Copying the electric organ of the eel
Before the Volta battery, the only way humans could generate electricity was by rubbing different materials together, usually silk on glass, and trapping the resulting static. This was neither an easy nor practical way to generate useful electrical power.
Volta knew that electric fish had an internal organ dedicated to generating electricity. He reasoned that if he could imitate its effect, he might be able to find a new way to generate electricity. A fish’s electrical organ is made up of long stacks of cells that look very much like a roll of coins. So Volta cut coin-like disks from sheets of different materials and started stacking them in different orders to see if he could find a combination that would produce electricity. These stacking experiments continued to yield negative results until he tried pairing copper discs with zinc discs, separating the stacked pairs with paper discs moistened with salt water.
This copper-zinc-paper sequence happened to produce electricity, and the electrical output was proportional to the height of the stack. Volta thought he had discovered the secret to how eels generate their electricity and that he had in fact created an artificial version of the electric organ of fish, so he initially called his discovery an “artificial electric organ.” But it wasn’t.
What makes eel really exciting?
Scientists now know the electrochemical reactions between different materials that Volta discovered have nothing to do with the way an electric eel generates its electricity. Rather, the eel uses an approach similar to the way our nerve cells generate their electrical signals, but on a much larger scale.
Specialized cells in the eel’s electrical organ pump ions across a semipermeable membrane barrier to produce an electrical charge difference between the inside and the outside of the membrane. When microscopic gates in the membrane open, the rapid flow of ions from one side of the membrane to the other generates an electric current. The eel can open all membrane ports at the same time to generate a huge electric shock, which it unleashes aimed at its prey.
Electric eels don’t scare their prey to death; them just electrical stunning it before you attack. An eel can generate hundreds of volts of electricity (American household outlets are 110 volts), but the eel’s voltage doesn’t supply current (amperage) long enough to kill. Each electrical pulse from an eel lasts only a few thousandths of a second and produces less than 1 amp. That is only 5% of the household current.
This is similar to how electric fences work, which provide very short pulses of high voltage electricity, but at a very low amperage. So they shock but don’t kill bears or other animal invaders trying to get through. It is also similar to a modern one Taser electroshock weaponwhich works by quickly delivering an extremely high voltage pulse (about 50,000 volts) at a very low current (just a few milliamps).
Modern attempts to mimic the eel
Like Volta, some modern electrical scientists looking to transform battery technology find their inspiration in electric eels.
A team of scientists from the United States and Switzerland is currently… working on a new type of battery inspired by eel† They envision that their soft and flexible battery could one day be useful for powering medical implants and soft robots internally. But the team admits they still have a long way to go. “The electric organs in eel are incredibly sophisticated; they are much better at generating power than we are,” lamented Michael Mayer, a team member from the University of Friborg. So the eel research continues.
In 2019, the Nobel Prize in Chemistry was awarded to the three scientists who: developed the lithium-ion battery† In awarding the prize, the Royal Swedish Academy of Sciences claimed that the winners’ work “laid the foundation for a wireless society without fossil fuels†
The “wireless” part is certainly true, as lithium-ion batteries now power virtually all portable wireless devices. We’ll have to wait and see what the claim of a “fossil fuel-free society” is, as today’s lithium-ion batteries are charged with electricity often generated by burning fossil fuels. No mention was made of the contributions of electric eels.
Later that same year, scientists at the Smithsonian Institution announced their… discovery of a new South American species of electric eel† this is notably the strongest known bioelectricity generator on earth. Researchers recorded the electrical discharge of a single eel at 860 volts, well above that of the previous record-holding eel species, Electrophorus electricuswhich clocked in at 650 volts and 200 times higher than the peak voltage of a single lithium-ion battery (4.2 volts).
Just as we humans try to congratulate ourselves on the magnificence of our newest portable energy source, the electric eels continue to humiliate us with theirs.
is the graduate program director of health physics and radiation protection and a professor of radiation medicine at Georgetown University.
This article was republished from The conversation under a Creative Commons license. Read the original article†
