Stretchable bio-fuel cells
Engineers from UC, San Diego, developed a soft, stretchable bio-fuel cells that can produce energy from the sweat and suitable of powering electronics. The biofuel cells can extract 10 times more power than any existing wearable biofuel cells, such as LEDs and Bluetooth radios.
Making the epidermal biofuel cells is a major breakthrough in the study. However, using lithography and screen-printing, engineers developed a stretchable electronic foundation for making 3D carbon nanotube based cathode and anode arrays.
The epidermal biofuel cells equipped with an enzyme that oxidizes the lactic acid present in human sweat to generate current.
Professor Joseph Wang from UC San Diego, explains, how to connect the biofuel cells to a customized circuit board and explained the device could power an LED while a person wearing it exercised on a stationary bike.
Compare with wearable devices, the biofuel cells are more flexible and stretchable. With this aspect, engineers decided to use and created a “bridge and island” structure. The cell structure is made up of rows of dots connected by spring-shaped structures. The spring-shaped structures can stretch and bend, making the cell flexible without damage the anode and cathode.
The process for the islands and bridges structure manufacture via lithography, and made of gold. Then the researchers used screen printing to security layers of biofuel materials on top of the anode and cathode dots.
However, increasing the biofuel cell’s energy density is a big challenge. Increasing energy density is key to increasing performance for the biofuel cells.
“We needed to figure out the best combination of materials to use and in what ratio to use them,” said, Amay Bandodkar, first author of the research.
For increasing power density, engineers printed a 3D carbon nanotube structure on top of the anodes and cathodes. The structure allows to load each anodic dot with more of the enzyme that reacts to lactic acid and silver oxide at the cathode dots. Moreover, the tubes allow easier electron transfer, to improve biofuel cell performance.
The team explores a way to store the energy produced while, the concentration of lactate is high enough and then release it gradually.
More information: [Energy & Environmental science]