Shifting Focus in EEG Research: Prioritizing Signal-to-Noise Ratio Over Low Impedance

In the world of EEG research, a paradigm shift is underway. The conventional
wisdom of prioritizing low impedance in pursuit of high-quality electrophysiological
recordings is being reevaluated. Its time to redirect our attention toward a more
meaningful metric: the signal-to-noise ratio (SNR).

For decades, the pursuit of low skin-electrode impedance held great importance.
This belief stemmed from an era when amplifiers drew significant input currents and
data points were meticulously plotted on graph paper. Back then, obtaining a quality
signal required the use of silver-silver chloride electrodes, electrolytes, and even skin
abrasion. The gold standard for EEG recording was set at an impedance of less than 5KΩ.

When coupled with sophisticated signal processing techniques researchers can now attain Impeccable recordings even when dealing with low amplitude signals, such as EEG.

Recordings with low amplitude signals

Fast forward to today, and modern amplifiers have revolutionized the landscape.
These advanced devices boast high input impedance, rendering the concern for
significant current draw obsolete. This breakthrough enables stable recordings to be
achieved with substantially higher skin-electrode impedance values. When coupled
with sophisticated signal processing techniques, researchers can now attain
impeccable recordings even when dealing with low amplitude signals, such as EEG.
This progress is particularly evident with the advent of cutting-edge technologies like
dry printed electrodes.

As we embark on this new frontier, its imperative to reassess our assumptions and
embrace the latest advancements in EEG recording. Rather than fixating on the
impedance metrics of the past, our focus should shift towards optimizing the signal-
to-noise ratio. By doing so, we open up doors to unprecedented insights and

For those eager to delve deeper into this transformation, there are several
compelling studies in the literature that shed light on the subject:

1. Printed soft skin electrodes for seamless bio-impedance measurements: our
latest paper on this topic
2. Investigation into the origin of the noise of surface electrodes: This study
uncovers the origins of electrode noise, providing invaluable insights into the
nuances of recording quality.
3. Scalp electrode impedance, infection risk, and EEG data quality: Delving into
the correlation between electrode impedance, infection risk, and data quality,
this research offers a comprehensive perspective on the trade-offs involved.
4. Signal Quality in Dry Electrode EEG and the Relation to Skin-electrode
Contact Impedance Magnitude: Exploring the connection between signal
quality in EEG recordings with dry electrodes and the magnitude of skin-
electrode contact impedance, this study demonstrates the practical
implications of embracing new electrode technologies.