Microelectromechanical Systems Technology Research Articles

Innovative Thermocatalytic H2 Sensor with Double-Sided Pd Nanocluster Films on an Ultrathin Mica Substrate.

Hydrogen (H2) is crucial in the future global energy landscape due to its eco-friendly properties, but its flammability requires precise monitoring. This study introduces an innovative thermocatalytic H2 sensor utilizing ultrathin mica sheets as substrates, coated on both sides with Pd nanocluster (NC) films. The ultrathin mica substrate ensures robustness and flexibility, enabling the sensor to withstand high temperatures and mechanical deformation. Additionally, it simplifies the fabrication process by eliminating the need for complex microelectro-mechanical systems (MEMS) technology. Constructed through cluster beam deposition, the sensor exhibits exceptional characteristics, including a wide concentration range (from 500 ppm to 4%), rapid response and recovery times (3.1 and 2.4 s for 1% H2), good selectivity, high stability, and repeatability. The operating temperature can be as low as 40 °C, achieving remarkably low power consumption. The study explores the impact of double-sided versus single-sided catalytic layers, revealing significantly higher sensitivity and response with the double-sided configuration due to the increased catalytic surface area. Additionally, the research investigates the relationship between the deposition amount of Pd NCs and the sensor's sensitivity, identifying an optimal value that maximizes performance without excessive use of Pd. The sensor's innovative design and excellent performance position it as a promising candidate for meeting the demands of a hydrogen-based energy economy.

Concept and simulation of a novel dual-layer linear ion trap mass analyzer for micro-electromechanical systems mass spectrometry.

This paper proposed a dual-layer linear ion trap mass analyzer (dLIT) based on micro-electromechanical systems (MEMS) technology and stacked-layer structure for the development of MEMS mass spectrometry. Its basic performance and potential capabilities were explored by ion trajectory simulations. The theoretical formulas were modified by implementing multipole expansion. The simulation results were confirmed to be highly consistent with theoretical calculations in multiple aspects, including stability diagram, secular frequencies, and mass linearity, with only a deviation of 1-2%. In the boundary ejection mode, close to 100% ejection was achieved in a single dimension by applying extra quadrupole DC voltage. Preliminary simulation results showed that dLIT can achieve a peak width of ∼2 mass units (full width at half maximum, FWHM) for m/z 60 ions even at pressures as high as 50 Pa. Furthermore, the application of AC frequency scanning mode in dLIT was also evaluated, and preliminary simulation results yield a peak width of 0.3-0.4 mass units (FWHM). The dLIT offered several advantages, including high-precision fabrication at the sub-millimeter scale, excellent high-pressure performance, and a clear physical model. It preliminarily proved to be an ideal mass analyzer for MEMS mass spectrometry.

A multidimensional integrated micro three-component fluxgate sensor based on microelectromechanical system technology

In this paper, a miniature three-component fluxgate sensor with U-shaped structure is fabricated by the multidimensional integration technology. We manufacture a batch of single axis solenoid fluxgate chips based on Micro Electromechanical System （MEMS） technology, which possesses the Co-based amorphous ribbon core and solenoid excitation-detection coil. According to multidimensional integration theory, a full integrated three-component fluxgate sensors is achieved through orthogonal linking of printed circuit board （PCB） substrates and bonding between single axis fluxgate chip and substrate. The chips used in the X-Y-Z axis have a sensitivity of 1947 V/T, 1951 V/T, and 1949 V/T, and noise power spectral density of 0.061 nT√Hz@1HZ, 0.077 nT√Hz@1HZ, and 0.087 nT√Hz@1HZ, and time-drift peaks of 21 nT, 17.4 nT, and 14.8 nT, respectively. The linear range of three chips is 0–70μT. After least square error correction, the peak-to-peak value of the in-situ total magnetic field decreases from 2.4 μT to 0.22 μT.

Flexible and Stretchable Electrodes for In Vivo Electrophysiological and Electrochemical Monitoring†

Comprehensive SummaryIn vivo monitoring of bioelectrical and biochemical signals with implanted electrodes has received great interest over the past decades. However, this faces huge challenges because of the severe mechanical mismatch between conventional rigid electrodes and soft biological tissues. In recent years, the emergence of flexible and stretchable electrodes offers seamless and conformable biological‐electronic interfaces and has demonstrated significant advantages for in vivo electrochemical and electrophysiological monitoring. This review first summarizes the strategies for electrode fabrication from the point of substrate and conductive materials. Next, recent progress in electrode functionalization for improved performance is presented. Then, the advances of flexible and stretchable electrodes in exploring bioelectrical and biochemical signals are introduced. Finally, we present some challenges and perspectives ranging from electrode fabrication to application.Key ScientistsIn 2001, a seminal work by Kipke et al. first showed flexible polyimide‐based intracortical electrode arrays.[1] This electrode was further expanded to 252‐channel using microelectromechanical systems technology by Stieglitz et al. in 2009 and achieved large‐scale cortical recordings.[2] Later, Lieber et al. created mesh electronics that allow for seamless and minimally invasive three‐dimensional interpenetration with nerve tissues, opening up unique applications for flexible electronics.[3] Subsequently, Rogers et al. described bioresorbable electronics for transient electrical activity recordings in 2016.[4] And Frank et al. proposed polymer electrode arrays capable of resolving single neurons in 2019.[5] It wasn't until 2020 that a significant breakthrough in biochemical signals monitoring by Peng et al. demonstrated functionalized carbon nanotube fibre bundles for multiple disease biomarkers monitoring.[6] Later on, Mooney et al. established the first fully viscoelastic electrode arrays for neural recordings from the brain and heart in 2021.[7] Recently, Bao et al. presented tissue‐mimicking, stretchable neurotransmitter interfaces for monitoring the brain and gut.[8]

Manufacturing and characterization of CMOS-MEMS magnetic field microsensors with isolated cavities

The study investigates a magnetic field (MF) microsensor with isolated cavities manufactured utilizing complementary metal oxide semiconductor (CMOS)-microelectromechanical system technology. This microsensor, which is a type of magnetic transistor, comprises four identical magnetic sensing elements, each featuring an emitter, a base, two collectors, and an additional collector. The magnetic transistor operates on the principles of the Lorentz force. This force is employed to modulate the electrical properties of the transistor, responding to changes in the surrounding MF. The MF microsensor chip is fabricated using the commercial CMOS process. Upon completing the CMOS process, post-processing is employed to etch the silicon substrate of the microsensor chip, generating isolated cavities on the silicon substrate. These isolated cavities effectively mitigate substrate leakage current, enhancing the sensitivity of the MF microsensor. The experimental results reveal that the sensitivity of the microsensor without isolated cavities is 60 mV T−1. In contrast, the microsensor with isolated cavities exhibits a sensitivity of 121 mV T−1. A comparison between microsensors with and without isolated cavities depicts that the sensitivity of the MF microsensor with isolated cavities doubled.

A miniaturized statically balanced compliant mechanism for on-chip ultralow wide-bandwidth vibrational energy harvesting

Abstract. This research demonstrates a miniaturized statically balanced compliant mechanism (SBCM) at the micro-electromechanical systems (MEMS) scale. The primary objective is to integrate the MEMS-scale SBCM on chip as the fundamental structure of vibrational energy harvesters for powering low-energy-cost sensors and circuits. The static and dynamic characteristics of the micro-scale SBCM are investigated based on a 2D finite element analysis (FEA) model in COMSOL Multiphysics®. Static balancing is achieved by finely tuning the geometric parameters of the FEA SBCM model. The analytical, numerical, and FEA results confirm that the MEMS-scale SBCM is sensitive to ultralow wide-bandwidth excitation frequencies with weak accelerations. This micro-scale SBCM structure provides a structural solution to effectively lower the working frequencies of MEMS vibrational energy harvesters to ultralow ranges within a wide bandwidth. It overcomes the working frequency limit imposed by the size effect. This would significantly improve the dynamic performance of vibrational energy harvesters at the MEMS scale. In addition, a conceptual structure of the MEMS-scale SBCM is preliminary proposed for the integration of piezoelectric materials by MEMS technologies for vibrational energy harvesting.

Application of PZT Nanofiber Flexible MEMS Technology in Human Resource Employment Pressure Management

The advancement of society has led to increasing pressure on employment in human resources. Effectively managing and alleviating this pressure has emerged as an urgent problem to be addressed. This study presents a novel pressure sensor utilizing microelectromechanical systems technology, with the aim of offering a fresh solution for managing employment pressure in the human resource sector. Firstly, this study presents the preparation and characterization of lead zirconate titanate nanofibers, followed by the development of a flexible pressure sensor using microelectromechanical systems technology specifically designed for these fibers. Finally, this study evaluates the performance of the developed pressure sensor. The results revealed that the open circuit output voltage of the sensor peaked at a pressure frequency of 110 Hz, indicating the highest level of response. In addition, it was observed that the open circuit output voltage of the fabricated sensor exhibited fluctuations within the voltage range of –3.8 V to 5.0 V, confirming its ability to precisely respond to variations in external pressure at any given moment. The features of this developed pressure gauge render it an ideal tool for real-time monitoring and evaluation of pressure, thereby possessing wideranging application prospects.

Photocatalytic Oxidization Based on TiO2/Au Nanocomposite Film for the Pretreatment of Total Phosphorus (TP)

Phosphorus, an essential rare element in aquatic ecosystems, plays a key role in maintaining ecosystem balance. However, excess phosphorus leads to eutrophication and algal proliferation. To prevent eutrophication, the pretreatment and measuring of the concentration of total phosphorus (TP) is crucial. Compared to conventional TP pretreatment equipment (autoclave), a lab-on-a-chip detection device fabricated using micro-electromechanical system technology and titania (TiO2) as a photocatalyst is more convenient, efficient, and cost-effective. However, the wide bandgap of TiO2 (3.2 eV) limits photocatalytic activity. To address this problem, this paper describes the preparation of a TiO2/Au nanocomposite film using electron-beam evaporation and atomic-layer deposition, based on the introduction of gold film and TiO2 to a quartz substrate. The photocatalytic degradation properties of TiO2/Au nanocomposite films with thicknesses of 1, 2, 3, and 4 nm were assessed using rhodamine B as a pollutant. The experimental results demonstrate that the deposition of gold films with different thicknesses can enhance photocatalytic degradation efficiency through synergetic reactions in the charge separation process on the surface. The optimal photocatalytic efficiency is achieved when the deposition thickness is 2 nm, and it decreases with further increase in the thickness. When the photocatalytic reaction time is 15 min, the lab-on-a-chip (LOC) device with a 2-nm-thick gold layer and autoclave exhibits a similar TP pretreatment performance. Therefore, the proposed LOC device based on photocatalytic technology can address the limitations of conventional autoclave equipment, such as large volumes, long processing times, and high costs, thereby satisfying the growing demand for on-site evaluation.

Nonlinearity-Induced Asymmetric Synchronization Region in Micromechanical Oscillators.

Synchronization in microstructures is a widely explored domain due to its diverse dynamic traits and promising practical applications. Within synchronization analysis, the synchronization bandwidth serves as a pivotal metric. While current research predominantly focuses on symmetric evaluations of synchronization bandwidth, the investigation into potential asymmetries within nonlinear oscillators remains unexplored, carrying implications for sensor application performance. This paper conducts a comprehensive exploration employing straight and arch beams capable of demonstrating linear, hardening, and softening characteristics to thoroughly scrutinize potential asymmetry within the synchronization region. Through the introduction of weak harmonic forces to induce synchronization within the oscillator, we observe distinct asymmetry within its synchronization range. Additionally, we present a robust theoretical model capable of fully capturing the linear, hardening, and softening traits of resonators synchronized to external perturbation. Further investigation into the effects of feedback strength and phase delay on synchronization region asymmetry, conducted through analytical and experimental approaches, reveals a consistent alignment between theoretical predictions and experimental outcomes. These findings hold promise in providing crucial technical insights to enhance resonator performance and broaden the application landscape of MEMS (Micro-Electro-Mechanical Systems) technology.

Strain/pressure sensors utilizing advanced nanomaterials

AbstractIn this study, the fabrication techniques employed for strain/pressure sensors are covered, highlighting advancements in materials and manufacturing processes. It discusses the use of nanomaterials, such as nanoparticles, nanowires, and graphene to enhance the sensitivity and durability of strain/pressure sensors. Various fabrication methods, including printing, thin‐film deposition, and microelectromechanical systems technologies, are discussed, emphasizing their superiority for strain/pressure sensing applications.

Driving Principle and Stability Analysis of Vertical Comb-Drive Actuator for Scanning Micromirrors.

We have developed a manufacturing process for micromirrors based on microelectromechanical systems (MEMS) technology. The process involves designing an electrostatic vertically comb-driven actuator and utilizing a self-alignment process to produce a height difference between the movable comb structure and the fixed comb structure of the micromirror. To improve the stability of the micromirror, we propose four instability models in micromirror operation with the quasi-static driving principle and structure of the micromirror considered, which can provide a basic guarantee for the performance of vertical comb actuators. This analysis pinpoints factors leading to instability, including the left and right gap of the movable comb, the torsion beams of the micromirror, and the comb-to-beams distance. Ultimately, the voltages at which device failure occurs can be determined. We successfully fabricated a one-dimensional micromirror featuring a 0.8 mm mirror diameter and a 30 μm device layer thickness. The height difference between the movable and fixed comb structures was 10 μm. The micromirror was able to achieve a static mechanical angle of 2.25° with 60 V@DC. Stable operation was observed at voltages below 60 V, in close agreement with the theoretical calculations and simulations. At the driving voltage of 80 V, we observed the longitudinal displacement movement of the comb fingers. Furthermore, at a voltage of 129 V, comb adhesion occurred, resulting in device failure. This failure voltage corresponds to the lateral torsional failure voltage.

Experimental study of the effect of target composition and heat treatment on the Ag deposit on the adhesion of the surfaces used in microelectromechanical systems (MEMS)

Adhesion force is one of the major factors in MEMS technology specifically during micro assembling via micro grippers. Regarding the light weight of MEMS devices, the contact force between MEMS devices and the microgripper surface causes distinct problems such as sticking the MEMS surface to the microgripper, so the assemble procedure can be affected and microparts not be placed in the right position. so decreasing adhesion force has a significant role in improving micron assembly. Accordingly, in the current research work, the effects of various coating materials, deposition, and annealing temperatures on the surface roughness of microgripper substrate and its morphology are experimentally investigated considering the DC sputtering magnetron method to decrease adhesion force between microgripper substrate and MEMS device. For this purpose, seventeen silicon surfaces were used of which sixteen of them coated and one is non-coated. Deposited substrates can be classified into four groups four of them are deposited with double layers using two kinds of coating materials including Ti/Ag, SiO2/Ag, Ti/Ag-Pd-Cu, and SiO2/Ag-Pd-Cu respectively. After sample deposition, the AFM method was used to measure, the topographic images, the surface roughness, and the adhesion force. Regarding the differences in layers and distinct temperatures, the height and shape of hillocks directly depend on deposition and preheating temperature ranges. So as the deposition and preheating temperature increase, more hillocks grow and the adhesion force is more consequently. to 373 K and 573 K. Additionally, these changes result in changes in adhesion force.

QEchemMEMS – A working electrode with high-resolution temperature sensing for studying electrochemical heat management systems

Electrochemical heat pumps are a new and interesting concept for efficient thermal energy management at the micro- and macro-scale. The development of new solutions for electrochemical heat pumps requires reliable and high-resolution measurements of the temperature changes resulting from redox reactions. A device for measuring such temperature variations, manufactured using microelectromechanical system technology, is presented and characterized in this study. The device contains a platinum working electrode suspended on a thin SixNy membrane for the electrochemical cell; this electrode also serves as a resistive thermal device (RTD). The device and temperature readout electronic implementations of the Anderson loop are characterized. The temperature coefficient of resistance is 2736 ppm/K. The theoretical noise performance is predicted and verified in practice. The voltage noise of the RTD is 28 nV, which results in a temperature measurement resolution of 1.3 mK despite a very small RTD bias current of 40 µA.

Ultra-Compact and High-Performance Suspended Aluminum Scandium Nitride Lamb Wave Humidity Sensor with Graphene Oxide Layer

The utilization of Microelectromechanical Systems (MEMS) technology holds great significance for developing compact and high-performance humidity sensors in human healthcare, and the Internet of Things. However, several drawbacks of the...

Design, modeling and experimental investigation of a novel solar sail with high area-to-mass ratios for efficient solar sailing

Solar sailing is a promising propellant-free approach to propelling spacecraft in space. However, the propelling efficiency of conventional solar sail spacecraft is limited by their area-to-mass ratios. This paper proposes a novel design of micro solar sails with area-to-mass ratios above 100 m2/kg for next-generation chip-scale spacecraft. Bilayer thin films developed by Microelectromechanical Systems (MEMS) technologies were patterned into grid microstructures, and theoretical analysis of a sail prototype was conducted. The electro-thermal and thermo-mechanical models of the solar sail in geospace were established by taking effects of Joule heating, solar radiation, and thermal re-emission into consideration, enabling rapid prediction of its three-dimensional (3-D) reconfiguration from the as-released two-dimensional (2-D) microstructure. Adjustment of the ChipSail’s acceleration arising from the sail’s morphing was also analytically modeled. Fabrication and characterization of the sail prototype made of multiple Al/Ni50Ti50 bilayer beams were accomplished. In-situ SEM imaging of the sail prototype in vacuum chamber witnessed an active and continuous 3-D reconfiguration under Joule heating, and over 90° deformation was detected by applying a DC voltage of 0.078 V. Theoretical and experimental work on the solar sail with at least 10 times higher area-to-mass ratios than conventional ones will lay a solid foundation for efficient solar sailing.

Micromachined piezoelectric sensor with radial polarization for enhancing underwater acoustic measurement

This work presents an underwater acoustic sensor featuring a radial polarized piezoelectric diaphragm, which aims to work in d33 mode to enhance its performance. For the sake of accomplishing the in-plane polarization, interdigital electrodes based on semi-circular ring patterns are designed on both sides and aligned along the thickness direction of the diaphragm. Effects of electrode parameters on the polarization orientation are numerically analyzed by the conversion relationship between different coordinates. Using the Kirchhoff plate theory and Rayleigh-Ritz method, a mathematical model is developed to investigate the dynamic properties of the sensor. The results indicate that the output voltages increase with the increase of the electrode inner radius, width, and spacing but decrease with the increase of the diaphragm thickness and radius. Sensor prototypes are fabricated by the microelectromechanical system (MEMS) technology in a clean room and characterized by impedance spectrums. An underwater testing system is established to conduct the experimental verification, whose results are in good accord with those of mathematical modeling. The sensor output voltage has fine linearity with the underwater acoustic pressure and achieves a flat frequency response. Moreover, the sensor has a sensitivity of −172.7 dB (Ref. 1 V/μPa) superior to the reported devices in the same categories. This work provides significant guidance for modeling radial field piezoelectric diaphragms and designing more efficient piezoelectric microsensors, which have a fine application prospect in underwater acoustic measurement.

Development and analysis of computer vision system for micromechanics

Summary: In micromechanics the best technologies are MicroElectroMechanical Systems (MEMS) and MicroEquipment Technology (MET). The MEMS used the electronic technology to produce mechanical components. Due to the advantages of the MET such as the development of low-cost micro devices, the possibility of using various manufacturing materials, the possibility of producing three-dimensional microcomponents it will be very useful to automatize all processes of mechanics production and develop different technological innovations. The automation and robotics are two closely related technologies since automation can be defined as a technology that is related to the use of mechanical-electrical systems based on computers for the operation and control of production. The field of micromechanics has been involved in different applications that cover almost all areas of science and technology, an example of this is the management of microdevices for the autofocus of digital cameras whose objective is image processing (recognizing and locate objects). The use of computer vision systems can help to automate the work of MEMS and MET systems, so the study of image processing using a computer is very important. The objective was to design a computer vision system that allows the movement of the lens to focus the work area, for the monitoring of the micromachine tool in manufacturing processes and assembly of microcomponents in real time using previously developed image recognition algorithms. The developed algorithms use the criterion of improving the contrast of the input image. We describe our approach and obtained results. This approach can be used not only in micromechanics but in nanomechanics too

In-situ TEM study from the perspective ofholders.

During the in situ transmission electron microscopy (TEM) observations, the diverse functionalities of different specimen holders play a crucial role. We hereby provide a comprehensive overview of the main types of holders, associated technologies and case studies pertaining to the widely employed heating and gas heating methods, from their initial developments to the latest advancement. In addition to the conventional approaches, we also discuss the emergence of holders that incorporate a micro-electro-mechanical system (MEMS) chip for in situ observations. The MEMS technology offers a multitude of functions within a single chip, thereby enhancing the capabilities and versatility of the holders. MEMS chips have been utilized in environmental-cell designs, enabling customized fabrication of diverse shapes. This innovation has facilitated their application in conducting in situ observations within gas and liquid environments, particularly in the investigation of catalytic and battery reactions. We summarize recent noteworthy studies conducted using in situ liquid TEM. These studies highlight significant advancements and provide valuable insights into the utilization of MEMS chips in environmental-cells, as well as the expanding capabilities of in situ liquid TEM in various research domains.

Characterization of Photocurable IP-PDMS for Soft Micro Systems Fabricated by Two-Photon Polymerization 3D Printing.

Recent developments in micro-scale additive manufacturing (AM) have opened new possibilities in state-of-the-art areas, including microelectromechanical systems (MEMS) with intrinsically soft and compliant components. While fabrication with soft materials further complicates micro-scale AM, a soft photocurable polydimethylsiloxane (PDMS) resin, IP-PDMS, has recently entered the market of two-photon polymerization (2PP) AM. To facilitate the development of microdevices with soft components through the application of 2PP technique and IP-PDMS material, this research paper presents a comprehensive material characterization of IP-PDMS. The significance of this study lies in the scarcity of existing research on this material and the thorough investigation of its properties, many of which are reported here for the first time. Particularly, for uncured IP-PDMS resin, this work evaluates a surface tension of 26.7 ± 4.2 mN/m, a contact angle with glass of 11.5 ± 0.6°, spin-coating behavior, a transmittance of more than 90% above 440 nm wavelength, and FTIR with all the properties reported for the first time. For cured IP-PDMS, novel characterizations include a small mechanical creep, a velocity-dependent friction coefficient with glass, a typical dielectric permittivity value of 2.63 ± 0.02, a high dielectric/breakdown strength for 3D-printed elastomers of up to 73.3 ± 13.3 V/µm and typical values for a spin coated elastomer of 85.7 ± 12.4 V/µm, while the measured contact angle with water of 103.7 ± 0.5°, Young's modulus of 5.96 ± 0.2 MPa, and viscoelastic DMA mechanical characterization are compared with the previously reported values. Friction, permittivity, contact angle with water, and some of the breakdown strength measurements were performed with spin-coated cured IP-PDMS samples. Based on the performed characterization, IP-PDMS shows itself to be a promising material for micro-scale soft MEMS, including microfluidics, storage devices, and micro-scale smart material technologies.

Recent advances in hydrodynamics of wing propulsive lifting systems for ships and underwater vehicles

A collaborative and interdisciplinary strategy spanning hydrodynamics, sophisticated materials, elasticity, and microelectromechanical systems technologies is required for the effective deployment of wing propulsive lifting systems in ships and underwater vehicles. The hydrodynamic characteristics play a crucial role in the motion performance of the marine vehicle, which employs a wing propulsive lifting system. The present study aims at reviewing the hydrodynamics of the wing propulsive lifting system for ships and underwater vehicles, covering the relevant classical work, mathematical models, numerical simulations, and experimental results. This study contributes to the academic discourse by conducting a meticulous examination of the hydrodynamics underlying wing propulsive lifting systems. The classification of research methods enables a comprehensive comparison of results, facilitating accurate performance evaluation. The review concludes by presenting key insight and recommending potential avenues for future research, thereby propelling the knowledge and development of wing-propulsive lifting systems within the scholarly community.