Low concentration ammonia micro sensor with polypyrrole coated graphene

• Main Authors: Wei-Chun Shen, 沈暐鈞
• Other Authors: 戴慶良
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/47403408502664504837

碩士 === 國立中興大學 === 機械工程學系所 === 104 === 　　This study presents a micro NH3 sensor. An NH3 sensing chip with a thermometer is fabricated through the commercial 0.18 μm CMOS-MEMS process of TSMC (Taiwan Semiconductor Manufacturing Company). Chemically reduced graphene oxide, polypyrrole coated graphene (PPy/RGO), is prepared by the oxidation-reduction method. We use different reductant dosage and reducing time to prepare different PPy/RGO. All sensing films are characterized by elemental analyzer (EA), field emission scanning electron microscope (FE-SEM), electron spectroscope for chemical analysis (ESCA) and high resolution X-ray diffraction (HR-XRD). In order to obtain the best sensing film, we compare their gas sensing properties. The sensing circuit board is made by photolithography. The SMD resistor and amplifier are bonded on the sensing circuit board. The sensing chip is attached on the sensing circuit board, and connected to each other by wire bonding. 　　The results reveal that PPy/RGO-8 is the best ammonia sensitive film. Therefore, this study adopts PPy/RGO-8 as the sensing film. PPy/RGO-8 sensing film is coated on the sensing electrodes of the sensing chip. The micro NH3 gas sensor can detect low concentration NH3 gas at room temperature. The sensing mechanism of the gas sensor is chemoresistor. The measurement results show that the NH3 gas sensor has a response of 1.83 % and 16 mV with the NH3 concentration of 0.1 ppm. The sensor has a good repeatability and selectivity to NH3. The sensor has the benefits of small size, low cost, low power consumption and easy fabrication.