Micromachines

20 pages, 7856 KB

Open AccessArticle

Single-Die-Level MEMS Post-Processing for Prototyping CMOS-Based Neural Probes Combined with Optical Fibers for Optogenetic Neuromodulation

by Gabor Orban, Alberto Perna, Matteo Vincenzi, Raffaele Adamo, Gian Nicola Angotzi, Luca Berdondini and João Filipe Ribeiro

Micromachines 2026, 17(2), 159; https://doi.org/10.3390/mi17020159 - 26 Jan 2026

Abstract

The integration of complementary metal–oxide–semiconductor (CMOS) and micro-electromechanical systems (MEMSs) technologies for miniaturized biosensor fabrication enables unprecedented spatiotemporal resolution in monitoring the bioelectrical activity of the nervous system. Wafer-level CMOS technology incurs high costs, but multi-project wafer (MPW) runs mitigate this by allowing [...] Read more.

The integration of complementary metal–oxide–semiconductor (CMOS) and micro-electromechanical systems (MEMSs) technologies for miniaturized biosensor fabrication enables unprecedented spatiotemporal resolution in monitoring the bioelectrical activity of the nervous system. Wafer-level CMOS technology incurs high costs, but multi-project wafer (MPW) runs mitigate this by allowing multiple users to share a single wafer. Still, monolithic CMOS biosensors require specialized surface materials or device geometries incompatible with standard CMOS processes. Performing MEMS post-processing on the few square millimeters available in MPW dies remains a significant challenge. In this paper, we present a MEMS post-processing workflow tailored for CMOS dies that supports both surface material modification and layout shaping for intracortical biosensing applications. To address lithographic limitations on small substrates, we optimized spray-coating photolithography methods that suppress edge effects and enable reliable patterning and lift-off of diverse materials. We fabricated a needle-like, 512-channel simultaneous neural recording active pixel sensor (SiNAPS) technology based neural probe designed for integration with optical fibers for optogenetic studies. To mitigate photoelectric effects induced by light stimulation, we incorporated a photoelectric shield through simple modifications to the photolithography mask. Optical bench testing demonstrated >96% light-shielding effectiveness at 3 mW of light power applied directly to the probe electrodes. In vivo experiments confirmed the probe’s capability for high-resolution electrophysiological measurements. Full article

(This article belongs to the Special Issue CMOS-MEMS Fabrication Technologies and Devices, 2nd Edition)

15 pages, 4576 KB

Open AccessArticle

Design of a Compact UHF Wilkinson Power Divider Using a Combined T-Shaped–CCMRC Resonator for Harmonic Suppression

by Saeed Roshani, Salah I. Yahya, Golshan Mohamadpour and Sobhan Roshani

Micromachines 2026, 17(2), 158; https://doi.org/10.3390/mi17020158 - 26 Jan 2026

Abstract

This paper proposes a compact UHF microstrip divider with wideband harmonic suppression. A combined resonator, formed by a T-shaped resonator and a pair of coupled compact microstrip resonant cells (CCMRCs), is embedded into each divider branch to replace the conventional quarter-wavelength transmission lines. [...] Read more.

This paper proposes a compact UHF microstrip divider with wideband harmonic suppression. A combined resonator, formed by a T-shaped resonator and a pair of coupled compact microstrip resonant cells (CCMRCs), is embedded into each divider branch to replace the conventional quarter-wavelength transmission lines. The divider is designed on an FR4 substrate (ε_r = 4.4, thickness = 60 mil) for a center frequency of 570 MHz. Full-wave electromagnetic simulations indicate equal power division at 570 MHz with return loss better than 39 dB and output-port isolation higher than 47 dB. Moreover, a wide stopband from 1.5 GHz to 3.5 GHz is obtained, yielding strong attenuation for the third-to-sixth harmonics. The proposed layout occupies 19.6 mm × 21.6 mm, which is about 76% smaller than a conventional 570 MHz divider (42.7 mm × 41 mm). The proposed design is suitable for modern wireless communication systems. Full article

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

► Show Figures

Figure 1

14 pages, 2551 KB

Open AccessArticle

Long Short-Term Memory Network for Contralateral Knee Angle Estimation During Level-Ground Walking: A Feasibility Study on Able-Bodied Subjects

by Ala’a Al-Rashdan, Hala Amari and Yahia Al-Smadi

Micromachines 2026, 17(2), 157; https://doi.org/10.3390/mi17020157 - 26 Jan 2026

Abstract

Recent reports have revealed that the number of lower limb amputees worldwide has increased as a result of war, accidents, and vascular diseases and that transfemoral amputation accounts for 39% of cases, highlighting the need to develop an improved functional prosthetic knee joint [...] Read more.

Recent reports have revealed that the number of lower limb amputees worldwide has increased as a result of war, accidents, and vascular diseases and that transfemoral amputation accounts for 39% of cases, highlighting the need to develop an improved functional prosthetic knee joint that improves the amputee’s ability to resume activities of daily living. To enable transfemoral prosthesis users to walk on level ground, accurate prediction of the intended knee joint angle is critical for transfemoral prosthesis control. Therefore, the purpose of this research was to develop a technique for estimating knee joint angle utilizing a long short-term memory (LSTM) network and kinematic data collected from inertial measurement units (IMUs). The proposed LSTM network was trained and tested to estimate the contralateral knee angle using data collected from twenty able-bodied subjects using a lab-developed sensory gadget, which included four IMUs. Accordingly, the present work represents a feasibility investigation conducted on able-bodied individuals rather than a clinical validation for amputee gait. This study contributes to the field of bionics by mimicking the natural biomechanical behavior of the human knee joint during gait cycle to improve the control of artificial prosthetic knees. The proposed LSTM model learns the contralateral knee’s motion patterns in able-bodied gait and demonstrates the potential for future application in prosthesis control, although direct generalization to amputee users is outside the scope of this preliminary study. The contralateral LSTM models exhibited a real-time RMSE range of 2.48–2.78° and a correlation coefficient range of 0.9937–0.9991. This study proves the effectiveness of LSTM networks in estimating contralateral knee joint angles and shows their real-time performance and robustness, supporting its feasibility while acknowledging that further testing with amputee participants is required. Full article

► Show Figures

Graphical abstract

15 pages, 4874 KB

Open AccessArticle

Hierarchical Porous Nickel Oxide Nanoparticles with High Specific Surface Area by Green Synthesis

by Kamilya Khalugarova, Yulia M. Spivak, Dmitriy A. Kozodaev, Vyacheslav A. Moshnikov, Anna A. Dombrovskaya and Ekaterina K. Khrapova

Micromachines 2026, 17(2), 156; https://doi.org/10.3390/mi17020156 - 26 Jan 2026

Abstract

Porous nickel oxide nanoparticles with a hierarchical structure and high specific surface area were obtained by green synthesis followed by thermal annealing. The influence of the choice of precursor plant extract (Fumaria officinalis L. and Origanum vulgare L.) and the extractants in [...] Read more.

Porous nickel oxide nanoparticles with a hierarchical structure and high specific surface area were obtained by green synthesis followed by thermal annealing. The influence of the choice of precursor plant extract (Fumaria officinalis L. and Origanum vulgare L.) and the extractants in aqueous solutions on the parameters of the synthesized particles was studied. Characterization of the NiO morphology and composition, as well as the specific surface area, was performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and the BET method of nitrogen thermal desorption. Resulting particles have a spherical shape and a size from 30 to 50 nm. According to the data obtained, it can be seen that when the precursor is changed from Fumaria officinalis L. to Origanum vulgare L., the size of the synthesized particles increases, while the structure becomes more friable. It has been revealed that certain parameters and the nature of the assembly of porous particles lead to an increase in the surface area: the highest value of the SSA of 130.0 m²/g is observed in NiO nanoparticles obtained using Fumaria officinalis L. extract based on isopropyl alcohol. Also, a relatively high SSA value of 73.5 m²/g is observed in nanoparticles obtained using the same extractant for Origanum vulgare L. extract, while the use of an ethyl alcohol-based extractant for Fumaria officinalis L. resulted in the lowest value of 40.2 m²/g. The developed semiconductor particles are promising for use in catalysis, sensors, and as part of supercapacitor electrodes and functional layers in device structures for solar cells. Full article

► Show Figures

Figure 1

12 pages, 7999 KB

Open AccessArticle

A Transition Structure from Stripline to Substrate-Integrated Waveguide Based on LTCC

by Lu Teng, You Zhou, Ting Zhang, Zhongjun Yu and Shunli Han

Micromachines 2026, 17(2), 155; https://doi.org/10.3390/mi17020155 - 26 Jan 2026

Abstract

With the advancement of wireless communication technologies into high-frequency millimeter wave and sub-THz bands, conventional transmission lines such as microstrip and stripline face significant limitations. Under the circumstances, along with the increased application of new transmission lines such as substrate-integrated waveguides (SIWs), the [...] Read more.

With the advancement of wireless communication technologies into high-frequency millimeter wave and sub-THz bands, conventional transmission lines such as microstrip and stripline face significant limitations. Under the circumstances, along with the increased application of new transmission lines such as substrate-integrated waveguides (SIWs), the design of transition structures between different transmission lines has become a practical requirement in modern signal transmission systems. This paper presents a novel stripline to SIW transition structure. Drawing inspiration from the classical microstrip probe techniques in metal waveguides, the proposed design employs Low-Temperature Co-fired Ceramic (LTCC) technology for both device fabrication and SIW implementation. The developed structure demonstrates a stable performance, structural simplicity, and manufacturing feasibility. Through fabrication and testing, the transition structure can achieve a return loss below −10 dB across the 89–100 GHz frequency range, with an insertion loss of approximately 0.75 dB. Full article

(This article belongs to the Special Issue Microwave Passive Components, 3rd Edition)

► Show Figures

Figure 1

19 pages, 1924 KB

Open AccessArticle

Thermal–Electrical Fusion for Real-Time Condition Monitoring of IGBT Modules in Transportation Systems

by Man Cui, Yun Liu, Zhen Hu and Tao Shi

Micromachines 2026, 17(2), 154; https://doi.org/10.3390/mi17020154 - 25 Jan 2026

Abstract

The operational reliability of Insulated Gate Bipolar Transistor (IGBT) modules in demanding transportation applications, such as traction systems, is critically challenged by solder layer and bond wire failures under cyclic thermal stress. To address this, this paper proposes a novel health monitoring framework [...] Read more.

The operational reliability of Insulated Gate Bipolar Transistor (IGBT) modules in demanding transportation applications, such as traction systems, is critically challenged by solder layer and bond wire failures under cyclic thermal stress. To address this, this paper proposes a novel health monitoring framework that innovatively synergizes micro-scale spatial thermal analysis with microsecond electrical dynamics inversion. The method requires only non-invasive temperature measurements on the module baseplate and utilizes standard electrical signals (load current, duty cycle, switching frequency, DC-link voltage) readily available from the converter’s controller, enabling simultaneous diagnosis without dedicated voltage or high-bandwidth current sensors. First, a non-invasive assessment of solder layer fatigue is achieved by correlating the normalized thermal gradient (

\nabla T_{P}

) on the baseplate with the underlying thermal impedance (

Z_{JC}

). Second, for bond wire aging, a cost-effective inversion algorithm estimates the on-state voltage (

V_{ce, on}

) by calculating the total power loss from temperature, isolating the conduction loss (

P_{cond}

) with the aid of a Foster-model-based junction temperature (

T_{J}

) estimate, and finally computing

V_{ce, on}

at a unique current inflection point (

I_{C, \inf}

) to nullify

T_{J}

dependency. Third, the health states from both failure modes are fused for comprehensive condition evaluation. Experimental validation confirms the method’s accuracy in tracking both degradation modes. This work provides a practical and economical solution for online IGBT condition monitoring, enhancing the predictive maintenance and operational safety of transportation electrification systems. Full article

(This article belongs to the Special Issue Insulated Gate Bipolar Transistor (IGBT) Modules, 2nd Edition)

19 pages, 1074 KB

Open AccessArticle

An Analysis of Diffracted Mode Outcoupling in the Context of Optical Gain Measurements of Organic Thin Films: A Diffracted Emission Profile Method

by Thilo Pudleiner, Jan Hoinkis and Christian Karnutsch

Micromachines 2026, 17(2), 153; https://doi.org/10.3390/mi17020153 - 23 Jan 2026

Abstract

The sustained interest in efficient, low-cost, and straightforward-to-manufacture lasers has prompted intense research into organic semiconductor laser emitter materials in recent decades. The main focus of this research is determining the optical gains and losses of amplified spontaneous emission (ASE) in order to [...] Read more.

The sustained interest in efficient, low-cost, and straightforward-to-manufacture lasers has prompted intense research into organic semiconductor laser emitter materials in recent decades. The main focus of this research is determining the optical gains and losses of amplified spontaneous emission (ASE) in order to describe materials by their amplification signature. A method that has been used for decades as the standard technique for determining gain characteristics is the variable-stripe-length (VSL) method. The success of the VSL method has led to the development of further measurement techniques. These techniques provide a detailed insight into the nature of optical amplification. One such method is the scattered emission profile (SEP) method. In this study, we present an extension of the SEP method, the Diffracted Emission Profile (DEP) method. The DEP method is based on the detection of ASE by partial decoupling of waveguide modes diffracted by a one-dimensional grating integrated into a planar waveguide. Diffraction causes a proportion of the intensity to exit the waveguide, transferring the growth and decay process of the waveguide mode to the transverse mode profile of the diffracted mode. In the present article, an approach to determine the amplification signature of an organic copolymer is presented, utilizing partial decoupled radiation. Full article

(This article belongs to the Special Issue Emerging Trends in Optoelectronic Device Engineering, 2nd Edition)

► Show Figures

Graphical abstract

29 pages, 17610 KB

Open AccessArticle

Dynamic Cutting Force Prediction Model and Experimental Investigation of Ultrasonic Vibration-Assisted Sawing

by Yangyu Wang, Yao Wang, Pengcheng Ni, Shibiao Qu, Qiaoling Yuan, Hui Wang, Xiaojun Lei, Jianfeng Wang and Yizhi Wang

Micromachines 2026, 17(2), 152; https://doi.org/10.3390/mi17020152 - 23 Jan 2026

Abstract

In conventional band sawing, the long-span compression of the flexible saw blade often results in large fluctuations in cutting force, low cutting efficiency, and poor force predictability. To address these issues, this study investigates the dynamic cutting force modeling and experimental validation of [...] Read more.

In conventional band sawing, the long-span compression of the flexible saw blade often results in large fluctuations in cutting force, low cutting efficiency, and poor force predictability. To address these issues, this study investigates the dynamic cutting force modeling and experimental validation of ultrasonic vibration-assisted band sawing using 304 stainless steel as the workpiece material. Based on an analysis of the band sawing mechanism, an ultrasonic vibration-assisted approach is proposed to modify the contact conditions between the saw blade and the workpiece. A dynamic model of the saw blade is established using the string vibration equation, and a multi-tooth dynamic cutting force prediction model is further developed by incorporating variable cutting depth characteristics under ultrasonic vibration. Comparative experiments are conducted between conventional sawing and ultrasonic vibration-assisted sawing to validate the proposed model. At feed rates of 0.1–0.4 mm/s and preload values of 0.1–0.5 mm, the proposed model predicts dynamic cutting forces with good agreement to experimental results, achieving an average relative error of 5.44%. Under typical cutting conditions for difficult-to-machine materials, ultrasonic vibration-assisted sawing reduces the average cutting force and feed force by approximately 15% and 18%, respectively, while decreasing surface roughness along the feed direction by about 21%, thereby improving sawing efficiency and surface quality. Full article

► Show Figures

Figure 1

19 pages, 2721 KB

Open AccessArticle

A Portable Extended-Gate FET Integrated Sensing System with Low-Noise Current Readout for On-Site Detection of Escherichia coli O157:H7

by Weilin Guo, Yanping Hu, Yunchao Cao, Hongbin Zhang and Hong Wang

Micromachines 2026, 17(2), 151; https://doi.org/10.3390/mi17020151 - 23 Jan 2026

Abstract

Field-effect transistor (FET) biosensors enable label-free and real-time electrical transduction; however, their practical deployment is often constrained by the need for bulky benchtop instrumentation to provide stable biasing, low-noise readout, and data processing. Here, we report a portable extended-gate FET (EG-FET) integrated sensing [...] Read more.

Field-effect transistor (FET) biosensors enable label-free and real-time electrical transduction; however, their practical deployment is often constrained by the need for bulky benchtop instrumentation to provide stable biasing, low-noise readout, and data processing. Here, we report a portable extended-gate FET (EG-FET) integrated sensing system that consolidates the sensing interface, analog front-end conditioning, embedded acquisition/control, and user-side visualization into an end-to-end prototype suitable for on-site operation. The system couples a screen-printed Au extended-gate electrode to a MOSFET and employs a low-noise signal-conditioning chain with microcontroller-based digitization and real-time data streaming to a host graphical interface. As a proof-of-concept, enterohemorrhagic Escherichia coli O157:H7 was selected as the target. A bacteria-specific immunosensing interface was constructed on the Au extended gate via covalent immobilization of monoclonal antibodies. Measurements in buffered samples produced concentration-dependent current responses, and a linear calibration was experimentally validated over 10⁴–10¹⁰ CFU/mL. In specificity evaluation against three common foodborne pathogens (Staphylococcus aureus, Salmonella typhimurium, and Listeria monocytogenes), the sensor showed a maximum interference response of only 13% relative to the target signal (ΔI/ΔImax) with statistical significance (p < 0.001). Our work establishes a practical hardware–software architecture that mitigates reliance on benchtop instruments and provides a scalable route toward portable EG-FET sensing for rapid, point-of-need detection of foodborne pathogens and other biomarkers. Full article

(This article belongs to the Special Issue Next-Generation Biomedical Devices)

► Show Figures

Figure 1

15 pages, 2317 KB

Open AccessArticle

Experimental Study on Double-Sided Chemical Mechanical Polishing of Molybdenum Substrates for LED Devices

by Zhihao Zhou, Jiabin Wang, Zhongwei Hu, Pinhui Hsieh and Xipeng Xu

Micromachines 2026, 17(2), 150; https://doi.org/10.3390/mi17020150 - 23 Jan 2026

Abstract

As LED devices continue to advance toward miniaturization and higher power density, heat dissipation has become a critical factor constraining their reliability and service life. Molybdenum is widely employed as a substrate material in LED devices owing to its high thermal conductivity and [...] Read more.

As LED devices continue to advance toward miniaturization and higher power density, heat dissipation has become a critical factor constraining their reliability and service life. Molybdenum is widely employed as a substrate material in LED devices owing to its high thermal conductivity and low coefficient of thermal expansion. However, substrate applications impose stringent requirements on surface finish, flatness, and low-damage processing. Chemical mechanical polishing (CMP) can effectively balance global and local flatness and serves as the final step in producing high-quality molybdenum substrate surfaces. To enable efficient and precise processing of molybdenum substrates, this study adopts an orthogonal experimental design for double-sided CMP to systematically investigate the effects of polishing pressure, polishing slurry pH, additives in the polishing slurry, and abrasive particle size on the material removal rate (MRR) and surface roughness (Sa). An optimal parameter combination was identified via weight-matrix optimization: a polishing pressure of 115 kPa, pH 11, H₂O₂ (0.5%) and glycine (5 mg/L) as additives, and an abrasive particle size of 0.6 μm. Under these conditions, the MRR reached 80 nm·min⁻¹ and Sa decreased to 1.1 nm, yielding a smooth, mirror-like surface. The results indicate that multi-factor synergistic optimization can substantially enhance both surface quality and processing efficiency in double-sided CMP of molybdenum substrates, providing a process basis for applications in high-power LED devices. Full article

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

► Show Figures

Figure 1

10 pages, 1722 KB

Open AccessArticle

High-Indium-Composition, Ultra-Low-Power GaAsSb/InGaAs Heterojunction Tunnel Field-Effect Transistors

by Yan Liu, Xiang Li, Dao-Hua Zhang, Meng-Qi Fan, Xiao-Ping Wang and Yun-Jiang Jin

Micromachines 2026, 17(2), 149; https://doi.org/10.3390/mi17020149 - 23 Jan 2026

Abstract

In this work, we report the first systematic examination of how the In composition in the intrinsic In_xGa_1-xAs layer and the p-type doping concentration in the p-type GaAsSb layer affect the device performance of side-gate p-GaAs_0.5Sb_0.5 [...] Read more.

In this work, we report the first systematic examination of how the In composition in the intrinsic In_xGa_1-xAs layer and the p-type doping concentration in the p-type GaAsSb layer affect the device performance of side-gate p-GaAs_0.5Sb_0.5/i-In_xGa_1-xAs/n-In_0.53Ga_0.47As TFETs, using the technology computer-aided design (TCAD) simulations with a non-local band-to-band model. By tuning these two parameters, a moderate staggered alignment is achieved, enabling self-off operation at zero gate bias while maintaining high on-current. This tunability is an intrinsic and significant advantage of the p-GaAsSb/i-In_xGa_1-xAs heterojunction that has not been previously explored. It is found that the best device performance does not occur in the TFET with an In composition of 0.53 in the intrinsic layer, which is lattice-matched to the InP substrate, but rather occurs in the device with a higher In composition of around 0.59 in the InGaAs layer, which has been verified by experimental data to some extent. Optimal parameter combinations yield a minimum subthreshold swing of 13.51 mV/dec and an ON-state current of 35.39 μA/μm at V_DS = V_GS = 0.5 V due to the enhanced tunneling capability. Full article

(This article belongs to the Special Issue Power Semiconductor Devices and Integration Technology)

► Show Figures

Figure 1

17 pages, 3206 KB

Open AccessArticle

Effect of Channel Height on CO₂-to-CH₄ Reduction in Microchannel Electrocatalysis

by Zheng-Yan Lei, Nguyen Van Toan, Masaya Toda, Ioana Voiculescu and Takahito Ono

Micromachines 2026, 17(2), 148; https://doi.org/10.3390/mi17020148 - 23 Jan 2026

Abstract

Electrocatalytic CO₂ reduction is a promising approach to mitigate rising atmospheric CO₂ levels while converting CO₂ into valuable products such as CH₄. Conversion into other useful substances further expands its potential applications. However, the efficiency of the CO [...] Read more.

Electrocatalytic CO₂ reduction is a promising approach to mitigate rising atmospheric CO₂ levels while converting CO₂ into valuable products such as CH₄. Conversion into other useful substances further expands its potential applications. However, the efficiency of the CO₂ reduction reaction (CO₂RR) is strongly influenced by device geometry and CO₂ mass transfer in the electrolyte. In this work, we present and evaluate microchannel electrocatalytic devices consisting of a porous Cu cathode and a Pt anode, fabricated via metal-assisted chemical etching (MACE). The porous surfaces generated through MACE enhanced reaction activity. To study the impact of the distance between electrodes, several devices with different channel heights were fabricated and tested. The device with the highest CH₄ selectivity had a narrow inter-electrode gap of 50 μm and achieved a Faradaic efficiency of 56 ± 11% at an applied potential of −5 V versus an Ag/AgCl reference electrode. This efficiency was considerably higher than that of the device with larger inter-electrode gaps (300 and 480 μm). This reduced efficiency in the larger channel was attributed to limited CO₂ availability at the cathode surface. Bubble visualization experiments further demonstrated that the electrolyte flow rate had a strong impact on supplied CO₂ bubble morphology and mass transfer. At a flow rate of 0.75 mL/min, smaller CO₂ bubbles were formed, increasing the gas–liquid interfacial area and thereby enhancing CO₂ dissolution into the electrolyte. These results underline the critical role of electrode gap design and bubble dynamics in optimizing microchannel electrocatalytic devices for efficient CO₂RR. Full article

(This article belongs to the Special Issue Energy Conversion Materials/Devices and Their Applications, 2nd Edition)

► Show Figures

Figure 1

19 pages, 3442 KB

Open AccessArticle

A Responsive and Precise Particle Position Control System Combining a Sidewall-Driven Peristaltic Micropump and a High-Speed Camera

by Yuta Tanaka and Toshio Takayama

Micromachines 2026, 17(2), 147; https://doi.org/10.3390/mi17020147 - 23 Jan 2026

Abstract

The systems to manipulate a single particle in a microfluidic channel can be adopted to pharmacological and cytological experiments of single-cell observation. The common cell position systems use syringe pumps driven by piezoelectric devices, and these have a flow quantity limit. To achieve [...] Read more.

The systems to manipulate a single particle in a microfluidic channel can be adopted to pharmacological and cytological experiments of single-cell observation. The common cell position systems use syringe pumps driven by piezoelectric devices, and these have a flow quantity limit. To achieve single-cell manipulation using actuators without limiting the flow quantity and with a low risk of contamination, we propose a particle control system that uses a sidewall-driven peristaltic micropump driven by pneumatic pressure. The adopted pump was integrated into a single-layer mold with a flow path and was simple to fabricate. Unlike syringe pumps, it not only pumps water forward, but also inhales from the back simultaneously, and can pump indefinitely. We developed a responsive and precise particle position control system using this pump in combination with a high-speed camera. In this system, the pumping pressure is operated by real-time adjustment of a pneumatic pressure supply to realize PID control. This approach moves the particle rapidly when it is far from a designated target position for a quick approach and slowly near the target position to position precisely. Full article

(This article belongs to the Special Issue MEMS Actuators and Their Applications)

► Show Figures

Figure 1

16 pages, 9493 KB

Open AccessArticle

Multi-Objective Optimization of Material Removal Characteristics for Robot Polishing of Ti-6Al-4V

by Fengjun Chen, Rui Bao, Meiling Du, Mu Cheng and Jiehong Peng

Micromachines 2026, 17(2), 146; https://doi.org/10.3390/mi17020146 - 23 Jan 2026

Abstract

This study employs a multi-objective particle swarm optimization (MOPSO) algorithm to address the dual-objective challenge in the robotic polishing of Ti-6Al-4V. The aim is to determine optimal parameters that minimize surface roughness while maximizing the material removal rate (MRR), thereby improving both surface [...] Read more.

This study employs a multi-objective particle swarm optimization (MOPSO) algorithm to address the dual-objective challenge in the robotic polishing of Ti-6Al-4V. The aim is to determine optimal parameters that minimize surface roughness while maximizing the material removal rate (MRR), thereby improving both surface quality and processing efficiency. First, a material removal depth model for end-face polishing is established based on Preston’s equation and theoretical analysis, from which the MRR model is derived. Subsequently, orthogonal experiments are conducted to investigate the influence of process parameters and their interactions on surface roughness, followed by the development of a quadratic polynomial roughness prediction model. Analysis of variance (ANOVA) and model validation confirm the model’s reliability. Finally, the MOPSO algorithm is applied to obtain the Pareto optimal solution set, yielding the optimal parameter combination. Experimental results demonstrate that at a normal contact force of 7.58 N, a feed rate of 4.52 mm/s, and a spindle speed of 5851 rpm, the achieved MRR and Ra values are 0.2197 mm³/s and 0.291 μm, respectively. These results exhibit errors of only 5.64% and 2.65% compared to model predictions, validating the proposed method’s effectiveness. Full article

(This article belongs to the Special Issue Ultra-Precision Surface Abrasive Micro-Machining: Advances and Applications)

► Show Figures

Figure 1

16 pages, 13695 KB

Open AccessArticle

InGaN Laser Diode with Spin-on-Glass Isolation Fabricated by Planarization and Etch-Back Process

by Katarzyna Piotrowska-Wolińska, Szymon Grzanka, Łucja Marona, Krzysztof Gibasiewicz, Anna Kafar and Piotr Perlin

Micromachines 2026, 17(2), 142; https://doi.org/10.3390/mi17020142 - 23 Jan 2026

Abstract

We report on the fabrication and characterization of InGaN-based ridge-waveguide laser diodes employing spin-on-glass (SOG) as the insulation and planarization layer. In contrast to conventional silicon dioxide (SiO₂) isolation deposited by PECVD, the SOG approach provides improved surface planarity, reduced processing [...] Read more.

We report on the fabrication and characterization of InGaN-based ridge-waveguide laser diodes employing spin-on-glass (SOG) as the insulation and planarization layer. In contrast to conventional silicon dioxide (SiO₂) isolation deposited by PECVD, the SOG approach provides improved surface planarity, reduced processing complexity, and lower fabrication cost. The laser structures were grown on GaN substrates by MOCVD, with the active region consisting of In_0.11Ga_0.89N quantum wells. Following ridge formation and SOG deposition, an etch-back process was used to form the electrical contacts. We have demonstrated the formation of high-quality insulating surfaces with strong adhesion to the ridge sidewalls. When using a Ni protective layer, the fabricated devices exhibited favorable electrical and optical characteristics and achieved stable laser operation under both pulsed and continuous-wave conditions. These results indicate that the SOG-based insulation process represents a promising alternative for the scalable and cost-effective fabrication of InGaN laser diodes targeting advanced photonic applications. Full article

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

► Show Figures

Figure 1

4 pages, 199 KB

Open AccessEditorial

Future Development Strategy of Piezoelectric Devices

by Kenji Uchino

Micromachines 2026, 17(1), 145; https://doi.org/10.3390/mi17010145 - 22 Jan 2026

Abstract

Firstly, the five key development trends in the field of piezoelectric materials are discussed to offer the present perspective: “Performance to Reliability,” “Hard to Soft,” “Macro to Nano,” “Homo to Hetero,” and “Single to Multi-functional [...] Full article

(This article belongs to the Section A：Physics)

16 pages, 4501 KB

Open AccessArticle

Millimeter-Level MEMS Actuators Based on Multi-Folded Beams and Harmful Mode-Suppression Structures

by Hangyu Zhou, Wei Bian and Rui You

Micromachines 2026, 17(1), 144; https://doi.org/10.3390/mi17010144 - 22 Jan 2026

Abstract

Module-level free-space optical interconnects require actuators to combine both large stroke and high stability. To address this core trade-off that plagues traditional folded-beam actuators, we have developed a millimeter-scale MEMS electromagnetic actuator integrating a Differential Motion Rejection (DMR) unit with a rigid frame. [...] Read more.

Module-level free-space optical interconnects require actuators to combine both large stroke and high stability. To address this core trade-off that plagues traditional folded-beam actuators, we have developed a millimeter-scale MEMS electromagnetic actuator integrating a Differential Motion Rejection (DMR) unit with a rigid frame. Its performance was systematically evaluated through magnetic–structural coupling modeling, finite element simulation, and experiments. The actuator achieved millimeter-scale stroke under sinusoidal drive, with a primary resonant frequency of approximately 31 Hz. The introduction of the DMR and frame proved highly effective: the out-of-plane displacement at resonance was reduced by about 97%, the static Z-direction stiffness increased by over 50 times, and the displacement crosstalk decreased to 0.265%. Optical testing yielded a stable deflection angle of approximately ±21°. These results demonstrate that this design successfully combines large stroke with high stability, significantly suppressing out-of-plane parasitic motion and crosstalk, making it suitable for module-level optical interconnect systems with stringent space and stability requirements. Full article

(This article belongs to the Collection Optical MEMS: Design, Fabrication, Control, Modeling and Developments)

► Show Figures

Figure 1

17 pages, 3961 KB

Open AccessArticle

Influence Mechanism of Quantization Error on the Key Parameters of the Whole-Angle Hemisphere Resonator Gyroscope

by Xiuyue Yan, Jingyu Li, Pengbo Xiao, Tao Xia, Xingyuan Tang, Yao Pan, Kaiyong Yang and Hui Luo

Micromachines 2026, 17(1), 143; https://doi.org/10.3390/mi17010143 - 22 Jan 2026

Abstract

The whole-angle hemispherical resonator gyroscope (WA-HRG) is critical to high-precision attitude control and navigational positioning, boasting significant deployment potential in both highly dynamic inertial navigation systems and industrial instrumentation. This paper presents a mechanistic analysis of quantization error inherent to the HRG’s hardware [...] Read more.

The whole-angle hemispherical resonator gyroscope (WA-HRG) is critical to high-precision attitude control and navigational positioning, boasting significant deployment potential in both highly dynamic inertial navigation systems and industrial instrumentation. This paper presents a mechanistic analysis of quantization error inherent to the HRG’s hardware detection and driving circuits, focusing specifically on its impact on parameter calculation and driving control in whole-angle mode. Furthermore, a simulation platform was constructed to verify and elucidate the correlations between the effects of quantization error and key resonator parameters, such as the major axis amplitude and the standing wave azimuth. Compared to existing HRG error studies which frame quantization error as isolated circuit noise, this work uniquely uncovers the azimuth-modulated periodic behavior of quantization error within the WA-HRG. It also formalizes a quantitative relationship between quantization error and the resonator’s key parameters, laying a critical theoretical foundation for suppressing quantization error and enhancing accuracy in high-performance WA-HRGs. Full article

► Show Figures

Figure 1

12 pages, 3014 KB

Open AccessArticle

The Application of High-Performance Silver Nanowire and Metal Oxide Composite Electrodes as Window Electrodes in Electroluminescent Devices

by Xingzhen Yan, Ziyao Niu, Mengying Lyu, Yanjie Wang, Fan Yang, Chao Wang, Yaodan Chi and Xiaotian Yang

Micromachines 2026, 17(1), 141; https://doi.org/10.3390/mi17010141 - 22 Jan 2026

Abstract

In this paper, composite structures were fabricated by incorporating silver nanowires (AgNWs) with various metal oxides via the sol–gel method. This approach enhanced the electrical performance of AgNW-based transparent electrodes while simultaneously improving their stability under damp heat conditions and modifying the local [...] Read more.

In this paper, composite structures were fabricated by incorporating silver nanowires (AgNWs) with various metal oxides via the sol–gel method. This approach enhanced the electrical performance of AgNW-based transparent electrodes while simultaneously improving their stability under damp heat conditions and modifying the local medium environment surrounding the AgNW meshes. The randomly distributed AgNW meshes fabricated via drop-coating were treated with plasma to remove surface organic residues and reduce the inter-nanowire contact resistance. Subsequently, a zinc oxide (ZnO) coating was applied to further decrease the sheet resistance (R_sheet) value. The pristine AgNW mesh exhibits an R_sheet of 17.4 ohm/sq and an optical transmittance of 93.06% at a wavelength of 550 nm. After treatment, the composite structure achieves a reduced R_sheet of 8.7 ohm/sq while maintaining a high optical transmittance of 92.20%. The use of AgNW meshes as window electrodes enhances electron injection efficiency and facilitates the coupling mechanism between localized surface plasmon resonances and excitons. Compared with conventional ITO transparent electrodes, the incorporation of the AgNW mesh leads to a 17-fold enhancement in ZnO emission intensity under identical injection current conditions. Moreover, the unique scattering characteristics of the AgNW and metal oxide composite structure effectively reduce photon reflection at the device interface, thereby broadening the angular distribution of emitted light in electroluminescent devices. Full article

(This article belongs to the Special Issue Energy Conversion Materials/Devices and Their Applications, 2nd Edition)

► Show Figures

Figure 1

Journal Description

Micromachines

Latest Articles

Journal Menu

Journal Browser

Highly Accessed Articles

Latest Books

E-Mail Alert

News

Topics

Conferences

Special Issues

Topical Collections

Further Information

Guidelines

MDPI Initiatives

Follow MDPI