基于NEMS技术的硅基纳机电探针阵列器件研究

进行一种用于高密度存储的硅基纳机电探针阵列器件研究.并采用理论计算和有限元模拟相结合方法对器件进行了设计;使用先进的微纳加工工艺技术将压阻敏感器和电阻加热器集成到超薄悬臂梁-针尖结构纳机电探针阵列器件上,实现器件制作;随后,进行器件电热特性及其敏感特性测试,测试结果与模拟结果相吻合;借助于原子力学显微镜在聚合物有机薄膜上实现了数据写入,优化写入条件后,数据记录面密度达31.6 GB/in2.     

一种冲击加速度传感器的研究

本文介绍一种周边固支圆形膜片硅压阻式冲击加速度计的工作原理和结构,以及硅膜片尺寸与传感器输出的计算关系,冲击加速度传感器的电阻设计,及其器件的制作工艺流程。通过冲击试验,证明了该加速度传感器在高加速度作用下的实用性。     

电子数字变阻器DS1668

DS1668电子数字变阻器的滑臂位置为64个,有三种标准阻值:10kΩ、50kΩ及100kΩ。它可以用手动控制,也可用数字信号控制。这种变阻器被Dallas公司称为Dallastat。该器件的特点是,可代替机械式可变电阻器,自身带有按钮,操作方便;无需外围元件;在掉电后滑臂位置可保持;输入电压范围较宽:从4.5～8V。该器件可应用于音量控制、音调控制、对比度控制及亮度控制等手控或遥控。     

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。     

叠加电桥检测的加速度传感器设计

基于压阻效应的叠加电桥检测法加速度传感器采用超对称"八悬臂梁—质量块"结构,构成惠斯通电桥的力敏电阻器布放在悬臂梁的两端,4个惠斯通电桥的输出电压叠加后作为传感器的最终输出,有效提高了加速度传感器的灵敏度。通过数学建模仿真分析验证了方案的可行性。性能测试结果表明:该加速度计的灵敏度为1.1381mV/gn,频响范围为0～1000Hz,灵敏度约为单电桥检测法和串联电桥检测法加速度传感器灵敏度的4倍。叠加电桥检测法为压阻式传感器提高灵敏度提供了一种新思路。     

高精度硅压阻式气压传感器系统设计

为了消除环境温度对硅压阻式传感器输出的影响,大幅提升硅压阻式传感器的测量精度,将传感器芯片与热源和测温原件封装在一起,通过控制加热的方式使传感器工作在恒定50℃的环境中,对传感器进行线性标定和测试.结果显示:在-45～45℃环境下,600～1 100 hPa量程内气压传感器的测量误差小于0.3 hPa.     

MEMS传感器敏感单元RTD的力敏特性优化

首先通过减小垒前阱的厚度消除了负阻区的"台阶区",提高负阻区的阻值为-7.916Ω,并通过加压测试RTD(共振隧穿二极管)的力电耦合灵敏度,使其灵敏度由原来的5.5 mA/g增大到7 mA/g,优化了RTD作为MEMS传感器敏感单元的灵敏度,同时也通过增大RTD结构的台面积大小,有效的消除了负阻区的"台阶区",并使其负阻区的阻值增大为-0.06Ω,提高了MEMS传感器敏感单元RTD结构的灵敏度。     

半导体集成传感器陈列

超大规模集成电路技术在传感制造中的应用,产生了高度密集的传感器阵列。这样的阵列可以用来获得被测量的一维或两维的信息。然而其设计有一系列的特殊问题,包括适当的集成水平,传感器的线性和均匀性等。木文将介绍目前最新发展起来的几种集成传感器的阵列的制造技术,工作原理,性能特征及读出电路的设计等。这些阵列主要有电容式和压阻式触觉传感器阵列,硅热电堆红外敏感阵列,集成P—n结温度计阵列,集成多通道记录阵列等。在此基础上总结集成传感器阵列设计中的若干问题。     

基于CAN总线的高精度程控电阻器设计

在电动汽车电池管理系统(BMS)的开发设计过程中,硬件在环(HIL)测试是基于开发和测试的V模式流程中必不可少的环节。通常情况下,在HIL环境中,为了准确模拟实际电池的温度变化,BMS需要高精度的电阻器模拟实际负温度系数(NTC)温度传感器的输出阻抗变换。针对这一问题,设计了一种基于CAN总线的高精度程控电阻器。为提升程控电阻阻值输出精度,给出了一种基于开关网络的程控电阻器改进拓扑结构。介绍了各电阻阻值的选取原则,并提出了基于称重比较算法的开关网络选择方法。借助飞思卡尔单片机及CAN总线接口,设计了基于LabVIEW的程控电阻实时控制上位机软件。试验测试数据表明:该电阻器可在6 MΩ内连续可调,当阻值小于100Ω,将绝对误差控制在1Ω以内;当阻值大于100Ω,相对误差可控制在0.05%以内,满足测试需求。该电阻器可以实现电阻并行控制输出以及在大量程内连续高精度输出,且为硬件在环测试提供了高效的工具设备。该系统可满足电动汽车自动化测试的要求。     

精密压阻弹性体及力敏传感器阵列

将金属钌(Ru)、二氧化钌(RuO2)、甲基乙烯基硅橡胶(PMVS)按特定比例混合,所得导电硅橡胶中的导电颗粒具有适当的聚集特性,而且该种导电硅橡胶呈现良好的压阻重复性和压阻敏感性.研究不同尺寸电极的压阻行为,发现此种导电硅橡胶在毫米尺寸以上电阻随载荷变化稳定,重复性较高.通过测量不同尺寸电极压阻关系和电阻弛豫关系,拟合了用于回归载荷的压阻曲线和弛豫曲线,用该曲线对每个传感单元的阻值校正,得到阵列上的载荷分布.结果表明,该种导电硅橡胶在一定尺寸范围内满足微型化要求,适用于集成的压阻弹性体应力测量阵列;利用该种导电硅橡胶,可以实现毫米尺度的静态或准动态载荷灰度成像.     

The mechanics of polymer swelling on microcantilever sensors

This paper investigates the swelling mechanics of polymer capture layers integrated into piezoresistive cantilever biochemical sensors. A finite element model investigates mechanical deformations in a polymer layer affixed to a silicon microcantilever. The polymer swells during analyte absorption, inducing deformations in the silicon cantilever which are sensed by a piezoresistive sensor integrated into the cantilever. The highest sensitivity is predicted for short and wide cantilevers that are coated with stiff polymer whose thickness is twice that of the cantilever. While the polymer swelling induces the deformations, the silicon carries most of the load. When portions of the silicon beam are removed to introduce stress concentrations, the system sensitivity can increase by 18% compared to the cantilever without stress concentrations. This study of stress distributions in the cantilever system allows sensor optimization that considers the full 3D effects of polymer swelling mechanics.     

一种集成式多参数硅微传感器

为了实现小体积多参数的测量,提出一种单片集成多功能传感器.该传感器包括压力、温度和湿度传感器.各部分分别基于半导体压阻效应、电阻迁移率变化、极板间电容变化为原理制作而成.该传感器采用n型(100)基底,利用体硅和面硅工艺加工而成.测量电阻通过离子注入B 形成扩散电阻.为减小各参数间的相互影响,压力传感器的测量电阻布置于[110]晶向,测温电阻沿[100]晶向布置.温度输出信号可以实现对传感器中压力输出时温度漂移的精确补偿.芯片大小为5mm× 5 mm.试验表明传感器具有良好的线性,小迟滞,较高的灵敏度.     

Design, fabrication, and testing of VDP MEMS pressure sensors

In this paper, a four-terminal piezoresistive sensor commonly known as a van der Pauw (VDP) structure is presented for its application to MEMS pressure sensing. In a recent study, our team has determined the relation between the biaxial stress state and the piezoresistive response of a VDP structure by combining the VDP resistance equations with the equations governing silicon piezoresistivity and has proposed a new piezoresistive pressure sensor. It was observed that the sensitivity of the VDP sensor is over three times higher than the conventional filament type Wheatstone bridge resistor. To check our theoretical findings, we fabricated several (100) silicon diaphragms with both the VDP sensors and filament resistor sensors on the same wafer so both the sensor elements have same doping concentration. Several diaphragms had VDP sensors of different sizes and orientations to find out their geometric effects on pressure sensitivity. The diaphragms were subjected to known pressures, and the pressure sensitivities of both types of sensors were measured using an in-house built calibration setup. It was found that the VDP devices had a linear response to pressure as expected, and were more sensitive than the resistor sensors. Also, the VDP sensors provided a number of additional advantages, such as its size independent sensitivity and simple fabrication steps due to its simple geometry.     

平面内谐振式微悬臂梁生化传感器的设计与制造

给出了一种新型的基于平面内谐振模态的电热驱动微悬臂梁的工作原理和制造方案。相比于传统的平面外谐振模态谐振式悬臂梁,该设计能有效地降低微悬臂梁在液体中工作时的拖曳力,从而降低其振动能量损失,使得其接入锁相环接口电路后的闭环品质因数达到了249。电热驱动和压阻检测方式便于工艺集成和快速检测。本文给出了基于SOI硅片和深反应离子刻蚀(DRIE)的悬臂梁制作方案,并分别在空气和水中对悬臂梁的谐振特性进行了测试。     

Design and characterization of MEMS-based flow-rate and flow-direction microsensor

This study designs and characterizes a novel MEMS-based flow-rate micro-sensor consisting of a platinum resistor deposited on a silicon nitride-coated silicon cantilever beam. Due to the difference between the thermal conductivities of the silicon nitride film and the silicon beam, the tip of the cantilever structure bends slightly in the upward direction. As air travels across the upper surface of the sensor, it interferes with the curved tip and displaces the beam in either the upward or the downward direction. The resulting change in the resistor signal is then used to calculate the velocity of the air. A flow-direction micro-sensor is constructed by arranging eight cantilever structures on an octagonal platform. Each cantilever is separated from its neighbors by a tapered baffle plate connected to a central octagonal pillar designed to attenuate the aerodynamic force acting on the cantilever beams. By measuring the resistor signals of each of the cantilever beams, the micro-sensor is capable of measuring both the flow rate and the flow direction of the air passing over the sensor. A numerical investigation is performed to examine the effects of the pillar height and pillar-to-tip gap on the airflow distribution, the pressure distribution, the bending moment acting on each beam, and the sensor sensitivity. The results show that the optimum sensor performance is obtained using a pillar height of 0.75 mm and a pillar-to-tip gap of 5 mm. Moreover, the sensitivity of the octagonal sensing platform is found to be approximately 90% that of a single cantilever beam.     

一种压阻式三轴加速度传感器的设计

介绍了一种基于SOI的硅压阻式三轴加速度传感器的设计和制备.该三轴加速度传感器采用四个相互垂直的悬臂梁支撑中间质量块的结构.加速度传感器通过利用合理布置的压敏电阻构成的惠斯通电桥测量三个方向的加速度.对加速度传感器结构进行了理论分析和有限元仿真优化,确定加速度传感器的结构尺寸,并详细论述了三轴加速度传感器的制备工艺步骤和测试结果.     

MEMS-based humidity sensor with integrated temperature compensation mechanism

This study applies conventional micro-electro-mechanical systems (MEMS) techniques to develop a novel low-cost humidity sensor comprising a silicon substrate, a freestanding cantilever and an integrated resistive thermal sensor. The cantilever has a composite structure comprising a thin layer of platinum (Pt) deposited on a silicon nitride layer and then covered with a polyimide sensing layer. The cantilever deflected in the upward direction as water molecules absorbed by the polyimide sensing layer. The humidity sensor chip caused a measurable change in the resistance of the platinum layer. By compensating the change in the measured resistance by the ambient temperature, the absolute value of the relative humidity can be directly derived. The experimental results show that the sensor has a time-response of 0.9 s when exposed to a sudden humidity change of 65%RH to 95%RH. The sensitivity of the sensors decreases as the temperature increases. Furthermore, the sensor with the longest Pt resistor has the greatest sensitivity. In additions, the temperature-calibrated resistance signal generated by the sensor varies linearly with the ambient humidity.     

A phase-locked loop frequency tracking system for portable microelectromechanical piezoresistive cantilever mass sensors

A closed-loop circuit is developed in this work for tracking the resonant frequency of silicon microcantilever mass sensors. The proposed closed-loop system is mainly based on a phase-locked loop (PLL) circuit. To lock onto the resonant frequency of the resonator, an actuation signal generated from a voltage-controlled oscillator is fed back to the input reference signal of the cantilever sensor. In addition to the PLL circuit, an instrumentation amplifier and an active low-pass filter are connected to the system for gaining the cantilever output signal and transforming a rectangular PLL output signal into a sinusoidal signal used for sensor actuation, respectively. To demonstrate the functionality of the system, a self-sensing silicon cantilever resonator with a built-in piezoresistive Wheatstone bridge is fabricated and integrated with the circuit. A piezoactuator is employed to actuate the cantilever into resonance. From the measurement results, the integrated closed-loop system is successfully employed to characterize a 9.4 kHz cantilever sensor under ambient temperature cross-sensitivity yielding a sensor temperature coefficient of ?32.8 ppm/°C. In addition to it, the sensor was also exposed to exhaled human breath condensates and e-cigarette aerosols to test the sensor sensitivity obtained from mass-loading effects. With a high frequency stability (i.e., a frequency deviation as low as 0.02 Hz), this developed system is intended to support the miniaturization of the instrumentation modules for cantilever-based nanoparticle detectors (CANTORs).     

Design and Characterization of Artificial Haircell Sensor for Flow Sensing With Ultrahigh Velocity and Angular Sensitivity

We report the development of an artificial hair cell (AHC) sensor with design inspired by biological hair cells. The sensor consists of a silicon cantilever beam with a high-aspect-ratio cilium attached at the distal end. Sensing is based on silicon piezoresistive strain gauge at the base of the cantilever. The cilium is made of photodefinable SU-8 epoxy and can be up to 700-mum tall. In this paper, we focus on flow-sensing applications. We have characterized the performance of the AHC sensor both in water and in air. For underwater applications, we have characterized the sensor under two flow conditions: steady-state laminar flow (dc flow) and oscillatory flow (ac flow). The detection limit of the sensor under ac flow in water is experimentally established to be below 1 mm/s. A best case angular resolution of 2.16deg is also achieved for the sensor's yaw response in air.