title: Toward a fully integrated neurostimulator with inductive power recovery front-end.
abstract: In order to investigate new neurostimulation strategies for micturition recovery in spinal cord injured patients, custom implantable stimulators are required to carry-on chronic animal experiments. However, higher integration of the neurostimulator becomes increasingly necessary for miniaturization purposes, power consumption reduction, and for increasing the number of stimulation channels. As a first step towards total integration, we present in this paper the design of a highly-integrated neurostimulator that can be assembled on a 21-mm diameter printed circuit board. The prototype is based on three custom integrated circuits fabricated in High-Voltage (HV) CMOS technology, and a low-power small-scale commercially available FPGA. Using a step-down approach where the inductive voltage is left free up to 20 V, the inductive power and data recovery front-end is fully integrated. In particular, the front-end includes a bridge rectifier, a 20-V voltage limiter, an adjustable series regulator (5 to 12 V), a switched-capacitor step-down DC/DC converter (1:3, 1:2, or 2:3 ratio), as well as data recovery. Measurements show that the DC/DC converter achieves more than 86% power efficiency while providing around 3.9-V from a 12-V input at 1-mA load, 1:3 conversion ratio, and 50-kHz switching frequency. With such efficiency, the proposed step-down inductive power recovery topology is more advantageous than its conventional step-up counterpart. Experimental results confirm good overall functionality of the system.
authors.affiliation: Department of Electrical Engineering, Polystim Neurotechnologies Laboratory, Ecole Polytechnique de Montreal, Montreal, QC H3T 1J4 Canada. faycal.mounaim@polymtl.ca
authors.forename: Fayçal
authors.initials: F
authors.lastname: Mounaïm
authors.forename: Mohamad
authors.initials: M
authors.lastname: Sawan
mesh_terms: D000818:Animals; D001698:Biomedical Engineering; D003201:Computers; D004285:Dogs; D011211:Electric Power Supplies; D004581:Electronics; D004582:Electronics, Medical; D004867:Equipment Design; D006801:Humans; D058542:Implantable Neurostimulators; D012815:Signal Processing, Computer-Assisted; D013119:Spinal Cord Injuries / Q000628:therapy*; D014521:Urethra / Q000294:innervation; D014554:Urination; D059015:Wireless Technology