Stiffness Engineering of Ti₃C₂T_X MXene-Based Skin-Inspired Pressure Sensor with Broad-Range Ultrasensitivity, Low Detection Limit, and Gas Permeability

High sensitivity and broad sensing range are considered as two crucial parameters toward flexible and wearable piezoresistive pressure sensors for human healthcare, human–machine interfaces, robots, and so on. Though various strategies are developed to improve the sensor performance, the trade-off between sensitivity and sensing range remains a bottleneck for device design. Besides, conventional pressure sensors without gas permeability normally cause discomfort and inflammation to the human skin. Herein, enlightened by the functions and structure of the human skin, this article proposes a stiffness engineering strategy for constructing Ti₃C₂T_X MXene-based porous spinosum structure to boost sensitivity over a broad detection range. Consequently, the as-fabricated pressure sensor exhibits superior performance, including ultrahigh sensitivity of 367 kPa⁻¹ over a widened detection range, a low detection limit of 1 Pa, good gas permeability, and exceptional mechanical stability over 5000 compression cycles at high pressure. Benefiting from such excellent performances, a variety of fancy applications in detecting static pressure, including physiological signals, stealth transmission, the magnitude and spatial distribution of external tactile stimuli, as well as differentiating spatiotemporal tactile stimuli, are demonstrated. It is believed that stiffness engineering is a universal strategy for tailoring the performance of other types of stress/strain sensors.