A waterproof and breathable Cotton/rGO/CNT composite for constructing a layer-by-layer structured multifunctional flexible sensor

Developing a cotton fabric sensing layer with good waterproofness and breathability via a low-cost and eco-friendly method is increasingly important for the construction of comfortable and wearable electronic devices. Herein, a waterproof and breathable cotton fabric composite decorated by reduced graphene oxide (rGO) and carbon nanotube (CNT), Cotton/rGO/CNT, is reported by a facile solution infiltration method, and we adopt such Cotton/rGO/CNT composite to develop a layer-by-layer structured multifunctional flexible sensor, enabling the high-sensitivity detection of pressure and temperature stimulus. Particularly, the multifunctional flexible sensor exhibits a high response toward tiny pressure, demonstrating salient superiority in the continuous and reliable monitoring of human physiological information. Concerning temperature sensing, a good linear response for the temperatures ranging from 28 to 40 °C is achieved by the multifunctional flexible sensor and gives rise to be successfully applied to the non-contact real-time monitoring of human respiration signal. Finally, an array consisting of multifunctional flexible sensors further demonstrates its feasibility in perceiving and mapping the pressure and temperature information of contact objects. This work provides a feasible strategy for designing cotton-based sensing layers that can effectively resist liquid water penetration and allow water vapor transmission, and offers reasonable insight for constructing comfort and multifunctional wearable electronics.