Permeable, Stretchable, and Recyclable Cellulose Aerogel On-Skin Electronics for Dual-Modal Sensing and Personal Healthcare

Abstract

Flexible on-skin electronics present tremendous popularity in intelligent electronic skins (e-skins), healthcare monitoring, and human-machine interfaces. However, the reported e-skins can hardly provide high permeability, good stretchability, and large sensitivity and are limited in long-term stability and efficient recyclability when worn on the human body. Herein, inspired from the human skin, a permeable, stretchable, and recyclable cellulose aerogel-based electronic system is developed by sandwiching a screen-printed silver sensing layer between a biocompatible CNF/HPC/PVA (cellulose nanofiber/hydroxypropyl cellulose/poly(vinyl alcohol)) aerogel hypodermis layer and a permeable polyurethane layer as the epidermis layer. The cellulose aerogel displays a high tensile strength of 1.14 MPa and tensile strain of 43.5% while maintaining good permeability. The cellulose aerogel-based electronics embrace appealing sensing performances with high sensitivity (gauge factor ≈ 238), ultralow detection limit (0.1%), and fast response time (18 ms) under strain stimulus. Owing to the disconnection and reconnection of microcracks in the sensing layer, both strain/humidity sensing and thermal healthcare can be easily achieved. The permeable electronics can be further integrated into an electronic mask for patient-centered healthcare with a power supply system, switching control device, and wireless Bluetooth module. Moreover, the prepared electronic system enables long-term wearing on human skin without skin irritation, and all components of the electronics can be recaptured/reused in water. This material strategy highlights the potential of next-generation on-skin electronics with high permeability and good environmental friendliness.