Sensing skin technology for structural health monitoring: from proof-of-concept to field validation

Abstract

The concept of using a capacitive-based sensing skin for structural health monitoring applications was proposed more than a decade ago. The sensing principle is to form a dense sensor network by assembling numerous soft elastomeric capacitors (SECs) in a matrix form, with each SEC acting as an independent strain gauge, resulting in a sensor network measuring local strain information over a global area analogous to biological skin. The SEC technology has considerably evolved since it was first conceptualized in 2009 in order to facilitate field implementation. For instance, the polymer mix and sensor design were modified to increase robustness and sensing performance, dedicated electronics was fabricated to improve resolution and accuracy, and various signal processing algorithms were formulated to transform measurements into actionable information. The objective of this paper is to discuss the evolution of the SEC technology starting from its conceptualization to its field validation in order to support and stimulate other research in sensor development geared towards structural health monitoring (SHM) applications. This includes discussions on 1) materials development; 2) signal acquisition and characterization; and 3) bridging the gap to field deployment.