This fish ‘tag’ runs on fish power | Science News for Students

This fish ‘tag’ runs on fish power

A teen developed an electrically powered tag that runs on the power provided by a fish’s swimming
May 17, 2019 — 10:31 am EST
Huai-pu Chen holding his new fish tag in front of his poster at ISEF 2019

Huai-pu Chen shows off his new fish tag (left). The tail of the tag bends in the water as a fish swims, which powers the electronics in the arrow-shaped head of that tag.

B. Brookshire/SSP

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.

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.

These tests were fishy

Huai-pu first tested his device with a computer model. It simulated how the system might work in the real world. Then, he built his fish tag and tested it in a tank of flowing water. Finally, he went to a fish farm and attached it to a slow-moving fish called a priapitinga. 

Even on a slow swimmer, the tag’s motion was sufficient to keep it powered. If attached to a large, speedy fish (such as a tuna), the tag could produce about 90 microwatts of energy, the teen reasons. But even swimming slowly, a fish would produce enough wave action to power the tag. And if it stays powered-up, the current design might allow the tag to operate for 1.5 years. In fact, Huai-pu would like it to make if last for up to 20.  

The teen brought his new tag here to the Intel International Science and Engineering Fair. This yearly event brings together more than 1,800 students from 80 countries to show off their research. Created and run by Society for Science & the Public, this year, ISEF is sponsored by Intel. (The Society also publishes Science News for Students.)

Huai-pu has lots of ideas for his tag. “We could [use it to] understand the migration path of fish,” he says. Even more, “the fish in this system could be an ocean exploration system.”

Fish can go places that people can’t, the teen notes. “Scientists can gather data like pressure and temperature from research vessels using sonar,” he says. However, this costs a lot in effort and money.” His new tags cost $400 to build, far less than a research ship. If he could tag many fish, all with devices that never ran out of power, “We could get a mass of data at low cost, and change the way human beings explore and research the ocean.”

And all the fish would need to do is swim.

Power Words

(more about Power Words)

3-D printing     A means of producing physical items — including toys, foods and even body parts — using a machine that takes instructions from a computer program. That program tells the machine how and where to lay down successive layers of some raw material (the “ink”) to create a three-dimensional object.

battery     A device that can convert chemical energy into electrical energy.

capacitor     An electrical component used to store energy. Unlike batteries, which store energy chemically, capacitors store energy physically, in a form very much like static electricity.

ceramic     A hard but brittle material made by firing clay or some other non-metal-based mineral at a high temperature. Bricks, porcelain and other types of earthenware are examples of ceramics. Many high-performance ceramics are used in industry where materials must withstand harsh conditions.

component     Something that is part of something else (such as pieces that go on an electronic circuit board or ingredients that go into a cookie recipe).

computer model     A program that runs on a computer that creates a model, or simulation, of a real-world feature, phenomenon or event.

dorsal     The back of something, usually an animal.

electric charge     The physical property responsible for electric force; it can be negative or positive.

engineering     The field of research that uses math and science to solve practical problems.

high school     A designation for grades nine through 12 in the U.S. system of compulsory public education. High-school graduates may apply to colleges for further, advanced education.

Intel International Science and Engineering Fair (Intel ISEF)      Initially launched in 1950, this competition is one of three created (and still run) by the Society for Science & the Public. Each year now, approximately 1,800 high school students from more than 80 countries, regions, and territories are awarded the opportunity to showcase their independent research at Intel ISEF and compete for an average of almost $5 million in prizes. 

migration     (v. migrate) Movement from one region or habitat to another, especially regularly (and according to the seasons) or to cope with some driving force (such as climate or war). An individual that makes this move is known as a migrant.

piezoelectric     An adjective describing the ability of certain materials (such as crystals) to develop an electric voltage when deformed, or squeezed.

pressure     Force applied uniformly over a surface, measured as force per unit of area.

sea     An ocean (or region that is part of an ocean). Unlike lakes and streams, seawater — or ocean water — is salty.

simulation     (v. simulate) An analysis, often made using a computer, of some conditions, functions or appearance of a physical system. A computer program would do this by using mathematical operations that can describe the system and how it might change over time or in response to different anticipated situations.

sonar     A system for the detection of objects and for measuring the depth of water. It works by emitting sound pulses and measuring how long it takes the echoes to return.

tag     (in conservation science) To attach some rugged band or package of instruments onto an animal. Sometimes the tag is used to give each individual a unique identification number. Once attached to the leg, ear or other part of the body of a critter, it can effectively become the animal’s “name.” In some instances, a tag can collect information from the environment around the animal as well. This helps scientists understand both the environment and the animal’s role within it.