High-performance capacitive strain sensors with highly stretchable vertical graphene electrodes

Stretchable/wearable capacitive strain sensors are crucial for e-skins to detect physical and physiological signals. However, the fabrication of large-sized, undamaged uniform electrodes with high stretchability by a simple preparation process is still a challenge. In this paper, a capacitive strain sensor based on stretchable vertical graphene (VGr) electrodes is fabricated using a simple chemical peeling (CP) method. The maximum stretch of the sensor is similar to 80% with a gauge factor of around 0.97. Furthermore, it exhibits a unique stress direction recognizing ability, making it capable of converting digital codes, such as the Morse code. It is found that the high stretchability of VGr stems from the zigzag cracks and bridging effect of branched VGr nanowalls.