An Auto Calibrated Digital Interfacing Circuit Design to Monitor the Effect of Ambient Temperature Variation for Gas Sensor Applications
Swapan Das, Sunipa Roy, Chandan Kumar Sarkar
Department of Electronics and Telecommunication Engineering, Jadavpur University, Kolkata 700032, India
A simple and assimilated architecture is introduced to measure the gas concentration with a nanocrystalline metal oxide MEMS based gas sensor. The temperature of the sensor is stabilized by controlling the temperature of the microheater. ADCs and potential divider circuits are used to measure the heater temperatures by sampling the heaters resistance. PIC16F877A microcontroller is used here to adjust the output of DACs in order to apply the proper steering voltage to the microheater. The emphasis is given in the simplicity of the design and on the use of different simple methods. Also, a sole microcontroller is used to drive and control the microheater temperature, to operate independently from the variation of the environmental parameters, particularly ambient temperature. An easy compensation technique is developed to nullify the effect of ambient temperature deviation to have a fixed output voltage at fixed temperature of the microheater.
Gas sensor; MEMS; microheter; microcontroller