Naslov
Neurophysiologic electrostimulation effect and measurement of electromagnetic field having arbitrary waveform

Autori
Živković, Zlatko

Vrsta, podvrsta i kategorija rada
Ocjenski radovi, doktorska disertacija

Fakultet
FESB Split

Mjesto
Split

Datum
26.08

Godina
2014

Stranica
265

Mentor
Šarolić, Antonio

Ključne riječi
biological effects and exposure assessment to EMF; broadband electric field probe; neurophysiologic arbitrary waveform electrostimulation; simulation and measurement of nerve response; SENN nerve model; earthworm (lat. Lumbricus terrestris); intermediate frequency range; envelope quadrature detection; twin field detector

Sažetak
The nerve tissue excitation, which arises as a consequence of induced currents (when exposed to external EMFs) or direct contact with electrical sources, will depend on the stimulus current waveform. Consequently, the proper human exposure assessment requires exact quantification of nerve response to complex- waveform stimuli as well as accurate measurement of relevant waveform parameters of incident complex-waveform EMFs. Within this dissertation the detailed analysis of nerve response to complex-waveform stimulus currents has been performed. The analysis was based on two-dimensional SENN model of single myelinated axon. The simulation results were also confirmed by experimental investigation which was based on transcutaneous stimulation of unmyelinated earthworm’s (lat. Lumbricus terrestris) medial axon. The experimental analysis was based on the custom-made current source capable of handling repetitive stimuli with arbitrary waveform in a broad frequency and amplitude range. The nerve response analysis involved wide variety of stimulus waveforms, including long-duration repetitive square pulses with arbitrary phase/pause durations (i.e. duty cycle) as well as general class of amplitude and pulse modulated fields with arbitrary carrier frequency and arbitrary envelope characteristics. Based on performed simulation and experimental analysis, the exact mathematical expressions that directly relate the excitability potential of certain stimulus waveforms to the continuous sinusoidal stimulus have been derived. The derived expressions that characterize nerve response to specific stimulus waveforms are based on temporal parameters of stimuli rather than frequency spectrum analysis and can be directly included in relevant international exposure assessment guidelines. To achieve more reliable exposure assessment to the complex waveform EMFs in the intermediate frequency range up to 10 MHz, EMF meters should adequately measure the temporal parameters described in the previous analysis. Consequently, the innovative broadband electric field probe, based on envelope quadrature detection in the small signal regime, has been proposed and realized. The proposed probe, based on the innovative twin field detector, can detect true RMS and peak value simultaneously, and also enables relevant temporal parameter characterization of the incident electric field. Moreover, this probe architecture has solved the inherent error issue that is related to common broadband probes with standard diode detection when measuring non-sinusoidal or modulated signals. As a result, the measured values can be directly incorporated in previously derived mathematical expressions for human exposure assessment in the intermediate frequency range, based on the neurophysiological stimulation effect.

Izvorni jezik
Engleski

Znanstvena područja
Elektrotehnika

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