| Summary: | 碩士 === 國立成功大學 === 機械工程學系碩博士班 === 91 === Cuff electrode is an important component of neural prostheses, and they are usually wrapped around the nerves to stimulate the motor fibers or to measure the electrical signals of sensory fibers. It is known that the highest endurable pressure of the peripheral nerves is only 20mmHg. For a pressure over the limit, the micro circulation in the nerve fascicles will be blocked, causing ischemia in nerve tissues. The goal of this study is to design and fabricate a micro pressure sensor by MEMS technology and to be integrated with the cuff electrodes for monitoring the wellbeing condition of the peripheral nerves.
The maximum sensitivity of pressure sensors was determined from the simulation of finite element method in the previous study. The dimension of one sensing electrode is 700 by 700 micro meters, the thickness of dielectric layer is 4 micro meters, the measure range is 0 to 100 mmHg, and the sensitivity is 1.81×10-4 pF / mmHg‧pF. The fabrication of cuff electrodes with embedded pressure sensors is completed. A capacitance conditioning circuit is found and a calibration system is set up to calibrate the pressure sensor. The mechanical property of the dielectric layer, PDMS, is also measured to discuss the relationship between Young’s modulus and the sensitivity. Beside, a nerve cuff electrode pressure sensor is used to measure the external pressure generated by the cuff electrode of different diameters. Finally, the feasibility of capacitive pressure sensor is tested through an animal experiment.
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