【作者】 赵倩云；

【导师】 李艳宁；

【作者基本信息】 天津大学 ， 测试计量技术及仪器， 2006， 硕士

【摘要】 微悬臂梁是一种高灵敏度的纳米传感元件，其应用极为广泛，例如应用于原子力显微镜中作为检测元件，应用于生物传感器中作为换能元件等。品质因数Q是微悬臂梁的一个物理参量，是衡量微悬臂梁振动特性的重要指标，它与微悬臂梁所受到的阻尼成反比。当微悬臂梁应用于液体环境中时，由于液体阻尼的影响，微悬臂梁的品质因数会降低。对于原子力显微镜，品质因数的降低会使扫描速度增加，微悬臂梁检测的灵敏度及分辨力会降低，但如果品质因数过高，微悬臂梁系统的稳定性会降低；对于生物传感器，利用共振模式检测法时，随着品质因数的增加，微悬臂梁响应的分辨力和灵敏度会提高。 本课题从微悬臂梁的振动模型出发，研究微悬臂梁的品质因数，设计出一种数字式微悬臂梁品质因数的调控技术。通过改变驱动微悬臂梁振动的激励信号来调控品质因数Q的值。实验结果表明，这种数字式品质因数Q控制电路能够调控品质因数Q的值，随着品质因数的改变，微悬臂梁振动的幅频曲线和相频曲线发生变化。 本课题的主要研究内容包括： 1．通过求解微悬臂梁的受激振动方程，探讨品质因数Q的物理机理和调控品质因数Q的基本原理；研究振动微悬臂梁与激励力之间的关系，建立品质因数Q控制模型； 2．开发基于数字技术的品质因数Q控制系统，编制相应的系统控制软件； 3．将品质因数Q控制系统和微悬臂梁连接，使用多普勒测振仪测量微悬臂梁的振动特性，并与没有Q控制电路时的振动特性曲线图进行比对，实现了品质因数的动态调控； 4．分析了数字式品质因数Q控制电路对微悬臂梁振动的幅频曲线及相频曲线产生的作用。更多还原

【Abstract】 Microcantilevers are nano-sensing devices with high sensitivity, wide applications in many areas such as the detection device used in atomic force microscopy, the transduction device applied in biosensors and so on. Quality factor is a physical parameter of microcantilever and an important pointer of the performance of microcantilever. Q is inversely proportional to the subjected damping of microcantilever. When a microcantilever works in the liquid condition, the quality factor decreases because of the effect of the liquid damping. For an atomic force microscopy, the decrease of quality factor of the key sensing device—the microcantilever will increase the scan speed but the sensitivity and resolution of microcantilever will decrease; however, if quality factor is too high, then the stability of the microcantilever will decrease accordingly; for biosensor, the resolution and sensitivity of microcantilever will increase because of the increase of the quality factor when the dynamic mode detection is used.In this thesis, the quality factor of the microcantilever based on dynamic mode of microcantilever is researched, and a digital quality factor controlling technique is designed. We tried to change the driving force and get the value of quality factor. The experiment results indicate that the function of digital control technique satisfies the preset requirement of the whole system. And, the amplitude-frequency curve and the phase-frequency curve of microcantilever will change accordingly in term of the quality factor.The followings are the main achievements of this thesis:1. Make research on the mechanism of quality factor and principles of controlling quality factor by solving the stimulated oscillation equation of microcantilever; the relation of oscillated microcantilever and exciting force is researched and the model to control quality factor is designed.2. Based on digital control technology, a system to control quality factor is developed, and the corresponding system control software is designed. Visual C language is applied for system programming.3. The designed control system of quality factor is applied to the microcantilever, and a Laser Doppler vibrometer is used to obtain its oscillation curve; comparisons of the experimental results of the oscillation curve of microcantilever with the control system of quality factor and without the control system are made. Thus the dynamic control of quality factor is realized.4. Analysis of the impact of circuit tuning of the quality factor on the phase-frequency curve and amplitude-frequency curve of the oscillated microcantilever and imaging interaction is made.更多还原