Fully Biodegradable Microsupercapacitor for Power Storage in Transient Electronics

TLDR

The study presents biodegradable microsupercapacitors fabricated from water‑soluble metal electrodes, a biopolymer hydrogel electrolyte, a biodegradable poly(lactic‑co‑glycolic acid) substrate, and polyanhydride encapsulation, outlining their materials, fabrication strategies, and potential applications. Enhanced electrochemical performance is achieved through pseudocapacitance generated by metal‑oxide coatings formed by electrochemical corrosion at the metal–hydrogel interface, while an encapsulation strategy that controls thickness, chemistry, and molecular weight tailors the device’s functional lifetime. Systematic studies of dissolution kinetics for each component and integrated device, together with demonstration experiments, confirm that the MSCs can transiently power LEDs and serve as charging capacitors for wireless power harvesting in integrated circuits.

Abstract

In this work, the authors report materials, fabrication strategies, and applications of biodegradable microsupercapacitors (MSCs) built using water‐soluble (i.e., physically transient) metal (W, Fe, and Mo) electrodes, a biopolymer, hydrogel electrolyte (agarose gel), and a biodegradable poly(lactic‐ co ‐glycolic acid) substrate, encapsulated with polyanhydride. During repetitive charge/discharge cycles, the electrochemical performance of these unusual MSCs is dramatically enhanced, following from the role of pseudocapacitance that originates from metal‐oxide coatings generated by electrochemical corrosion at the interface between the water‐soluble metal electrode and the hydrogel electrolyte. Systematic studies reveal the dissolution kinetics/behaviors of each individual component of the MSCs, as well as those of the integrated devices. An encapsulation strategy that involves control over the thickness, chemistry, and molecular weight of the constituent materials provides a versatile means to engineer desired functional lifetimes. Demonstration experiments illustrate potential applications of these biodegradable MSCs as transient sources of power in the operation of light‐emitting diodes and as charging capacitors in integrated circuits for wireless power harvesting.