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Thursday, December 14, 2006

Plastic Sheet of Power

Printing flexible electronics on plastic provides a way to wirelessly power gadgets.

By Kate Greene

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These sheets of flexible electronics can wirelessly transmit power to gadgets. The sheet in hand has copper coils for power transmission; the black and brown squares are switches for turning the current on and off; the next set of copper coils senses the position of a gadget; and the black and white grid is an array of organic transistors that detect the position of the gadget and direct current flow.
Credit: Takao Someya
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•  Video: See a model system in action

Researchers at the University of Tokyo have demonstrated a prototype that could offer a new way to power gadgets. The prototype, which consists of plastic and flexible electronics, can wirelessly supply power to any device that touches its surface.

The power sheet, says Takao Someya, professor of engineering at the University of Tokyo, relies on the well-known physical principle of electromagnetic induction, used to charge electric toothbrushes and some RFID tags. However, he says, his system is designed in a way that overcomes the limitations of common induction schemes. Traditional induction systems can only spread small amounts of power over a relatively large area, and fairly large amounts of power can only be supplied to precise locations (such as a toothbrush mount). Someya's power sheets, in contrast, can be large, and they can still supply a large amount of power to gadgets placed near them.

This new capability, he says, is enabled by a novel design and by advances in the fabrication of flexible electronics. The power system actually consists of two types of sheets: one sheet senses the position of an object, and the other sheet supplies power to the object's point of contact, but not to the rest of the sheet. "In this way, the system selectively feeds power as high as 30 watts to electronic objects placed upon it," Someya says.

The position-sensing sheet relies on two types of flexible electronics. Using a technique similar to silk screening, the researchers printed an array of copper coils 10 millimeters in diameter. In addition, they used a modified inkjet printer to print an array of organic transistors. Both devices are thin and flexible enough to bend with a sheet of plastic.

Gadgets would need to be equipped with a coil and special power-harvesting circuitry to use the power pad. As the gadget gets closer to the pad, the electrical resistance of the pad's coils decreases. The array of transistors detects the exact position of the change in resistance and effectively directs the subsequent power flow, which is provided by devices on the second sheet of plastic.

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  • Power pads
    protn7 on 12/14/2006 at 11:51 AM
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    I bet it wastes a lot of electricity. Bad idea in light of the greenhouse warming we are going through.
    Rate this comment: 12345
    • Re: Power pads
      randman420 on 12/14/2006 at 11:59 PM
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      6
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      Actually it said it was using the principles of induction which would mean that it would only use the actual power being consumed by the device, in other words it would use no more electricity than if you had simply plugged it in to a receptacle as we currently do. But I am please to see your concerned about the environment and global warming, good for you!
      Rate this comment: 12345
      • Re: Power pads
        kitode on 12/31/2006 at 5:45 PM
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        2
        This would imply gadgets being off grid, right? 
        Rate this comment: 12345
  • Safety?
    micro on 12/31/2006 at 10:27 AM
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    1
    If I place my hand on that surface and it erroneously detects a gadget and turns the power on - what will happen to my hand?
    Rate this comment: 12345
    • Re: Safety?
      caz on 12/31/2006 at 11:33 AM
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      1
      Exactly the same as if you went up and put your hand on any normal electric sheathed cable that is supplying electricity to a device: nothing.

      as mentioned in the article it uses electromagnetic induction (magnetic fields) to generate electricity in the device sitting on top of the  plastic sheet. if you want to learn more, wikipedia would be a good starting point.
      Rate this comment: 12345
  • Endless possibilities...
    anastas on 01/29/2007 at 1:01 AM
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    1
    I really think they should interweave a layer of some form of data transfer into this system so essentially you could move a monitor around and be able to get power and data at the same time... among millions of other things. You can already transfer data over electrical lines, so it might even be easier than that.

    This type of transferring system has massive potential. I think it was what they had in mind in Minority Report with the MagLev systems seen in this link.
    --> http://uplink.space.com/attachments/514680-Maglev2cb.JPG
    Rate this comment: 12345
    • Re: Endless possibilities...
      evolvingwheel on 05/06/2007 at 12:32 PM
      Posts:
      5
      The proposition of data transfer along with power sounds promising.. however any innovation is controlled by demand, implementation ease, cost benefit, and competitive environment. There is enormous amount of data being transfered (or in the research level) wirelessly. Huge amount of capital investments are in place for 4G wireless and etc etc. Gigabit level transfer is hitting over the air.. through cell phones, wi-fi etc. Besides, gadgets are already now equipped with the facilities and there are industry standards in place. So getting data through a pad which is being developed with a electrical purpose will not be a easy sell.. So ideas are often not feasible in the context of market commercialization.

      http://innovech.wordpress.com
      Rate this comment: 12345
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