A Safe Transmission Strategy for Power and Data Recovery in Biomedical Implanted Devices

The prime concern in the design of biomedical implants is safety. This paper addresses several safety features and proposes a new scheme to transmit power and data from the central implant to the stimulator "pods" while maintaining failsafe operation. The proposed scheme demultiplexes the stimulation command close to the electrodes and uses three wires in total to provide power and data to all stimulator "pods" from the central implant. Thus, it greatly reduces the number of wires routed to the stimulation sites and is able to stimulate more stimulator "peas". The circuit used to recover the power is shown, utilizing the three wires as the only inputs. The power recovery circuit features a varactor as the storage capacitor which gives a faster pumping speed than a linear capacitor. The idea is verified with circuit simulations in a 0.6mum CMOS technology. The proposed scheme ensures that in the event of cable failure, the current will be charge-balanced, thereby avoiding the generation of harmful electrochemical products.