Printed Electronic Sensor Array for Mapping Tire Tread Thickness Profiles

Tire tread wear is a significant vehicular safety concern; yet, monitoring tread depth (or thickness) still relies on manual detection, which is rarely done by consumers and is time-consuming for service lane technicians. In this paper, we present a fully printed, one-dimensional electrode array that is able to electrically measure the thickness profile of tread across the width of a tire. The sensor array consists of printed millimeter-sized electrodes composed of a hybrid silver nanoparticle-carbon nanotube (CNT) structure. The array is positioned directly against the outside of a tire (simulating a vehicle driving over the sensors). The thickness profile is then determined by applying an oscillating voltage between each of the electrode pairs in the array and measuring the associated electrical response. Correlation between the electrical response and tread depth across a tire is demonstrated for two distinct, measurable parameters: signal reflectance (S11) and impedance. A 2D electrostatic simulation is applied to explain the operation of the sensors and how the differentiation between grooves and tread blocks is possible based on differing electric field attenuation with distance. This printed sensor array shows promise for electrically monitoring tread profiles using relatively low-cost, readily implemented components.