3D Extruded Graphene Thermoelectric Threads for Self-Powered Oral Health Monitoring.

Flexible sensors play a crucial role in intelligent electronic devices, while strain-sensing is the fundamental feature for these sensors of different fields. Therefore, developing high-performance flexible strain sensors is essential for building the next generation of smart electronics. Here, a self-powered ultrasensitive strain sensor based on graphene-based thermoelectric composite threads through a simple 3D extrusion method is reported. The optimized thermoelectric composite threads show a large stretchable strain of over 800%. After 1000 cycles of bending, the threads still maintain excellent thermoelectric stability. The thermoelectric effect-induced electricity can realize ultrasensitive strain and temperature detection with high resolution. As wearable devices, the thermoelectric threads can also realize self-powered physiological signals monitoring, including the opening degree of mouth, occlusal frequency, and force of the tooth during the eating process. It provides significant judgment and guidance for promoting oral healthcare and developing good eating habits.