Study On The Micro-Accelerometer Inspired From Spider's Vibration Sensing Mechanism

Supported by "Research on Biomimetic Multidimensional Microvibrometer and Its Application Inspired from the Vibration Sensilla of Spiders", an National Natural Science Foundation of China (Grant No.50675193), spider's vibration mechanism and their application in biosensors development, such as slot-cantilever sensors and an novel piezoresistive accelerometers, were studied in this dissertation. The rearsearch work was carried out by combining theoretical analysis, numerical simulation with experimental verification.In Chapter 1, the background and significance of the research were introduced, the development trend and current research situations of the biomimetic microsystems based on animals and plants'sensilla, micro-cantilever type sensors and accelerometers'development were explatiated, then the research contents of this dissertation were proposed.In Chapter 2, firstly, spider's vibration sensing organs were studied by anotomy and SEM experiment. For spider's hair, the flow sensing mechanism was studied, and their potential applications in bio-sensing technologies were proposed. As for slit sensilla, the vibration sensing mechanism and slits'stress concentration effects were studied. Then, a novel design method of bio-sensors was presented.In Chapter 3, based on spider's lyriform slits sensilla and combing MEMS technologies, piezoresistive slot-cantilever were presented. Analytical modeling was established to analyze the slits location and geometries effect on the sensing performance of cantilever sensors. The results show that the sensing performance and mechanical properties of cantilever can be greatly improved and adjusted by optimizing the slits and cantilever's structural and location parameters.In Chapter 4, based on the above chapters analysis, a novel slot-cantilever type piezoresistive accelerometer was proposed. Then, an analytical models was established to study the sensing performance, such as output voltage, sensitivity, resonant frequency, noise floor, resolution, dynamic frequency responses, and etc. The results show that the sensing performance of the proposed bio-accelerometer can be effectively improved, especially for improving sensitivities and without decreasing the resonant frequency. In Chapter 5, for piezoresistive accelerometer's optimization design, sensitivity, noise floor, resolution were selected as optimization objectives, the effects of structural dimensions, process parameters and working conditions were systematically analyzed. Then, sensitivity, noise floor or resolution was studied for single objective optimization design, respectively. As for the confliction of design parameters and objectives, a multi-objective optimization design method by using nondominated sorting genetic algorithm (NSGA-â…¡) is proposed to achieve the design optimization. The results demenstrated that the sensing performance of piezoresistive accelerometer can be greatly enhanced by using multi-objective optimization.In Chapter 6, in order to fabricate the designed accelerometer, a set of process flows are brought forward and a series of important process steps are carried out to optimize the process parameters and flows. Then, the proposed accelerometer was eventually fabricated. For the packaging process, wafer-level packaging was designed to improve the sensing performance. An analytical models was presented to study the dynamic performance of the packaged accelerometer. The results show that the sensing performance can be enhanced by optimizing the air gaps of top silicon cap and bottom glass substrate to the middle sensing structure.In Chapter 7, to verify the theory mentioned above and study the sensing performance for the developed accelerometer, the experimental setup was built on the standard vibration testing table. A series of experiments were carried out to study the sensing performance, such as sensitivity, linearity, bandwidth, noise level and etc. The results shown that the proposed accelerometer features high performance, such as higher sensitivity and relative large bandwidth. For the nonlinearity and cross sensitivity, the induced mechanism and improvements were studied. At last, as for the method of installation, analytical modeling was presented to study the effects of installation, then the improvements were proposed to eliminate these effects.In Chapter 8, the chief work and innovations of this dissertation were summarized, and the further research subjects were proposed.