Skin-Like Stretchy Photodiodes Could Power Artificial Eyes, Robot Vision, and More

A team of researchers at the Georgia Institute of Technology have developed a light-sensing semiconductor material with a difference: It can stretch like human skin, hitting 200 percent of its original size without major current loss.

"Think of a rubber band or something that's soft and stretchable like human skin yet has similar electrical semiconducting properties of solid or rigid semiconductors," says Canek Fuentes-Hernandez, associate professor and co-principal investigator in the project. "We’ve shown that you can build stretchability into semiconductors that retains the electrical performance needed to detect light levels that are around hundred million times fainter than produced by a light bulb used for indoor illumination."

Created using an elastomer blended with a donor-like polymer and an acceptor-like molecule, the active layer of the device — known as an elastomeric bulk heterojunction, or e-BHJ — offers a performance similar to that of more traditional low-noise silicon photodiodes (SiPDs).

"Moving around can drastically affect the usability of collected data but being able to reposition devices on the body to minimize or eliminate motion artifact is a big deal,” says Gabriel Cahn, PhD and Georgia Tech graduate, of the work. "Having electronics that can flex, twist, bend, and conform to non-flat surfaces and move with your body will allow you to place these sensors in more advantageous places to collect biometric data. It will be infinitely more useful in helping diagnose or monitor existing medical illnesses."

"The soft device also could be attractive for implantable electronics for bio-electronic applications," adds Kyungjin Kim, who was responsible for finding a suitable thickness of material that would retain its ability to stretch, "since the interfaces comply with the dynamic motion of the soft biological tissues, reducing the foreign body reaction."

"The potential is fantastic," enthuses co-author Felipe Andres Larrain. "In the long-term, you could develop sensors that could enhance or even replace the human eye or be applied to robotic eyes."

The team's work has been published in the journal Science Advances under open-access terms.