Scalable fabrication of precise flexible strain sensors using organic semiconductor single crystals

Organic semiconductor (OSC) single crystals feature flexibility, solution processability, and high-mobility coherent carrier transport, which are advantageous for printed flexible electronic applications. A mechanical strain sensor is a target device whose high sensitivity and wide measurement range have been demonstrated when OSC single crystals were employed as the active channel. However, there have been limited reports on scalable fabrication of devices and reliable measurements, which limits the use of strain sensors in a wide range of applications. In this study, we present a comprehensive approach to address these issues through advanced device processing, design, and measurements. Our resistive strain sensors showed a small drift owing to the stable and effective p-type chemical doping of the OSC single crystals. A Wheatstone bridge circuit and compact lock-in amplifier were designed to accurately measure resistance changes at low noise levels. The experimental results demonstrated a substantial reduction in noise and achieved high-precision measurements with precision of ± 1.8 ppm. These results demonstrate the scalable fabrication of organic semiconductor strain sensors with high precision and reliability, which opens up the possibility of employing them in various industrial sectors.