Conductive Sponge Sensor with Tunnel Crack Based on a Combination of Physical Vapor Deposition and Electroless Deposition

Abstract

Tunnel crack-based conductive sponge sensors have drawn much interest due to their broad range and great sensitivity. On intricate 3D sponge structures, conductive coatings created by physical vapor deposition invariably have a nonuniform thickness. The poor stability of the crack structure and the random width of the tunnel cracks formed on the nonuniform conductive coatings significantly limit the repeatability of the sensors. This research suggests a combination of physical vapor deposition and electroless deposition to prepare conductive coatings on sponges with a uniform thickness; this enhances the consistency of the tunnel crack widths that are later constructed. After a thin layer of conductive coating is deposited to the sponge surface using physical vapor deposition, the treated sponge undergoes electroless deposition to enhance the uniformity of the conductive coating, and cyclic compression is used to create the tunnel cracks. The sensor is more stable with the electroless deposition process than the untreated sponge sensor, and there is not much difference between the various sensor samples. This work presents the design of a sensor with excellent stability, low cost, easy preparation, and exemplary performance in human activity signal detection, indicating a wide range of applications.