Patterned Carbon Nanotube Bundles as Stretchable Strain Sensors for Human Motion Detection

Although numerous studies have been conducted to develop wearable strain sensors with high sensitivity and a wide detection range, developing strain sensors with tunable sensitivity for practical purposes remains challenging. Strain sensors with tunable sensitivity have great potential in applications such as human motion detection and health monitoring. This paper introduces strain sensors that adopt zigzag-patterned carbon nanotube (CNT) bundle arrays embedded in a polymer matrix. Owing to the zigzag pattern, the sensors exhibited an extensive detection range up to 500% strain and high sensitivity (gauge factor of 64.08). In this study, the CNT bundle array synthesized on a Si wafer was transferred to a silicone elastomer substrate using a roll-transfer technique, forming a sheet-like structure of overlapped CNT bundles. The separation occurring between the CNT bundles with the applied strain followed the shape of the zigzag pattern. The sensors exhibited excellent repeatability and durability with negligible hysteresis behavior, and their sensitivity was tunable based on the pattern design. Furthermore, this study investigated the sensing mechanism of the sensors and their potential use in wearable electronics.