Analytical Modeling of Voltage to Time Conversion Circuit for Gas Sensing System and Some Experimental Studies

摘要

The present experimental work introduces a voltage to time conversion scheme for realization of thin film based gas sensing system where WO3 and ZnO thin films have been fabricated using simple sol-gel method. Simple analytical model for the system has been developed, whose realization needs a limited number of component for its hardware. In this system, an incremental change in resistance of the sensing element due to the variation of gas concentration produces a corresponding incremental voltage which on amplification gives a variable voltage of desired level to activate a timing circuit. The fabrications, experimental characterization and analysis of the complete system are reported here. The experimental results are found to be in good agreement with the theoretical predicted values, thereby, establishing the accuracy of our developed systems.