Mechanical durability enhancement of gold-nanosheet stretchable electrodes for wearable human bio-signal detection

Wearable electronics demonstrate great potential for a wide range of applications, including electronic skin, implantable bio-medical devices, and health monitoring sensors. Such applications require highly stretchable and durable electrodes for adequate reliability and superior performance. Although extensive works on intrinsically stretchable electrodes have been reported, obtaining both mechanical integrity and electrical conductivity remains challenging owing to a trade-off effect. In addition, the lack of mechanical resilience to external stimulation of the stretchable electrodes has limited practical commercialization in numerous industrial fields. Here, intrinsically stretchable gold nanosheet (AuNS) electrodes with enhanced mechanical durability due to optimized hot-pressing fabrication conditions is studied. The AuNS stretchable electrodes exhibited lifetimes 8 times longer against repetitive sliding cycles under 88 kPa contact pressure compared to other hot-pressing conditions. Furthermore, the AuNS stretchable electrodes maintained a 5 Ω/sq. sheet resistance under 50% mechanical strain and 1000 stretch-release cycles. Application of hot-pressing to the AuNSs facilitated a firm contact between the AuNSs and hence they remained intact when stretched. Also, it is successfully demonstrated that AuNS stretchable electrodes can form a conformal contact with human skin and capture dynamic human bio-signals, exhibiting excellent performance compared to existing commercial wearable devices.