A Portable Low-Voltage Low-Power ppm-Level Resistive Sensor Measurement System

Abstract

<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Objective:</i> The objective of the paper is to present a novel systematic approach for the design and development of a portable, low-voltage low-power resistive sensor measurement system with high sensitivity. The goal of the proposed system is to be able to measure the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta {R}/{R}_{s}$ </tex-math></inline-formula> for a wide range of baseline resistance of sensor <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{s}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1 {k}\Omega $ </tex-math></inline-formula> to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1 {M}\Omega $ </tex-math></inline-formula> i.e. 3 orders of magnitude) with high resolution and programmable sensitivity. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Method:</i> An auto-calibrated resistive sensor interface using a novel half-bridge based circuit is presented. The square-wave excitation and square-wave demodulation technique are utilised to reduce the power consumption of the proposed technique. Moreover, the sensitivity of the system is fully auto-calibrated for a wide range of base resistors. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Results:</i> With a supply voltage of 3.3 V and bandwidth of 10 Hz, the developed system is able to measure a minimum <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta {R}/{R}_{s}$ </tex-math></inline-formula> of about 20 ppm for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$100 {k}\Omega $ </tex-math></inline-formula> base resistance. Overall, the power consumption of the developed system is 36.3 mW (for four channels). <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Significance:</i> The system is useful for low-voltage low-power sensor nodes as a highly sensitive readout for the resistive sensor arrays. In addition, the developed system is useful for the stain sensors in the development of flexible hybrid electronics for wearable applications.