Flexible and Stretchable Crystals as an Alternative Material for Electronic Applications
A recent paper describes new materials that can be used to make single crystal electronics that are inherently more flexible and stretchable.
These are properties that could make the new materials ideal for use in robotics and sensing applications. The paper was published on April 27 in the journal of the German Chemical Society by Ying Diao her fellow researchers.
A More Flexible Alternative to Conventional Materials
Silicon and germanium are typically used for making electronics. However, these materials have proven difficult to use on skin or in robotics applications where stretching and flexibility are required because they fray and break when they come under too much tension.
Currently, researchers use two ways to make stretchable electronics: They either carve patterns out of silicon or they design new and unique polymer materials. “However, these approaches either involve complicated processes or they compromise the perfect order of the molecules,” says Ying, an assistant professor of chemical and biomolecular engineering.
To get around this limitation, Diao’s research group has been looking for single crystal materials that can be stretched easily without any damage being caused. Inspired by nature, the team looked towards a mechanism found in a virus called the bacteriophage T4 virus.
The virus’ tail is a single crystal of protein molecules that is compressed to over 60% when the virus injects its DNA. “The compression occurs without losing structural integrity,” according to Diao. “We discovered that bis(triisopropylsilylethynyl)pentacene crystals can be stretched over 10%, which is ten-fold that of the elastic limit of most single crystals.” said Sang Kyu Park, a postdoctoral researcher in the Diao group.
Ying Dao, the leading researcher in the study focused on uncovering new materials for use in robotics and sensing applications. Image Credit: L. Brian Stauffer, the University of Illinois at Urbana-Champaign
The Potential of Electronic Crystals
The molecules in the team’s single crystals are able to rotate and glide to accommodate mechanical strain beyond their elastic limit. "This mechanism also is found in shape memory alloys that are available in retail stores,” Park said. “You can distort the wire and then restore it back into its original shape by heating it. However, we are the first to discover this phenomenon in organic electronic crystals,” said Sang Kyu Park, a postdoc researcher.
The team claims that its work will make possible high-performance ultra-flexible single-crystal organic electronics for use in sensing, memory, and robotics applications.