Elvis Paćelat

Measurement of electrode–tissue interface characteristics during high current transcranial pulse electrical stimulation

Abstract Strong electrical stimulation pulses are needed for activation of the brain motor area during general anaesthesia in cases with the intact patient’s head mostly because of high skull and scalp impedance. In transcranial electrical stimulation, two types of electrodes with small area are used in order to enable selective neural stimulation: Ag–AgCl cup EEG electrodes and stainless steel corkscrew electrodes. The influence of pulse current stimuli parameters on the characteristics of cup EEG and corkscrew electrodes at high current density was investigated. In contrast to the corkscrew electrodes that showed nearly linear behaviour, the cup electrodes showed non-linear properties, i.e. a significant increase in pulse voltage to current ratio at high current density. The design of a microprocessor-based transcranial stimulator, enabling fast setting of stimulation parameters due to the implemented fast measurement circuits and a multidimensional look-up table is described.

Measurement of myoelectric silent period parameters: evaluation of an automatized algorithm

Electromyography is used in dentistry to assess the relationship of craniomandibular muscle activity, facial morphology and occlusal stability. Myoelectric silent periods are used in clinical diagnostics and treatment follow-up. Rather complicated instrumentation is demanded for silent-period parameter measurement. Supported with appropriate software tools, measurement procedures become less demanding. In this paper, an automated silent-period parameter measurement algorithm is described and validated on signals recorded from jaw-closing muscles. Compared to the measurement results of an expert, the parameter values obtained by the algorithm show a good match in 65% of the evaluated signals.