Totally implantable dimension telemetry.

A totally implantable dimension telemetry system has been developed to instrument animals for chronic physiological research. Implantable signal processing electronics allow free-roaming animals with no percutaneous leads while retaining the long-term redproducibility of fixed implanted transducers. Two low-powered, custom-integrated circuits have been developed and assembled into an implantable package capable of measuring one dimension channel. The system has been operated in the amplitude modes of through-transmission and reflection as well as in a new Doppler-power configuration and aimed at determining interfaces between blood and surrounding structures. In a addition to single channel systems, these ICs are key elements in multimode, multidimensional implants capable of more accurate characterization of deep body structures.