Polyaniline doping PVA Micro Humidity Sensors

• Main Authors: Wei-Yi Lin, 林威邑
• Other Authors: Ching-Liang Dai
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/qkt7a6

碩士 === 國立中興大學 === 機械工程學系所 === 99 === This paper presents the fabrication of a micro humidity sensor integrated with a sensing circuit using complementary metal oxide semiconductor (CMOS) process. The humidity sensor is composed of a sensing film and an interdigitated electrode, and the sensing film is coated on the interdigitated electrode. The sensing film of the humidity sensor is a composite film synthesized by the polymerization method, and the film consists of polyaniline and polyvinyl alcohol (PVA). The polyaniline is doped with PVA to form the composite sensing film. When water attaches to the composite film, water molecule contacts with PVA producing intermolecular hydrogen bonds around PVA, and the hydrogen bonds increases the conductivity of the film, resulting in decreasing the film resistance. The sensing circuit is utilized to convert the resistance of the humidity sensor into the voltage output. The experimental results showed that the composite film with PAn of 65 wt% doped PVA of 35 wt%. The resistance decrease from 1274 kΩ to 579 kΩ as the relative humidity changes frome 30 % to 85 % at 25 °C. The ouput voltage varied from 1.651 V to 2.257 V as the humidity changed from 30 % to 80 %RH at 25 °C. The sensitivity of the micro humidity sensor is about 10.14 mV / %RH at 25 °C.