Update, Friday morning: Check out this Microsoft Research video that shows the concepts discussed in the patent filing -- including a demonstration of how to use muscle movement to play Guitar Hero, air-guitar style. (Thanks, Manan for pointing this out.)

[Original post follows.]

We've covered lots of offbeat Microsoft patent applications in 2009, and here's a doozy to round out the year. According to a newly surfaced filing, the company is seeking patents on a method of controlling computers using Electromyography, or EMG -- a system that translates electrical activity from muscles into instructions for the computer.

One of the filings suggests doing this by attaching sensors to a user's forearm, but another goes further by proposing a completely wearable system of sensors on the head, chest, arm and leg. Here's how one of the filings describes the overarching concept.

Human-computer interactions have been primarily detected using direct manipulation of devices such as mice, keyboards, pens, dials, and touch-sensitive surfaces. As computing and digital information becomes integrated into everyday environments, situations arise where it may be inconvenient or difficult to use hands to directly manipulate an input device. For example, a driver attempting to query a vehicle navigation system might find it helpful to be able to do so without removing his or her hands from the steering wheel. A person in a meeting may wish to unobtrusively interact with a computing device. Furthermore, direct physical manipulation spreads microbes, so hands-free input mechanisms can helpful in areas sensitive to contamination, for example surgery rooms.

Most implement-free or hands-free interaction approaches have involved speech and computer vision. While improving, these technologies still have drawbacks. They can be unreliable, sensitive to interference from environmental noise, and can require a person to make obtrusive motions or sounds.

Another approach is to infer user input from sensed human muscle activity. Advances in muscular sensing and processing technologies make it possible for humans to interface with computers directly with muscle activity. One sensing technology, electromyography (EMG), measures electrical potentials generated by the activity of muscle cells. EMG-based systems may use sensors that are carefully placed according to detailed knowledge of the human physiology. Specific muscle activity is measured and used to infer movements, intended or not.

Put it in a European sports car and suddenly it all seems very James Bond. But what will this electric muscle-generated input mechanism look like? Here's the key visual from that "wearable system" patent filing. Ready to try this on?

On the off chance you're jumping at the chance, don't hold your breath. Microsofties named in the filing are from the company's research unit, which suggests that this probably won't be on store shelves anytime soon.

Update, Friday morning: The Microsoft Research site wasn't responding for me when I posted this yesterday, so I wasn't able to check there for additional background on the project at the time, but blogger Manan subsequently got in and pointed to the MSR "Muscle Computer Interfaces" page for more information, including the video above.

Also see this paper (PDF) from a 2008 Computer Human Interaction conference. Microsoft researchers Dan Morris and Desney Tan collaborated on the project with Ravin Balakrishnan of the University of Toronto and Scott Saponas of the University of Washington.