Circuits for Bio-Potential Recording from the Brain

Advances in CMOS technology have made ultra-small electronic sensors become part of wearable and implantable devices. There are many challenges in designing components for such a device, however, the analog front-end circuits located right at the signal source is one of the most critical one to determine the overall performance. This tutorial will focus on low-power CMOS electronics for non-invasive and invasive bio-potential recoding from the central nervous system. Electro-encephalography (EEG) is the most popular method for non-invasive brain imaging but medical grade EEG devices are still bulky and requires frequent professional assistance. However, ambulatory EEG recording is of great interest both for healthcare and life-style applications. We will review the CMOS circuit design techniques to provide high quality EEG data with maximum patient comfort. Similarly, invasive neural recording has been a primary technique used by neurophysiologists to study brain function over many decades. It is only recently that high-density silicon neural probes have become available. The second part of the tutorial will focus on CMOS design methodologies related to such devices.