Researchers at Rensselaer Polytechnic Institute have created a paper-sized device that functions as a high-energy battery and a supercapacitor that can use human blood and sweat to recharge.

This week, RPI announced the development of a nano-engineered battery that looks like a small sheet of black paper. Researchers published the details of the project in a report entitled, "Flexible Energy Storage Devices Based on Nanocomposite Paper" for the Aug. 13 issue of Proceedings of the National Academy of Sciences.

The device is lightweight, thin, flexible, and geared toward future use for medical implants, transportation, and gadgets. The battery can function in temperatures up to 300 degrees Fahrenheit and down to 100 below zero. Researchers have filed a patent application.

More than 90% of the device is made up of cellulose, which is used to make paper products. The "paper" is infused with aligned carbon nanotubes, which allow the device to conduct electricity.

Ionic liquid -- a liquid salt that does not contain water -- serves as the battery's electrolyte and allows it to withstand extreme temperatures. Researchers said it doesn't contain toxic chemicals and is environmentally safe. Researchers demonstrated that the "paper batteries" could be printed without electrolytes so naturally occurring electrolytes in human body fluids could activate it.

Researchers said the materials are inexpensive but they still need to find a way to mass produce them cheaply.

The device can provide a power output similar to a conventional battery, and a supercapacitor's quick burst of high energy. It can be rolled, twisted, folded, cut, molded, or stacked into many shapes with no loss of mechanical integrity or efficiency, RPI said.

"It's essentially a regular piece of paper, but it's made in a very intelligent way," paper co-author Robert Linhardt, professor of biocatalysis and metabolic engineering at Rensselaer, said in a prepared statement. "We're not putting pieces together -- it's a single, integrated device. The components are molecularly attached to each other: the carbon nanotube print is embedded in the paper, and the electrolyte is soaked into the paper. The end result is a device that looks, feels, and weighs the same as paper."

The New York State Office of Science, Technology, and Academic Research and the National Science Foundation supported the project at the Nanoscale Science and Engineering Center at Rensselaer.