A team of five Latvian scientists have created a prototype jacket that uses electromagnetic induction to generate electricity from the wearer's motion. Normally, induction requires the use of a big coil of wire, but the team made an important innovation by finding a way to reduce the size of the coil.

"What is very important is that our system is flat," said Juris Blums, a physicist at Riga Technical University who worked on the project.



"So, it is not necessary to take a bag or it’s not necessary to place this system in a pocket, for example," he told Deutsche Welle.

The system can be implemented in a normal-looking men’s jacket by placing flat induction coils in each side of the garment.

Measuring just 1.5 centimeters in diameter each, the coils aren't noticeable. The mini-generator also features a tiny standard microelectronic transformer placed beside the coils which turns the energy from the jacket's wearer into electricity.

Juris Blums shows one of the device's basic components, a flat copper coil

"Coils are placed in the sides of the jacket, and at the end of the sleeve we have a magnet," Blums explained. "The natural motions of our hand which we are moving while going forward - this energy of the motion is transformed into electrical energy."

Several hours to power an iPhone

The average person's walking speed is around five kilometres per hour (three miles per hour). That means that a pedestrian can generate 200 to 300 microwatts during an hour.

At that rate, powering an iPhone would take several hours, and it's enough to power wireless sensors for up to six hours.



There are about 16 interconnected coils hidden in both sides of the jacket at the pocket area and they are sewn in layers with up to 4 coils at a time.

The more coils there are, the faster the jacket can produce electricity. But there are limitations, since too many coils will start to deform the cloth.

One alternative that allows for more coils is attaching the spirals to the surface of the clothing.



"The coil can be turned into an element of decoration - it can be hidden in a crocheted apple or in a star made using different embroidery techniques, for instance," explained Aumsa Vilumsone, a professor at the Textile Technology and Design Institute at Riga Technical University, who is also involved in the project.



"In this case, the decorations depend on the design of clothing and whether they go together well," she added.

Vilumsone and her colleagues are also looking for ways that the power generator could be made airtight, which would make the technology water-resistant and the garment washable.





Both flat copper coils and embroidered coils can be used in the clothing

Military applications

The idea to harvest the body’s energy to produce electricity has roused interest among the National Armed Forces of Latvia. The military would like to adopt energy harvesters for what they call a Combat Individual Protection System.

That's a kit that includes all of the standard gear - camouflage systems, helmets, sleeping bags, boots, night vision goggles and more. The energy technology would allow the soldiers to recharge their devices while they are in the field without having to carry extra batteries.

The Latvian research team says they need about another year of testing before the vest could be released as a commercial product. There's good news for potential buyers, though, as the researchers expect the new technology will add little to the current retail price.

The microgenerators could also be useful in a special ventilation vest which is now being tested by Latvian soldiers in Afghanistan, said Igors Sitvjenkins, a researcher with the Latvian army's Defense Science Research Centre.

Though the vests are also still in the test phase, they might one day be powered by the energy harvesters, if approved by the Ministry of Defense.

"There are two fans inside the vest which are powered by rechargeable batteries," Sitvjenkins said of the garment. "Then you just put special pockets inside that start to blow so you can prevent yourself from overheating."

Author: Ģederts Ģelzis, Riga / gsw

Editor: Cyrus Farivar