A soft, ‘fleshy’, electric eel-inspired battery could be key for the development of future medical implants. Currently, this power source is able to produce 110 volts (about the same amount of power provided by wall sockets), but researchers are working on increasing this capacity considerably.
Anirvan Guha’s team from the University of Fribourg in Switzerland placed thousands of hydrogels across a thin, pliable surface in evenly spaced bubbles. The group then placed two of these sheets together and filled the space between them with a saline solution. The structure of this new material is similar to the layers of skin that allow electric eels to produce a deadly jolt.
The ions in the saline solution create friction and electricity in the gel layers. This provides 110 volts at open circuit, or 27 milliwatts per square meter in each gel cell upon ‘simultaneous, self-registered mechanical contact activation of gel compartment in series’. The device was assembled using soft gel material (polyacrylamide hydrogel), saline solution and a 3D printer.
The investigation derives from the effort to make gels thinner, with a larger contact area, to increase the power capacity. Scientists believe that the voltage produced could be further increased by improving the way in which the gels repel ionised atoms. ‘It is reasonable to expect that making the gels even thinner would further increase the power density of the system’ Guha commented.
Inspiration for the design came from the electric organ of the knifefish Electrophorus electricus, commonly known as the electric eel.
The current voltage generated by the ‘electric eel-inspired battery’ is not enough to power medical devices but a 40-fold increase – and a corresponding increase in current – would make it possible.
The power source developed by Guha’s group is soft, transparent, mechanically flexible, potentially biocompatible, and is able to ‘harness the chemical energy available inside biological systems’.
Moreover, as the power source is soft and flexible, it can be easily integrated into existing tissue. Therefore, this could provide a continuous power source for medical devices such as pacemakers or prosthetic devices in hybrids of living and non-living systems without the need for replacing the battery periodically.