Microsoft Research has recently applied for a patent to develop a new way we interact with electronic devices. Typically, the mechanical force we exert on objects (e.g., using a keyboard) has been the interaction of choice to control electronic devices. This emerging technology uses the electric activity of muscles detected by electrodes on the skin. With a little gesture recognition the system can be calibrated to produce different inputs to an electronic device.
One example given in the video below is how the opposition of different fingers (index-to-thumb, pinky-to-thumb) is recognized as different finger placements on guitar strings of a popular video game. The ultimate in air guitaring!
It sounds like a great idea and I use surface EMG almost every day in my lab. So, naturally I have a few speculations about how reliable their technology can be. Obstacles include cross-talk between the dozens of active muscles of the forearm during what could be thought of as a simple contraction, keeping electrodes securely fastened over time, and positioning the electrode precisely given that human anatomy varies from person to person.