Remember the last time you wanted to recharge your cellphone only to discover that you forgot the electric cord somewhere else? And if you are hopelessly dependent on your cellphone and there is no replacement charger in sight, then you have a problem.
It doesn’t have to be that way, says Massachusetts Institute of Technology (MIT) spinoff WiTricity, a global producer of devices that generate wireless electricity. “The next generation of cellphones will have wireless charging in them,” says Kaynam Hedayat, WiTricity’s Vice President of Product Management and Marketing.
The technology to generate wireless electricity was invented nearly 120 years ago – with significant limitations. So for wireless electricity to be transmitted at the time, “the device that is the source of the power or electricity and the device that is receiving it … have to be exactly aligned and in very close proximity – less than one millimeter,” said Hedayat.
Highly resonant devices, tuned to the same frequency, exchange energy through a magnetic field. The magnetic field transfers electricity over distances of one to several feet and allows for “positional freedom.” That means that the receiver and the transmitter need not be aligned and can move around the room while seizing power.
“Resonance,” says Hedayat, “basically means that you are oscillating the magnetic field … at frequencies that are open in the frequency band, sometimes referred to as ISM band [i.e., industrial, scientific and medical radio bands reserved internationally for purposes other than telecommunications.]”
For all that to happen, a power source is needed. “That goes into a device we call the source, to refer to it as the source of wireless electricity,” said Hedayat. “This source has some electronics inside, which are very cost-effective.”
Those include a coil and capacitors and inductors that generate the magnetic field.
By nature, magnetic fields do not radiate energy, although they interfere with electronic devices. With WiTricity, Hedayat says the company has shielded the magnetic field to prevent such interference.
But is it harmful? “It depends on how much power you want to transfer,” replied Hedayat. “For the applications that we are targeting – from cellphone applications all the way to automotive charging – it is not harmful,” he said. “And our systems are designed to meet the safety level limitations set by standards bodies around the globe.”
Hedayat argues that WiTricity is safe enough to recharge devices that are implanted in human bodies such as pacers or pumps. Such transfers use 20 watts of power over a distance of 20 centimeters. Without wireless electricity, the devices require either a “wire sticking out of the patient” or biannual or more frequent surgery to remove the battery, he said.
The company also sees its technology as a viable alternative to batteries in places like oil fields and areas too hazardous for humans, deep at sea where submarines have to return to a station to recharge and in conflict zones to recharge military equipment.
But its biggest momentum is in recharging electric and hybrid cars. With Toyota licensing the technology for the next generation of its Prius plug-in hybrids, Hedayat says other automakers will follow.
“When you drive into the garage of your home, you don’t have to plug anything in,” he said. “And you go to your business and the car automatically detects Witricity … and starts charging itself.”
The current technology wirelessly charges vehicles within a distance of around 20 centimeters. While the system can be deployed redundantly to increase range, Hedayatssays the company’s lab tests “have demonstrated a transfer of power in one to two meters,” depending on the application.
Whatever the range, cars and cellphones will automatically recharge themselves once they detect WiTricity. And Hedayat says the technology “will not have any significant impact” for consumers once it is onboard the car or the cellphone, especially as volumes go up.
And he expects WiTricity to spread much in the same way as Wi-Fi did. “Initially there will be solutions that are integrated loosely into devices such as sleeves for cellphones or dongles that go into laptops,” he said.” But slowly, “you will see this technology embed itself into the actual cell phone and the actual laptop and PCs.”
Add to that the “room of the future” that Hedayat envisions where WiTricity runs through carpeting to light the entire room. Any cellphones equipped with WiTricity will automatically recharge themselves – no cords attached!