? The control of multifunctional myoelectric prostheses is a substantive area of research with the potential to improve dramatically the independence of transradial amputees. This project will provide exploratory data for the development of a new technique for obtaining multiple electromyographic (EMG) signals for controlling multifunction myoelectric hand and wrist prosthesis. It presents a simple, inexpensive, and robust alternative to implanted telemetry systems and percutaneous electrodes. A completely embedded passive conductor is proposed to transmit intramuscular EMG signals to a distant location just beneath the skin surface. These signals will be recorded with conventional surface electrodes. The surface recorded intramuscular EMG (SRI EMG) signals will closely follow the electrical potential at the muscle fiber source. They will be extremely selective, and the well-known effect of spatial filtering, which reduces the amplitude and frequency content of surface EMG signals, will be virtually eliminated. ? ? It will, therefore, be possible to access control signals from deep or small muscles that would otherwise be unavailable. Based on this technique, a new generation of multifunction myoelectric prostheses can be developed. ? ? Aim 1: To use computer models to explore the characteristics of SRI EMG signals. Using model simulation, it will be confirmed that it is possible to record intramuscular EMG signals using an embedded conductor and electrodes at the skin surface above the conductor termination. The EMG signals will be simulated using the finite element method. The amplitude and frequency content of the simulated intramuscular and SRI EMG signals will be compared. ? Aim 2: To use computer models to optimize the design of the intramuscular conductor. The objective is to design a conductor that is minimally invasive, provides recording flexibility, and yields a reliable SRI EMG signal. Model simulations will be used to examine the effect that the termination architecture, recording area and other conductor parameters have on the SRI EMG signal. Using this information, an optimal design for the embedded conductor will be proposed. ? Aim 3: To demonstrate experimentally that SRI EMG signals can be recorded in vivo. Intramuscular fine-wire electrodes will be inserted into the extensor carpi ulnaris of 10 healthy human subjects. Insulated wires running outside the body will connect each electrode to a conductor termination. In five subjects, the conductor terminations will be inserted under the skin above biceps brachii muscle in the remaining subjects they will be inserted into a phantom tissue model to avoid surgical implantation of terminations with more complex design. Intramuscular, surface, and SRI EMG signals will be recorded simultaneously. ? ?