Nanshu Lu has combined nanoribbons with a soft polymer substrate to allow development of flexible electronic circuits that can be attached to human skin.
Advances in miniaturized bio-sensors and controllers hold out the promise of being able to measure, regulate and even control body functions and movements. The problem is that even the smallest conventional electronics are stiff and brittle. Any such device implanted or attached to body tissue can cause tearing and other damage from normal body motion.
Lu, an assistant professor at UT Austin, used a 30-micron-thick patch of transparent, supersoft polymer as the substrate on which to layer on a circuit made up of a mesh of nanoribbon webbing. Circuits built using this technique can run sensors and even LEDs in a package nearly as soft and pliable as body tissue.
Lu’s team used the technique to build a prototype circuit designed to be worn on the skin like a tattoo. The circuits are printed onto silicone supported by a stiffer layer of water-soluble polymer. Placed on dry skin and wetted, the polymer layer dissolves while intermolecular attractions between the silicone and skin make the silicone layer bond with the skin for a week through showers and exercise without irritating the skin.
To test potential applications of the body-friendly circuits, Lu’s team has used a patch that measures electrical activity of throat muscles to allow subjects to control Sokoban games through spoken commands like “left,” “right,” “up,” and “down.”
Lu wants to develop patches for health-related applications. One stuck to the forehead could be used to monitor the brain’s electrical activity. Another stuck on skin can alert surgeons if it is being overstretched during plastic surgey. Still others can be used to monitor heart rate and muscle activity or to track healing of wounds.
Lu is also developing variations of the body-friendly circuitry. One version would use an array of microneedles to create more robust connections that can be used to attach sensors to heart muscle to detect heart-attack risks like reduced blood flow or even to sense irregular heartbeats and instantly send an electric jolt to restore regular heartbeat.
Somewhat farther out are transdermal devices to detect changes in protein levels linked to specific disorders to automatically trigger the release of drug remedies.
Nanshu Lu has been an assistant professor at the department of aerospace engineering and engineering mechanics at The University of Texas at Austin since August 2011.
She received a BS in solid mechanics in 2005 from Tsinghua University in Beijing and a master’s degree in Applied Physics in 2006 from Harvard’s School of Engineering and Applied Science at Harvard University. Lu began her research in thin film mechanics with Professors Zhigang Suo and Joost Vlassak at Harvard to earn her PhD in 2009.
Lu received a Beckman Postdoctoral Fellowship and became a postdoctoral researcher working with Professor John Rogers at the University of Illinois at Urbana-Champaign where she studied the design and micro-fabrication of stretchable electronics.
