Detection of Tributyrin and H2O2 by Using SiO2 and Gd2O3 Sensing Membranes in Electrolyte-Insulator-Semiconductor Structure

• Main Authors: SUBHODEEP CHATTERJEE, 蘇查靖
• Other Authors: S. Maikap
• Format: Others
• Language: en_US
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/m9z7pq

碩士 === 長庚大學 === 電子工程學系 === 104 === The pH sensing performance of SiO2 and Cu/SiO2 membranes in electrolyte-insulator-semiconductor (EIS) structure has been investigated. Both Cu/SiO2 and Gd2O3 membranes show higher pH sensitivity approximately 54 mV/pH than those of the pure SiO2 membranes (approximately 49 mV/pH with pH values 6 to 10) owing to Cu nanostructures or crystalline structures of the as-deposited Gd2O3 films. However, drift rate of pure SiO2 membrane is lower than the Cu membrane and it is higher than the Gd2O3 membranes. The SiO2 membranes detect tributyrin with sensitivity of 11 mV/mM within linear range of 1 mM to 4 mM. Time-dependent tributyrin response and sensing mechanism have been explained. It is found that a moderate time of <10 minutes is needed to detect tributyrin. The thicker (15 nm-thick) crystalline Gd2O3 membrane in EIS structure detects H2O2, which has been reported here for the first time. However, the SiO2, Cu/SiO2, thinner (3 nm-thick) Gd2O3 membranes do not show H2O2 sensing. The crystalline structure and thickness of each film have been observed by transmission electron microscope. The composition of the Gd2O3 films have been investigated by using X-ray photo-electron spectroscopy. Time-dependent H2O2 response has been observed. It is found that a short time of <2 minutes is needed to sense H2O2. The reference voltage shift increases with increasing H2O2 concentrations ranging from 100 µM to 800 µM owing to oxidation-reduction (redox) of the GdOx membrane or the conversion of Gd2+ ions to Gd3+ or vice versa. Basically, generation of Gd3+ ions with increasing the H2O2 concentration shows reference voltage shift. Therefore, the SiO2 and Gd2O3 membranes detect tributyrin and H2O2, which will help to diagnosis disease in human body in future.