Mechanical Devices and Composites

Mechanical devices have been used to replace body parts for years. For example, prosthetics have been used to replace missing hands, arms, and legs. Artificial hips, knees and elbows are commonly used today. While we could talk about the biophysics of these devices, we will not do so. Instead we will look at two unique adaptations where biomechanical devices are interfaced with biological tissues and organs.

The first is the use of arm muscles to control an artificial hand. Imagine if you placed a sensor on a tendon of a muscle that causes your index finger to flex. Imagine further that if the tendon moved, this could be converted into a signal that would cause a mechanical index finger to also flex.

A system of this type has been developed at Rutgers University. In the near future, a young child, born without a hand or lower arm, will be fitted with a prosthesis that will transmit movement of specific tendons into a signal that will cause the fingers of the prothesis to move. Will a amputee be able to type at the computer keyboard?

• Why do you think that the researchers concentrated on tendons instead of the specific muscles that control finger movement?

The second system involves artificial muscles.