提高膜片式F-P腔光纤压力传感器灵敏度的试验研究

膜片式F-P腔光纤压力传感器是基于法布里-珀罗干涉原理,采用微电子机械系统(MEMS)技术加工而成。在实际应用中,不同的测试环境对传感器灵敏度的要求各不相同,如果针对不同灵敏度,分别采用MEMS工艺批量化生产,则会造成生产成本过高,经济化效益降低。本文利用湿法腐蚀的方法对传感器进行膜片减薄试验,在一定范围内提高了传感器的压力灵敏度,从而满足了不同的测试需求。膜片减薄后,传感器的灵敏度可达34.2 nm/kPa,压力标定曲线的线性度为0.9997,传感器的非线性误差为0.05%,能够实现0~120 kPa(绝压)范围内压力的准确测量。     

Modeling analysis and fabrication of MEMS capacitive differential pressure sensor for altimeter application

This paper proposes the modeling analysis of MEMS highly sensitive Capacitive Differential Pressure Sensor (CDPS) and also the development of a fabrication process for CDPS structures for aircraft altimeter applications. Highly sensitive CDPS structure models using circular and square sandwich polyimide diaphragm membranes, with and without center boss, were adopted, whereas other studies report on silicon diaphragms. CDPS characterization was carried out to analyze the deflection sensitivity, capacitive sensitivity, stress on diaphragm membrane and the effect of temperature on capacitive sensitivity. Simulation results of square diaphragm without center boss show better characteristics than other proposed diaphragm structures. This design yields 145.8 nm/mbar and 0.574 fF/mbar of deflection and capacitive sensitivity, respectively. The maximum stress developed on the diaphragm at maximum working pressure is less than the yield stress of polyimide material by a factor of 1.77 and capacitive sensitivity deviates at ±0.00195%/°C. From the modeling analysis, square diaphragm CDPS structure yields better characteristics and hence the fabrication process for CDPS has been developed, and its fabrication process flow verified using Intellisuit virtual fab tool.     

Wearable Microfluidic Diaphragm Pressure Sensor for Health and Tactile Touch Monitoring

Flexible pressure sensors have many potential applications in wearable electronics, robotics, health monitoring, and more. In particular, liquid‐metal‐based sensors are especially promising as they can undergo strains of over 200% without failure. However, current liquid‐metal‐based strain sensors are incapable of resolving small pressure changes in the few kPa range, making them unsuitable for applications such as heart‐rate monitoring, which require a much lower pressure detection resolution. In this paper, a microfluidic tactile diaphragm pressure sensor based on embedded Galinstan microchannels (70 µm width × 70 µm height) capable of resolving sub‐50 Pa changes in pressure with sub‐100 Pa detection limits and a response time of 90 ms is demonstrated. An embedded equivalent Wheatstone bridge circuit makes the most of tangential and radial strain fields, leading to high sensitivities of a 0.0835 kPa^?1 change in output voltage. The Wheatstone bridge also provides temperature self‐compensation, allowing for operation in the range of 20–50 °C. As examples of potential applications, a polydimethylsiloxane (PDMS) wristband with an embedded microfluidic diaphragm pressure sensor capable of real‐time pulse monitoring and a PDMS glove with multiple embedded sensors to provide comprehensive tactile feedback of a human hand when touching or holding objects are demonstrated.     

基于Au-Si共晶键合的高灵敏MEMS电容薄膜真空规设计

为了解决真空腔电极引线导致的真空漏气,进一步拓展真空规的测量下限,提出了一种基于Au-Si共晶键合的绝压式MEMS电容薄膜真空规设计方案.阐述了该新型MEMS电容薄膜真空规的制作工艺流程、用浓硼掺杂法制备感压薄膜技术,采用阳极键合协同Au-Si共晶键合技术实现真空腔的密封.通过理论计算和构建有限元模型,针对不同宽厚比,...     

Several Applications of MEMS in Fluid Area

In order to discuss the several applications of MEMS in fluid area,study the components of MEMS.And introduce the principles,types and applications based on flow sensor and pressure sensor. In the last,discuss the problems when the sensors was applied in the fluid areas.     

Robust Free‐Standing Nano‐Thin SiC Membranes Enable Direct Photolithography for MEMS Sensing Applications

This work presents fabrication of micro structures on sub–100 nm SiC membranes with a large aspect ratio up to 1:3200. Unlike conventional processes, this approach starts with Si wet etching to form suspended SiC membranes, followed by micro‐machined processes to pattern free‐standing microstructures such as cantilevers and micro bridges. This technique eliminates the sticking or the under‐etching effects on free‐standing structures, enhancing mechanical performance which is favorable for MEMS applications. In addition, post‐Si‐etching photography also enables the formation of metal electrodes on free standing SiC membranes to develop electrically‐measurable devices. To proof this concept, the authors demonstrate a SiC pressure sensor by applying lithography and plasma etching on released ultrathin SiC films. The sensors exhibit excellent linear response to the applied pressure, as well as good repeatability. The proposed method opens a pathway for the development of self‐sensing free‐standing SiC sensors.     

Highly Sensitive,Flexible MEMS Based Pressure Sensor with Photoresist Insulation Layer

Pressure sensing is a crucial function for flexible and wearable electronics, such as artificial skin and health monitoring. Recent progress in material and device structure of pressure sensors has brought breakthroughs in flexibility, self‐healing, and sensitivity. However, the fabrication process of many pressure sensors is too complicated and difficult to integrate with traditional silicon‐based Micro‐Electro‐Mechanical System(MEMS). Here, this study demonstrates a scalable and integratable contact resistance‐based pressure sensor based on a carbon nanotube conductive network and a photoresist insulation layer. The pressure sensors have high sensitivity (95.5 kPa⁻¹), low sensing threshold (16 Pa), fast response speed (<16 ms), and zero power consumption when without loading pressure. The sensitivity, sensing threshold, and dynamic range are all tunable by conveniently modifying the hole diameter and thickness of insulation layer.     

Smooth Contact Capacitive Pressure Sensors in Touch- and Peeling-Mode Operation

Capacitive (C) pressure sensors typically sense quadratic changes in $C$ as a pressure difference $(P)$ deflects a flexible conducting diaphragm near a rigid ground plane. Touch-mode capacitive pressure (C-P) sensors, where the conducting diaphragm touches a dielectric coated ground plane, often show a more linear response, but with less sensitivity, particularly at low-$P$ . Initial contact of the diaphragm often occurs at a critical $P$. Until $P_{rm crit}$ is reached, the sensitivity is typically too low for accurate measurements. In this work, two different types of electrodes with “parabolic” and “donut” cavity-shapes have been designed, fabricated, and tested to achieve high-sensitivity at low-pressures. A flexible conducting diaphragm touches the bottom electrode smoothly, and both cavity shapes permit initial contact at a zero-pressure differential. This type of C-P sensors can have touch-mode and peeling-mode operations. The sensitivities of these sensors in two operation modes were measured, and their resolutions were smaller than 0.1 Pa at a mean pressure of ${10} ^{5}~{rm Pa}$. Both sensors in two modes have the resolution over total-pressure less than ${10} ^{-6}$, which is difficult to achieve at atmospheric pressure.      

The Future of Microelectromechanical systems (MEMS)

Abstract:  MEMS-based products produced in 2005 had a value of $8bn, 40% of which was sensors. The balance was for products that included micromachined features, such as ink jet print heads, catheters and RF IC chips with embedded inductors. Growth projections follow a hockey stick curve, with the value of products rising to $40bn in 2015 and $200bn in 2025! Growth to date has come from a combination of technology displacement, as exemplified by automotive pressure sensors and airbag accelerometers and new products, such as miniaturised guidance systems for military applications and wireless tire pressure sensors. Much of the growth in MEMS business is expected to come from products that are in the early stages of development or yet to be invented. Some of these devices include disposable chips for performing assays on blood and tissue samples, which are now performed in hospital laboratories, integrated optical switching and processing chips, and various RF communication and remote sensing products.The key to enabling the projected 25-fold growth in MEMS products is development of appropriate technologies for integrating multiple devices with electronics on a single chip. At present, there are two approaches to integrating MEMS devices with electronics. Either the MEMS device is fabricated in polysilicon, as part of the CMOS wafer fabrication sequence or a discrete MEMS device is packaged with a separate ASIC chip. Neither of these approaches is entirely satisfactory, though, for building the high-value, system-on-chip products that are envisioned. It is this author's opinion that a combination of self-assembly techniques in conjunction with wafer stacking, offer a viable path to realizing ubiquitous, complex MEMS systems.     

Study on the micro-heater geometry in In,2O3 micro electro mechanical systems gas sensor platforms and effects on NO2 gas detecting performances

Micro electro mechanical systems (MEMS) platforms for gas sensing devices with the co-planar type micro-heaters were designed, fabricated and its effects on the In2O3 gas sensors were investigated. Micro-heaters in MEMS gas sensor platforms were designed in the four-type heater patterns with different geometries. Electro-thermal characterizations showed that the designed platforms had highly thermal efficiency because the micro hot-plate structures were formed in the diaphragm and the thermal efficiencies were analyzed for all of 16 models and compared with each other, respectively. The designed micro-platforms were fabricated by MEMS process, and Indium oxide (In2O3) nanoparticles were synthesized by sol-gel process and dropped on the MEMS platforms for detecting the noxious oxide gas (NO2) Fabricated micro-platforms had a very low power consumption in the fabricated 16-type models, especially, the minimum power consumption was 41 mW at the operating temperature of 250 degrees C. After experiments on gas sensing characteristics to NO2 gases, fabricated In2O3 gas sensors had almost the same gas sensitivity (Rs) at the operation temperature of 250 degrees C. It is concluded that the micro-heater geometries, pattern shapes and sizes, can be influential on the power consumption of the devices and its gas sensing characteristics.     

Silicon Nanowires Driving Miniaturization of Microelectromechanical Systems Physical Sensors: A Review

The miniaturization of microelectromechanical systems (MEMS) physical sensors is driven by global connectivity needs and is closely linked to emerging digital technologies and the Internet of Things. Strong technical advantages of miniaturization such as improved sensitivity, functionality, and power consumption are accompanied by significant economic benefits due to semiconductor manufacturing. Hence, the trend to produce smaller sensors and their driving force resemble very much those of the miniaturization of integrated circuits (ICs) as described by Moore's law. In this respect, with its IC-, and MEMS-compatibility, and scalability, the silicon nanowire is frequently employed in frontier research as the sensor building block replacing conventional sensors. The integration of the silicon nanowire with MEMS has thus generated a multiscale hybrid architecture, where the silicon nanowire serves as the piezoresistive transducer and MEMS provide an interface with external forces, such as inertial or magnetic. This approach has been reported for almost all physical sensor types over the last decade. These sensors are reviewed here with detailed classification. In each case, associated technological challenges and comparisons with conventional counterparts are provided. Future directions and opportunities are highlighted.     

感压膜片预张力对电容薄膜真空规输出特性的影响

电容薄膜真空规中感压膜片在安装时通常须先施加预张力,再固定.为研究感压膜片预张力对电容薄膜真空规输出特性的影响,以现有电容薄膜真空规为对象,基于COMSOL Multiphysics软件,建立有限元模型,得到了不同预张力下输出电容的仿真解,并与理论计算结果进行了比较,分析了预张力对输出电容的影响.同时分析了真空规线性度...     

Optimization of sputtered Cr/Au thin film for diaphragm-based MEMS applications

An optimization study on the sputtering of Cr/Au thin film for diaphragm-based MEMS applications is presented. The effects of the film thickness, process pressure and process power on the residual stress of the film are investigated. A low-stress silicon nitride diaphragm-based device characterization platform is fabricated to study the influence of the Cr/Au film stress on the diaphragm compliance. The fabricated devices are characterized by measuring the capacitance change under a bias voltage from 0 to 40 V. For the 8-µm and 10-µm air gap device characterization platforms, the largest capacitance changes of 5.1% and 4.3%, respectively, occur at a compressive film stress of − 200 MPa. A large capacitance change indicates a more sensitive diaphragm, which is desired in pressure sensor design.     

MEMS-Capacitive Pressure Sensor Fabricated Using Printed-Circuit-Processing Techniques

Microelectromechanical systems (MEMS)-based capacitive pressure sensors are typically fabricated using silicon-micromachining techniques. In this paper, a novel liquid-crystal polymer (LCP)-based MEMS-capacitive pressure sensor, fabricated using printed-circuit-processing technique, is reported. The pressure sensor consists of a cylindrical cavity formed by a sandwich of an LCP substrate, an LCP spacer layer with circular holes, and an LCP top layer. The bottom electrode and the top electrode of the capacitive pressure sensor are defined on the top side of the LCP substrate and the bottom side of the top-LCP layer, respectively. An example pressure sensor with a diaphragm radius of 1.6 mm provides a total capacitance change of 0.277 pF for an applied pressure in the range of 0-100 kPa     

Composite Si/PS membrane pressure sensors with micro and macro-porous silicon

Porous Silicon (PS) is a versatile material with many unique features making it viable in the field of Microelectromechanical Systems (MEMS). In this paper, we discuss the optimization of formation parameters of micro and macro PS with different porosity and thickness for use in pressure sensors. The optimized material is used in the fabrication of composite Si/PS membranes in piezo-resistive pressure sensors and tested. Pressure sensors with composite membranes have higher sensitivity than those with single crystalline silicon membrane with the sensitivity increasing as the porosity increases. For the same porosity and thickness of the PS layer, Si/micro PS membranes exhibit higher sensitivity than Si/macro PS ones. The offset voltage in these sensors is found to be high and can be due to the stress induced in the membrane during PS formation. Offset voltage and stress values are found to be higher in composite membranes with micro PS as compared to macro PS.     

用于微电子机械系统封装的体硅键合技术和薄膜密封技术

对静电键合、体硅直接键合和界面层辅助键合等三种体硅键合技术，整片操作、局部操作和选择保护等三种密封技术，以及这些技术用于微电子机械系统的密封作了评述，强调在器件研究开始时应考虑封装问题，具体技术则应在保证器件功能和尽量减少芯片复杂性两者之间权衡决定。     

Embedded micromachined fiber-optic Fabry-Perot pressure sensors in aerodynamics applications

Small size, high bandwidth pressure sensors are required for instrumentation of probes and test models in aerodynamic studies of complex unsteady flows. Optical-fiber pressure sensors promise potential advantages of small size and low cost in comparison with their electrical counterparts. We describe miniature Fabry-Perot cavity pressure sensors constructed by micromachining techniques in a turbine test application. The sensor bodies are 500 /spl mu/m squared, 300 /spl mu/m deep with a /spl sim/2 /spl mu/m-thick copper diaphragm electroplated on one face. The sensor cavity is formed between the diaphragm and the cleaved end of a single mode fiber sealed to the sensor by epoxy. Each sensor is addressed interferometrically in reflection by three wavelengths simultaneously, giving an unambiguous phase determination; a pressure sensitivity of 1.6 radbar/sup -1/ was measured, with a typical range of vacuum to 600 kPa. Five sensors were embedded in the trailing edge of a nozzle guide vane installed upstream of a rotor in a full-scale turbine stage transient test facility. Pressure signals in the trailing edge flow show marked structure at the 8 kHz blade passing frequency. To our knowledge, this is the first report of sensors located at the trailing edge of a normal-sized turbine blade.     

水下仪器压力补偿用波纹膜片性能分析

以水下压力传感器为研究对象,分析了波纹膜片的压力补偿机理,基于液体的可压缩性,提出了一种分析波纹膜片压力补偿性能的方法,推导出传感器工作水深与波纹膜片的补偿体积以及内外压差之间的关系式,并给出了内外压差的计算流程,为压力补偿用波纹膜片的分析和设计提供依据。对相同材料和尺寸的波纹膜片与平膜片的压力补偿性能进行了分析,结果表明存在一个衡量两种膜片压力补偿性能的水深临界值,当水深大于该临界值时,波纹膜片的压力补偿性能优于平膜片。     

A SiC MEMS Resonant Strain Sensor for Harsh Environment Applications

In this paper, we present a silicon carbide MEMS resonant strain sensor for harsh environment applications. The sensor is a balanced-mass double-ended tuning fork (BDETF) fabricated from 3C-SiC deposited on a silicon substrate. The SiC was etched in a plasma etch chamber using a silicon oxide mask, achieving a selectivity of 5:1 and etch rate of 2500 Aring/min. The device resonates at atmospheric pressure and operates from room temperature to above 300degC. The device was also subjected to 10 000 g shock (out-of-plane) without damage or shift in resonant frequency. The BDETF exhibits a strain sensitivity of 66 Hz/muepsiv and achieves a strain resolution of 0.11 muepsiv in a bandwidth from 10 to 20 kHz, comparable to state-of-the-art silicon sensors     

Investigation based on nano-electromechanical system double Si3N4 resonant beam pressure sensor

This paper presents a type of NEMS (Nano-Electromechanical System) double Si3N4 resonant beams pressure sensor. The mathematical models are established in allusion to the Si3N4 resonant beams and pressure sensitive diaphragm. The distribution state of stress has been analyzed theoretically based on the mathematical model of pressure sensitive diaphragm; from the analysis result, the position of the Si3N4 resonant beams above the pressure sensitive diaphragm was optimized and then the dominance observed after the double resonant beams are adopted is illustrated. From the analysis result, the position of the Si3N4 resonant beams above the pressure sensitive diaphragm is optimized, illustrating advantages in the adoption of double resonant beams. The capability of the optimized sensor was generally analyzed using the ANSYS software of finite element analysis. The range of measured pressure is 0-400 Kpa, the coefficient of linearity correlation is 0.99346, and the sensitivity of the sensor is 498.24 Hz/Kpa, higher than the traditional sensors. Finally the processing techniques of the sensor chip have been designed with sample being successfully processed.