Stretchable Organic/Hybrid/Organic Multi-Layer Electrodes Prepared By Co-Sputtering for Wearable, Stretchable Sensors and Touch Panels

Abstract

We demonstrate an Organic (PTFE)/Hybrid (AgPdCu-PTFE)/Organic (PTFE) multi-layer electrodes on Polyurethane (PU) substrate using co-sputtering for wearable and stretchable sensor. Co-sputtering process of the polytetrafluoroethylene (PTFE) of Organic/Hybrid/Organic (OHO) multi-layer electrodes improved mechanical flexibility and stretchability in AgPdCu (APC)-PTFE hybrid layer which coated at the middle of OHO electrodes. We applied the power in the DC 10 W and RF 40 W for APC and PTFE, respectively. PTFE single layers of OHO electrodes are deposited to improve mechanical stability and transmittance. To investigate a mechanical and electrical characteristics of OHO electrodes, we measured sheet resistance, and stretchability depending on individual PTFE thickness. Average transparency towards visible light was measured ≥ 45% for OHO multi-layer structure. The average value of sheet resistance is 32.6 Ohm/square without significant change in the thickness of PTFE, which means that this uniform conductive network is formed in the hybrid layer. The stretching test was conducted 40 % strain under all conditions and reversible to confirm that hysteresis and stretchability were good for 30 nm of PTFE thickness. Minimal changes to resistance even after 20000 cycles under 20 % strain. In addition, a very small critical inner/outer bending radius below 1 mm indicates that the OHO multi-layer structure could also be applied as highly wearable devices. In addition, applicability is further verified by using it as commercial EL/LED interconnector and strain sensor. We confirmed the high electrical stability and feasibility by applying OHO multi-layer structure electrodes to the touch panels and electromyography (EMG) sensor.