Voluntary closing allows the patient to have substantially greater grip force, often over 50 pounds, but does not allow the patient to relax without losing grasp. This category of prosthesis uses small electrical motors to provide function . An electrically-powered prosthesis utilizes a rechargeable battery system to power the motors. Because electric motors are used to operate hand function, grip force of the hand is significantly increased, often in excess of 20-32 pounds. In most cases a single control scheme is chosen.
Myoelectric control is possibly the most popular control scheme.
A microvolt is one millionth of a volt. To put that in perspective, a typical light bulb uses 110 to 120 volts, so this signal is a million times smaller than the electricity required to power a light bulb. Using sensors called electrodes that contact the surface of the skin, the EMG signal can be recorded. Once recorded, the signal is amplified and then processed by a controller that switches the motors on or off in the hand, wrist, or elbow to produce movement and function. If you are interested in this option, the first step that is required is a Myoelectric Test .