Search Results (256)

Electrostatic MEMS micromirrors provide a compact and low-power beam-steering solution for miniaturized laser communication terminals. However, when they are used for quasi-static beam pointing rather than resonant scanning, the nonlinear voltage–angle relationship, bidirectional actuation asymmetry, and terminal-level installation errors can significantly degrade pointing accuracy. In this paper, a nonlinear modeling and differential-voltage control method is investigated for a two-axis electrostatic MEMS micromirror used in a miniaturized laser communication terminal. The device under test is a bonded aluminum MEMS micromirror with a 5.0 mm aperture. Static and dynamic characterization results show that the micromirror achieves maximum mechanical deflection angles of 5.215° and 5.161° along the X and Y axes, respectively, with resonant frequencies of 317 Hz and 319 Hz. To improve the accuracy of quasi-static pointing, the differential-voltage actuation principle is analyzed, and a nonlinear voltage–angle model is established based on measured deflection data. Compared with a first-order linear model, the cubic nonlinear model reduces the root-mean-square fitting error from 0.142° to 0.0127° for the X axis and from 0.132° to 0.0109° for the Y axis. Furthermore, a terminal-level calibration architecture based on a quadrant detector is introduced to map the MEMS angular deflection to the received spot position. The proposed modeling and calibration approach provides an actuator-level basis for accurate beam pointing and closed-loop acquisition in miniaturized laser communication terminals. Full article

This article introduces the current status of the 0.18-micron CMOS MEMS foundry service platform provided by the Taiwan Semiconductor Research Institute (TSRI), extensively covering the CMOS MEMS components that it has supported in development and fabrication. It also attempts to expand the foundry service scope to the broader categories of capacitive sensors and electrostatic actuators. On the one hand, for fabless MEMS component designers, TSRI currently directly allows the design of two types of components: flow sensors with uniformly perforated membranes and actuators with comb-shaped interdigital electrodes. This service also includes tape-out and wire bonding packaging procedures, following procedures similar to those used by general IC designers. On the other hand, this article specifically presents a clear and feasible approach for MEMS designers equipped with simple wet-etching facilities and a clear and feasible approach to develop further CMOS MEMS components such as capacitive pressure sensors, accelerometers, micro mirrors, and scratch drive actuators with minimal post-processing and chip packaging steps. This work provides a practical CMOS-MEMS design and post-processing guideline for extending the current TSRI foundry platform toward capacitive sensing and electrostatic actuation applications with minimal additional fabrication complexity. Full article

Artificial muscles are an emerging class of actuators designed to mimic the compliant, efficient, and versatile behavior of biological muscles for fields including the following: soft robotics, prosthetics, wearable enhancements, haptic interfaces, and biomedical devices. These systems encompass various actuation mechanisms, including pneumatic, hydraulic, thermal, ionic, electrochemical, and electrostatic. Each with distinct tradeoffs in voltage, strain, output force, bandwidth, efficiency, and manufacturability. Among them, electrostatic actuators have attracted increased attention due to their fast response times, high energy densities, strong compatibility with soft materials, and scalability from microscale devices to large-area and stacked actuators. However, challenges such as dielectric breakdown, material fatigue, and fabrication complexity continue to limit widespread deployment. This review presents a structured classification of various artificial muscle technologies and an in-depth examination of electrostatic actuators including dielectric elastomers, electrostrictive and ferroelectric polymers, liquid crystal elastomers, electrostatic film motors, stacked architectures, and microscale/milliscale devices. In this review the operating principles, materials, architectures, performance characteristics, and failure modes of electrostatic actuators will be discussed. Additionally, a comparison will highlight tradeoffs across actuator families based on metrics such as voltage, force, strain, bandwidth, and manufacturability. Lastly, we outline future research directions in materials, physics-informed modeling, system integration, and scalable fabrication necessary to advance electrostatic artificial muscles toward practical, real-world deployment. Full article

The concept, design, technological fabrication and experimental characterization of a function unit consisting of two mechanically coupled MEMS micromirrors, denoted in this paper as Tandem Micromirrors (TMM) unit, are presented. Conventional single micromirrors reveal much faster closing than reopening times, which is undesirable for some applications. The future and final goal is to equalize these two characteristic times using TMM. Methodologically, this shall be achieved by combining the closing operation of a first mirror with the opening operation of a second one and the closing operation of the second mirror with the opening operation of the first. The focus of this paper is the design and development of the coupling elements between the two mirrors, as well as the technological fabrication and characterization of the mechanically coupled bidirectional electrostatic actuation of the tandem micromirrors. Full article

Magnetic photonic crystal microspheres (MPCMs) have emerged as a versatile platform for intelligent sensing and display applications, owing to their integration of magnetic actuation with structural coloration. However, their practical implementation is limited by a fundamental structural constraint: most reported MPCMs adopt anisotropic architectures, resulting in angle-dependent optical responses that require continuous magnetic alignment to maintain uniform coloration. Herein, we propose a different structural paradigm based on non-close-packed, optically isotropic MPCMs. Driven by electrostatic repulsion in solutions, monodisperse Fe₃O₄@tannic acid (TA) core–shell nanoparticles spontaneously assemble into non-close-packed amorphous colloidal arrays, also known as photonic glasses, which are subsequently immobilized within stimuli-responsive polymer networks via emulsification-assisted thermal polymerization. By integrating poly(2-hydroxyethyl methacrylate-co-N-vinylpyrrolidone) (HEMA–NVP) or poly(N-isopropylacrylamide) (PNIPAM) as responsive matrices, the resulting MPCMs exhibit sensitive solvent- or thermo-dependent optical responses. Crucially, structural isotropy ensures angle-independent coloration, eliminating the need for continuous magnetic alignment during optical readout. As evidenced by the unchanged structural color and reflection peak under various magnetic field orientations, this design effectively decouples optical sensing from magnetic actuation. The intrinsic free volume of the non-close-packed architecture allows for isotropic lattice expansion and contraction, leading to broad spectral tunability. Collectively, this work establishes a promising design framework for magnetic photonic microsensors. Full article

This review deals with the development and progress of micro-electromechanical systems (MEMS) actuators, which are needed in microfluidic applications, such as lab-on-a-chip and diagnostics. In the last 10 years, there have been tremendous advances in materials, microfabrication and computational modeling that have increased the functionality and scope of MEMS-based microfluidic actuation. This study classifies MEMS actuators on the basis of the physical method of actuation, including electrostatic, piezoelectric, and pneumatic actuation designs, in comparison with their application in pumping, valving, and droplet control. It examines the suitability of emerging structural and functional materials, such as piezoelectric thin-films and electroactive polymers, paying special attention to their reliability and biocompatibility. It also highlights the progress in multiphysics modeling that incorporates electrical, thermal, mechanical, and fluidic models, which facilitates the efficient design and performance optimization procedures. Other trends are multifunctional actuators with built-in sensing capability and the use of artificial intelligence (AI)-assisted design in production. With these developments, however, there exist issues of power efficiency, thermal control, fabrication uniformity and operational durability, and also the absence of standardized benchmarking. Finally, future research directions are outlined, including hybrid MEMS actuation, intelligent microfluidic operations, to improve the performance of the system and enable the transfer of the lab demonstrations to the large scale application of the system. Full article

Since the first synthetic macrocyclic receptors were shown to bind ions selectively, supramolecular host–guest chemistry has enabled the translation of molecular recognition events into physical signals. Early coupling of such receptors to ion-sensitive field-effect transistors established a bridge between supramolecular chemistry and solid-state electronics. Today, this bridge is rebuilt in iontronics, where ions carry information through nanoconfined media and ionic transport becomes highly sensitive to electrostatic gradients, surface charge, and surface molecular interactions. As a result, ionic flux can serve as an efficient transduction mechanism that responds precisely, reversibly, and rapidly to changes in the chemical environment. Within this regime, host–guest chemistry offers a powerful means to exert direct control over ionic behavior, allowing molecular recognition to modulate conductance, rectification, and ion selectivity, thereby conferring practical function to nanofluidic systems. This review highlights systems in which host molecules act as chemical actuators that modulate nanochannel surface chemistry, thereby regulating ionic flux and enabling reversible, tunable, and stimulus-responsive behaviors. We survey architectures in which crown ethers, calixcrowns, pillararenes, and related hosts are integrated into solid-state nanochannels, emphasizing representative achievements such as biological-level Na⁺/K⁺ selectivity in crown ether-based systems and nanomolar-level detection of ions using calixcrowns- and pillararene-functionalized nanochannels. Finally, we discuss how temperature, pH, light, and redox state act as external stimuli that reversibly switch between conductive states, yielding ion-selective platforms for sensing and ion sieving. Full article

With the rapid development of high-voltage DC (HVDC) power systems, accurate measurement of surface electrostatic potential on insulating components has become critical for electric field assessment and insulation reliability. This paper proposes an electrostatic potential sensor based on cantilever micro-vibration modulation, which employs piezoelectric actuators to drive high-frequency micro-vibration of cantilever-type shielding electrodes, converting the static electrostatic potential into an alternating induced charge signal. An electrostatic induction model is established to describe the sensing principle, and the influence of structural and operating parameters on sensitivity is analyzed. Multi-physics coupled simulations are conducted to optimize the cantilever geometry and modulation frequency, aiming to enhance modulation efficiency while maintaining a compact sensor structure. To validate the effectiveness of the proposed sensor, an electrostatic potential measurement platform for insulating components is constructed, obtaining response curves of the sensor at different potentials and establishing a compensation model for the working distance correction coefficient. The experimental results demonstrate that the sensor achieves a maximum measurement error of 0.92% and a linearity of 0.47% within the 1–10 kV range. Surface potential distribution measurements of a post insulator under DC voltage agreed well with simulation results, demonstrating the effectiveness and applicability of the proposed sensor for HVDC insulation monitoring. Full article

Triboelectric nanogenerators (TENGs) offer intrinsically high open-circuit voltages in the kilovolt range; however, conventional diode rectifier interfaces clamp the voltage prematurely, restricting access to the high-energy portion of the mechanical cycle and preventing delivery-centric control. This work develops a unified physical basis for contact–separation (CS) TENGs by confirming the consistency of the canonical $V_{oc}$–$C_s$ relation with a dual-capacitor energy model and analytically establishing that both terminal voltage and storable electrostatic energy peak near maximum plate separation. Leveraging this insight, a self-powered gas-discharge-tube (GDT) rectifier bridge is devised to replace two diodes and autonomously trigger conduction exclusively in the high-voltage window without auxiliary bias. An inductive buffer regulates the current slew rate and reduces $I^{2}R$ loss, while the proposed topology realizes two decoupled power rails from a single CS-TENG, enabling simultaneous sensing/processing and actuation. A low-power microcontroller is powered from one rail through an energy-harvesting module and executes an operator-based nonlinear controller to regulate the actuator-side rail via a MOSFET–resistor path. Experimental results demonstrate earlier and higher-efficiency energy transfer compared with a diode-bridge baseline, robust dual-rail decoupling under dynamic loading, and accurate closed-loop voltage tracking with negligible computational and energy overhead. These findings confirm the practicality of the proposed self-powered architecture and highlight the feasibility of integrating operator-theoretic control into TENG-driven rectifier interfaces, advancing delivery-oriented power extraction from high-voltage TENG sources. Full article

Hydraulically Amplified Self-Healing Electrostatic (HASEL) actuators promise a future of adaptive robotics in a world where robotics is becoming increasingly integrated into our daily lives. Adaptive robotics needs to control multiple outputs with precision and speed. Unfortunately, expensive High Voltage control restricts the development of the HASEL actuator for commercial applications. This paper demonstrates a low-cost multi-channel High Voltage Power Supply (HVPS). The HVPS takes a 6 V input and controls multiple HASEL actuators from 0 to 10 kV, with a slew rate of up to 117.7 kV/s. In addition to controlling multiple channels, the low-cost HVPS can control two outputs with a single control module in an alternating pattern, similar to the way muscles control movement in alternating sequences—e.g., biceps and triceps. Previous work has shown that this low-cost HVPS is 95% cheaper than other power supplies used in the field of HASEL actuators. This work builds on the work reducing the cost of the HVPS by an additional 40%. This low-cost HVPS also reduces the amount of input required for control from four PWMs to one PWM with enable pins, drastically improving the performance of the device for multi-channel operation. Full article

Tailoring the spin crossover (SCO) effect in molecular materials remains a fundamental challenge, driven by the need to control critical parameters, such as the spin transition temperature (T₁/₂), hysteresis width, cooperativity, and switching kinetics for applications in sensing, memory, and actuation devices. SCO behavior is highly sensitive to small changes in the structure or crystal structure of the surrounding environment. In this context, achieving predictable and reproducible control remains elusive. Embedding SCO complexes into polymer matrices offers a more versatile and processable approach, but understanding how matrix–guest interactions affect spin-state behavior is still limited. In this study, we investigate a polymer-mediated strategy to tune SCO properties by incorporating the well-characterized Fe(II) complex [Fe(1,10-phenanthroline)₂(NCS)₂] into three polymers with distinct structural features: polylactic acid (PLA), polystyrene (PS), and polysulfone (PSF). In terms of potential electrostatic interaction between the complex and the polymeric matrixes, the polymers offer distinct features. Either there does not seem to be any specific interaction (PLA case) or, rather, there is π-π stacking between the aromatic rings of the SCO complex, and the corresponding ones present either in the backbone or in the side chain of the polymer (PSF and PS, respectively). The latter can potentially influence spin-state energetics and dynamics. Importantly, we also reveal and quantify the migration behavior of SCO particles within different polymer matrices, an aspect that has not been previously examined in SCO–polymer systems. Using magnetic susceptibility, spectroscopic, diffraction, and migration studies, we show that the polymer environment, PLA as well, actively modulates the SCO response. PSF yields lower T₁/₂, slower switching kinetics, and enhanced retention of the complex, indicative of strong matrix confinement and interaction. In contrast, PLA and PS composites exhibit sharper transitions and higher migration, suggesting weaker interactions and greater mobility. In addition, the semi-crystalline nature of PLA seems to induce the extension of the hysteresis width. These results highlight both the challenge and the opportunity in SCO polymer composites to tune SCO behavior, offering a scalable route toward functional hybrid materials for thermal sensing and responsive devices. Full article

Biocompatible electroactive hydrogels with bidirectional pH-responsive bending are important for the creation of biomedical actuators. This study developed chitosan/carboxymethylcellulose (CS/CMC) semi-interpenetrating networks (SIPNs) with different volume ratios, which were crosslinked with glutaraldehyde. The swelling and bending behaviors of SPINs were systematically characterized as a function of the pH of the solution and the magnitude of the applied electric field. The hydrogels exhibited pH-dependent bidirectional actuation, with the maximum swelling of 4.67–6.00 at pH ≈ 3.9 and minimum swelling of 1.58–2.53 at pH ≈ 5.7. The SPINs with CS/CMC = 1:1 composition achieved the highest bending angle of 77° at pH ≈ 5.7, while cathodic bending up to an angle of −13.7° was observed in basic conditions. The electromechanical response was significantly enhanced by decreasing the electrode distance and increasing the applied voltage. The observed correlation between the composition, swelling behavior, and bending performance was explained in terms of the electrostatic interactions between NH₃⁺ and COO⁻ groups present in the CS/CMC mixtures. These findings provided novel insight into the ongoing efforts for the development of non-toxic electroactive hydrogels with tailored electromechanical bending behavior necessary for use as artificial muscles and biomedical actuators. Full article

Triboelectric nanogenerators (TENGs) have emerged as a promising technology for harvesting mechanical energy via contact electrification (CE) at diverse interfaces, including solid–liquid, liquid–liquid, and gas–liquid phases. This review systematically explores fluid-based TENGs (Flu-TENGs), introducing a foundational and novel classification framework based on direct versus indirect charge transfer to the charge-collecting electrode (CCE). This framework addresses a critical gap by providing the first unified analysis of charge transfer mechanisms across all major fluid interfaces, establishing a clear design principle for future device engineering. We comprehensively compare the underlying mechanisms and performance outcomes, revealing that direct charge transfer consistently delivers superior energy conversion—with specific studies achieving up to 11-fold higher current and 8.8-fold higher voltage in solid–liquid TENGs (SL-TENGs), 60-fold current and 3-fold voltage gains in liquid–liquid TENGs (LL-TENGs), and 34-fold current and 10-fold voltage enhancements in gas–liquid TENGs (GL-TENGs). Indirect mechanisms, relying on electrostatic induction, provide stable Alternating Current (AC) output ideal for low-power, long-term applications such as environmental sensors and wearable bioelectronics, while direct mechanisms enable high-efficiency Direct Current (DC) output suitable for energy-intensive systems including soft actuators and biomedical micro-pumps. This review highlights a paradigm shift in Flu-TENG design, where the deliberate selection of charge transfer pathways based on this framework can optimize energy harvesting and device performance across a broad spectrum of next-generation sensing, actuation, and micro-power systems. By bridging fundamental charge dynamics with application-driven engineering, this work provides actionable insights for advancing sustainable energy solutions and expanding the practical impact of TENG technology. Full article

Actuating monolithic photonic components (particularly slab waveguides) requires higher force due to their inherent stiffness. However, two primary constraints must be addressed: actuator footprint and fabrication limits. Increasing the number of fingers to provide the required force is not a viable solution due to space constraints, and we must also adhere to the process design kits of standard fabrications and respect their design limits. Therefore, it is crucial to increase the actuator force output without significantly enlarging the actuator footprint while maintaining the necessary travel range. In order to achieve this, we utilize arrays of electrostatic comb drives, with each repeating cell geometry optimized to produce the highest force per actuator footprint. Our optimization strategy focuses on finger geometry, the arrangement of fingers and arms design in the comb structure, including the number of fingers per arm and arm length, ensuring that each repeating cell delivers maximum force per unit area or force intensity. Co-optimizing a repeatable, footprint-optimized comb-array unit cell (arm length, arm width, finger pitch, finger count) and validating it against an asymmetric slab waveguide load, we reach a maximum pre-pull-in force intensity of about 342 N m⁻² at 70 V with about 6 µm travel, confirmed by analytical modeling, numerical simulation, and measurement. Despite fabrication challenges such as over-etching and variations in electrode dimensions, detailed SEM analyses and correction functions ensure that the theoretical models closely match the experimental data, confirming the robustness and accuracy of the design. These optimized actuators, capable of achieving substantial force output without sacrificing travel range or mechanical stability, are particularly effective for applications in optical beam steering for in-plane silicon-photonics and related optical microsystems applications. Full article

As MEMS design encounters growing challenges, particularly stiction between movable and stationary electrodes, dielectric charging, pull-in instability, and multi-valued response characteristics, the integration of dimple-equipped structures has emerged as a pivotal solution to mitigate these fundamental issues. Consequently, this study investigates the dynamic behavior of an electrostatically actuated double-clamped microbeam incorporating dimples and contact pads. While the dimples enhance the beam’s travel range, they may also induce an impact mode upon contact with the landing pads, leading to complex nonlinear dynamic phenomena. A reduced-order model was developed to numerically solve the governing equation of motion. The microbeam’s response was analyzed both with and without dimples using multiple analytical techniques, including bifurcation diagrams and discrete excitation procedures near the impacting regime. The findings demonstrate that the inclusion of dimples effectively suppresses stiction, pull-in instability, and multi-valued responses. The results indicate that upon contacting the landing pads, the beam exhibits pronounced nonlinear dynamic behaviors, manifesting as higher-period oscillations such as period-3, period-4 and period-5 and then fully developed chaotic attractors. Indeed, this specifically demonstrates the potential of using the dynamic transition from a steady-state to a chaotic response to build novel MEMS sensors. Full article