A Method to Pattern Silver Nanowires Directly on Wafer-Scale PDMS Substrate and Its Applications

This study describes a fabrication method of microsized AgNW patterns based on poly dimethylsiloxane (PDMS) substrate using a poly(p-xylylene) (parylene) stencil technique. Various patterns of AgNW conductive sheets were created on the wafer scale area in the forms of straight and serpentine lines, texts, and symbols, which dimensions ranged from a few tens of micrometers to hundreds of micrometers. We demonstrated the electrical performance of straight line and serpentine line patterned AgNW electrodes when subjected to mechanical strains. The gauge factor and stretchability ranged from 0.5 to 55.2 at 2% uniaxial strain and from 4.7 to 55.7%, respectively, depending on the shapes and structures of the AgNW electrodes. Using the developed AgNW patterning technique, we fabricated strain sensors to detect small body signals epidermally such as hand motion, eye blink and heart rate. Also, tactile sensors were fabricated and exhibited the sensitivity of 3.91 MPa(-1) in the pressure range lower than 50 kPa, and 0.28 MPa(-1) in the pressure range greater than 50 kPa up to 1.3 MPa. From these results, we concluded that the proposed technique enables the fabrication of reliable AgNW patterns on wafer-scale PDMS substrate and the potential applications for various flexible electronic devices.