20.500.12556/RUL-189752 Raziskava vzrokov za upad električnega toka med dovajanjem monopolarnih elektroporacijskih pulzov Investigation into the causes of a drop in electric current during the delivery of monopolar electroporation pulses Pri elektroporaciji z monopolarnimi pulzi električni tok med zaporednimi pulzi pogosto upade, pri napetostno enakovrednih bipolarnih pulzih pa ne. V delu eksperimentalno ločimo možne vzroke: segrevanje, mehurčke iz elektrolize, elektroosmozo in spremembe pH. Poskuse izvedemo v agaroznem fantomu brez celic, zato elektroporacije ni. Uporabimo tiskano elektrodo z radialnima poloma in vlake 500 pulzov pri 250 in 500~V. Bipolarne pulze primerjamo z monopolarnimi pri odprtem prehodu v središču elektrode, skozi katerega plin uide in pri zaprtem prehodu, ki plin zadrži. Pokritost elektrode z mehurčki določimo iz videoposnetkov in jo vnesemo v osnosimetrični model v programu COMSOL s segrevanjem in od temperature odvisno prevodnostjo. Prevodnost upade le, ko mehurčki ostanejo na elektrodi. Pri 500~V z zaprtimi prehodi izrazito upade pri treh od petih zagonov, z odprtimi pa pri nobenem. Prevodnost pri monopolarnih pulzih z odprtimi prehodi narašča hitreje kot pri bipolarnih, čeprav je dovedena energija približno enaka. Razlika narašča z neto nabojem, kar nakazuje na spremembe pH ob elektrodah. Model z izmerjeno pokritostjo zajame razlike med zagoni, tega naraščanja pa ne. Pri monopolarnih pulzih torej delujeta dva nasprotna mehanizma: mehurčki prevodnost znižujejo, prispevek, vezan na neto naboj, pa jo zvišuje. Tok je zato odvisen predvsem od tega, ali plin lahko uide z elektrode. With monopolar electroporation pulses, the electric current often decreases over successive pulses, but not with voltage-equivalent bipolar pulses. In this work, we experimentally separate the possible causes: heating, bubbles from electrolysis, electroosmosis and pH changes. Experiments are done in a cell-free agarose phantom, so there is no electroporation. We use a printed electrode with two radial poles and trains of 500 pulses at 250 and 500~V. Bipolar pulses are compared with monopolar pulses with an open via in the electrode center, through which gas escapes and a closed one, which retains it. The bubble coverage of the electrode is determined from video recordings and used as input to an axisymmetric COMSOL model with heating and temperature-dependent conductivity. Conductance decreases only when bubbles remain on the electrode. At 500~V it drops markedly in three of five runs with closed vias and in none with open vias. The conductance with monopolar pulses and open vias increases faster than with bipolar pulses, although the energy is about the same. The difference grows with the net charge, which points to pH changes near the electrodes. The model with measured coverage captures the differences between runs, but not this increase. Two opposing mechanisms thus act with monopolar pulses: bubbles decrease the conductance, while a contribution linked to the net charge increases it. The current therefore depends mainly on whether gas can escape from the electrode. elektroporacija monopolarni pulzi mehurčki elektroliza elektroosmoza numerično modeliranje COMSOL agarozni fantom electroporation monopolar pulses bubbles electrolysis electroosmosis numerical modeling COMSOL agarose phantom true false false Slovenski jezik Angleški jezik Magistrsko delo/naloga 2026-10-14 14:15:09 2026-10-14 14:15:20 2026-10-15 04:13:26 0000-00-00 00:00:00 2026 0 0 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 1970-01-01 63504 Hrovat_Matej_-_Raziskava_vzrokov_za_upad_elektricnega_toka_med_dovajanjem_monopolarnih_elektropo.pdf Hrovat_Matej_-_Raziskava_vzrokov_za_upad_elektricnega_toka_med_dovajanjem_monopolarnih_elektropo.pdf 1 BD30B666C97C105593977883E29E56F9 ff6a21e8af9871f15cbdc82536c4d60e0f05103da6584546fc6ed6d0f359a417 c176b5c0-c7c8-11f1-8bc5-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=250537 Fakulteta za elektrotehniko 0 0 0