Scientists from l’Université Grenoble Alpes and University of California (UC) San Diego have collaborated to create a unique new device—a fuel cell that is flexible and can be worn on someone’s skin to produce energy using their own perspiration.

With the growing adoption of wearable technology, researchers are constantly looking to design new energy sources that aren’t dependent on typical batteries and instead can harvest energy from other sources for autonomous power.

The device is designed to use “biofuels” present in the compounds of human sweat. It functions by following deformations in the skin and produces energy by reducing oxygen and the oxidation of the lactate present in perspiration.

Image of the wearable biofuel cell applied to the arm, powering a diode attached to the black armband on the forearm. (Image source: Xiaohong Chen/Université Grenoble Alpes)

Scientists from the molecular chemistry department of the French university who specialize in bioelectrochemistry teamed up with UC San Diego nanotechnology experts to create the device, which incorporates technology from various disciplines, including biosensors and nanobioelectronics.

Researchers have developed a whole host of novel ways to create energy-harvesting devices to replace batteries in wearable technology. However, many of those have focused on using people’s natural movements to create electricity rather than actual bodily fluids.

Improving Device Design

Researchers at UC San Diego first developed the technology that is the basis of the fuel cell two years ago. They later collaborated with the team from l’Université Grenoble Alpes to improve the device and develop its latest incarnation.

The current device is comprised of a flexible conductive material made from carbon nanotubes, crosslinked polymers and enzymes, and joined by flexible connectors that are screen-printed directly onto the material.

“The functionalized [buckypaper] electrodes are assembled onto a stretchable screen‐printed current collector with an ‘island–bridge’ configuration, which ensures conformal contact between the wearable BFC (biofuel cell) and the human body and endows the BFC with excellent performance stability under stretching condition,” the researchers wrote in a paper on their work in the journal Advanced Functional Materials.

Researchers tested the device and found that once applied to someone’s arm, it can use a voltage booster to continuously power an LED. They envision that it can one day meet the need for a reliable and efficient energy sources for wearable devices, particularly those that provide fitness and health monitoring.

The new device is relatively simple and inexpensive to produce, the researchers said. The production of the enzymes that transform the compounds found in sweat is the most expensive part of its construction.

However, the device currently has limitations in voltage, something the researchers aim to improve in the future. An amplification in voltage means that the fuel cell can be used to power larger portable devices than is currently possible, they said.

Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco and New York City. In her free time she enjoys surfing, traveling, music, yoga and cooking. She currently resides in a village on the southwest coast of Portugal.