Smart-Sensing Interface for Chemo-Resistive Sensor Based on a Wheatstone Quarter-Bridge

This paper presents the architecture of a signal-conditioning circuit designed for resistive sensors and based on the properties of a Wheatstone quarter-bridge. The bridge comprises one sensing element, consisting of a small-resistance-variation sensor and three fixed resistors. The proposed circuit was designed using NI Multisim software; simulations were carried out for various scenarios in order to ensure maximum accuracy versus component values and tolerances. The output signal of the proposed circuit was found to have less than 0.5 % non-linearity relative error for a sensing element value variation of 3 ohms.