Investigation on the Coupling Effect Induced by Bilayer Structure of Thin Au Film and Graphene Nanoplates for Strain Gauge

Wearable strain sensors have attracted huge attention due to their potential applications in healthcare systems and robotics controlling. In this study, we put emphasis on the investigation of strain-sensing material, which is a key component of strain sensor. Since advanced carbon-type nanomaterials and noble metal nanomaterials are proved to be the excellent strain-sensing materials which can endow strain sensor with high electro-mechanical performance. Thus, we selected a carbon-type nanomaterial graphene nanoplates (GNPs) and a noble metal thin gold film (AuF) as strain-sensing materials to coat on an ultraflexible textile polyurethane yarn (PUY) successively to investigate the combining effect on electro-mechanical performance of the bilayer structure. On the basis of GNPs coated PUY strain sensor which shows outstanding electro-mechanical performance and wide strain-sensing range of 50%, we further deposited an AuF layer to certify whether the coupling of AuF and GNPs affects its electro-mechanical performance or not. Specifically, we deposited four AuFs with different thicknesses on four GNPs/PUY strain sensors, respectively, and deeply investigated the relationship between AuF thickness and electro-mechanical performance. By comparing their electro-mechanical performance, we selected an optimal AuF thickness of 10 nm, and the coupling of GNPs and AuF effectively broadened the strain-sensing range of the strain sensor to 100% while kept an outstanding sensitivity.