Stretchable electronics could become even more prevalent thanks to a new 3D printing-like manufacturing approach being studied by Missouri University S&T researchers.
Basically elongated or twisted electronic components, Missouri S&T researchers assess that the emerging field of stretchable electronics will focus on a new conductor that can be built on or set into the surface of a polymer known as elastomer.
These conductors could one day replace the rigid, brittle circuit board that powers many of today’s electronic devices. They could be used, for example, as wearable sensors that adhere to the skin to monitor heart rate or brain activity, as sensors in clothing or as thin solar panels that could be plastered onto curved surfaces.
Key to the future of stretchable electronics is the surface, or substrate, asserts Missouri S&T’s researchers. Elastomer, as its name implies, is a flexible material with high elasticity, which means that it can be bent, stretched, buckled and twisted repeatedly with little impact on its performance.
One challenge facing this class of stretchable electronics involves “overcoming mismatches” between the flexible elastomer base and more brittle electronic conductors. This is where Additive Manufacturing could come in, writes the research team led by Dr. Heng Pan, assistant professor of mechanical and aerospace engineering at Missouri S&T.
In their paper, the researchers suggest that additive manufacturing could be used to “print” very thin layers of highly conductive materials onto an elastomer surface: “With the development of additive manufacturing, direct writing techniques are showing up as an alternative to the traditional subtractive patterning methods,” the S&T researchers say.
Subtractive approaches include photolithography, which is commonly used to manufacture semiconductors.
Pan and his colleagues see additive manufacturing as a relatively economical approach to creating these new devices. At Missouri S&T, they are testing an approach that Pan calls “direct aerosol printing.” The process involves spraying a conductive material and integrating with a stretchable substrate to develop sensors that can be placed on skin.
“With the increase of complexity and resolution of devices, higher requirements for patterning techniques are expected,” they write. “Direct printing, as an additive manufacturing method, would satisfy such requirements and offer low cost and high speed in both prototyping and manufacturing. It might be a solution for cost-effective and scalable fabrication of stretchable electronics.”
Image credits: John Rogers, University of Illinois/courtesy of the National Science Foundation