Design Techniques for Log Based Closed-Loop Neurostimulation System-On-Chip.

[摘要] This thesis describes research on design techniques for a log-based closed-loop neurostimulation system-on-chip (SoC) for treatment of neurological disorders. Deep brain stimulation (DBS) has become one of the most effective therapies for numerous neurological disorders and epilepsy. A single-chip closed-loop neurostimulation system for treatment of neurological disorders is proposed.The system is comprised of five major parts: a recording path, a stimulation path, a digital processing unit, a power harvester, and an RF transceiver. Unlike any previous work, the recording path and digital processing unit of this work operate entirely in the log-domain to represent neural signals effectively with fewer bits while consuming less power. The recording path incorporates four channel low-noise amplifiers (LNAs), a logarithmic 8-bit pipeline analog-to-digital converter (ADC), and two sets of a logarithmic digital low-pass filter (LPF) and high-pass filter (HPF). The stimulation path includes two high-current digital-to-analog converters (DACs), six general-purpose DACs, and dedicated stimulation controllers. The high-current DACs are capable of both electrical and optical stimulation.Even though there has been over a decade of research on the mechanism of DBS, the algorithms of closed-loop DBS are still unclear. Recently, the energy of the local field potential (LFP) has emerged as an important and effective feedback indicator. In the proposed system, the digital processing unit detects the LFP energy and extracts optimalxvistimulation parameters by analyzing the LFP energy information. The digital processing unit includes a generic PI-controller for analysis of the LFP energy.The proposed system also includes a power harvester that converts a 915MHz RF carrier to 1.8V power supplies for the system, an RF transceiver to transmit recorded signals to an external device for further research. A backscatter scheme is chosen for the type of transmitter to minimize power consumption.A prototype system is designed and fabricated in 180nm CMOS technology. The prototype system occupies 4 mm2 and consumes 468 μW for recording and processing neural signals, stimulation, and RF communication. The proposed closed-loop neurostimulation system utilizes the LFP energy for closed-loop stimulation and log-domain computation for the first time, and achieves a single-chip operation requiring no external circuit components.

[发布机构] University of Michigan

[效力级别] Electrical Engineering

[关键词] Design Techniques for Log-based Wirelessly-powered Closed-loop Deep Brain Stimulation System-on-Chip With RF Telemetry;Electrical Engineering;Engineering;Electrical Engineering