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Open AccessEditorial

Editorial for the Special Issue on MEMS/NEMS Devices and Applications, 3rd Edition

by Zhi-Xuan Dai, Takahito Ono and Ching-Liang Dai

Micromachines 2026, 17(2), 205; https://doi.org/10.3390/mi17020205 - 2 Feb 2026

Viewed by 601

Abstract

Microelectromechanical systems (MEMS) and nanoelectromechanical systems (NEMS) have experienced rapid and sustained development in recent years and have become key enabling technologies for intelligent sensing [...] Full article

(This article belongs to the Special Issue MEMS/NEMS Devices and Applications, 3rd Edition)

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Research

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13 pages, 2512 KB

Open AccessArticle

Radio-Frequency Characteristics of Stacked Metal–Insulator–Metal Capacitors in Radio-Frequency CMOS Devices

by Tae Min Choi, Hwa Rim Lee and Sung Gyu Pyo

Micromachines 2026, 17(1), 54; https://doi.org/10.3390/mi17010054 - 30 Dec 2025

Viewed by 896

Abstract

This paper describes the radio-frequency (RF) characteristics of stacked metal–insulator–metal (MIM) capacitors used in RF CMOS technology. To ensure accurate analysis, various de-embedding methods for stacked MIM capacitors were verified, and an improved RF model was constructed accordingly. To develop an equivalent circuit [...] Read more.

This paper describes the radio-frequency (RF) characteristics of stacked metal–insulator–metal (MIM) capacitors used in RF CMOS technology. To ensure accurate analysis, various de-embedding methods for stacked MIM capacitors were verified, and an improved RF model was constructed accordingly. To develop an equivalent circuit for the improved RF model by analyzing the RF characteristics of stacked MIM capacitors, we compared de-embedding methods for measured stacked MIM capacitors: one-step (open-pattern or short-pattern) de-embedding and two-step (combined open-pattern and short-pattern) de-embedding. For the analysis of stacked MIM capacitors, at least two-step de-embedding was used, while for precise de-embedding, three-step de-embedding using a thru pattern was employed. Based on the measured values obtained using these two-step de-embedding methods, a modified equivalent circuit was constructed. This circuit was analyzed based on various parameters, including MIM capacitance, quality factor, S-parameter, and Y-parameter, and the results were comparatively examined. The findings highlight outstanding accuracy of the modified model, which is maintained even in high frequency bands. Full article

(This article belongs to the Special Issue MEMS/NEMS Devices and Applications, 3rd Edition)

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16 pages, 5163 KB

Open AccessArticle

CMOS-Compatible Micro Photovoltaic Generator with Post-Processing Enhanced Optical Absorption

by Hung-Wei Chen, Chi-Yuan Lee and Ching-Liang Dai

Micromachines 2026, 17(1), 48; https://doi.org/10.3390/mi17010048 - 30 Dec 2025

Viewed by 1043

Abstract

This work reports the design and realization of a silicon-based micro photovoltaic generator (MPG) fabricated using a standard 0.18 μm complementary metal oxide semiconductor (CMOS) technology. The device harvests optical energy and converts it into electrical power through the photovoltaic effect, leveraging a [...] Read more.

This work reports the design and realization of a silicon-based micro photovoltaic generator (MPG) fabricated using a standard 0.18 μm complementary metal oxide semiconductor (CMOS) technology. The device harvests optical energy and converts it into electrical power through the photovoltaic effect, leveraging a network of engineered p–n junctions formed within the semiconductor. A grid-structured architecture is adopted, in which patterned p-type regions are embedded inside an n-well platform. This configuration expands the effective junction area, increases carrier-collection paths, and strengthens the internal electric field, thereby enhancing photocurrent generation. To further improve optical coupling, a specialized post-CMOS treatment is introduced. A wet etching is used to selectively remove the silicon dioxide layer that normally covers the junction regions in CMOS processes. Eliminating this dielectric layer enables direct photon penetration into the depletion region minimizes reflection-related losses, resulting in a significant improvement in device performance. Under an illumination intensity of 1000 W/m², the fabricated microgenerator delivers an open-circuit voltage of 0.49 V, a short-circuit current of 239 µA, and a maximum output power of 90 µW. The device exhibits an overall energy conversion efficiency of 12.9%, confirming the effectiveness of the grid-like junction design and the post-processing oxide removal. Full article

(This article belongs to the Special Issue MEMS/NEMS Devices and Applications, 3rd Edition)

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13 pages, 4656 KB

Open AccessArticle

Experimental Study on the Performance of Light-Controlled Ion Drag Pump Based on PLZT Ceramic

by Yujuan Tang, Yujie Shi, Zhen Lv, Zihao Guo and Xinjie Wang

Micromachines 2026, 17(1), 45; https://doi.org/10.3390/mi17010045 - 29 Dec 2025

Viewed by 1016

Abstract

Light-controlled ion drag pumps have attracted considerable interest in soft robotics, biomedical engineering, and microelectromechanical systems (MEMS) due to their non-contact energy supply and high spatiotemporal controllability of light. However, experimental studies on their pumping performance and influencing factors remain limited. This study [...] Read more.

Light-controlled ion drag pumps have attracted considerable interest in soft robotics, biomedical engineering, and microelectromechanical systems (MEMS) due to their non-contact energy supply and high spatiotemporal controllability of light. However, experimental studies on their pumping performance and influencing factors remain limited. This study integrates the photoelectric effect with field emission phenomena to design and fabricate a light-controlled ion drag pump using lanthanum-modified lead zirconate titanate (PLZT) ceramic. The light-controlled pump enables non-contact energy transfer and fluid transport via high-energy laser irradiation. A series of experiments systematically investigate its pumping performance and key influencing factors. Results indicate that optimizing electrode structure and fluid channel design, along with increased light intensity, significantly enhances pumping performance. This work provides fundamental design guidelines for the application of light-controlled ion drag pumps in microfluidics, flexible robotics, and microdevice thermal management. Full article

(This article belongs to the Special Issue MEMS/NEMS Devices and Applications, 3rd Edition)

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14 pages, 1727 KB

Open AccessArticle

Behavior of Electrothermal Actuator Analyzed by Polynomial Point Interpolation Collocation Method

by Yujuan Tang, Aidong Qi, Yuanhu Gu, Yinfa Zhu, Haojie Li, Dao Gu and Hao Chen

Micromachines 2025, 16(12), 1415; https://doi.org/10.3390/mi16121415 - 16 Dec 2025

Viewed by 474

Abstract

This paper presents a novel implementation of the Polynomial Point Interpolation Collocation Method (PPCM) for analyzing the coupled electrothermal and thermomechanical behavior of V-shaped microactuators. Within the PPCM framework, the governing equations for heat transfer and structural mechanics are discretized over the computational [...] Read more.

This paper presents a novel implementation of the Polynomial Point Interpolation Collocation Method (PPCM) for analyzing the coupled electrothermal and thermomechanical behavior of V-shaped microactuators. Within the PPCM framework, the governing equations for heat transfer and structural mechanics are discretized over the computational domain. The resulting discrete electrothermal system is solved in a fully coupled manner via an incremental load method to determine the temperature field. Subsequently, the displacement field is computed by solving the discrete mechanical equation, which incorporates terms from the natural boundary conditions. The MQ radial basis function behaves well in convergence when its parameters p_a and p_q are 1 and 1.8. Under a 6 V voltage, the difference between the PPCM and FEM temperature values is less than 1 °C. Meanwhile, the discrepancy between the PPCM and experimental temperature values is approximately 20 °C, corresponding to an approximate error of 10%. Furthermore, the displacement error between the PPCM and FEM is as low as approximately 2 μm under an applied voltage of 12 V. These results validate the PPCM for predicting the driving characteristics of V-shaped microactuators. Full article

(This article belongs to the Special Issue MEMS/NEMS Devices and Applications, 3rd Edition)

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15 pages, 5631 KB

Open AccessArticle

Design and Evaluation of a Capacitive Micromachined Ultrasonic Transducer(CMUT) Linear Array System for Thickness Measurement of Marine Structures Under Varying Environmental Conditions

by Changde He, Mengke Luo, Hanchi Chai, Hongliang Wang, Guojun Zhang, Renxin Wang, Jiangong Cui, Yuhua Yang, Wendong Zhang and Licheng Jia

Micromachines 2025, 16(8), 898; https://doi.org/10.3390/mi16080898 - 31 Jul 2025

Cited by 2 | Viewed by 3995

Abstract

This paper presents the design, fabrication, and experimental evaluation of a capacitive micromachined ultrasonic transducer (CMUT) linear array for non-contact thickness measurement of marine engineering structures. A 16-element CMUT array was fabricated using a silicon–silicon wafer bonding process, and encapsulated in polyurethane to [...] Read more.

This paper presents the design, fabrication, and experimental evaluation of a capacitive micromachined ultrasonic transducer (CMUT) linear array for non-contact thickness measurement of marine engineering structures. A 16-element CMUT array was fabricated using a silicon–silicon wafer bonding process, and encapsulated in polyurethane to ensure acoustic impedance matching and environmental protection in underwater conditions. The acoustic performance of the encapsulated CMUT was characterized using standard piezoelectric transducers as reference. The array achieved a transmitting sensitivity of 146.82 dB and a receiving sensitivity of −229.55 dB at 1 MHz. A complete thickness detection system was developed by integrating the CMUT array with a custom transceiver circuit and implementing a time-of-flight (ToF) measurement algorithm. To evaluate environmental robustness, systematic experiments were conducted under varying water temperatures and salinity levels. The results demonstrate that the absolute thickness measurement error remains within ±0.1 mm under all tested conditions, satisfying the accuracy requirements for marine structural health monitoring. The results validate the feasibility of CMUT-based systems for precise and stable thickness measurement in underwater environments, and support their application in non-destructive evaluation of marine infrastructure. Full article

(This article belongs to the Special Issue MEMS/NEMS Devices and Applications, 3rd Edition)

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9 pages, 2576 KB

Open AccessArticle

Novel Debris Material Identification Method Based on Impedance Microsensor

by Haotian Shi, Yucai Xie and Hongpeng Zhang

Micromachines 2025, 16(7), 812; https://doi.org/10.3390/mi16070812 - 14 Jul 2025

Cited by 1 | Viewed by 925

Abstract

Oil condition monitoring can ensure the safe operation of mechanical equipment. Metal debris is full of friction information, and the identification of debris material helps to locate wear of parts. A method based on impedance analysis is proposed to identify debris material in [...] Read more.

Oil condition monitoring can ensure the safe operation of mechanical equipment. Metal debris is full of friction information, and the identification of debris material helps to locate wear of parts. A method based on impedance analysis is proposed to identify debris material in this article. The differences in permeability and conductivity result in the nonlinear variation trend of inductance–resistance amplitude with debris volume. By establishing a database of amplitude–size curves, debris information (material and size) can be obtained through impedance analysis. Based on experimental and simulation results, iron, stainless steel, aluminum, copper, and brass particles are effectively distinguished. This method is not affected by oil’s light transmittance, other impurities, and debris surface dirt and can be used to distinguish metals with similar colors. This work provides a novel solution for debris material identification, which is expected to promote the development of fault diagnosis. Full article

(This article belongs to the Special Issue MEMS/NEMS Devices and Applications, 3rd Edition)

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18 pages, 3047 KB

Open AccessArticle

A Rotary Piezoelectric Electromagnetic Hybrid Energy Harvester

by Zhiyang Yao and Chong Li

Micromachines 2025, 16(7), 807; https://doi.org/10.3390/mi16070807 - 11 Jul 2025

Cited by 4 | Viewed by 1730

Abstract

To collect the energy generated by rotational motion in the natural environment, a piezoelectric electromagnetic hybrid energy harvester (HEH) based on a planetary gear system is proposed. The harvester combines piezoelectric and electromagnetic effects and is mainly used for collecting low-frequency rotational energy. [...] Read more.

To collect the energy generated by rotational motion in the natural environment, a piezoelectric electromagnetic hybrid energy harvester (HEH) based on a planetary gear system is proposed. The harvester combines piezoelectric and electromagnetic effects and is mainly used for collecting low-frequency rotational energy. The HEH has a compact structure and contains four sets of piezoelectric energy harvesters (PEHs) and electromagnetic energy harvesters (EMHs) inside. The working principle of the energy harvester is analyzed, its theoretical model is established, and a simulation analysis is conducted. To verify the effectiveness of the design, an experimental device is constructed. The results indicate that the HEH can generate an average output power of 250 mW under eight magnets and an external excitation frequency of 7 Hz. In actual power supply testing, the HEH can light up 60 LEDs and provide stable power supply for the temperature–humidity meter. Full article

(This article belongs to the Special Issue MEMS/NEMS Devices and Applications, 3rd Edition)

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19 pages, 6232 KB

Open AccessArticle

Study on the Driving Performance and Influencing Factors of Multi-Electrothermal Co-Actuation Devices Considering Application Environments

by Yujuan Tang, Zihao Guo, Yujiao Ding and Xinjie Wang

Micromachines 2025, 16(6), 603; https://doi.org/10.3390/mi16060603 - 22 May 2025

Cited by 3 | Viewed by 842

Abstract

Electrothermal actuators, with their simple structure, small size, strong anti-interference ability, and easy integration, have emerged as a promising solution for micro-drive technology. However, deploying them in extreme environments, such as the fuze systems—which demand exceptional reliability under high mechanical overloads. In this [...] Read more.

Electrothermal actuators, with their simple structure, small size, strong anti-interference ability, and easy integration, have emerged as a promising solution for micro-drive technology. However, deploying them in extreme environments, such as the fuze systems—which demand exceptional reliability under high mechanical overloads. In this study, a device based on multi-electrothermal co-actuation is designed for the fuze system of loitering munition. The overall structure and work principle of the multi-electrothermal co-actuation device is discussed. Considering application environments, the effect factors of V-beam numbers, air gap, type of contact surface, external load force, periodic voltage and gas damping on the output performance of the multi-electrothermal co-actuation device are systematically addressed via simulation and experimental method. Furthermore, the high overload resistance performance of the co-actuation device applied in loitering munition is studied. The results show that the proposed multi-electrothermal co-actuation device could operate stably under a high overload (12,000 g/73.79 μs) environment, fully meeting the demanding requirements of fuze system for loitering munition. In addition, this study identifies laser processing-induced thermal gradients and mechanical stresses as critical fabrication challenges. This study provides significant insights into the design and optimization of multi-electrothermal actuation systems for next-generation fuze applications, establishing a valuable framework for future development in this field. Full article

(This article belongs to the Special Issue MEMS/NEMS Devices and Applications, 3rd Edition)

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13 pages, 4832 KB

Open AccessArticle

Enhancement of Quality Factors in a 6.5 GHz Resonator Using Mo/SiC Composite Microstructures

by Binghui Lin, Yupeng Zheng, Haiyang Li, Yuqi Ren, Tingting Yang, Zekai Wang, Yao Cai, Qinwen Xu and Chengliang Sun

Micromachines 2025, 16(5), 529; https://doi.org/10.3390/mi16050529 - 29 Apr 2025

Cited by 1 | Viewed by 1003

Abstract

This study addresses the critical challenge of lateral acoustic wave energy leakage in high-frequency film bulk acoustic resonators (FBARs) and elucidates the reflection mechanism of acoustic waves at acoustic reflection boundaries. Based on the theory of acoustic impedance mismatch, a novel Mo/SiC composite [...] Read more.

This study addresses the critical challenge of lateral acoustic wave energy leakage in high-frequency film bulk acoustic resonators (FBARs) and elucidates the reflection mechanism of acoustic waves at acoustic reflection boundaries. Based on the theory of acoustic impedance mismatch, a novel Mo/SiC composite microstructure is designed to strategically establish multiple acoustic reflection boundaries along the lateral acoustic wave leakage paths. Finite element simulations reveal that SiC microstructures effectively suppress vibration amplitudes in non-resonant regions, thereby preventing acoustic wave leakage. By integrating Mo and SiC microstructures, the proposed composite structure significantly enhances the resonator’s acoustic confinement and energy retention capabilities. A resonator incorporating this Mo/SiC composite microstructure is fabricated, achieving a series resonance frequency of 6.488 GHz and a remarkable quality factor (Q) of 310. This represents a substantial 51.2% improvement in Q compared to the basic FBAR, confirming the effectiveness of the proposed design in mitigating lateral acoustic wave leakage and enhancing resonator performance for high-frequency, low-loss applications. This work offers valuable insights into the design of next-generation RF resonators for advanced wireless communication systems. Full article

(This article belongs to the Special Issue MEMS/NEMS Devices and Applications, 3rd Edition)

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19 pages, 14110 KB

Open AccessArticle

A 3D DC Electric Field Meter Based on Sensor Chips Packaged Using a Highly Sensitive Scheme

by Pengfei Yang, Xiaolong Wen, Xiaonan Li, Zhaozhi Chu, Chunrong Peng and Shuang Wu

Micromachines 2025, 16(4), 484; https://doi.org/10.3390/mi16040484 - 20 Apr 2025

Cited by 2 | Viewed by 2930

Abstract

This study presents a 3D DC electric field meter (EFM) that uses three identical 1D MEMS chips. The shielding electrodes and sensing electrodes of the MEMS chips employ a combination of rigid frames and short strip-type beams to improve vibrational stability. To enhance [...] Read more.

This study presents a 3D DC electric field meter (EFM) that uses three identical 1D MEMS chips. The shielding electrodes and sensing electrodes of the MEMS chips employ a combination of rigid frames and short strip-type beams to improve vibrational stability. To enhance sensitivity, our MEMS chips feature inner convex packaging covers. Moreover, the integrated design and wireless transmission efficiently eradicate the impact of ground potential on detection results. Detailed simulations have been conducted to analyze the electric field distribution within the chip package and the electric field distribution on the EFM’s surface. A prototype was then developed, calibrated, and validated. The test results indicate that the sensitivity of our proposed 3D EFM is at least 4.64 times higher than the highest sensitivity observed in previously reported MEMS 3D EFMs. The maximum relative deviation is a mere 2.2% for any rotation attitude. Remarkably, even in high humidity conditions, the EFM’s linearity remains within 1%. Additionally, the resolution of any single axis is less than 10 V/m. Full article

(This article belongs to the Special Issue MEMS/NEMS Devices and Applications, 3rd Edition)

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14 pages, 2588 KB

Open AccessArticle

Accelerated Electro-Optic Switching in Liquid Crystal Devices via Ion Trapping by Dispersed Helical Carbon Nanotubes

by Rajratan Basu and Christian C. Kehr

Micromachines 2025, 16(4), 457; https://doi.org/10.3390/mi16040457 - 12 Apr 2025

Cited by 4 | Viewed by 1601

Abstract

Free ion impurities in liquid crystals significantly impact the dynamic electro-optic performance of liquid crystal displays, leading to slow switching times, short-term flickering, and long-term image sticking. These ionic contaminants originate from various sources, including LC cell fabrication, electrode degradation, and organic alignment [...] Read more.

Free ion impurities in liquid crystals significantly impact the dynamic electro-optic performance of liquid crystal displays, leading to slow switching times, short-term flickering, and long-term image sticking. These ionic contaminants originate from various sources, including LC cell fabrication, electrode degradation, and organic alignment layers. This study demonstrates that doping LCs with a small concentration of helical carbon nanotubes effectively reduces free ion concentrations by approximately 70%. The resulting reduction in ionic impurities lowers the rotational viscosity of the LC, facilitating faster electro-optic switching. Additionally, the purified LC exhibits enhanced dielectric anisotropy, further improving its performance in display applications. These findings suggest that helical carbon nanotubes doping offers a promising approach for mitigating ion-related issues in liquid crystals without the need for additional chemical treatments, paving the way for an efficient liquid crystal display technology. Full article

(This article belongs to the Special Issue MEMS/NEMS Devices and Applications, 3rd Edition)

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Review

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22 pages, 4298 KB

Open AccessReview

Examination of Impact of NBTIs on Commercial Power P-Channel VDMOS Transistors in Practical Applications

by Danijel Danković, Emilija Živanović, Nevena Veselinović, Dunja Đorđević, Marija Petrović, Lana Tasić, Miloš Marjanović, Sandra Veljković, Nikola Mitrović, Vojkan Davidović and Goran Ristić

Micromachines 2026, 17(1), 52; https://doi.org/10.3390/mi17010052 - 30 Dec 2025

Viewed by 563

Abstract

In this paper, the impact of negative bias temperature instabilities (NBTIs) on commercial power p-channel Vertical Double-Diffused MOS (VDMOS) transistors from the standpoint of practical applications was analyzed. The effects of NBTI are one of the main reliability concerns for this type of [...] Read more.

In this paper, the impact of negative bias temperature instabilities (NBTIs) on commercial power p-channel Vertical Double-Diffused MOS (VDMOS) transistors from the standpoint of practical applications was analyzed. The effects of NBTI are one of the main reliability concerns for this type of device, so it is necessary to investigate how these effects influence various applications. A series of experiments were carried out including negative bias temperature stressing, infra-red thermographic recording and circuit characterization, with the goal of evaluating the effects of negative bias temperature stressing on the self-heating of samples in load-driving circuits operating with higher currents and circuit performance of a CMOS inverter circuit containing the examined samples. The findings suggest that negative bias temperature stressing-induced threshold voltage shift directly affects increased self-heating in load-driving circuits and that it also directly affects transfer and dynamics characteristics in CMOS inverters. Full article

(This article belongs to the Special Issue MEMS/NEMS Devices and Applications, 3rd Edition)

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31 pages, 11019 KB

Open AccessFeature PaperEditor’s ChoiceReview

A Review of Tunnel Field-Effect Transistors: Materials, Structures, and Applications

by Shupeng Chen, Yourui An, Shulong Wang and Hongxia Liu

Micromachines 2025, 16(8), 881; https://doi.org/10.3390/mi16080881 - 29 Jul 2025

Cited by 10 | Viewed by 6883

Abstract

The development of an integrated circuit faces the challenge of the physical limit of Moore’s Law. One of the most important “Beyond Moore” challenges is the scaling down of Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) versus their increasing static power consumption. This is because, at [...] Read more.

The development of an integrated circuit faces the challenge of the physical limit of Moore’s Law. One of the most important “Beyond Moore” challenges is the scaling down of Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) versus their increasing static power consumption. This is because, at room temperature, the thermal emission transportation mechanism will cause a physical limitation on subthreshold swing (SS), which is fundamentally limited to a minimum value of 60 mV/decade for MOSFETs, and accompanied by an increase in off-state leakage current with the process of scaling down. Moreover, the impacts of short-channel effects on device performance also become an increasingly severe problem with channel length scaling down. Due to the band-to-band tunneling mechanism, Tunnel Field-Effect Transistors (TFETs) can reach a far lower SS than MOSFETs. Recent research works indicated that TFETs are already becoming some of the promising candidates of conventional MOSFETs for ultra-low-power applications. This paper provides a review of some advances in materials and structures along the evolutionary process of TFETs. An in-depth discussion of both experimental works and simulation works is conducted. Furthermore, the performance of TFETs with different structures and materials is explored in detail as well, covering Si, Ge, III-V compounds and 2D materials, alongside different innovative device structures. Additionally, this work provides an outlook on the prospects of TFETs in future ultra-low-power electronics and biosensor applications. Full article

(This article belongs to the Special Issue MEMS/NEMS Devices and Applications, 3rd Edition)

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