Engineers at Stanford have developed a new component to help stretch the potential of wearable electronics. A team of researchers has created a flexible transistor that can be stretched to double its original length without losing much of its conductivity.
Building better wearables has been tough because most semiconductor material is made of silicon, which is typically rigid and usually cracks or breaks well before stretching enough to conform to the many contours of the human body. Deforming even further to move with a body in motion compounds the challenge more.
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A team of researchers led by Jie Xu in Stanford's Department of Chemical Engineering fabricated an organic semiconducting film that is stretchable but maintains conductivity as it deforms using a technique called nanoconfinement. Conductive so-called conjugated polymers are trapped inside a rubbery polymer matrix at the nanoscale, allowing them to bend without breaking.
The researchers say the technique is scalable to the device level and less expensive to produce than other approaches because the two polymers don't like to mix with each other, leading the conductive polymers to automatically form thin bundles within the rubbery matrix.
In testing, the researchers say they saw no visible cracks in the film, even after stretching it 100 times. The current even continues to flow when poked with a sharp object.
The researchers envision combining stretchy transistors with other components that could easily form wearable electronics that maintain conductivity even when stretched around the length of a human finger as it flexes and relaxes.