Materials and Designs for Extremely Efficient Encapsulation of Soft, Biodegradable Electronics

Effective encapsulation is essential for reliable operation of bio-integrated electronics, particularly those containing dissolvable elements, under humid environments for desired periods of time; however, conventional inorganic or organic encapsulants often suffer from tissue-incompatible mechanical rigidity and insufficient water-barrier performance. Here, a mechanically resilient and efficient encapsulation strategy is proposed that can exceed a functional lifetime of state-of-the-art soft encapsulations by several tens of magnitudes. The exceptional protection arises from the high aspect ratio of dissolvable yet impermeable inorganic fillers embedded within biodegradable polymers, which significantly extend the diffusion length of biofluids or water components. Theoretical modeling and experimental analysis elucidate the effects of types, shapes, and concentrations of the fillers on encapsulation performance, as well as mechanical/physical properties. The operation of electronic components under aqueous solutions for prolonged periods demonstrates the practical feasibility of the encapsulation approach for versatile types of soft, biodegradable electronics.