Design and analysis of piezoresistive microcantilever for surface stress measurement in biochemical sensor

Piezoresistive microcantilever has been proposed to measure the surface stress generated by biochemical analytes. Such in situ measurement is desirable for biochemical sensors with on-chip microsystem integration. A two-dimensional model is presented to analyze the four-layer piezoresistive microcantilever subject to the surface stress effect generated by biochemical reaction and the thermal effect induced by the piezoresistive layer. Analysis shows that both effects are detrimental to sensor measurement. Conventional wisdom by changing the aspect ratio of a microcantilever is futile to achieve higher sensitivity. An improved design by having the stripe pattern on the immobilized layer is developed to increase the measurement sensitivity. Higher sensitivity can also be obtained by having thicker bottom insulation layer and thinner piezoresistive layer. It is shown that the microcantilever design is superior to the stress concentration region (SCR) design commonly seen in atomic force microscopy (AFM).     

压阻式微悬臂梁传感器检测生化毒剂的响应动力学研究

为了探索压阻式微悬臂梁传感器检测靶分子的信号响应规律,在利用压阻式微悬臂梁传感器生化毒剂大量实测数据的基础上,基于配体-受体动力学和吸附动力学创建了两种压阻式微悬臂梁传感器检测靶分子的动力学模型,利用创建的动力学模型对检测数据进行了分析.结果表明:创建的模型能很好地拟合抗体、适配子等不同敏感分子检测不同种类(大分子蛋白毒素、小分子化学毒剂)、不同浓度生化毒剂的实测数据,相关系数R值均在0.948 5以上(p<0.01).两种模型中,基于配体-受体特异结合动力学模型由于考虑了敏感膜与靶分子间的特异相互作用,对传感器实际检测数据的拟合效果更佳,相关系数R值均在0.957 1以上(p<0.01),能更好的反映压阻式微悬臂梁传感器检测靶分子的响应特点和规律;并且能求出更有意义的平衡响应电压(ΔUe)、响应时间(t0)等参数,根据曲线拟合方程求出的ΔUe、t0均与实测值非常接近.     

The effect of piezoresistive microcantilever geometry on cantilever sensitivity during surface stress chemical sensing

We have designed, fabricated, and tested five piezoresistive cantilever configurations to investigate the effect of shape and piezoresistor placement on the sensitivity of microcantilevers under both point loading and surface stress loading. The experimental study reveals that: (1) high aspect ratio cantilevers that are much longer than they are wide are optimal for point-loading applications such as microscopy and force measurements; (2) low aspect ratio cantilevers that are short and wide are optimal for surface stress-loading scenarios such as those that occur in biological and chemical sensor applications. The sensitivity data for both point loads and surface stress are consistent with previously developed finite-element models.     

微悬臂梁压阻桥式传感器的微弱信号检测技术研究

针对微悬臂梁压阻桥式传感器的输出信号非常微弱的特点,设计了基于该类传感器的微弱信号检测电路,采用锁相放大技术来提取淹没在强噪声背景下的微弱信号,通过理论和实验证明:该设计方法很好地提取了反映变化量性质的有用信号,同时也很好地提高了系统的信噪比,满足了实际情况的需要。     

压阻式硅微型加速度传感器的研制

利用微加工技术制作了压阻式硅微型加速度传感器,对制作的加速度传感器样品进行了动态测试,单臂梁结构的加速度传感器的灵敏度为1μV/gn,双臂梁结构加速度传感器的灵敏度为1.6μV/gn,结果与理论设计值基本吻合。     

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.     

微型硅压阻式压力传感器研制

结合多晶硅材料的压力敏感特性,通过在硅膜片上沉淀多晶硅压敏电阻及精密的微型化封装工艺,设计了微型硅压阻式土压力和孔隙水压力传感器.传感器通过将硅膜片在压力下的电阻值变化转换为电信号输出,通过标定实验得出:传感器的零点输出小,动态频响高,线性拟合度高,且适用于监测精度要求高的实际工程及受尺寸限制的室内模型试验.     

硅压阻式压力传感器的现场可编程自动补偿技术

为了提高硅压阻式压力传感器温度性能指标,并实现快速补偿,通过以ADμC816微处理器为核心设计了智能压力传感器,提出了传感器在宽温区下测量误差的自动补偿办法,通过对IC sensor系列压力传感器的应用,使其温度性能提高了1~2个数量级。     

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     

硅压阻式气压高度计的设计与实现

采用硅压阻式压力传感器,以ATmega88PA为控制器设计了气压高度计。内嵌全温度范围的曲面拟合算法进行温度补偿及线性化处理,解决了压力传感器的温漂和非线性问题,并用海拔高度与气压的关系计算高度。测量结果通过RS-485接口发送给上位机。测试结果表明,该气压高度计压力测量误差优于0.50‰,分辨率为0.01 h Pa,线性度为0.999 9;标准大气环境下高度测量误差为0.16 m,线性度为0.999 8。该气压高度计具有质量小、功耗低、精度高、工作可靠等优点。     

基于硅压阻式压力传感器的TPMS无线传感器节点设计

针对量程在800kPa以上进口TPMS传感器芯片价格非常昂贵和目前大客/货车安装胎压监测的必要性之间的矛盾,本文使用TI公司生产的处理器MSP430F2112,提出了一种高性价比的TPMS无线传感器节点设计方案,包括总体方案、压力传感器非线性补偿算法、详细的硬件设计、软件控制策略.最后通过实验室测试表明:该设计的硬件电...     

Die separation and packaging of a surface micromachined piezoresistive pressure sensor

The processing steps required to obtain a useful single medical sensor assembly are discussed, starting from an entire silicon wafer with thousands of surface micromachined sensors. Experiences concerning dicing and packaging of a piezoresistive pressure sensor are described, together with proposals for solutions. Problems with fracture of essential sensor structures are solved by use of a wafer protection tape. Existing solutions for flip–chip bonding and design of substrate for electrical interconnection are pushed to their limits due to the very small size of the novel sensor. As many of the processes can be simplified by an improved MEMS design, critical points related to the design are addressed.     

Determination of exposure to engineered carbon nanoparticles using a self-sensing piezoresistive silicon cantilever sensor

A novel MEMS-based cantilever sensor with slender geometry is designed and fabricated to be implemented for determining personal exposure to carbon engineered nanoparticles (NPs). The function principle of the sensor is detecting the cumulative mass of NPs deposited on the cantilever surface as a shift in its resonant frequency. A self-sensing method with an integrated full Wheatstone bridge on the cantilever as a piezoresistive strain gauge is introduced for signal readout replacing optical sensing method. For trapping NPs to the cantilever surface, an electrostatic field is used. The calculated equivalent mass-induced resonant frequency shift due to NPs sampling is measured to be 11.78?±?0.01?ng. The proposed sensor exhibits a mass sensitivity of 8.33?Hz/ng, a quality factor of 1,230.68?±?78.67, and a temperature coefficient of the resonant frequency (TC _f ) of ?28.6?ppm/°C. These results and analysis indicate that miniaturized sensors based on self-sensing piezoresistive microcantilever can offer the performance to fulfill the requirements of real-time monitoring of NPs-exposed personnel.     

压阻式压力传感器实时自校正方法研究

目前的传感器误差校正方法,由于都是以传感器初始标定数据作为依据,从而随着使用时间的增加,传感器参数发生变化,其校正误差会逐步增大。针对这种情况,研究了用多基准恒流源模拟标准压力自动对传感器进行标定得到实时输出特性曲线,并据此求得测量压力。实验结果表明:该校正方法切实可行,若采用4个基准源校正,可在一定的温度和压力范围内实现0.15%的精度。     

Optimization and comparison of photonic crystal resonators for silicon microcantilever sensors

Microcantilever sensors have been known as a fundamental design used in force sensors, strain sensors and biochemical sensors. The fast-growing applications in nanoelectromechanical systems (NEMS) lead to strong demands in new sensing mechanism in order to downsize the sensing elements to nanometer scale. Photonic crystal (PC) based resonators have been investigated as promising solutions because the bandgap structure and resonator characteristics are extremely sensitive to the deformation and position shift of holes in PC resonators. In addition to the well-known nano-cavity resonator (NCR), we proposed hexagonal nano-ring resonators (NRR) of two different layout configurations. When a microcantilever under different force loads, both of the resonant wavelength and the resonant wavelength shift can be measured as a linear function of force load. The linear relationship between wavelength shifts and strain is observed as well. The minimum detectable force and detectable strain for NRR configuration 1 is derived as small as 0.0757 μN and 0.0023%. The outstanding sensing capability renders PC resonators as a promising nanomechanical sensing element to be integrated in various transducers for NEMS applications.     

Design and development of a piezoresistive pressure sensor on micromachined silicon for high-temperature applications and of a signal-conditioning electronic circuit

The deposition of diamond films on silicon substrate by MWPECVD is described and microstructural characteristics of the obtained films are reported. The resistive and piezoresistive properties of the diamond-on-silicon films have been measured beyond 200 °C by means of a purposely developed apparatus, and experimental results are reported. The piezoresistive properties at high temperature are exploited in the development of a micromachined pressure sensor capable of operating at up to 350–380 °C. A dedicated signal-conditioning electronic circuit is being designed and its functioning principle is here described.This work was funded by the Italian National Research Council under the project MADESS.This paper was presented at the Conference of Micro System Technologies 2001 in March 2001.     

Multiwalled carbon nanotube-polyimide nanocomposite for MEMS piezoresistive pressure sensor applications

Multiwalled carbon nanotube (MWCNT)-polyimide (PI) nanocomposite was prepared with different MWCNT concentrations and characterized for their piezoresistive response. The morphology and mechanical behavior of the nanocomposite was investigated by scanning electron microscopy and force–displacement spectroscopy respectively. The surface conductivity of the nanocomposite was determined by atomic force microscopy in current mode. Studies reveal that this nanocomposite will be useful for strain-sensing element in micro electro mechanical system (MEMS)/nano electro mechanical system (NEMS) based piezoresistive pressure sensor applications. The study shows that the nanocomposite with 2 % MWCNT content is a unique piezoresistive sensing element for MEMS/NEMS pressure sensor.     

Graphene piezoresistive flexible MEMS force sensor for bi-axial micromanipulation applications

Microsystem Technologies - The aim of this work is to design, simulate, and analyze a bi-axial piezoresistive MEMS (Micro-Electro-Mechanical System) force sensor, which has the capability of...