基于微悬臂梁的生化传感器

由微机械加工技术和集成电路工艺制作的微悬臂梁,通过在其表面修饰以生化敏感层,能将电、热、应力和化学等信号变化转换成一个机械响应,配合以信号采集电路和测量系统,能够达到很高的灵敏度和精度。回顾微悬臂梁作为传感器的发展历程,介绍悬臂梁的工作原理,微梁的激励、检测方法以及基于微悬臂梁阵列传感器的优点,总结了世界上硅基微悬臂梁生化传感器的最新动态,并且展望微悬臂梁传感器这一新领域的应用前景。     

谐振微悬臂梁传感器的工作原理及其在生化检测中的研究进展

谐振微悬臂梁是一种可以将质量变化转换为频率信号的微质量型传感器，因其分辨率高、灵敏度高、成本低、易于集成和小型化等优点而备受关注。谐振微悬臂梁现已被广泛应用于流量控制、生物医学痕量检测、气态和液态分子分析等领域。近年来，随着微机电系统（Micro-Electro-Mechanical System,MEMS）技术的快速发展，针对谐振式微悬臂梁传感器的研究与应用越来越多，对近年来谐振式微悬臂梁传感器在环境检测、生物医学等领域的具体应用进行了综述，并对未来的发展方向做出了展望。     

基于锁相环接口电路的高性能扭转谐振模态微悬臂梁传感器研究

扭转谐振模态微悬臂梁低能耗、高品质因数的特性,使它比传统的弯曲模态悬臂梁拥有更高的灵敏度和分辨率.将微传感器加工技术和生物检测技术相结合,利用扭转谐振模态微悬臂梁传感器对生物素和亲和素的特异性反应进行检测,结果传感器的灵敏度为0.9 pg/Hz,分辨可达到49 fg.本文还着重介绍了为谐振梁传感器设计的以锁相环(Phase-Locked Loop简称PLL)为核心的闭环接口电路,分析了悬臂梁和电路在闭环系统中的工作特性,并探讨了解决谐振式传感器在使用中常见的稳定性差、噪声干扰强等问题的方法.     

微悬臂梁谐振式气体传感器研究进展

微机械谐振式传感器已经成为微型机电系统(MEMS)领域的研究热点。讨论了微悬臂梁谐振式气体传感器的工作原理,介绍微悬臂梁表面修饰的关键技术、主要方法和基于微悬臂梁的谐振式气体传感器领域的研究状况以及近五年以来该领域的研究进展,并对基于微悬臂梁的谐振式气体传感器的发展方向和应用前景做了展望。     

微机械悬臂梁中的机械噪声机制分析

本文采用能量统计分布方法研究微机械悬臂梁的噪声模型,对热机械噪声理论模型进行了拓展和修正,使之适用于低温和高频条件.研究了温度、压力和频率对热机械噪声、温漂噪声和吸附-脱附噪声的影响.根据研究结果对静态检测悬臂梁和动态频率响应悬臂梁传感器进行了具体分析.对于静态下工作的微机械悬臂梁,振幅的随机变化取决于热机械噪声.对于工作在谐振状态的微米尺度悬臂梁,在室温常压下热机械噪声是主要的噪声机制;当尺寸进一步缩小至纳米尺度时,表面效应变得显著,吸附-脱附噪声成为主要的噪声机制.基于对不同情况下噪声特性的分析,对微机械悬臂梁传感器的优化设计规则进行了探讨.     

应力型微悬臂梁生化传感器响应机理研究进展

针对静态微悬臂梁表面特异性结合产生表面应力信号的响应机制问题,介绍了微悬臂梁生化传感器的工作原理,阐述了应力响应机制的简化模型,从纵向界面上和横向分子间2个方面对特异性吸附引起的悬臂梁表面应力的变化进行了剖析,讨论了界面能变化、位阻作用、静电力、氢键作用等与表面应力大小及方向之间的关系,总结了应力型微悬臂梁生化传感器的响应机理的研究。     

一种压阻式微悬臂梁免疫传感器及其动力学分析

针对传统光学读出微悬臂梁传感器所需测量系统复杂的局限,将生物素—亲和素系统的放大效应与压阻式微悬臂梁传感技术结合起来,成功构建了一种读出方式简单的压阻式微悬臂梁免疫传感器。利用构建的传感器对相思子毒素进行检测,检测限达8μg/L,反应在20 min内基本完成,具有很好的特异性和重现性,能满足水样、土壤、食品等实际模拟样品检测的要求。建立了压阻式微悬臂梁免疫传感器检测相思子毒素的反应动力学模型,并对实际检测数据进行了拟合分析,相关系数R值在0.971 1以上(P0.001)。根据拟合方程求出的传感器对不同浓度相思子毒素反应达到平衡的响应电压ΔU e、响应时间t0均与实测值非常接近。     

梯形变截面悬臂梁式微质量传感器设计与分析

针对微小集中质量测量问题,提出并制备了一种梯形变截面悬臂梁式微质量传感器,建立了梯形变截面悬臂梁式微质量传感器的振动分析模型。采用有限元方法求解其振动控制方程,获得了微质量传感器的灵敏度。仿真分析结果表明,相对于等截面矩形悬臂梁式微质量传感器,单层压电和双层压电结构的变截面悬臂梁传感器的灵敏度分别提高了127.00%和263.00%。采用线切割工艺,加工制备了单压电层梯形变截面结构的微质量传感器并对传感器进行了实验测试,在误差允许范围内,仿真结果与实验结果基本一致,验证了采用梯形变截面悬臂梁式结构可以有效的提高传感器的灵敏度。     

用于化学气体检测的压阻检测式二氧化硅微悬臂梁传感器

文中演示了一种高分辨率的压阻检测式二氧化硅微悬臂梁传感器及其制作方法,并利用该传感器实现了对化学气体的检测.通过传感器在线检测以及其它表征手段,验证了该传感器通过单分子自组装方法获得敏感层的可行性.经过Cu2 /巯基十一酸单分子自组装层修饰的微悬臂梁传感器可以对甲基膦酸二甲酯(DMMP)气体进行快速响应,最小检测浓度可达数ppb(×10-9).     

高g光学微腔加速度计的结构设计

针对高量程加速度测试需求,提出了一种基于光弹效应的新型光学加速度传感器;利用MATLAB软件和时域差分有限元(FDTD)对微环谐振腔悬臂梁加速度计的结构进行优化设计,详细分析了波导传输模态,传感器灵敏度以及工作带宽与波导尺寸、微悬臂梁尺寸的关系。在优化设计的基础上,通过ANSYS软件对悬臂梁的抗冲击性能进行仿真,其抗冲击可达104gn,灵敏度为10-2pm/gn,能有效满足高冲击、强烈振动场合的特殊测试要求,可以应用于侵彻系统,并为集成小型化高灵敏抗冲击微光机电系统(MOEMS)传感器提供理论参考。     

Effect of thermal and mechanical properties variations on microcantilever mass sensor performance

Ensuring desirable performance for piezoelectric microcantilever sensors constitutes a crucial research subject particularly for the applications such as detection of biochemical entities, virus particles or human biomarkers. However, these sensors’ performance may be affected by the environmental conditions such as temperature variation, and/or the uncertainty in the material properties. The objective of this study is to explore Young modulus uncertainty of microcantilever’s structural layer, thermo-mechanical and geometrical temperature dependency effects, on the natural frequency, bias and sensitivity of microcantilever mass sensors. These effects have been investigated for different sensor lengths and resonant modes. Also, a temperature compensation method which omits the need for bulky non-contact thermometers or fabrication of built-in temperature sensor has been proposed. As theoretical model, Euler–Bernoulli beam theory has been employed and solved by Galerkin expansion procedure. Using this model, it is demonstrated that the sensitivity of microcantilever sensor decreases with increasing the added mass. The microcantilever sensor sensitivity operating at the second resonant mode has been improved almost five times comparing to the first mode sensitivity regardless of microcantilever length. The simulation results show that temperature variation causes thermal frequency shift which in turn introduces a significant mass bias far beyond the sensors’ minimum detectable mass. This mass bias is constant for a given microcantilever in its first and second resonant mode. Additionally, the effect of temperature variation on the sensitivity of the given mass sensors is negligible. However, it has been shown that the variations in sensors sensitivity due to uncertainty of Young modulus remain constant for different lengths and two resonant modes of the microcantilever sensor.     

Micromachined SiO<Subscript>2</Subscript> microcantilever for high sensitive moisture sensor

Ultra-sensitive and selective moisture sensors are needed in various industries for processing control or environmental monitoring. As an outstanding sensor platform, surface-stress sensing microcantilevers have potential application in moisture detection. To enlarge the deflection of the microcantilever under surface stress induced by specific reactions, a new SiO₂ microcantilever is developed which features a much lower Young’s modulus than conventional Si or SiN_x microcantilevers. For comparing SiO₂ cantilever with Si cantilevers, a model of the cantilever sensor is given by using both analysis and simulation, resulting in good agreement with the experimental data. The results demonstrate the SiO₂ cantilever can achieve a much higher sensitivity than the Si cantilever. In order to fabricate this device, a new fabrication process using isotropic combined with anisotropic dry etching to release the SiO₂ microcantilever beam by ICP (Inductively Coupled Plasma) was developed and investigated. This new process not only obtains a high etch rate at 9.1 μm/min, but also provides good profile controllability, and a flexibility of device design. Attributed to the high sensitivity, a significant deflection amplitude of the surface modified SiO₂ microcantilever was observed upon exposure to 1% relative humidity. The SiO₂ cantilevers are promising for inexpensive and highly sensitive moisture detection.     

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。     

压电微悬臂梁气体传感器静态弯曲模型的研究

压电微悬臂梁是一种灵敏度高、尺寸小的生化传感器.分子或原子在压电微悬臂梁功能化表面的吸附会引起悬臂梁的静态弯曲,通过静态变形可以得到微悬臂梁的表面应力.将表面应力引起的微悬臂梁中性层位置的变化引入建模过程,并与能量法相结合,建立了压电微悬臂梁在单分子层吸附稳定后的静态弯曲理论模型.结果发现在相同吸附表面积和吸附量条件下...     

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。     

基于电化学的固态CO2传感器研究进展

用于检测环境中气体的电位传感器已经在传感器技术领域发展为一个成熟的方向。由于在各个行业有着广泛的应用,可靠廉价的CO2传感器有着巨大的市场潜力。总结了基于电化学的固态CO2传感器类型,分析了它们的检测过程,提供关于其传感原理和特性研发的广泛概述,并描绘了基于电化学的固态CO2传感器在未来各种应用的可能性。     

基于FDMA技术的无线环境监测系统

为了提高环境参数采集的自动化水平,提升效率,本文利用无线传感器网络技术和FDMA技术,设计了一个基于无线的环境监测传感系统。系统运用了ZigBee技术、传感器技术和嵌入式技术,实现了对环境温度、湿度、光照度以及可燃性气体浓度等参数的检测,可满足对环境参数实时监测的要求。     

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.     

Characterization and analytical validation of a microcantilever-based sensor for the determination of total carbonate in soil samples

A microcantilever device has been used as a miniaturized sensor for the determination of total carbonate in soil samples. The method is based on the selective generation of CO₂ (g) from samples and the measure of the pressure effect on the microcantilever sensor located in a closed system. The experimental set-up uses a manifold including the sample reaction minichamber and a dedicated flow-cell designed and built for housing the microcantilever. The response of this sensor was electronically and analytically characterized by using conductance signals. The analytical performance of the sensor was compared to that provided by the conventional quartz crystal microbalance (QCM), demonstrating advantages in terms of sensitivity, linear range of response and resolution. After the optimization of the method, it was validated for its use for direct determination of carbonate in soil samples. The method allowed the determination of carbonate in the 3–75 mg range, with a precision of 1.7%, expressed as relative standard deviation. It was applied to the analysis of different soil samples, obtaining results in agreement with those produced by the official method.