Design and Fabrication of an Ultra-low Noise Ag-AgCl Electrode

TL;DR

This paper introduces a novel fabrication method for ultra-low noise Ag-AgCl electrodes, achieving high stability and minimal noise, which are crucial for precise biomedical measurements.

Contribution

A new fabrication process for Ag-AgCl electrodes that significantly reduces noise and enhances stability for biomedical applications.

Findings

Achieved differential noise potential of 16 nanovolt RMS at 1 Hz.

Identified offset voltage spectrum and variance as indicators of electrode noise.

Demonstrated high stability and low noise in fabricated electrodes.

Abstract

We have developed a new method for fabrication of ultra-low noise silver-silver chloride (Ag-AgCl) reference electrode with dramatically high stability, useful in biomedical precise measurements. Low noise level and high stability are the most important features when evaluating reference electrode for example when used as a half-cell at electrochemical cells. The noise was measured for bare Ag-AgCl electrode pairs in a saline electrolyte without any junction. The noise spectral density for such measurements increases at low frequencies due to flicker (1/f) noise. Thermal noise from the real part of the electrode impedance is always lower than 1/f noise and is shown as offset voltage in noise spectrum. Electrode noise is highly correlated to its offset voltage. Moreover, the variance of the potential difference in our measurements is correlated to the noise level of electrodes. In this paper, offset voltage spectrum and the variance of data while doing measurements are proposed for identification of noise in our electrodes. The results presented suggest a new process for fabrication of electrode pairs with differential noise potential of 16 nanovolt root mean square at frequency of 1 Hz.