The day may come when the shirt on your back can charge your cellphone, say U.S. researchers who've helped developed flexible, foldable solar cells.

Scientists at Penn State, who worked with international colleagues, said the silicon-based optical fiber with solar-cell capabilities can be made to almost any length and paves the way for flexible, curved or twisted solar fabrics.

The team worked to overcome the challenge of merging optical fibers with silicon-based integrated circuits found in most semiconductor electronic devices such as solar cells, computers, and cellphones, a university release said Thursday.

The solution was an optical fiber thinner than a human hair, with its own integrated electronic component, bypassing the problem of having to integrate fiber-optics with flat electronic chips.

"Our goal is to extend high-performance electronic and solar-cell function to longer lengths and to more flexible forms. We already have made meters-long fibers but, in principle, our team's new method could be used to create bendable silicon solar-cell fibers of over 10 meters in length," Penn State chemistry Professor John Badding said.

"Long, fiber-based solar cells give us the potential to do something we couldn't really do before: We can take the silicon fibers and weave them together into a fabric with a wide range of applications such as power generation, battery charging, chemical sensing and biomedical devices."

Most current solar cells are expensive to produce and create a flat, inflexible device, he said.

"But woven, fiber-based solar cells would be lightweight, flexible configurations that are portable, foldable and even wearable," he said.

The military has shown great interest in wearable power sources for soldiers in the field, Badding said.