Wireless Power Transmission

Site of the day: http://www.wired.com/

Invisible Power

Marin Soljacic couldn't sleep. The problem was his wife's Nokia cell phone. The tyrannical device beeped on the bedside table when it needed to be plugged in. It could not be disabled.

Instead of taking a hammer to the phone, Soljacic marveled at the fact that this device, and billions of others like it, was sitting a few feet away from all the electricity it could ever need. Why couldn't it receive power wirelessly, just as laptops get Wi-Fi?

Being a physics professor, not an electrical engineer, Soljacic didn't know the history of failed attempts to produce wireless electricity. (Thomas Edison and his rival Nikola Tesla were among the first to envision long-distance power-beaming.) Soljacic also didn't pause to consider conduction, the kind of close-range charging used in electric toothbrushes, which is about as far as wireless electricity got before him.

Soljacic learned that if you could get two magnetic fields to resonate -- to sing the same note, in effect -- they could transfer an electric current. With two large magnetic coils, he found in an experiment described in Science magazine in 2007, you can throw 60 watts across a room, powering a lightbulb. (Keeping the two resonators in perfect harmony over a distance is not simple; Soljacic spent several years running lab experiments before he built a system that worked reliably.)

MIT, his employer, quickly patented the technology (Soljacic's name is on the patent) and encouraged Soljacic to start a company. He would sit on the board but find executives to run it full time. The result can be found on the second floor of a brick building in Cambridge, Mass. leased to the company by the big-and-tall tailor on the ground level.

WiTricity's 15 employees are hard at work proving that Soljacic's magnetic coils can power almost any electrical device. David Schatz, director of business development, shows me a TV, a DVD player and a computer, all of them wireless.

"This was our No. 1 request from business users," Schatz says, switching on a projector. "Look: no batteries, no wires, nothing up my sleeve." The coil sending out the power is hidden behind an abstract painting that the CEO's wife rescued from their basement.

Schatz is the first to admit that the housing they've hurriedly built for the receiving coils is too bulky. "No one would want to buy this," he says, pointing to the pack that juts out from the back of the laptop, a pregnant plastic bulge that's about a third as large as the device itself.

Given sufficient cooperation from equipment manufacturers, WiTricity is confident that it can incorporate its coil into the guts of any device. (Think of how computermakers like Apple (AAPL, Fortune 500) turned bulky Webcams into fingernail-size lenses that fit in a thin laptop case.) CEO Eric Giler, a veteran tech executive who ran a telecom company for 22 years, understands the importance of letting potential partners play with patented technology.

So far about a dozen companies -- including Intel (INTC, Fortune 500) and Sony (SNE) -- have tried replicating Soljacic's groundbreaking MIT experiment in their own research facilities, just to make sure it's the real deal. That might make other CEOs nervous, but not Giler.

"Our best customers are going to be the guys who try to do this," he says, "because it is really hard." The company is also talking to furniture manufacturers about fitting coils into desks and cubicle walls. The first announcement of a WiTricity partner product is expected toward the end of 2010.

Most of Giler's potential customers have one major question: safety. "There's a real perceptual problem," he says. "People think we're putting electricity in the air, and that's called lightning, and they know to stay away from that."

In fact, the coils turn electricity into magnetic fields, then back into electricity. And as any physicist will tell you, magnetic fields interact weakly with humans; as far as the fields are concerned, we are no different from air. (The Earth itself exudes a magnetic field.)

Initially, Giler was skeptical. Magnetism from MRI machines can disable pacemakers. Wouldn't wireless electricity pose similar risks? Soljacic replied that MRI magnetism is about 10,000 times stronger than his version. The Institute of Physics in London concurs: WiTricity's magnetic field "has no detrimental effects on the human body."

Giler makes a point of standing between the coils whenever he demonstrates the technology. At the Nikkei electronics conference in Tokyo in October, he was able to power a 1,000-watt klieg light from across the room -- a far cry from that 60-watt lightbulb in Soljacic's first experiment. "We're going up the power curve," he says.

WiTricity's record so far is 3,000 watts -- enough to fully charge an electric car, so long as it's in the same room (or garage). How big could WiTricity get? "Every single person in the world can relate to the problem of running out of batteries or having wires everywhere," Giler says. "The market is so potentially huge that numbers become meaningless."

A wireless electric world could free up designers to create entirely new kinds of products, no longer hemmed in by the need for boxy batteries or power supplies. As one of Giler's VC investors says, "I bet you that's your bestseller in five years' time. You don't even know what it is yet."

By Chris Taylor

(http://money.cnn.com/2009/11/24/smallbusiness/next_little_thing_2010.fsb/index3.htm)

More articles:
http://gizmodo.com/5471431/mit-wireless-power-discovery-proves-two-is-better-than-one
http://www.newscientist.com/article/dn18521-more-is-merrier-for-wireless-power-supply.html

Nanoprinter could have cells lining up to be tested

Site of the day: http://openwetware.org/

BORROWING a trick from the office photocopier may make it possible for a nanoscale printer to precisely manipulate biological cells for use in artificial tissue.

In 2007, John Rogers at the University of Illinois at Urbana-Champaign and colleagues produced a printer small enough to print electronic circuits from conductive ink on the nanoscale. By modifying the technique, they think it should be possible to manipulate biological cells or biomolecules such as DNA, says Rogers.

The team's electrohydrodynamic jet (e-jet) printer works by establishing a voltage difference between its metallic nozzle and a substrate below. The resulting electric fields cause charged ions in the ink to congregate in a meniscus at the nozzle. Because the charged ions repel one another, the meniscus deforms into the shape of a cone, creating an ultra-fine tip from which tiny ink droplets are shed.

This process produces an imbalance in the quantities of positive and negative ions in the printed ink, and the team realised that by switching the polarity of the voltage, they could print intricate patterns of positive or negative charge onto the substrate (Nano Letters, DOI: 10.1021/nl903495f).

Once a pattern of charge is printed onto a substrate, the static could attract charged molecules and cells, marshalling them into shape in the same way toner inside a photocopier is forced into the required design. "[But] xerography itself does not offer comparable resolution," says Rogers.

The technique could complement cell-printing techniques for artificial tissue manufacture by helping to guide cells too fragile to be printed into position inside a 3D matrix. "It could be very useful indirect manipulation of cells," says Vladimir Mironov, a biofabrication researcher at the Medical University of South Carolina in Charleston.

(http://www.newscientist.com/article/mg20527455.700-nanoprinter-could-have-cells-lining-up-to-be-tested.html)