According to the team behind the electric eel-inspired device, the results show potential for a soft power source to draw on a biological system's chemical energy.
Ions are charged atoms or molecules and when ions accumulate on either side of a cell membrane, they form an ion gradient. The researchers explained that they harvested energy from the electric potential across the ion gradients, the voltage increasing as more hydrogels were stacked on top of each other, resulting in a total of 110V.
Anirvan Guha, graduate student at the University of Fribourg's Adolphe Merkle Institute, explained that in order to stack the thousands of individual hydrogels necessary to generate this high voltage, they used a printer that: “Deposits little droplets of gel, with the precision and spatial resolution to print an array of almost 2,500 gels on a sheet the size of a normal piece of printer paper.”
The team's next goal is to increase the current running through the hydrogel. "Right now, we're in the range of 10 to 100s of microamperes [the basic unit for measuring an electrical current], which is too low to power most electronic devices," Guha said.
The researchers hope their results will help develop power sources for implantable devices that can, ‘utilise the [ion] gradients that already exist within the human body’.
"Then you may be able to create a battery which continuously recharges itself, because these ionic gradients are constantly being re-established within the body,” Guha concluded.