A Readout System for High Speed Interface of Wide Range Chemiresistive Sensor Array

This paper aims at designing a compact readout system for chemiresistive sensor array with high speed and high accuracy. The proposed scheme is based on Resistance-to-Voltage (R-V) conversion and targets high density wide ranged chemiresistive sensor, with input resistance range of 1 $\text{K}\Omega $ - 1 $\text{M}\Omega $ and 0.1% sensitivity. The proposed approach uses Adaptive Reference Resistor Tuning (ARRT) technique implemented with a digital variable potentiometer to achieve a high accuracy without sacrificing the dynamic range and the speed. The system is implemented on a printed circuit board with a microcontroller and a 16-bit Analog-to-Digital Converter (ADC), and it has a compact dimension of 10 cm $\times6$ cm, which is suitable for portable applications. The readout system works with a 5 V power supply, and the overall system power consumption is 150 mW. The system is designed to interface with a 118 sensor array and the experimental results achieved a satisfactory accuracy of 0.88%, as well as a measuring speed of 8.5 ms per sensor. Compared with existing approaches, our work targets a high density wide ranged chemiresistive sensor array and demonstrated high accuracy, high speed with the lowest circuit complexity, which is the novelty of this work.