Flexible pressure sensors are currently at the center stage of wearable electronics. Despite tremendous progress in the recent years, flexible pressure sensors with high sensitivity, high stability, and mechanical robustness are still challenging. In this paper, as inspired by the bean pod structure, a sensor architecture consisting a microspacer core layer of polystyrene (PS) microspheres, sandwiched between two laser-induced graphene/polyurethane (LIG/PU) films, is presented. A flexible and self-healable pressure sensor is prepared, achieving ultrahigh sensitivity, improved linearity, wide sensing range up to 100 kPa, and excellent stability (for over 1000 loading-unloading cycles). Specifically, the pressure sensor achieves high sensitivities of 149, 659, and 2048 kPa-1 for the pressure ranges of 0-1, 1-10, and 10-100 kPa, respectively. Upon three cut-heal cycles at room temperature, severely damaged devices are self-healed and are able to maintain high sensitivity. The sensors have been further verified in stringent applications, such as human arterial pulse monitoring and gait detection. The novel device architecture enabling facile fabrication and high performance paves the way to the scalable production of pressure sensors for human physiological diagnostics and other advanced wearable applications.
Keywords: bioinspired; flexible pressure sensor; highly sensitive; laser-induced graphene; polystyrene microsphere.