Thin Film Electronics on Edible Substrates

Abstract

The recent years have seen the development biocompatible ingestible and implantable devices for human health monitoring. The major issue is the toxicity of the organic materials (polymers) used in the implants and consequently the need for second surgery to remove the electronic implants. This, in turn, shows the significance and the need for electronic materials which is edible in nature.

The key challenge in the use of edible materials as the substrate lies in the requirements for robust chemical resistance, vacuum compatibility and temperature stability to accommodate different fabrication processes such as spin coating, photolithography, and etching processes because, during the fabrication processes, the substrate needs to be exposed to high temperatures or harsh chemical solvents.

This necessitates research in the direction of exploring new food and food-based substrates for electronics which would be assimilated by the human body.

Motivated by these existing problems, the thesis discusses the different forms of sugar, (Isomalt, sugar paper and sugarin) and the method to fabricate basic electronic passive and active components, and functional devices for wireless transmission.

The main objective of the thesis is to develop food-based substrates, its characterization, building active and passive components and its demonstration. To incorporate these materials into electronics, the morphology, electrical, mechanical, and optical properties were extensively studied. The thesis discusses three modules of inductor design based on isomalt- sugarin, edible capacitor and its corresponding LC circuits have been discussed and the results compared. The demonstration of the relay on 2D substrates is done successfully. The thesis then explores the development and characterization of TFTs on sugar paper.

Despite successful demonstrations, there exist certain limitations in the fabrication of TFTs using sugar based substrates. The thesis finally outlines these limitations and suggests methods to overcome these.