Self-Healing Circuits

March 9, 2021
Image courtesy: Sanjiv Sambandan

Flexible electronic devices such as foldable display screens, wearable sensors, and self-powered, portable energy devices are made up of millions of circuits composed of thin-film transistors (TFTs). These devices are prone to open-circuit failures due to mechanical stress from bending or stretching, electric stress from electrostatic discharge arising from human contact or corrosion from moisture or sweat. Could their durability be enhanced by employing self-healing TFT circuits?

Researchers from the Department of Instrumentation and Applied Physics, IISc, and the Department of Engineering, University of Cambridge, have collaborated to develop such circuits. They packaged particles that can conduct electricity in the TFT circuit such that when gaps are generated, the open current induces the particles to align and form a conductive bridge, thereby completing the circuit and “healing” it. Such particles can only align in the presence of an open current, and otherwise remain dispersed and insulated in the circuit.

In flexible TFTs, silver particles of a specific size, embedded in insulating silicone oil at an optimum density, were found to be ideal for healing gaps arising from electric failure or mechanical stretching.

The authors also describe a strategy for efficiently packaging these particles in TFT circuits for large-scale manufacturing. This could potentially widen the scope of applications of flexible electronic devices.