What is stretchable electronics?

Imagine carrying your solar panel rolled up like a grapefruit while going camping and stretching it to the size of a room on the spot. It will not break, since it is made from fracture-proof electronics that is super compliant. Well, for the moment, that is the dream of Professor Darren Lipomi, department of Nano engineering, University of California at San Diego.

Darren has a vision of self-repairing skins for sensors. A special super-thin layer of organic material will make up the stretchable skin, very similar to a thin layer of plastic. As this will be as pliable as foil, it will allow the semiconductor to conform to the object and stretch with movement. Such a new phase of bendable materials will influence change in the supply chain by turning flexible electronics into a layer similar to skin. Not only will this give a new meaning to the current phrase – mobile technology, to accommodate to the transition, OEMs will have to alter their manufacturing processes.

Darren is exploring different materials and types of electronics that have molecular structures for allowing conductive materials to function even when deformed or contorted in any direction for long durations. Of importance here, is the molecular level structural details of organic semiconductors. According to the scientists at the University of California, the super-thin film-like material, sometimes as thin as 100 nanometers, could be made to stretch without any loss in its electronic functions. Display light emitters need only be about one hundred billionth of a meter thick, according to Darren.

The professor is interested in solar panels, which he plans on making in the form of a thin, stretchable film on any object such as a piece of clothing or a tent. He describes this as an extremely large solar module that is fracture proof while generating electricity. He also envisions flexible commercial displays used in wearable devices such clothing and watches from Microsoft, Samsung, LG, Google, Apple and many others.

The professor’s research has identified several types of electronic materials that can stretch. However, he feels the major challenge here is to understand the way in which the molecular structure of the flexible materials influences the mechanical and electrical properties. This is especially true when moving from the laboratory material to a commercial product. Depending on the acceptance of the industry towards development of new processes and technology, Darren expects stretchable organic materials will find use in about 10-20 years.

The research is proceeding in two directions. One way is trying to obtain working electronic properties from films of highly amorphous nature. The other is trying to prepare stretchable fabrics or nanowires from processing solutions or by electro spinning. According to the researchers, the latter path forms the middle ground between molecular and composite approaches to elastic semiconductors.

This presents a challenge of representing high-performance molecular semiconductors that have predictable mechanical properties. A tight collaboration will be required from materials scientists, device engineers, synthetic chemists along with theorists – specializing in both the mechanical behavior of soft materials and the electronic structure calculations.