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。     

Thermal Properties Measurement of Micro-electromechanical System Sensors by Digital Moire Method

Abstract:  The thermal properties of a micro-electromechanical system sensor were analysed by a novel digital moiré method. A double-layer micro-cantilever sensor (60  μ m long, 10  μ m width and 2  μ m thick) was prepared by focused ion beam milling. A grating with frequency of 5000 lines mm⁻¹ was etched on the cantilever. The sensor was placed into a scanning electron microscope system with a high temperature device. The observation and recording of the thermal deformation of the grating were realised in real-time as the temperature rose from room temperature to 300 °C at intervals of 50 °C. Digital moiré was generated by interference of the deformed grating and a digital virtual grating. The thermal properties including strain distribution of the sensor and the linear expansion coefficient of polysilicon were accurately measured by the phase-shifted moiré patterns.     

Investigation for dimension effect on mechanical behavior of a metallic curved micro-cantilever beam

This paper is aimed at studying the mechanical behaviors such as maximum stress, contact force, and fatigue life of a special designed metallic curved micro-cantilever beam, using analytical, numerical (FEM), and experimental methods. This micro-beam is an applicable specimen generally used in MEMS devices. The focus is at determining the dimensions which are very important in functional conditions, reliability evaluation, and durability of this specimen and at finding a guideline for optimum design. Various types of samples that have different dimensions have been simulated and some specific specimens requested to be fabricated by a manufacturing company. In our research work, the material of the specimen is assumed to be of metallic alloys, which have good mechanical and electrical properties. Also, the structure of the specimen has a special shape and includes some fingers which have effect on mechanical behavior and electrical conductivity. In experimental method, with specified boundary conditions, mechanical loading is applied to the beam by simple but accurate methods. In analytical approach, after some mathematical calculations, for a curved cantilever beam, the equations related to the mechanical behaviors are obtained. Finally, the results obtained from the foregoing methods are compared with each other and the most fundamental effective dimension parameter on mechanical behavior of this special designed metallic curved micro-cantilever beam is determined.     

太赫兹辐射的多重反射光杠杆探测方法

提出了一种新型的微光学太赫兹辐射探测方法,以双材料微悬臂梁结构热探测方法为基础,通过多重反射光杠杆系统测量微结构的纵向微位移,从而实现太赫兹辐射量的测量。多重反射光杠杆探测方法微位移理论分辨率小于1 nm。搭建了微位移测量系统,实验结果表明,测试系统理论分辨率小于4 nm,实际分辨率优于10 nm。给出了基于该方法的太赫兹探测器设计方案和参数。因其具有良好的抗空气扰动和光束串扰能力,可以在常温下工作,适用于非制冷、实时、低成本、微小型化的太赫兹探测器和阵列式成像设备。     

微悬臂梁的平衡和稳定性研究

对原子力显微镜(AFM)在接触和非接触工作模式下的平衡状态和稳定性进行了研究,分析研究了微悬臂梁的长度以及探针与被测样品表面之间的距离对平衡位置的影响,获得了平衡位置与悬臂梁的长度以及与被测表面之间的规律,该结论为微悬臂的设计和改进提供了理论指导。     

光纤Bragg 光栅的谐振传感实验研究

利用微悬臂梁对光纤Ｂｒａｇｇ光栅的振动传感特性进行了实验研究,其频率传感范围达到２．５ｋＨｚ,并给出了实验拟合曲线。研究表明：光纤Ｂｒａｇｇ光栅反射波长漂移的扫描平均值△λ对微悬臂梁的谐振频率υｎ响应灵敏。     

压电微悬臂梁共振频率的检测系统

介绍了一种压电微悬臂梁共振频率检测系统.压电材料沉积在微悬臂梁上,在压电层的上下电极之间施加交变电压使其振动,当微悬臂梁的振动频率等于它的固有频率时,发生共振,此时微悬臂梁的振幅最大.结合所设计的激励电路以及微悬臂梁共振频率检测电路,对压电微悬臂梁进行了检测实验.实验结果表明,放大电路能够检测出压电微臂梁的共振频率,并且压电微悬臂梁达到共振时,共振频率附近振幅远大于其他频率对应的振幅,振幅最大值接近600 nm.     

低温环境下MEMS微构件的动态特性及测试系统

研究了微机电系统(MEMS)微构件的谐振频率等动态特性在低温环境下的变化规律,从理论上分析了改变环境温度对微悬臂梁谐振频率的影响,并对低温环境下微构件的动态特性测试技术进行了研究。研制了低温环境下MEMS动态特性测试系统,采用半导体冷阱实现低温环境,利用压电陶瓷作为底座激励装置的驱动源,通过底座的冲击激励,使微悬臂梁处于自由衰减振动状态,使用激光多普勒测振仪对微悬臂梁的振动响应进行检测,从而获得微悬臂梁的谐振频率。利用研制的测试系统,在-50℃～室温的环境下对单晶硅微悬臂的谐振频率进行了测试,结果表明,随着温度的降低,微悬臂梁的谐振频率略有增大,其谐振频率的温度变化率约为-0.263 Hz/K,与理论分析的结果基本一致。该测试装置能够有效地完成在-50℃～室温环境下微构件的动态特性测试。     

硅微悬臂梁谐振器的电激电拾方法研究

采用电热激励、压电拾取方法对硅微机械悬臂梁的谐振性能进行了实验研究。成功实现了对硅微悬臂梁谐振器前三阶振型的实验测试。电热激励利用在硅微机械悬臂梁表面优化设计的热激励电阻加以实现。为拾取硅微悬臂梁的微弱谐振信号,在硅微悬臂梁表面优化设计并制作了压敏电阻全桥,利用压敏电阻的压电效应实现对谐振微弱信号的拾取。     

In situ micro-cantilever tests to study fracture properties of NiAl single crystals

In situ micro-cantilever tests were carried out to determine the anisotropic fracture toughness of NiAl single crystals. Notched micro-cantilever beams with a beam length of 8 μm, 1.5 μm thickness and 1.8 μm width were milled in so-called “hard” and “soft” orientations of NiAl using a focused ion beam. These cantilevers were loaded in situ with the help of a cantilever-based nanoindenter mounted inside a scanning electron microscope. A fracture toughness of 3.52 ± 0.29 MPa m^1/2 was obtained for the “soft” orientation and 5.12 ± 0.50 MPa m^1/2 for the “hard” orientation, which is in good agreement with literature values on the fracture toughness of macroscopic NiAl specimens. Furthermore, nanoindentations were performed for studying the size effects occurring at small length scales for both orientations. The applicability of the small sample geometries for testing the fracture toughness is finally discussed in terms of size effects in the flow stress of the material due to dislocation nucleation and strain gradients at the crack tip.