微型热膜传感器的水下壁面剪应力标定研究

针对水下壁面剪应力的测量需求,建立了恒流模式下微型热膜传感器的剪应力测量与标定的数学模型,设计采用了扁薄矩形水槽剪应力发生装置,并在0 ～5 Pa范围内对传感器进行了测量标定实验.实验结果验证了测量与标定模型的正确性,标定实验的确定系数均超过了0.995,均方差保持在10-4量级,呈现良好的重复性与一致性,为水下壁面剪应力的测量应用奠定了重要基础.     

微悬臂梁矩阵细胞牵引力测量传感器研制

提出一种采用聚碳酸酯核孔膜为模版来制作高深宽比聚二甲基硅氧烷微悬臂梁矩阵的新方法,用来作为生物微机电系统传感器探测细胞微纳力学及在体外研究细胞的机械特性,并对其制作工艺进行研究.通过选择不同的膜,可以便捷制作不同规格的微悬臂梁矩阵来满足不同精度的测量需求.细胞贴附在经表面处理后的微悬臂梁矩阵顶端生长并延展迁移,造成微悬臂梁弯曲形变.通过对形变共焦荧光显微图像处理,可以精确描绘出细胞牵引力分布.实验结果表明该制作方法有效,测量精度达到nN/μm.     

基于Fluent的新型微流量热分布式质量流量计的仿真分析及实验研究

提出了一种新型微流量热分布式质量流量计的管道结构,基于Fluent技术建立管道结构仿真模型,在不同流速下对其温度场进行仿真,得出不同流速下的热量分布.通过MATLab软件画出温差与质量流量的关系图.根据热分布式质量流量计的原理建立流量测量的实验平台.通过实验测量,对比实验结果与仿真结果的数据,确定其在低流速条件下的测量范围,最终达到对传统热分布式质量流量计的应用拓展.     

基于驱动电流的水下热敏剪应力微传感器灵敏度研究

驱动电流是热敏式剪应力微传感器的一个重要参数。增大驱动电流可以提高传感器的灵敏度,但传感器的安全工作温度又限制了驱动电流的增大。研究了如何基于驱动电流来最大程度地提高传感器灵敏度。从理论上分析了传感器灵敏度随剪应力输入的变化规律。通过静水中的I-V特性测试实验,确定了传感器在水下工作的最大允许驱动电流。通过电压—剪应力特性测试实验,验证了传感器灵敏度与驱动电流的关系,得到了传感器在最大允许驱动电流激励下的灵敏度。研究,发现最大允许驱动电流可以使传感器在剪应力为0.2Pa时的灵敏度达到23.8mV/Pa。     

基于柔性热膜传感器的流体壁面剪应力测量系统

为实现流体壁面剪应力在线测量,设计了一种基于柔性热膜传感器的流体壁面剪应力测量系统.通过分析柔性热膜传感器作用机理,研发了基于LTZ1000电压基准的高精度恒流驱动电路,开发了基于DSP2812,AD7609的18位真差分同步高速数据采集模块,并通过温度补偿方法对传感器输出信号进行了环境温漂修正.系统性能测试表明:当流场温度在10 ～30℃范围变化时,剪应力测量分辨率在0～10 Pa范围内优于0.2Pa,流体温度变化引起的系统输出信号偏差为0.6％/℃,满足实际流体壁面剪应力测量要求.     

基于MEMS工艺的压阻式湿度传感器的设计制作

提出用硅-硅直接键合的SOI片制作压阻式湿度传感器.它是利用涂覆在硅膜上聚酰亚胺膜吸湿发生膨胀,导致双膜结构发生弯曲产生应力的原理进行工作的.为了确定传感器结构、优化尺寸,采用ANSYS软件进行了模拟计算、设计了MEMS湿度传感器的制造工艺,对制作的微湿度传感器进行了测试,其灵敏度为0.21 mV%RH,最大湿滞为8%RH.     

基于无掩模腐蚀技术的高性能微加速度传感器

针对深沟槽内结构制作困难的问题,基于单晶硅各向异性腐蚀原理,推导了[100]单晶硅在KOH溶液中无掩模腐蚀过程台阶宽度与无掩模腐蚀深度之间的解析表达式,通过工艺实验确定了单晶硅[311]面与[100]面的腐蚀速率比;采用适合于三明治微加速度传感器硅芯片制作的无掩模腐蚀成型工艺流程,实现了深沟槽内悬臂梁的准确成型,研制出一种±100gn量程的微加速度传感器.样品测试表明:运用无掩模腐蚀技术制作的微加速度传感器相对精度优于6 ×10-5,灵敏度为17.78 mV/gn.     

硅基光纤温度传感器研究

基于单晶硅折射率随温度变化的热光效应,研究了一种硅基双波长光纤温度传感器.理论分析了单晶硅膜温度传感的机理,通过计算得到了硅膜厚度与温度测量范围之间的关系.运用双波长信号处理方法对传感器反射光强度进行分析并解调出所测量的温度.实验结果表明,在测温范围25～45℃内,当传感器测温波长为1 534.3 nm、1 554.3 nm时,该传感器对温度的响应具有良好的线性,其线性拟合度达0.989 8.该温度传感器的研究对设计制作温度补偿型的硅基压力或其它物理量的测量传感器具有一定的参考价值.     

基于强度解调的Fabry－Perot型光纤MEMS压力传感器

运用微机械系统加工技术制作了一种新型法布里-珀罗干涉型光纤微机电系统压力传感器,该传感器通过测量反射光谱的移动测量压力.运用多腔干涉原理对该传感器进行理论以及模拟分析得出,通过改变压力传感器的尺寸可较容易的调节压力线性测量范围和灵敏度.实验结果表明,在压力线性测量范围[0.1～1.0]MBa内,灵敏度可达到12.71 nm/MPa(光谱移动/压力).     

平面波导硅基结构表面的APTES修饰研究

3-氨丙基三乙氧基硅烷（APTES）是一种常用的表面修饰剂,通过化学键合的方式覆盖在硅结构表面形成APTES膜层,用以链接功能性生物分子。本文基于平面波导生物传感器器件的研究,通过对结构表面膜层的物理化学特性进行分析,对实验方案进行优化,降低表面微粗糙度,提升生物分子膜层的活性。文中在相同的实验环境下,将APTES分别溶于PBS、乙醇、甲苯溶液,进行APTES分子膜的生成,通过原子力扫描显微镜（AFM）、接触角测试仪、X-射线光谱仪（XPS）对不同样品表面微粗糙度（RMS）、接触角、成分等物理化学特性进行分析,确定应用于光学生物传感器器件APTES表面修饰的最佳配剂,为提高平面波导生物传感器的灵敏度提供了理论支持。     

A contact-type piezoresistive micro-shear stress sensor forabove-knee prosthesis application

A prototype contact-type micro piezoresistive shear-stress sensor that can be utilized to measure the shear stress between skin of stump and socket of above-knee (AK) prosthesis was designed, fabricated and tested. Micro-electro-mechanical system (MEMS) technology has been chosen for the design because of the low cost, small size and adaptability to this application. In this paper, the finite element method (FEM) package ANSYS has been employed for the stress analysis of the micro shear-stress sensors. The sensors contain two transducers that will transform the stresses into an output voltage. In the developed sensor, a 3000×3000×300 μm³ square membrane is formed by bulk micromachining of an n-type (100) monolithic silicon. The piezoresistive strain gauges were implanted with boron ions with a dose of 10¹⁵ atoms/cm². Static characteristics of the shear sensor were determined through a series of calibration tests. The fabricated sensor exhibits a sensitivity of 0.13 mV/mA-MPa for a 1.4 N full scales shear force range and the overall mean hysteresis error is than 3.5%. In addition, the results simulated by FEM are validated by comparison with experimental investigations     

A microfabricated wall shear-stress sensor with capacitative sensing

A silicon-based micromachined, floating-element sensor for low-magnitude wall shear-stress measurement has been developed. Sensors over a range of element sizes and sensitivities have been fabricated by thin-wafer bonding and deep-reactive ion-etching techniques. Detailed design, fabrication, and testing issues are described in this paper. Detection of the floating-element motion is accomplished using either direct or differential capacitance measurement. The design objective is to measure the shear-stress distribution at levels of O(0.10 Pa) with a spatial resolution of approximately O(100 /spl mu/m). It is assumed that the flow direction is known, permitting one to align the sensor appropriately so that a single component shear measurement is a good estimate of the prevalent shear. Using a differential capacitance detection scheme these goals have been achieved. We tested the sensor at shear levels ranging from 0 to 0.20 Pa and found that the lowest detectable shear-stress level that the sensor can measure is 0.04 Pa with an 8% uncertainty on a 200 /spl mu/m/spl times/500 /spl mu/m floating element plate.     

Design and simulation of a thermo transfer type MEMS based micro flow sensor for arterial blood flow measurement

Thermo transfer type MEMS (Micro Electro Mechanical System) based micro flow sensing device have promising potential to solve the limitation of implantable arterial blood flow rate monitoring. The present paper emphasizes on modeling and simulation of MEMS based micro flow sensing device, which will be capable of implantable arterial blood flow rate measurement. It describes the basic design and model architecture of thermal type micro flow sensor. A pair of thin film micro heaters is designed through MEMS micro machining process and simulated using CoventorWare; a finite element based numerical code. A rectangular cross section micro channel has been modeled where in micro heater and thermal sensors are embedded using the same CoventorWare tools. Some promising and interesting results of thermal dissipation depending upon very small amount of flow rate through the micro channel are investigated. It is observed that measuring the variation of temperature difference between downstream and upstream, the variation of fluid flow rate in the micro channel can be measured. The numerical simulation results also shows that the temperature distribution profile of the heated surface depends upon microfluidic flow rate i.e. convective heat transfer is directly proportional to the microfluidic flow rate on the surface of the insulating membrane. The simplified analytical model of the thermo transfer type flow sensor is presented and verified by simulation results, which are very promising for application in arterial blood flow rate measuring in implantable micro devices for continuous monitoring of cardiac output.     

高于室温环境的热式气体微流量传感器性能分析

为了探索平板微热管的传热特性,了解微热管内不同温度区间的蒸汽传输特性,开展了热式气体微流量传感器及其检测系统的设计。设计了一种便于探索最佳温度测量点的热式微流量传感器结构,利用MEMS工艺进行加工制作,在不同环境温度下对其性能进行了测试,得到了环境温度与热式微流量传感器性能的关系。基于MSP430单片机和C＃语言自主开发了流量传感器检测系统,可对一定范围内的流量进行实时检测,并实时绘制流速随时间的变化曲线。研究表明,采用本文设计的热式微流量传感器结构,可以检测高于室温环境下的微流量气体,并可通过提高加热器温度或改变测温电阻对的测量位置来提高测量灵敏度。     

集成微流体测控芯片的研制

设计、研制了集成有微泵、微沟道、微流量传感器、温度传感器的微流体测控芯片.采用有限元软件ANSYS模拟分析了将其作为冷却芯片时微沟道的散热作用,分析确定了芯片上各元件的结构.该集成芯片为硅-玻璃结构,在硅片上,利用ICP法刻蚀无阀微泵泵体和微沟道;在7740玻璃片上,以溅射、剥离法制作微流量和温度传感器;图形精确对准后硅/玻璃以静电键合方法封接.无阀微泵采用压电元件驱动.测试结果表明:集成芯片具有冷却功能,循环水的流速最大可达25.4mm/s.     

A microfabricated floating-element shear stress sensor usingwafer-bonding technology

A microfabricated floating-element (120 μm×140 μm×5 μm) liquid shear stress sensor has been developed using wafer-bonding technology. The sensor has been designed for high shear stresses (1-100 kPa) and high-pressure environments (up to 6600 psi) and utilizes a piezoresistive transduction scheme. Analytical and finite-element method (FEM) modeling have been performed to predict the sensor response. The sensor has been tested for both its mechanical integrity in high-pressure environments and its output response in the controlled environment of a cone and plate viscometer. The processing steps in the fabrication of the sensor, the analytical and FEM modeling, the experimental procedures, and the results of the experiments are described     

A flexible encapsulated MEMS pressure sensor system for biomechanical applications

 The use of pressure sensors made of conductive polymers is common in biomechanical applications. Unfortunately, hysteresis, nonlinearity, non-repeatability and creep have a significant effect on the pressure readings when such conductive polymers are used. The objective of this paper is to explore the potential of a new flexible encapsulated micro electromechanical system (MEMS) pressure sensor system as an alternative for human interface pressure measurement. A prototype has been designed, fabricated, and characterized. Testing has shown that the proposed packaging approach shows very little degradation in the performance characteristics of the original MEMS pressure sensor. The much-needed characteristics of repeatability, linearity, low hysteresis, temperature independency are preserved. Thus the flexible encapsulated MEMS pressure sensor system is very promising and shows superiority over the commercially available conductive polymer film sensors for pressure measurement in biomechanical applications. Received: 1 December 1999/Accepted: 17 August 2000     

Design and fabrication of a flexible three-axial tactile sensor array based on polyimide micromachining

This paper describes the design and fabrication of a flexible three-axial tactile sensor array using advanced polyimide micromachining technologies. The tactile sensor array is comprised of sixteen micro force sensors and it measures 13 mm × 18 mm. Each micro force sensor has a square membrane and four strain gauges, and its force capacity is 0.6 N in the three-axial directions. The optimal positions of the strain gauges are determined by the strain distribution obtained form finite element analysis (FEA). The normal and shear forces are detected by combining responses from four thin-film metal strain gauges embedded in a polyimide membrane. In order to acquire force signals from individual micro force sensors, we fabricated a PCB based on a multiplexer, operational amplifier and microprocessor with CAN network function. The sensor array is tested from the evaluation system with a three-component load cell. The developed sensor array can be applied in robots’ fingertips, as well as to other electronic applications with three-axial force measurement and flexibility keyword requirements.     

A micro shear stress sensor based on laterally aligned carbon nanotubes

This paper reports the development of a micro thermal shear stress sensor that utilizes multiwalled carbon nanotubes as the sensing element. The sensor was fabricated by laterally aligning randomly distributed nanotubes into a 360 μm long and 90 μm wide conductive trace between two triangular shaped micro electrodes through the use of a high frequency AC electric field. During operation, the aligned nanotubes are electrically heated to an elevated temperature and surface shear stress is measured indirectly by the amount of convective heat transfer from the heated nanotubes to the surrounding fluid flow.The nanotube alignment process was primarily controlled by three different phenomena: dielectrophoresis, joule heating, and Brownian motion. Numerical simulations, together with experimental verifications, indicated that a successful alignment could only be realized if: (1) the dielectrophoretic force was positive, (2) the electro-thermal force was also positive, and (3) the dielectrophoretic force was high enough to overcome Brownian motion. The aligned nanotube trace has a room-temperature resistance of 580 Ω, which corresponds to a conductivity of 2.7 × 10⁴ S/m. The absolute temperature coefficient of resistivity ranges from 0.01 to 0.04% °C⁻¹. This is about one order of magnitude smaller than the highly doped polysilicon sensing material used in the MEMS micro shear stress sensor. The shear stress sensitivity of the nanotube trace operated at a 3% overheat ratio is found to follow the theoretical sensor power ∝ (shear stress)^1/3 relationship, provided the shear stress level is higher than 0.34 mPa. This result confirms the feasibility of using aligned multi-walled carbon nanotubes as a thermal shear stress sensing material.     

热通量传感器的应用及检定

通过对热通量传感器在新材料的研制及热分析仪参量测量领域的研究,分别给出了其在表面安装和热分析仪中的应用方法,并针对应用中出现的问题提出解决方案,同时通过比较法求解检定常数。给出了热通量传感器的检定方法,提出了热通量微观效应的概念,对埋入绝缘材料和表面镀金属层热偶的微观效应进行了分析。结果证明,周围材料的不同是影响检定误差的重要因素。