Slashdot Mirror
A Tablecloth to Charge Your Laptop
moscowde writes "Research scientists at the University of Tokyo have come up with a unique sheet-like material that can transmit electrical energy over a large area to nearby devices without the need for direct contact, so it can be made into a tablecloth or wallpaper and your appliance can be anywhere on a surface to get charged.
The system uses organic molecules as transistors, microelectromechanical switches, and miniature copper coils to transmit energy using electromagnetic induction."
I cannot find any reference, however I recall reading an article several years ago which detailed a consumer deskpad which contained dozens of micro contacts. The idea was you simply lay your laptop, mobile phone, pda on the pad, and it begins to charge. Of course this product assumed that your devices were outfitted to use the charger. A microcontroller would actively sense the current between pad contacts, allowing charging, but preventing short circuits. Again, as I cannot locate this product now, I expect it did not take off.
Inductive charging also seems inefficient to me. The article claims 80% efficiency. What exactly do they mean? How many AC-DC conversions take place within this charger?
Also, my laptops require more like 80w. It may be okay for PDAs and mobile phones.
IMO, a good research project, but not yet near a consumer product.
In original research paper published in "Nature Materials" there is a picture of a fish tank with fish inside. The light inside the tank is powered using this transmitting material. Power cables, sockets, and plugs are not required, and all of the metallic parts are coated with insulating materials. So it is safe.
"Coherer" is NOT a coil. See http://en.wikipedia.org/wiki/Coherer for details.
Wardenclyffe tower would have never worked, intensity of electromagnetic field obeys inverse square law, so you'll need a LARGE antennae to catch more than a few milliwatts at a distance more than a few hundred meters.