Biodegradable photolithography compatible substrate for transparent transient electronics and flexible energy storage devices

Abstract

Transient electronic devices (TED) can disappear with non-traceable or minimal remains once their intended lifetime is over, and hence form a growing area of research in defence and healthcare industry. However, due to the incompatibility of the TED substrates with high throughput micro-fabrication processes like UV lithography, they are obligated to rely on slow and low resolution processes like transfer printing and stencil printing. Therefore, the development of a substrate that is compatible with UV lithography would not only enable micro-fabrication but would also allow for a smooth transition of TED from lab to shelf.In this study, we demonstrate the suitability of agarose, a carbohydrate, as a substrate for transient electronics. Agarose is chemically modified with HMDS that imparts a hydrophobic character to otherwise hydrophilic agarose. Consequently, unlike other available biodegradable substrates that are incompatible with water based processing during UV lithography, these silylated agarose substrates provide a compatible window for aqueous processing steps. After establishing suitable thermal and optical properties of such a substrate, its compatibility with UV lithography is demonstrated by micropatterning antibody and aluminium patterns. Additionally, in order to demonstrate its wider applicability in the area of energy storage, a flexible-biodegradable battery is stencil printed on it that can sustain a small electronic device in both relaxed and flexed state.