An Electronic System for Extracellular Neural Stimulation and Recording

VLSI;Electrodes;Stimulation artifact;Electrode modeling;Wavelets

Blum, Richard Alan ; Electrical and Computer Engineering

University:Georgia Institute of Technology

Department:Electrical and Computer Engineering

关键词: VLSI;    Electrodes;    Stimulation artifact;    Electrode modeling;    Wavelets;   

Others  :  https://smartech.gatech.edu/bitstream/1853/16192/1/blum_richard_a_200708_phd.pdf

美国|英语

来源: SMARTech Repository

【 摘 要 】

A system for extracellular neural interfacing that had the capability for stimulation and recording at multiple electrodes was presented.As the core of this system was a custom integrated circuit (IC) that contained low-noise amplifiers, stimulation buffers, and artifact-elimination circuitry.The artifact-elimination circuitry was necessary to prevent the activity of the stimulation buffers from interfering with the normal functioning of the low-noise amplifiers.The integrated circuits were fabricated in in a 0.35 micron CMOS process.We measured input-referred noise levels for the amplifiers as low as 3.50 microvolts (rms) in the in the bandwidth 30 Hz-3 kHz, corresponding to the frequency range of neural action potentials.The power consumption was 120 microwatts, corresponding to a noise-efficiency factor of 14.5.It was possible to resume recording signals within 2 ms of a stimulation, using the same electrode for both stimulation and recording.A filtering algorithm to remove the post-discharge artifact was also presented. The filtering was implemented using a field-programmable gate array (FPGA).The filtering algorithm itself consisted of blanking for the duration of the stimulation and artifact-elimination, followed by a wavelet de-noising.The wavelet de-noising split the signal into frequency ranges, discarded those ranges that did not correspond to neural signals, applied a threshold to the retained signals, and recombined the different frequency ranges into a single signal.The combination of the filtering with the artifact-elimination IC resulted in the capability for artifact-free recordings.