Ultrasensitive capacitive tactile sensor with heterostructured active layers for tiny signal perception

The development of capacitive tactile sensors with both ultrasensitivity and ultrafast response/relaxation is crucial for the development of intelligent healthcare monitoring technology. Despite the significant improvement in the sensing performance presented by the introduction of microstructures into the dielectric or electrode layers, meeting the demands of intellectualization remains a major challenge. Herein, a strategy to simultaneously introduce microstructures in both the dielectric and electrode layers is developed. The hierarchical sea-urchin TiO2 particle-in-micropore (HSP-MP) structure in the dielectric layer induces stress concentration near the micropore regions, significantly enhancing the sensitivity and toughness of the device. The sparsely spaced large microcone improves the sensitivity of the hierarchical microcone (HM) structure in the electrode layer, while the small microcone reduces the hysteresis caused by interfacial adhesion. With the synergistic effect of the HSP-MP&HM structure, the proposed tactile sensor achieves ultrasensitivity of 10.5 kPa−1, ultrafast response/relaxation time of 5.6/5.6 ms, and ultralow limit of detection of 0.1 Pa. These sensing properties are demonstrated in practical applications, including tiny signal perception of the human fingertip pulse, tiny muscle motion perception for Morse code transmission, and high-resolution flexible perception array with pressure mapping capability.