Liquid Metal/Wood Anisotropic Conductors for Flexible and Recyclable Electronics

Next-generation electronics requiring high performance, recyclability, and low environmental impact are still in its infancy because of limited design strategies and materials. Herein, a facile approach for constructing liquid metal/wood anisotropic (LMWA) conductors via integration of gallium based LMs and delignified flexible wood (DF-wood) is reported. Using a delignification treatment and a subsequent LM transfer process with patterns, a rigid and electrically insulating wood slice is converted into a flexible wood-based LM conductor while retaining its original hierarchical porous structure. The LMWA conductor demonstrates a remarkable anisotropic electrical conductivity (σ_z/σ_x) on the order of 10⁸. Subsequently, the LMWA conductors are successfully applied as flexible four-channel tactile sensor, which exhibits excellent tactile sensitivity. Moreover, by immersing in a deep eutectic solvent (DES) composed of choline chloride with oxalic acid to dissolve the LM circuit, recycling of the LM is achieved with efficiency up to 96%. This is the first time that a DES is used to recycle LM, leading to increased economic and environmental viability of these sustainable electronics. The present LMWA conductors, which have the potential for a scalable and feasible fabrication process, substantially extend the scope of next-generation electronics toward flexible and recyclable systems.