A New Method to Design Safe Neural Microstimulators

In the recent years, the development of biomedical implantable devices has had a great role in treatment of diseases and disabilities. Cochlear implant, cardiac pacemaker, and retinal implant are some biomedical implantable devices that have progressed recently. Functional electrical or neural stimulation (FES/FNS) is the common purpose of these devices to restore lost functions of damaged tissues. Electrical stimulation is based on charge injection into the tissue, initiation action potentials and excitation neural reactions. Charge-balanced stimulation is necessary to achieve safe electrical stimulation. In this work, a new active charge balancing technique for functional electrical stimulation is presented where the voltage of the electrode is sensed to be used in tuning the current value of the following phase. This method was adopted in a conventional micro-stimulator. Simulations in high-voltage 0.18-μm CMOS technology validate the feasibility of the approach and its low power consumption. The power consumption of the proposed charge-balancing circuits is 2.178 μW which contributes 3. % of the overall power consumption of the system.