A 5 $\mu$W/Channel Spectral Analysis IC for Chronic Bidirectional Brain–Machine Interfaces

Abstract

This paper describes an amplification and spectral processing IC for extracting key bioelectrical signals, or ldquobiomarkersrdquo, which are expressed in the brain's field potentials. The intent is to explore using these biomarkers to drive prosthetic actuators or titrate therapy devices such as a deep-brain neurostimulator. The prototype IC uses 5 muW/channel to resolve signals on the order of 1 muV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rms</sub> . The four channels on the device provide independent spectral analysis from DC to 1 kHz, with variable bandwidth and power filtering characteristics. The noise floor and flexible spectral processing support a broad range of potential applications including sleep staging, Parkinson's disease, detection of movement intention for neuroprosthesis, and detection of high frequency ldquofast ripplesrdquo for exploring seizure prediction. To fully demonstrate the IC's functionality, we include results from a prototype ldquoclosed-looprdquo neurostimulator implementing adaptive titration of therapy based on measured field potential activity.