Microsoft has been awarded a patent for a technology that uses the conductivity of the human body to create a network. The patent covering transmitting power and data using the human body was awarded in late June and is a fascinating insight into the type of personal network we may all be using within a few years, in the words of a company which will almost certainly be one of the defining players in the evolution of human computing.
Microsoft's patent covers a technology that distributes both power and data to devices (e.g. a speaker, display, watch, keyboard, etc) coupled to the human body via electrodes. A pulsed DC signal or AC signal is used as the power source, and by using multiple power supply signals of differing frequencies, different devices can be selectively powered.
Digital data and/or other information (e.g., audio signals), can be modulated on the power signal using frequency and/or amplitude modulation techniques.
The illustration at right is the illustration provided by Microsoft for the patent application. Microsoft's patent application is available on the net and is an interesting read as it offers plenty of detail and rationale for the technology. In essence, the logic for the network makes perfect sense and can be summarised as follows:
1 - Small portable electronic devices such as wristwatches, radios, pagers, cell phones, PDAs are commonplace today
2 - As electronics have improved, weight and power consumption requirements have decreased and capabilities have increased and it is now possible to power many devices with relatively little power.
3 - Given the small portable nature of many devices, people have begun wearing multiple devices on their bodies and there is a significant amount of redundancy. For example, a watch, pager, PDA and radio may all include a speaker.
4 - In order to reduce the redundancy in input/output devices, networking of portable electronic devices has been proposed. By exchanging data as part of a network, a single data input or output device can be used by multiple portable devices, eliminating the need for each of the portable devices to have the same input/output device.
5 - Current portable electronic devices frequently rely on batteries which have a limited energy storage capability and regularly need to be replaced or recharged. One single power source for all these items would significantly reduce weight, size and redundancy.
The detail in Microsoft's patent application is interesting. At one point it cites that "some wearable devices, such as earrings, are not big enough to have any kind of interface at all" and that the network would enable the use of a whole new class of wearable devices.
From the patent transcript, "These devices do not have a direct interface, but are instead used as relays for collecting and transmitting information to the user. For example earrings, which can be used to measure the persons pulse rate or even deliver sound to the ear via a phone worn on the person's belt. To program the earring directly would be a quite cumbersome task; however, the earrings parameters could be set via another device that is large enough and has the appropriate user interface to enter data. The user could use this device to control the volume of the earrings or to control other function of this device. This concept could be extended to many other such devices that are worn on the body: jewellery, watches, and eyeglasses to name a few."
Click http://patft.uspto.gov/netacgi/nph-Parser?u=/netahtml/srchnum.htm&;Sect1=PTO1&Sect2;=HITOFF&p;=1&r;=1&l;=50&f;=G&d;=PALL&s1;=6754472.WKU.&OS;=PN/6754472&RS;=PN/6754472to read the full Microsoft Patent Application.