A micro interdigitated thin film metal oxide capacitive sensor for measuring moisture in the range of 175-625 ppm

In this paper we present the development of a nanostructured hyper thin film sensor for the measurement of humidity in ppm level using the micro sized interdigitated electrode capacitive structure. The sensor electrode has been fabricated using the optical lithography technique on the oxide sensing film deposited on the quartz substrate. The nanoporous metal oxide thin film of gamma-Al2O3 has been fabricated by simple sol-gel drop coating method. The electrical characteristics of the sensor have been determined in the moisture range from 175 to 625 ppm by Agilent 4294A impedance analyzer at 1 kHz, 50 kHz and 100 kHz respectively. The sensor has excellent yield ratio because of complete avoidance of shorting problem of the electrode. The response time is very fast (T-r = 12 s) in comparison to the conventional commercial parallel plate gold electrode capacitive thin film aluminum oxide sensor. The proposed sensor can be useful for measuring moisture dispersion inside electronic gadgets and packages where the performance of the devices is deteriorated due to moisture entrapment. (C) 2015 Elsevier B.V. All rights reserved.