Self-Healable, Superhydrophobic, and Flexible Strain Sensor Based on Polyurethane Composite for Underwater Sensing

As one of the most important wearable devices, flexible sensors have attracted the attention of researchers because they can be installed onto the skin of a human to monitor their movement, and they have the advantages of excellent flexibility and comfort. However, most of the devices cannot be used in an underwater environment, and they may be destroyed by mechanical forces in harsh working conditions. There are many approaches to solve these issues, but unfortunately, less research has been carried out to solve them simultaneously. To overcome these challenges, this research proposes a method for developing a sensor integrating superhydrophobicity and self-healing ability. The experimental results demonstrated that the sensor exhibited excellent performance with a water contact angle of 153.6°, a gauge factor of 145, and more than 10 000 cycle stability. In addition, it could self-heal at 50 °C after scratch, and the self-healing efficiency was 85.6%. It was capable of monitoring various movements, such as coughing, speaking, the bending and stretching of knees, elbows, and fingers. Furthermore, this device can be employed to monitor the human movement of swimming, and it can also realize underwater vibration and impact of tiny droplets. This work provides a valuable design strategy for electrical devices that can be widely applied in various fields.