Self-Adaptive Hierarchical Gradient Structure-Based In Situ Sensor with High-Pressure Resolution

Pressure sensors are a promising design paradigm for wearable devices required to interact gently with the environment. To enable flexible sensors to respond intelligently to the surroundings, microstructures for subtle pressure and force waveform detection are needed. Here, a self-adaptive pressure sensor is reported in which graphene-based flakes adhere to the melamine sponge backbones forming hierarchical structures and exhibiting high-pressure resolution. Under a high preload pressure of 100 kPa, the pressure sensor demonstrates a high-pressure resolution ability of ≈1‰. The self-adaptive microstructure change and mechanical behavior are observed simultaneously and dynamically using in situ electron microscopy. The high-pressure resolution of the pressure sensor enables it to monitor subtle human ballistocardiogram signals, which demonstrates excellent potential in multifarious applications of human motion detection and health monitoring.