Implementation of digital stimulus generation system for a passive programmable medical implant

Electrical stimulation by means of a medical implant is used as a means of restoring the lost functionality of different physiological organs. An active implant which works on a battery or a passive implant which works on power wirelessly transferred to it, could be used for this purpose. The future developments and applications will be in passive implants because of their smaller size and greater implantability. At the moment Manchester encoding is utilized as the data encoding scheme in medical implants. But this work proposes an alternative encoding scheme called Pulse Interval Encoding(PIE) for application in a passive implant. PIE offers the advantage of a simpler decoding methodology and greater power transferred to the implant. A PIE decoder that is resilient to data jitter to the tune of 2.5 μs and that works with clock frequency between 1.52 MHz and 1.76 MHz is implemented in this work. The electrical stimulation patterns that the implant generate will vary according to the application. This work also presents the design of an universal digital stimulus generator which can be programmed to generate the stimuli patterns for a variety of applications like pain relief and bladder control.