Plugging Away: UBeam’s Meredith Perry during an interview with the BBC.

Plugging Away: UBeam’s Meredith Perry during an interview with the BBC. Photo by Courtesy Photo

“I was very surprised about their claims,” said Boser about Theranos. “How could they possibly do that? Now we know they can’t.”

Resistance

Yet Perry, who holds a bachelor’s degree in paleobiology from the University of Pennsylvania, remains unambiguously confident.

“UBeam will be there just like you see free Wi-Fi in windows as you walk by shops,” said Perry in a USA Today interview in February. “It will be everywhere from your local coffee shop to the hotel to theaters to stadiums to airports. You name it.”

UBeam’s technology sends energy wirelessly through a multistep process.

Simply put, uBeam electrifies a crystal, which vibrates and creates ultrasonic waves that travel through the air, hitting another crystal fixed inside a cellphone case. The second crystal then turns the vibrations back into electricity. UBeam claims this system can generate at least 1 watt of electricity up to 15 feet away, enough to provide a trickle of electricity to an iPhone.

Ultrasound has been used to transmit energy before, said Henry Scarton, a mechanical engineer and director of the Laboratory for Noise and Vibration Control Research at Rensselaer Polytechnic Institute in Troy, N.Y. Scarton has built systems that project ultrasonic energy through metal submarine hulls to underwater listening devices and through oil-carrying pipe to sensors.

But under closely controlled conditions, those systems only generate a maximum of 50 percent efficiency, he said.

“In air, it would be ridiculously small. Not practical,” Scarton said.

Moving ultrasonic energy through air, rather than water, metal or even human flesh – as in medical exams – is inefficient, experts say.

Other factors, such as humidity – or denim pants pockets – could further reduce efficacy, experts say.

To generate a trickle of charging power, a large amount of electricity would have to be pumped into uBeam’s transmitter, explained Mike Bailey, a senior principal engineer at the University of Washington’s Center for Industrial and Medical Ultrasound in Seattle. “There’s a lot of loss in converting electrical energy to acoustic energy and then receiving it and converting it back.”

When the university’s engineers heard about uBeam’s approach to wireless charging a month ago, the concept sparked a discussion about a textbook exercise they teach their students, he added.

“There’s a problem in an acoustics textbook: How long would you have to yell at a cup of coffee to make it boil?” said Bailey. “It’s something like 10 years.”

Invention

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