Hierarchically buckled Ti3C2Tx MXene/carbon nanotubes strain sensor with improved linearity, sensitivity, and strain range for soft robotics and epidermal monitoring

A flexible sensor can be applied to monitor human motion, which can further be engineered with soft robotics to monitor their motion in the real time. However, to realize deformation detection with high-sensitivity in soft robots while simultaneously maintaining a high linearity and cyclic stability of the sensor yet remains as an unmet challenge. Herein, we fabricated strain sensors exhibiting a buckle and a sandwich like structure by spraying MXene (Ti 3 C 2 T x )/carbon nanotubes (CNTs)/fluoro-rubber composite materials onto a 200 % pre-stretched flexible rubber substrate. The resulting strain sensors displayed a wide range of detection (e.g., 1–150 %), high sensitivity (gauge factor (GF) for up to 461), good linearity, fast response time (21.2 ms), large stretching (150 %) as well as, excellent repeatability and stability. This sensor can further monitor the human physiology and the motion of the body. We also developed a soft robot with integrated sensors that enabled it to crawl like a caterpillar while leveraging its sensing function to detect its status in the real time. Conclusively, these hybrid strain sensors may have broad implications for robotics as well as wearable sensors for health monitoring and physiological recordings.