Resonant Link plans to release its first remote smartphone charger to the public this year

SOUTH BURLINGTON — It’s 9:30 a.m. at Resonant Link’s headquarters, in an industrial park next to Ben & Jerry’s, and nearly every cubicle is still empty for two reasons, explains Rachel Allard, the company’s director of marketing: Engineers tend to get late, work late, And the company left room for explosive growth in hiring this year, from 48 employees currently to about 80 by year’s end.

“We definitely have a little bit of moving to do, as you can see,” Allard says.

Resonant Link moved into its new offices this past spring. The company’s headquarters were in Shelburne. Fifteen months ago, it had seven employees. By the end of 2021, it had 18 people, including founders Aaron Stein, Phu Ong Kyaw, and Grayson Zuloff. Last year, it hired 30 more employees.

“It’s exactly what we need for Vermont’s economy,” said Lauren Bass, director of LaunchVT, a Burlington-based accelerator. Resonant Link has been accepted as one of eight companies in LaunchVT’s 2020 Corporate Suite. Companies receive mentoring and training and meet with investors.

“We need the next Resonant Links, we need the next Betas,” Bass said, referring to Burlington-based electric aircraft manufacturer Beta Technologies. “They have (intellectual property). They are in the technology. They are creating jobs at the low end that are high five-figure employment opportunities for Vermonters. They are attracting talent.”

Also important, Bass said, is that Resonant Link raises money outside of Vermont.

“These are some of the best investors out there,” Bass said. “They’re market makers and they’re institutional money, and that’s the highest degree of validation in terms of telling the public and telling the market that someone put in some serious effort because they think this business is going to grow.”

Resonant Link employees are now spread across 12 states and three countries.

“People will work on a board or circuits or something,” Allard said. “They’ll ship it overnight to a colleague in Denver. And that person can work on the same piece of physical hardware.”

Founded in 2017, Resonant Link builds on its revolutionary method of transmitting power wirelessly using coils made of layers of foil and thin-film dielectrics, a dielectric that can be polarized by an applied electric field.

“We build coils in a very different way than traditional wireless chargers,” said Zelf, CEO of Resonant Link. “Our layers are made of alternating foil like you can buy at the grocery store and then shoot, instead of what others do, which is basically take braided wire and twist it into a loop.”

Al Zulf said the technology uses a fifth of the power of other current wireless technologies. It was developed by Stein and Kyaw in the lab of Professor Charles Sullivan in the Thayer School of Engineering at Dartmouth College in New Hampshire.

“Charlie had this original idea for this new type of wireless coil that was really exciting,” said Stein, chief technology officer of Resonant Link.

That idea was the resonant link after which the company was named.

Stein, who was doing postdoctoral research at Dartmouth, worked with Qiao to turn Sullivan’s idea into reality in his lab. They found that the wireless coil performed five to 10 times better than the other coils. They learned that by calculating a factor called Q, which measures stored energy divided by energy dissipated during a wireless transmission, it essentially determines how much energy is transmitted to the receiver rather than dissipated, Allard explained.

“All of a sudden, we had this amazing result,” Stein said.

They’ve taken their results to conferences, Stein said, and found that people are excited. So they thought they should market their idea. Stein wrote a grant application for the National Science Foundation to fund and implement the company. In 2018, they received a grant worth approximately $225,000.

“Once that was there, we had a little money and a few people with big hearts and big ideas, and we set off trying to see what we could do from there,” Stein said.

Stein said all of their clients share a need to find strength through something hard to come by. Their medical customers need to transmit power to the devices through the human body without overheating them. Customers of their lift trucks have to get the power through the air for as many centimeters as possible without dissipating too much energy, because this dissipated energy will heat things around them and make them unsafe to touch or parts may fail.

“The tricky thing about that is that you have to create large magnetic fields to pass energy through that air gap,” Stein said.

The company’s technology can wirelessly power electronics from small 20mW medical devices to 19.2kW chargers for lift trucks.

At the company’s headquarters, Allard opened a drawer and pulled out the smallest charger the company makes—the Molly implant—holding it in the palm of her hand. She said she’s been telling people it’s about the size of a fingernail, but at three millimeters in diameter, it’s actually much smaller.

Ranan Link’s customer, Allard said, wants to make saliva test the new blood. The implant, a wireless charging receiver, is designed to rest in a retainer or over a tooth like a crown. It would run the included saliva diagnostic tool, which would detect biomarkers that could help diagnose medical conditions ranging from diabetes to throat cancer.

Eventually, Allard said, the device could be used to power the electronics that control seizures in patients with epilepsy. In such a case, the charger’s transmitter could be in a pillow and recharge the implanted device while the patient is asleep, she said, or it could be in a headband or cap.

The largest medical device charger the company is developing, she said, is the left ventricular assist device, a device that pumps the heart one-half to one-fifth the size of current chargers. The charger can be worn in a jacket.

Wireless chargers for medical devices eliminate the need for surgery to replace implanted batteries and the need for wires that exit the body to an external charger. Besides being stressful, wires can lead to infection, according to Allard.

Resonant Link medical device chargers work from four to six centimeters, Allard said.

“If you have something on your heart’s mind, you can basically wear the charger in your chest pocket,” she said. “The possibilities are pretty much endless.”

In the past, she noted, materials for implanted receivers were limited because they had to be biocompatible so the body wouldn’t reject them or overheat.

Allard said Resonant Link medical device chargers meet FDA requirements that prevent medical devices from heating body tissues by more than 3.6 degrees Fahrenheit.

The company’s medical chargers are currently being tested on animals. After human trials, Zulf said he expects to get its first FDA approval next year.

Resonant Link won’t disclose its customers, but Zulauf said it works with 12 medical device manufacturers. Allard said the company is also working with a major smartphone maker. She said Resonant Link hopes to have the smartphone charger on store shelves by the end of this year, around the holidays.

Wireless chargers for smartphones are already available in the market. One thing that makes the Resonant Link different, Allard said, is that its chargers are more flexible.

“We’ve all been frustrated with wireless chargers where you have to have them in exactly one place to power them,” Allard said. “Our chargers must work with the way people live and work.”

Allard said the Resonant Link’s smartphone charger works twice as far from the phone as any other competitor. And she’s faster, too. The electronics constantly monitor how much power is being transferred, so maximum power is being sent at any given time, but not as much as overcharging, which destroys the batteries over time, she said.

“So these people are constantly saying, ‘How much power are you receiving, battery?'” Well great. She said.

Zolff said more than 1 billion electronic devices, mostly smartphones, have been charged with built-in wireless charging. He said the charger, which Resonant Link plans to offer later this year, could be dropped into those phones. He said the company’s charger would cost the same as the existing files.

“When you put our coil in the phone, you can wirelessly charge that phone three times faster than you can today,” Zulf said.

Customers have to be convinced that wireless power can be fast enough, small enough, lightweight enough and inexpensive enough to make it worth their time integrating it, Zalf said.

“So people are really convinced of what wireless power can do for them,” he said. “They were just waiting for a company that could deliver on the promise of wireless power.”

Allard said current wireless lift truck chargers require the lift truck to be parked within an inch or two of the charger. Lift trucks are similar to forklifts, but have a smaller turning radius that allows them to work in tight spaces in warehouses.

“Have you ever tried to park a lift truck an inch or two from a base station?” she asked. “We wanted to make it easy to use by not having to park perfectly.”

Skyler Cornell, the electrical engineer who was working on the rechargers, explained that the Resonant Link’s base station, which contains one of the power coils to recharge the lift trucks, can be within 10 feet of the transmitter’s power electronics. Power electronics regulate the amount of energy transmitted. A transmitter that wirelessly sends a charge to a receiver on the truck can be as far as 10 inches away. Chargers can recharge lead-acid batteries as well as lithium-ion batteries. Allard said the system works with both manually operated vehicles and self-driving vehicles.

When Cornell showed the charging sequence, the charger jumped from zero to 400 amps in less than a second.

“No one has been able to do 400 amps yet, so that power level is key to charging speed,” Allard said. “Basically, they are interconnected.”

Cornell explained that Resonant Link’s wireless lift truck charger reaches 90% efficiency, which means that 90% of the power transmitted wirelessly is received.

Other wireless chargers for lift trucks are on the market, Allard said, but they only achieve 40% to 50% efficiency.

Allard said efficiency affects how quickly you can recharge a lift truck.

“Every minute counts at the warehouse,” she said.

Zelf said Resonant Link chargers can recharge a lift truck two to four times faster than any other wireless charger on the market.

When something like a wrench is placed between the transmitter and receiver, the charger turns off, Allard showed in a demonstration. A person would not get caught between the two, she said, but the body could heat up so much that it could burn someone trying to pick it up.

“Warehouses are very chaotic environments,” Allard said.

Allard said that if someone touches the battery on the lift truck while it’s being recharged, it will feel warm, but not so it could harm the person.

The company expects to ship initial production units of its lift truck chargers to a limited number of customers for testing in March, Allard said, before it begins mass-producing them later this year.

“Resonant Link has an opportunity to revolutionize strength and energy and how we deliver that,” said Stein. “I imagine Resonant Link will be a major player in strength and energy going forward.”

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