Thin Hydrogel–Elastomer Multilayer Encapsulation for Soft Electronics

Abstract

AbstractIn the exciting race to design and engineer biointegrated and body‐like electronic systems, many efforts concentrate on the integration of hydrogels in electronic assemblies. The versatility of hydrogels chemistry combined with their tissue‐mimicking properties inspires numerous demonstrations of hydrogel‐based touch panels, robots, and sensors over the years. However, their long‐term integration in a thin and functional electronic assembly remains a challenge: their sensitivity to both air‐drying and water swelling leads to important volume change of the network that is incompatible with the cohesion of a multilayer system, and has irreversible impact on the electronic properties of the assembly. To tackle this issue, proposed is a method to fabricate a hydrogel–elastomer micrometric bilayer with a stable interface, using of a low‐swelling type of hydrogel, i.e., poly(2‐hydroxyethyl methacrylate) and silicone rubber. The bilayer can sustain multiple hydration/dehydration cycles without delamination and can be kept for several months in its dry configuration. Combined with soft metallization technology, the bilayer can be readily integrated into a soft electronic circuit thereby opening a technological route for microfabricated, on‐demand morphing systems.