Implantable volume monitor and miniaturized stimulator dedicated to bladder control.

This paper describes a new miniaturized implantable bladder controller that is composed of 4 main parts: a volume monitoring device based on the tomography approach, a fully programmable miniaturized central processor and stimulator, a bidirectional data and power link, and an external controller. The proposed system is intended to restore both normal bladder functions (retention and voiding) to spinal cord injured patients. The system contains a mixed-signal (analog/digital) feedback loop to command the bladder functions through neuromuscular stimulation techniques. The implantable circuitry is powered by a single encoded radiofrequency carried and may have up to 8 independently controlled monopolar (4 bipolar) channels. The microstimulator is able to generate a wide range of stimulation patterns, including selective stimulation waveforms. In addition, an optical link transmits the state of the implant and volume monitoring results to the external controller.