A CMOS-MEMS Capacitive Tactile Sensor For Non-Invasive Blood Flow Monitoring

• Main Authors: Chang-Jung Hsieh, 謝昌融
• Other Authors: Wei-Cheng Tian
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/28865467265328434687

碩士 === 國立臺灣大學 === 電子工程學研究所 === 100 === In this research, we try to develop a capacitive tactile sensor for non-invasive blood flow monitoring. The capacitance variation of the capacitive tactile sensor was measured with the membrane deflection by an external pressure. This capacitive sensor is realized by using the CMOS-MEMS fabrication process which is based on TSMC 0.35μm 2P4M (2 polycrystalline silicon and 4 metal) process and self-developed post process. Two metal sacrificial layers of M1 and M3 are etched so the sensing electrodes of other two metal layers of M2, M4, and one polycrystalline silicon layer were formed. Two sensing capacitors consisting of three parallel sensing electrodes were connected vertically. The sensitivity of the sensor can be enhanced by a specific configuration of two sensing capacitors. Two different structure designs were proposed to cope with different sensing ranges. The detection range of L-type design is from 0 to 50 mmHg while the Square-type design is from 0 to 200 mmHg. The capacitance variation was recorded via an oscillator circuit converting a capacitance change into a frequency change. The maximum sensitivity of two designs are 0.1723 Hz/mmHg and 0.588 Hz/mmHg.