Start-up charged by sound science
A student who wondered why wireless devices have wire chargers defied naysayers to make one that is powered by sound waves
Meredith Perry with a covered prototype of her uBeam wireless charger. Photograph: Peter DaSilva/The New York Times
Meredith Perry’s notebooks in which she recorded ideas and trials during the development of her uBeam device. Photograph: Peter DaSilva/The New York Times
Sometimes, there is an actual eureka moment. For Meredith Perry, it was in late 2010, during her senior year studying astrobiology at the University of Pennsylvania. She was searching for an idea to enter into the college’s innovation competition.
“It was my last year to do it,” she said, “so I literally would just carry around a notebook and write down any annoyances, because that would be an opportunity to solve a problem and have an invention.”
An “professional Googler” she’d been researching all day on her computer when she decided to pack it in for the night.
“I was just standing in my room,” she said, “wrapping up my laptop charger and trying to fit it into my bag and suddenly it occurred to me: wow, this is so archaic. Why are we using these 20-foot wires to plug in our quote-unquote wireless devices?”
“See past old paradigms” is one of those cheesy riffs one might hear from an innovation expert working the business speakers’ circuit. Yet here it was, a question that inched just past what was simply accepted: why, in a wireless age, do we still have electrical wires?
As Perry soon learned, there are very good reasons why we don’t beam electricity through the air. Although you can transmit the entire electromagnetic spectrum, from radio waves to gamma rays, there are problems.
“I realised that anything on the right half of the spectrum was too dangerous to beam,” she said, “and anything on the left half of the spectrum, that was closer to radio, was either too inefficient or tightly regulated by the government.”
So she started looking elsewhere and came upon piezoelectricity – a form of charge that is created in certain crystals and ceramics when vibrated. If you have seen Internet assertions about T-shirts “that charge your mobile phone while you wear them”, or about boots on the ground creating the charge for a soldier’s radio, you are familiar with the idea of piezoelectricity. Those applications rely on something that’s in motion.
And here’s where the second eureka happened – enabling her to see how she might build a device to wirelessly charge a battery in a mobile phone or a computer from across a room.
“How do I create vibration in the air without actually moving something?” The answer came instantly – it was almost like a stoner’s aha: “Sound is vibration in the air.”
Sound frequency “is basically how many cycles per second air is being pushed through a space”, Perry says.
“We have little hairs in our ears that vibrate in response to sound. We interpret that change in air pressure as sound. But sound is something that exists outside our heads. It’s just air particles moving in an arranged fashion.”
So was it possible to deploy sound waves that humans couldn’t hear or feel, in order to charge a phone? Nothing in her training prepared Perry for this kind of research. She was an astrobiologist, after all. She was just 21 and had spent the previous two summers interning at NASA.
So she did what most everybody else does. She clicked on Wikipedia. She started with the “ultrasound” page, then “acoustic.” Soon enough, she was reading academic papers at the forefront of various disciplines.