A microcontroller embedded ASIC for an implantable electro-neural stimulator

Modern medical solutions to overcome disabilities and deseases tend to increasingly utilize implantable microelectronic systems, which are controlled and monitored from outside the body. One example is the electrical stimulation of nerves which have lost their natural functionality by an accident. This ASIC was developed as the central component in implantable, batteryless electro-neural stimulation systems. The first application being an implant for restoring basic movement abilities of a disabled hand, caused by a spinal cord injury. It allows stimulation of nerves with two independently controlled currents on one or more of 12 neural electrodes. The system is controlled and powered using an 80 kBit/s transcutaneous RF-telemetry link. The on-chip microcontroller was optimized to perform multi-tasking protocol handling and signal processing at a low-power level. The ASIC provides an 8-bit ADC to secure the integrity of the stimulation sub-system before activating, and a low speed load-shift keying RF-link to transfer protocol and measurement data to the external device.