Tags that researchers use to track fish can run out of power. A teen from Taiwan invented a tag that converts fish swimming into the electricity needed to keep it running.
PHOENIX, Ariz. — Under the sea, scientists tag fish to track their numbers and learn about the ocean. But those tags have one problem: Their batteries run out of energy. Now, a teen has designed a tag that never loses power as long as its host is alive. All the fish has to do? Just keep swimming.
“I am a big fish fan,” says Huai-pu Chen, 16. “I go fishing and dive almost every day.” Spending so much time around fish, this junior at Keelung Municipal Anle Senior High School in Taiwan began to ponder whether the animals might be able to use their strong swimming for a different type of power.
“When I was little, I saw fish in the ocean. They swam rapidly and energetically and I thought, ‘What if we could use fish to produce energy?’” More recently, Haui-pu wondered if these fish might be able to power the technology in electronic tags.
Scientists tag fish, snakes, sea turtles, whales and more to learn about their lives and the oceans through which they swim. But these tags run on batteries. And batteries don’t last forever.
Explainer: How batteries and capacitors differ
Huai-pu wanted to see if a fish’s swimming could make a longer-lasting battery. He turned to a special ceramic — a hard, brittle material — that is piezoelectric. Such a material can develop an electric charge when it is bent or squeezed. The teen took bands of piezoelectric ceramics and hooked them up to a tiny capacitor — an electrical component that stores energy. The whole device rests in a 3-D-printed plastic case that is shaped like a small arrow.
The teen hooks his tag just below the dorsal fin on a fish’s back. As the animal swims, the motion of the water around that tag bends the ceramic back and forth. This bending action builds up an electric charge that gets stored in the capacitor. A little more swimming, and the tag can light a small bulb, power a thermometer or measure such things as water depth.