Biological Signals Acquisition

One possible application: artificial eyes and recreation of  "natural" eye movement.

In most cases eye replacement patients (who have just lost the eyeball) benefit from a moveable artificial eye called the Bio-eye hydroxyapatite ocular implant which has been available since the 1980s.  The Bio-eye is made of porous material like coral which the body grows into. Muscles attach to the artificial eyeball and allow a good range of movement in synchrony with the normal eye. But for less than 1% of the people needing an artificial eye and who have lost the entire content of an orbit, including the muscle, fat, bone and nerve due to extensive cancer or trauma, such a technology is not possible.
These patients have to endure the social stigma of a static, staring artificial eye.

Detection of the Natural Eye's Movement:

A team of engineers from the University of Alberta designed the first robotic eye implant to mimic the movement of a real human eye. The robotic eye detects and follows the movement of the remaining natural eye. 

There is a very small motor that drives the artificial eyeball which is mounted in the socket where the person's eye used to be. The tiny motor sits inside the hollow sphere of the artificial eyeball on a shaft, about which the eye rotates horizontally.
 Its motion is driven by information sent by the natural eye's movement and received by a small computer chip in the artificial eye.

One method to detect the natural's eye movement, is to have an infrared sensor array mounted on a pair of eyeglasses transmit data about the eye's position to the robotic eye.
With another newer method, electrodes sense the electrical signals sent from the brain to the natural eye to cause movement and forward the information to the artificial eye.
Both methods are tested outside of the body using input from natural eyes to move artificial ones mounted in plastic eye pits.
The newer system using the electrical signals from the eye offers net cosmetic advantages: it would get rid of the external device (the eyeglasses) and use the human signal itself internally. The aim would eventually be to eliminate the electrodes used outside of the body and get the signal from the eye socket only. (Work published in the August issue of Robotics and Autonomous Systems)