Microsoft patents body power

Patent number 6,754,472 describes a method of transmitting power and data to devices worn on the body, and for communication of data between those devices.

In its filing, Microsoft cites the proliferation of wearable electronic devices, such as wristwatches, pagers, PDAs (worn on people's belts) and small displays that can now be worn mounted on headgear.

"As a result of carrying multiple portable electronic devices, there is often a significant amount of redundancy in terms of input/output devices included in the portable devices used by a single person," says the filing. "For example, a watch, pager, PDA and radio may all include a speaker."

To reduce the redundancy of input/output devices, Microsoft's patent proposes a personal area network that allows a single data input or output device to be used by multiple portable devices.

Personal area networks -- or PANs -- are nothing new. Some, such as Bluetooth, use radio signals, while others use infrared. Some work has been done on near-field intrabody communications -- most notably by IBM's Almaden Research Labs, which at Comdex '96 demonstrated a prototype device that let two people exchange electronic business cards by shaking hands.

IBM's work, which was led by Thomas Zimmerman, took advantage of the natural salinity of the human body, which makes it an excellent conductor of electrical current. IBM's device, which was the size of a pack of playing cards, used a current of one-billionth of an amp (one nanoamp) -- lower than the natural currents already in the body -- to transmit data at the equivalent rate of an old 2400-baud modem, though speeds of up to 400,000 bits per second were mooted.

Aside from transmitting data between two people, IBM proposed the exchange of information between personal communications devices carried by an individual, "including cellular phones, pagers, personal digital assistants (PDAs) and smart cards". For example, said IBM in a paper published at the time, upon receiving a page, the number could be automatically uploaded to the cellular phone, requiring the user to simply hit the "send" button. This automation increases accuracy and safety, especially in driving situations.

Such functionality is today commonly provided by Bluetooth.

In its filing, which was published on Tuesday, Microsoft says its work addresses wearable devices that are too small to have any kind of interface or even a battery, such as earrings. Its solution uses pulsed AC or DC signals to power the devices -- a 100Hz signal could be used to power one device while a 150Hz signal could be used to power another, said the company, and data signals can be modulated on top of these power signals.

Furthermore, said Microsoft, the physical resistance offered by the human body could be used to create a virtual keyboard on a patch of skin. And just to make sure it has covered all its bases, the filing concludes with a note that could see the toy poodle haircut catching on: "It will be apparent," it says, "that the body may be that of a wide variety of living animals and need not be limited to being a body of a human being."