An integrated flexible sensor for decoupled omnidirectional strain and human motion monitoring

Omnidirectional strain sensors are of paramount importance in the accurate detection of human movements. The mask printing technology is employed to fabricate an integrated omnidirectional flexible strain sensor for human motion monitoring. Silica particles were incorporated into the liquid metal to improve its rheological properties and enhance its patterning capability. The developed sensor exhibits excellent characteristics, including a wide strain sensing range (1–300 %), high sensitivity as evidenced by gauge factors ranging from 1.82 to 3.34 across its operational range, and excellent cyclic stability (more than 5000 cycles) with minimal signal degradation, ensuring reliable long-term monitoring. It is particularly noteworthy that the integrated flexible strain sensor can achieve real-time decoupling of both the magnitude and direction of the principal strain at the measurement point. The reliability of the sensor is verified by utilizing the specified strain magnitude and direction. This unique capability to resolve complex multi-axis deformation patterns provides higher accuracy than conventional unidirectional strain sensors and enables precise and intelligent identification of various human actions. The strain sensing platform has great application potential in fields such as health monitoring and rehabilitation medicine.