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

Abstract

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 K -1 M 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 × 6 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.

Two Proposals of a Simple Analog Conditioning Circuit for Remote Resistive Sensors with a Three-Wire Connection

“…Many electronic interface circuits for resistive sensors can be found in the literature. According to [4], these circuits can be classified in five groups: (1) voltage divider [5] and bridge circuits (e.g., Wheatstone bridge); (2) circuits based on a current source (e.g., Howland current source); (3) resistance-to-frequency converters (e.g., 555 timer-based oscillator); (4) resistance-to-phase converters; and (5) direct interface circuits (DIC), which do not have any active device between the sensor and the digital processing unit [6]. For the digitization of the information, circuits that belong to groups 1 and 2 require an analog-todigital converter, whereas those that belong to groups 3, 4, and 5 usually employ a digital timer that performs a time-to-digital conversion.…”

Design of a Wide-Range and High-Precision Analog Front-End Circuit for Multi-Parameter Sensors

“…In summary, the existing analog front-end circuits are primarily tailored for specific sensors, neglecting the simultaneous consideration of detection range and precision [19][20][21][22]. The baseline compensation circuits are relatively limited and offer a narrow range of compensation [23].…”