Breathable and Waterproof Electronic Skin with Three-Dimensional Architecture for Pressure and Strain Sensing in Nonoverlapping Mode

Abstract

Wearable sensors have recently attracted extensive interest not only in the field of healthcare monitoring but also for convenient and intelligent human–machine interactions. However, challenges such as wearable comfort, multiple applicable conditions, and differentiation of mechanical stimuli are yet to be fully addressed. Herein, we developed a breathable and waterproof electronic skin (E-skin) that can perceive pressure/strain with nonoverlapping signals. The synergistic effect from magnetic attraction and nanoscaled aggregation renders the E-skin with microscaled pores for breathability and three-dimensional microcilia for superhydrophobicity. Upon applied pressure, the bending of conductive microcilia enables sufficient contacts for resistance decrease, while the stretching causes increased resistance due to the separation of conductive materials. The optimized E-skin exhibits a high gauge factor of 7.747 for small strain (0–80%) and a detection limit down to 0.04%. The three-dimensional microcilia also exhibit a sensitivity of ?0.0198 kPa^–1 (0–3 kPa) and a broad detection range up to 200 kPa with robustness. The E-skin can reliably and precisely distinguish kinds of the human joint motions, covering a broad spectrum including bending, stretching, and pressure. With the nonoverlapping readouts, ternary inputs “1”, “0”, and “–1” could be produced with different stimuli, which expands the command capacity for logic outputs such as effective Morse code and intuitive robotic control. Owing to the rapid response, long-term stability (10?000 cycles), breathability, and superhydrophobicity, we believe that the E-skin can be widely applied as wearable devices from body motion monitoring to human–machine interactions toward a more convenient and intelligent future.