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Optimizing Laplacian estimation for the finite dimensions model of a commercial tripolar concentric ring electrode and comparing it to the optimal electrode configuration via finite element method modeling
* 1 , 2 , 2 , 2
1  Diné College
2  Centro de Investigación e Innovación en Bioingeniería (CI2B) Universitat Politècnica de València (UPV) Valencia, Spain
Academic Editor: Francisco Falcone (registering DOI)

Concentric ring electrodes are showing promise in noninvasive electrophysiological measurement but electrode design criteria are rarely detailed and justified. Toward that goal, the use of realistic finite dimensions model of concentric ring electrode in this study was two-fold. First, it was used to optimize the surface Laplacian estimate coefficients for tripolar electrode configuration with dimensions approximating the commercially available t-Lead electrodes manufactured by CREmedical. Two differential signals representing differences between potentials on the middle ring and on the central disc as well as on the outer ring and on the central disc are combined linearly into the Laplacian estimate with aforementioned coefficients representing the weights of differential signals. Second, it was used to directly compare said tripolar configuration to the optimal tripolar concentric ring electrode configuration of the same size via finite element method modeling based computation of relative and normalized maximum errors of Laplacian estimation. Obtained results suggest the optimal coefficients for Laplacian estimate based on the approximation of the t-Lead dimensions to be (6, -1) as opposed to (16, -1) widely used with this electrode in the past. Moreover, compared to the optimal tripolar concentric ring electrode configuration, commercially available tripolar electrode of the same size leads to a median increase in Laplacian estimation errors of over 4 times. These results are consistent with previously obtained results based on both negligible and finite dimensions models but further investigation on real life phantom and human data via physical concentric ring electrode prototypes is needed for conclusive proof.

Keywords: electrophysiology; measurement; wearable sensors; noninvasive; concentric ring electrodes; Laplacian; estimation; optimization; finite element method; modeling