Bioinspired dry-state polylactic acid adhesives-based wearable sensor with reversible adhesive performance in harsh environments via building hierarchical liquid metal bead structure

Dry-state self-adhesive wearable sensors show great application in various fields. However, the poor adhesive performance, unsatisfied reversible performance, and low sensitivity in a harsh environment still limit its broad applications. Mimicking the biological design for strong adhesive has given promise for realizing reversible adhesive and high-performance sensor capacity. Drawing inspiration from the biomimetic mechanism of mussels and the mechanical interlocking adhesion mechanism, we have devised a multi-level micro/nano adhesion strategy. This innovative approach aims to create polylactic acid (PLA)-Liquid metal (LM) 3D beaded structured adhesives, with the ultimate goal of achieving significantly enhanced adhesive strength, improved water resistance, and superior mold resistance. The bioinspired PLA-based adhesives exhibit bond shear adhesion strength of 2.7625 MPa and adhesion peel strength of 290 kPa, which is higher than that of reports. Importantly, the new concept of sunlight harvesting function was introduced into the system. The adhesives show enhanced shear strength (10.77% increment) under solar irradiation due to the photothermal capacity of EGaIn. For the concept of proof, a self-adhesive LM-based wearable sensor can be assembled to detect the electrical signals triggered by strain. This work paths the way for developing multifunctional bioinspired dry-state adhesives for wearable electronics.