation by introducing an adjustable axial displacement between a primary [...] Read more.

Conventional microlens arrays (MLAs) are often constrained by their static focal properties, which limit post-fabrication adaptability in dynamic optical systems. To address this, we demonstrate a tunable beam shaper capable of real-time spot-size modulation by introducing an adjustable axial displacement between a primary lens and an MLA. A critical advancement of this work is the fabrication of ultra-thin MLAs featuring an exceptionally low aspect ratio (1:187.5) and continuous surface profiles. Through optimizing 3D lithography and ion beam etching (IBE) workflows, we achieved an optical-grade surface finish with a roughness (Sa) of 3 nm. This high-fidelity, low-profile component enables efficient beam homogenization with reconfigurable working distances and spot dimensions. The proposed architecture provides a versatile and robust solution for advanced laser material processing, bridging the gap between static beam shaping and dynamic laser delivery. Full article

(This article belongs to the Special Issue Recent Advances in Micro/Nanofabrication, 3rd Edition)

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10 pages, 14258 KB

Open AccessArticle

Computational Approach to Fast Analysis of Electrochemical Impedance Spectroscopy

by Cristiano Lo Pò, Stefano Boscarino and Francesco Ruffino

Micromachines 2026, 17(2), 249; https://doi.org/10.3390/mi17020249 - 15 Feb 2026

Viewed by 360

Abstract

Electrochemical Impedance Spectroscopy (EIS) is a widely used technique for characterizing the electrode–electrolyte interface. EIS analysis can be very complex and tedious. In this work, a fitting algorithm written in C is implemented on OriginPro software to avoid the data import/export operation and [...] Read more.

Electrochemical Impedance Spectroscopy (EIS) is a widely used technique for characterizing the electrode–electrolyte interface. EIS analysis can be very complex and tedious. In this work, a fitting algorithm written in C is implemented on OriginPro software to avoid the data import/export operation and speed up the analysis. An automated fitting procedure that assigns the initial parameters is implemented for the simplest equivalent circuit. In addition, the possibility of using a custom error function is explored, with results comparable to that of reference software. The developed algorithm is tested on two different case studies. Full article

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9 pages, 3147 KB

Open AccessArticle

A Simple Microfluidic Device to Mitigate the Effect of Faradaic Reactions in Cross-Stream Particle Migration in DC-Electrokinetics

by Juan Arcenegui-Troya, Pablo García-Sánchez and Antonio Ramos

Micromachines 2026, 17(2), 248; https://doi.org/10.3390/mi17020248 - 13 Feb 2026

Viewed by 357

Abstract

Direct-current (DC) electrokinetics in microfluidic channels is inherently affected by Faradaic reactions at the electrode–electrolyte interfaces, which induce local changes in pH and conductivity and, consequently, alter particle behavior. In this work, we present a simple microfluidic T-junction device designed to mitigate these [...] Read more.

Direct-current (DC) electrokinetics in microfluidic channels is inherently affected by Faradaic reactions at the electrode–electrolyte interfaces, which induce local changes in pH and conductivity and, consequently, alter particle behavior. In this work, we present a simple microfluidic T-junction device designed to mitigate these effects by continuously flushing the regions near the electrodes with fresh electrolyte, thereby preserving the physicochemical properties of the main channel. Using fluorescence imaging with a pH-sensitive dye and electrical resistance measurements, we demonstrate that electrolyte acidification caused by water electrolysis can be effectively suppressed when advection overcomes electromigration of H⁺ ions. Order-of-magnitude estimates based on ion transport reveal that this condition is achieved when the flow velocity exceeds the characteristic electromigration velocity. We further investigate the effect of Faradaic reactions on cross-stream particle migration in electrophoresis experiments by quantifying the separation between suspended particles and the channel walls. We find that the particle–wall separation is significantly larger when electrolyte modifications are suppressed, clearly demonstrating the influence of Faradaic reactions on this phenomenon. Our results show that minimizing electrolyte modifications leads to a significantly enhanced particle-wall separation, highlighting the strong influence of Faradaic reactions on electrokinetic outcomes. These findings emphasize the importance of controlling electrochemical effects in DC electrokinetics and provide a simple and robust strategy to improve the accuracy and reproducibility of microfluidic electrophoresis experiments. Full article

(This article belongs to the Special Issue Electrokinetic and Electrochemical Phenomena in Microsystems)

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17 pages, 3422 KB

Open AccessArticle

MOF-Derived Co₃O₄ Dodecahedrons with Abundant Active Co³⁺ for CH₄ Gas Sensing at Room Temperature

by Xueqi Wang, Yu Hong, Guohui Wu, Yujie Hou, Shengnan Zhao, Binbin Dong, Jianchun Fan and Jun Yu

Micromachines 2026, 17(2), 247; https://doi.org/10.3390/mi17020247 - 13 Feb 2026

Viewed by 1204

Abstract

Gas sensors based on metal oxide semiconductors (MOS) have attracted significant attention in monitoring of methane emission and leakage monitoring due to their high sensitivity, fast response time, simple structure and low cost. However, the high power consumption caused by long-term high-temperature operation [...] Read more.

Gas sensors based on metal oxide semiconductors (MOS) have attracted significant attention in monitoring of methane emission and leakage monitoring due to their high sensitivity, fast response time, simple structure and low cost. However, the high power consumption caused by long-term high-temperature operation of MOS sensors restricts their application in mobile and portable devices. In this study, MOF-derived Co₃O₄ dodecahedrons for low-concentration methane detection at room temperature was prepared using Zeolitic Imidazolate Framework-67 (ZIF-67) as a template and with various calcination temperatures. Among them, the Co₃O₄-350 calcined at 350 °C exhibited the optimal CH₄ sensing performance at room temperature, with a response of R_g/R_a = 1.53 to 2000 ppm CH₄. This enhanced gas sensing performance is attributed to the highest Co³⁺ proportions and the largest specific surface area in Co₃O₄-350 nanomaterials, which provided more active sites for gas adsorption and reaction. To address the challenge of slow response speed and irrecoverability during CH₄ detection at room temperature, the Co₃O₄ nanomaterials were printed onto a micro-heater plate (MHP) to form a MEMS gas sensor. By introducing a pulse heating mode to the MEMS sensor, the response and recovery time were significantly reduced to 26 s and 21 s, respectively. This enhancement improves both the efficiency and reliability of the MEMS gas sensor for early-stage detection of CH₄ leaks in various industrial applications. Full article

(This article belongs to the Special Issue MEMS Gas Sensors and Electronic Nose)

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21 pages, 12375 KB

Open AccessReview

Research Progress of Acoustic Monitoring Technology in Welding and Additive Manufacturing Processes

by Qiang Zhu, Zaile Huang and Huan Li

Micromachines 2026, 17(2), 246; https://doi.org/10.3390/mi17020246 - 13 Feb 2026

Viewed by 1392

Abstract

Continuous innovations in welding and additive manufacturing (AM) technologies have introduced challenges related to process stability and uncertainties in ensuring high quality. Given the high complexity and transient nature of these processes, effective online acoustic monitoring is crucial for ensuring manufacturing quality and [...] Read more.

Continuous innovations in welding and additive manufacturing (AM) technologies have introduced challenges related to process stability and uncertainties in ensuring high quality. Given the high complexity and transient nature of these processes, effective online acoustic monitoring is crucial for ensuring manufacturing quality and improving processing efficiency. This paper first elucidates the principles of acoustic signal generation in welding and additive manufacturing. It then provides a comprehensive review of the application of acoustic methods for quality monitoring in these processes, covering both structural acoustic emission (AE) and airborne acoustic monitoring techniques. Finally, it summarizes the current challenges and issues faced by acoustic monitoring technologies in welding and additive manufacturing and outlines potential future development directions. Full article

(This article belongs to the Special Issue Future Prospects of Additive Manufacturing, 2nd Edition)

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Micromachines, Volume 17, Issue 2 (February 2026) – 131 articles

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