Eco-Friendly Bionic Flexible Multifunctional Sensors Based on Biomass–MXene Composites

Flexible sensors with multifunctions have attracted great attention for their extensive application values. Most of the reported multifunctional flexible sensors lack the intuitive signal display function, have limitations of work environment, and are weakly resistant to electromagnetic waves, and the landfill and incineration of the sensor wastes could pose irreversible damage to the environment. Herein, a trilayer composite (referred to as TGM) is prepared by the layer-by-layer assembly of MXene, gelatin, and a water-based multiporous membrane (WMM), which exhibits a hierarchically ordered bionic heterostructure. The top layer is multilayers of MXene nanosheets, the middle layer consists of artificial neural cages and synapses from an MXene@gelatin structure, and the bottom layer is a brick-mortar mimic of MXene@WMM. The resulting TGM heterostructure displays excellent performance in pressure sensing both in air and under water due to the ready variation of the electrical conductivity with applied pressures. The TGM composite also shows an apparent actuation response under IR, moisture, and heating stimulations. These multifunctional characteristics can be integrated for visual sensing of environmental temperature and humidity. Additionally, the composite possesses efficient electromagnetic shielding and shows great degradation. Results from this study highlight the unique potential of MXene–biomass composites in the development of eco-friendly multifunctional sensors.