Flexible Neural Probe Modelling for Optimal Microelectrode-Tissue Interaction

Miniaturized electrodes have become the state-of-the-art devices of treating neurological disorders, such as epilepsy and Parkinson's Disease. However, their use entails an increased impedance, and the reduction in Signal-to-Noise Ratio (SNR). The selection of the microelectrodes' materials and the design of the analogue front end (AFE) are therefore essential to mitigate these issues. In this paper, we present an analysis of 3 different electrode materials: gold, iridium and platinum, through COMSOL Multiphysics® and SPICE simulations, to evaluate the optimum configuration for neural probe microelectrodes. In addition, we evaluate signal performance using active filtering in the AFE. Our results demonstrate that gold presents the lowest impedance across different surface areas
${(439.2\Omega\pm 5{\%})}$
and the highest gain, for both active and passive configurations of the AFE (-65dB and -85dB respectively), with a higher gain and lower noise obtained on active filtering for platinum and iridium electrodes. These results demonstrate that the use of active filtering might be considered as a way to further enhance SNR across commonly used microelectrode materials.