engleski

Analysis of Corkscrew Electrode Failure Origins

In this paper we have investigated the causes of Corkscrew EEG electrode failure appearance. The faulty electrodes were supplied by the manufacturer in order to investigate the mechanical or physical causes of failure. It is shown that the failure is the result of mechanical defectsor electromigration processon the steel-solder junction at the tip of the electrode. Mechanical stress, manifested through the physical separation of the steel tip from the solder, causes the decrease of overall current density through the tip while the electromigration is the source of high level of noise in the output signal. In order to investigate failures caused by mechanical stress, the tip of the electrode has been recorded using optical stereomicroscope with magnification of 50x to 230x. Recorded images show the existence of cracks between the steel and solder as well as tearing of the thin wires caused by repetitive tip displacement during everyday use. Electromigration influence on the output signal is detected and analyzedusing time-frequency representation of the signal(spectrogram). Using the K-means based algorithm for denoising and Hoshen-Kopelman (HK) method for component detection, we have shown the existence of failure in the time-frequency signal representation by comparing the lengths of the useful information contents of faulty and reference electrodes’ denoised spectrograms.

EEG; Corkscrew electrode; failure; electromigration; Hoshen-Kopelman; K-means; Spectrogram

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