Highly stretchable metal-polymer hybrid conductors for wearable and self-cleaning sensors

Abstract

We fabricated semitransparent and stretchable hybrid Ag-polytetrafluoroethylene (PTFE) conductors on a polyurethane (PU) substrate for use in high-performance wearable and self-cleaning sensors. The highly conductive Ag metal and stretchable PTFE polymer matrix were cosputtered, embedding the self-formed Ag in the PTFE matrix. Depending on the cosputtering RF and DC power ratio, the Ag-PTFE conductors showed a sheet resistance of 3.09–17.23 Ω/square and an optical transparency of 25.27–38.49% at a wavelength of 550 nm. Under the optimal cosputtering conditions, the Ag-PTFE electrode showed outstanding stretchability (strain 20%) and reversible hysteresis, enabling the production of stretchable and semitransparent conductors. In addition, the very small critical inward/outward bending radius near 1 mm and the hydrophobic surface indicate that the Ag-PTFE films could also be applied in wearable and self-cleaning devices. The suitability of the high stretchability and low sheet resistance of the sputtered Ag-PTFE conductor was verified by using it as a stretchable interconnector for commercial ELs, LEDs, and strain sensors. We applied the Ag-PTFE film as a semitransparent conductor for stretchable touch panels and electromyography sensors. Cosputtered Ag-PTFE films are promising stretchable conductors for a variety of applications in next-generation wearable devices.