SXFA-SAW传感器的稳定性研究

以SXFA聚合物为敏感膜材料制成能够检测有机磷化合物的声表面波传感器.研究结果表明该传感器具有噪音小、对沙林检测灵敏度高、重现性强等性能;通过气体流速实验和统计学假设检验分析证实流速在0.5～1.5 L/min的范围内对传感器响应频移不产生影响,说明该传感器具有较好的稳定性.     

一种基于温差测量原理工作的集成型流量传感器􀀂

在比较已有的几种低流速流体的流速流量测量方法基础上,提出一种利用与流速相关温差的测量方案,并用芯片集成方法构成流量传感器加以验证,实验结果与理论预期基本相符.该传感器的主要优点是在低流量条件下具有高灵敏度.     

一种热温差式悬空结构气体流量传感器设计

基于热温差原理,利用MEMS技术加工制备出高灵敏度微型气体流量传感器。该流量传感器采用热敏电阻器悬空结构,其热隔离性能较好,并利用温度系数大的VO2制备热敏电阻器;同时,利用机械性能和密封性能好的SU—8胶制备气流沟道,工艺简单,稳定性好,且成本较低,适合批量生产。实验表明:当传感器处于适当偏压下时,在0～30 mL/min的流速范围内响应速度快,灵敏度高,而且具有良好的线性度,适合生化检测、医疗等领域的应用。     

变宽度悬臂梁的FBG流速传感器

通过对光纤传感器进行设计,提出了一种基于变宽度悬臂梁的光纤(Bragg)光栅(FBG)流速传感器.传感部分由不锈钢材质的悬臂梁和粘贴在其特定位置上的FBG构成,悬臂梁采用等腰梯形和矩形相结合的外形结构设计,传感头两部分之间的衔接不需要用销子固定,整个传感头浑然一体,无额外附加重量,制作方法简易,且实验设置参考光栅,实验结果不受温度变化的影响.实验表明:传感器的Bragg波长漂移量与流速变化有很好的线性关系,传感器的灵敏度为0.025 m/s.可测流速范围为0～2 m/s,传感器不仅实现了对温度的补偿,而且提高了测量精度、灵敏度.     

压阻式微压力传感器结构参数设计

在研究压阻式微压力传感器的结构参数的基础上,根据传感器的灵敏度与线性度特点,设计了一种量程为200 kPa的微压力传感器.在满足计算要求的条件下,对该传感器的每一个参数进行ANSYS仿真;并根据灵敏度、线性度及制作工艺的难易程度选择这些参数的最佳值.仿真结果表明,该设计方法对微压力传感器的研制具有一定的参考价值.     

大量程六维力传感器设计与标定研究

为提高大量程六维力传感器的灵敏度,设计了一种适用于机械臂末端的应变式传感器.该传感器采用十字梁式弹性体结构,通过优化应变梁结构和合理布置应变片等方式,使传感器在大量程条件下仍具有较高的刚度和灵敏度.使用有限元法分析验证了传感器应力分布的合理性,并根据最小二乘法标定原理对传感器进行解耦标定实验,实验结果表明:传感器静态性能良好,最小灵敏度为0.375 mV/N,满足使用要求.     

基于LCP衬底的柔性湿度传感器研究

介绍了一种新型柔性电容式湿度传感器.该柔性电容式湿度传感器采用液晶高分子聚合物(LCP)作为衬底,金属铜(Cu)作为叉指电极,聚酰亚胺(PI)作为湿度传感器的湿敏介质.LCP衬底的应用使得该传感器具有良好的柔性和可弯曲性.该柔性湿度传感器与传统硅基湿度传感器相比较具有成本低廉、结构简单、制作方便等优点.该柔性湿度传感器在25℃下的平均灵敏度为0.04%pF/%RH,最大回滞为±4.16%RH,其平均灵敏度在25℃~70℃范围内受温度影响较小.在25℃下其响应时间和恢复时间分别为36 s和39 s.该柔性湿度传感器可以应用于环境湿度检测、人工电子皮肤系统和可穿戴设备等领域.     

电容式传感器用于检测医疗输液液位的研究

设计一种变介电常数型电容式液位传感器,通过对不同宽度电极下传感器输出电容与对应液位的实验数据分析,发现传感器灵敏度随电极宽度的增加而近似线性提高;同时,发现传感器灵敏度与液位下降速度相关。建立传感器数学模型,分析影响传感器灵敏度的因素和机理。研究结果表明:以范德华力附着在瓶壁内侧的吸附水在电场作用下极易极化,会引起其介电常数超常增大;吸附水对传感器的灵敏度有直接影响。     

一种可用于风速测量的CMOS光点位置检测传感器的设计

介绍了一种可用于风速风向测量的光点位置检测传感器的结构、特点、工作原理,给出了传感器的理论模型,分析了传感器测量分辨率和灵敏度.该传感器在用于大风速测量有较高的测试灵敏度.在0～20 m/s测试量程内,测得风向的灵敏度为7 mV/度,风速的灵敏度为2.5 mv//μm..该传感器结构简单,工艺制作方便,能与CMOS工艺兼容,无温度漂移.     

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。     

一种高性能MEMS气体流量传感器设计

使用MEMS技术研制出一种高灵敏度热温差式流量传感器。器件采用热隔离性能良好的衬底挖空结构,且热敏电阻器与热源距离可调,保证了系统的灵敏度和响应速度。同时热敏电阻器、加热电阻器与电桥电阻器集成在传感器片内,提高了系统的稳定性。实验表明:合适的电阻器间距可以获得较高的灵敏度,而在0~20 mL/min的量程范围内系统线性度较好,因此,在生化检测、医疗等领域具有良好的推广前景。     

A new edge-detected lift force flow sensor

A lift force gas flow sensor which uses the force normal to the fluid flow to measure the flow velocity has recently been introduced. Two thin plates mounted at an angle are deflected when they are subjected to fluid flow. For most mechanical flow sensors the flow sensitivity is closely connected to the time response. A weaker structure gives higher flow sensitivity but a lower natural frequency, i.e., a slower response time. The lift force sensor is designed for measurements of respiratory gas flow in ventilators, where, in addition to low flow restriction, both high sensitivity and fast response are required. A new type of suspension has now been realized for the lift force flow sensor. The detection is separated from the suspension of the airfoil plate with the strain gauges placed on separate detector beams. This leads to separate parameters for optimization of the lift force concept with "independent" control of flow sensitivity and natural frequency. This paper presents an analytical model, simulations and measurements on the new structure. The new edge-detected sensor has been experimentally evaluated for different lengths (100-600 /spl mu/m), widths (20-100 /spl mu/m) and thicknesses (8-20 /spl mu/m) of the detector beams. In accordance with the theory, the measurements show that the new structure has approximately three times the natural frequency of the old, center detected structure and similar or improved flow sensitivity. The evaluation has also resulted in a design scheme for optimal performance. A flow sensitivity of 0.65 /spl mu/V/V/(l/min)/sup 2/ has been obtained for the best edge-detected sensor with a natural frequency of 3.2 kHz.     

Exploitation of aeroelastic effects for drift reduction,in an all-polymer air flow sensor

This paper presents a vibration amplitude measurement method that greatly reduces the effects of baseline resistance drift in an all-polymer piezoresistive flow sensor or microtuft. The sensor fabrication is based on flexible printed circuit board (flex-PCB) technology to enable the potential for low-cost and scalable manufacture. Drift reduction is accomplished by discriminating the flow-induced vibration (‘flutter’) amplitude of the microtuft-based sensor as a function of flow velocity. Flutter peak-to-peak amplitude is measured using a microcontroller-based custom readout circuit. The fabricated sensor with the readout circuitry demonstrated a drift error of 2.8 mV/h, which corresponds to a flow-referenced drift error of 0.2 m/s of wind velocity per hour. The sensor has a sensitivity of 14.5 mV/(m/s) with less than 1% non-linearity over the velocity range of 5–16 m/s. The proposed vibration amplitude measurement method is also applied to a sensor array with a modified structure and a reduced dimension, which demonstrated a sensitivity of 13.2 mV/(m/s) with a flow-referenced drift error of 0.03 m/s of wind velocity per hour.     

Flow profile measurement in microchannel using the optical feedback interferometry sensing technique

The need to accurately measure flow profiles in microfluidic channels is well recognised. In this work, we present a new optical feedback interferometry (OFI) flow sensor that accurately measures local velocity in fluids and enables reconstruction of a velocity profile inside a microchannel. OFI is a self-aligned interferometric technique that uses the laser as both the transmitter and the receiver thus offering high sensitivity, fast response, and a simple and compact optical design. The system described here is based on a commercial semiconductor laser and has been designed to achieve a micrometer-range spatial resolution. The sensor performance was validated by reconstructing the velocity profile inside a circular cross-section flow-channel with 320  $\upmu $ m internal diameter, with a relative error smaller than 1.8 %. The local flow velocity is directly measured, thus avoiding the need for model based profile calculation and uncertainties inherent to this approach. The system was validated by successfully extracting the flow profiles in both Newtonian and shear-thinning liquids.     

A thermal-calorimetric gas flow meter with improved isolating feature

This paper presents design and characterization of a novel thermal-calorimetric flow-meter using suspended-cantilever-structure. There is an air gap between the heater and each individual thermistor providing a good thermal isolation. Due to the suspended-structure which consists of three cantilevers, the thermal convection effect is present on both sides of the active area. Also the velocity boundary layer thickness of the cantilever is much less than closed-membrane one. This characteristic enhances the sensitivity of sensor. The simulation results indicate that the average temperature difference between upstream and downstream thermistors are 36.5 and 1.04 K for flow rate of 1 m/s and the worst case of 0.1 m/s respectively. This solution significantly improves the sensitivity compared to the closed-membrane-structures. The maximum temperature difference causes 94 mV at the output of Wheatstone bridge with 3 V of voltage supply. The calculated and simulated results show that the maximum power consumption of sensor is 4.7 mW at the maximum flow velocity of 1 m/s. The operational range of the designed flow meter is from 0 to 1 m/s. The features of the device are analytically evaluated and simulated under various conditions.

     

Focal Flow: Velocity and Depth from Differential Defocus Through Motion

We present the focal flow sensor. It is an unactuated, monocular camera that simultaneously exploits defocus and differential motion to measure a depth map and a 3D scene velocity field. It does this using an optical-flow-like, per-pixel linear constraint that relates image derivatives to depth and velocity. We derive this constraint, prove its invariance to scene texture, and prove that it is exactly satisfied only when the sensor’s blur kernels are Gaussian. We analyze the inherent sensitivity of the focal flow cue, and we build and test a prototype. Experiments produce useful depth and velocity information for a broader set of aperture configurations, including a simple lens with a pillbox aperture.     

制冷系统中润滑油质量分数的实时测量

根据润滑油和制冷剂对紫外光的不同吸收特性 ,利用GaN基紫外光敏感器件 ,对制冷系统中润滑油质量分数进行实时测量 ,分析了压缩机转速对润滑油质量分数测试结果的影响。通过与标准方法比较 ,证实了这种方法的可靠性