With the ever-increasing military demand to reduce the size and weight of unmanned aircraft while lengthening flight times, Air Force Office of Scientific Research officials in Arlington (Virginia) are funding a project to integrate solar power cheaply and easily into the base materials used to build them.
Dr. Max Shtein and his team at the University of Michigan are investigating the energy harvesting potential of many different device applications, including thin film solar cells reshaped and coated onto long continuous filaments, or fibers.
When such organic semiconductor coated fibers are woven into a fabric system, the resulting textile can be used not only to form the structural make-up of the unmanned aircraft, but also to generate the electricity to power it.
To date, Doctor Shtein and his team have demonstrated small, stand-alone prototypes that strongly suggest that this type of application is possible.
Integrating the solar cells in the desired configuration; however, will require building more sophisticated fabrication equipment. They are currently working on a customized coating apparatus for making large quantities of fiber-based energy conversion devices.
Once finished, Doctor Shtein plans to develop new models that synergize optics, mechanics, electrical and energy transport, and energy storage mechanisms.
"These models will allow us to optimize the device structure using multifunctional design constraints, improving energy conversion efficiency and power density of our devices in practical configurations," he said.
Combining these functionalities would reduce the bulk mass associated with separate optical, mechanical and electrical systems leading to vehicles that have increased power, but weigh much less.
Unmanned aircraft built with these materials would be light and compact, and their renewable energy source would also allow them to experience longer flight times and power propulsion systems and on-board sensors, drastically increasing state-awareness.
As a current recipient of the Presidential Early Career Award for Scientists and Engineers, Doctor Shtein received a $200,000-a-year grant for five years to continue this innovative work.
Molly LaChance
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