Flexible solar energy harvesters that can be sewn into the jackets and backpacks of U.S. soldiers could soon be powering up electronic devices in the field. MC10, a Cambridge startup that specializes in flexible electronics, has signed a contract with the army to develop and test its solar cell technology for military use. Over the course of this next year, the U.S. Army Natick Soldier RD&E Center and MC10 will work together to scale up the flexible solar panel prototypes MC10 has already built, and assess their efficiency as functional battery chargers.
MC10 specializes in re-engineering stiff, brittle parts of electronics into sleeker, softer, and stretchier versions of their former selves. MC10 has made steady headway in applying its techniques to build thin, soft sensors for use in surgeries and is testing those at partner sites like Boston's Mass. General Hospital. The company is perhaps furthest along in the devices they are building or for athletes. The sensors, which look like a square inch of tape, cling onto an athlete's forearm and record biological information like temperature, heart rate and hydration over time. In a recent partnership with NASCAR MC10 tested a sensor on race car driver Paulie Harakka as he competed.
The solar cells are another manifestation of the company's skill in semiconductor engineering. Early in 2011 the company's co-founder John Rogers led a team that demonstrated how gallium arsenide—the light harvesting metal compound built into high-efficiency solar panels found on rooftops—could be stamped onto stretchable semiconducting silicon sheets.
For added flexibility the photovoltaic metal isn't plastered on as one continuous sheet. Rather, it is stamped on as a grid, with metal islands just millimeters across rising up from the polymer. Each is connected with its neighbors by a strip of gold ribbon wrapped in a soft conducting polymer.
Work on the solar microcells has been ticking along since then, in part, to make them hardier and durable under harsh conditions. This opportunity to collaborate with the army will see the research project scale up, Ben Schlatka, MC10's cofounder and VP of business development tells Fast Company. "At the end of it we'll have fully functional devices that are integratable into backpacks and helmets and jackets," Schlatka says.
The program will last for one year. By the end of that time, the goal is to show a 25 to 50 percent increase in the battery life of the power packs soldiers carry, freeing them up to carry fewer around.
Reasonably enough, course military uses aren't the only applications MC10 is planning. "Picture your favorite shirt with power harvesting capability," Schlatka says. On the back of the scale-up work with the army, wearable solar cells that MC10 will sell commercially to the rest of us are next on the horizon.
[Image: John Rogers, University of Illinois, Urbana-Champaign]