Changes of the Electrode Surface Roughness Induced by High-Voltage Electric Pulses as Revealed by AFM

The changes of the surface topography of stainless-steel and aluminium electrodes occurring due to the action of electric pulses which are utilized for cell electroporation, have been studied by using atomic force microscopy. The surfaces of the polished stainless-steel electrodes were smooth - the average roughness was 13-17 nm and the total roughness 140-180 nm. The total roughness of the aluminium electrodes was about 320 nm. After the treatment of the chambers filled with 154 mM NaCl solution by a series of short (20-40 μs), high-voltage (4 kV) pulses with the total dissolution charge of 0.20-0.26 A s/$cm^{2}$, the roughness of the surface of the electrodes has increased, depending on the total amount of the electric charge that has passed through the unit area of the electrode. Up to a two- and threefold increase of the surface roughness of the stainless-steel and aluminium anodes respectively was observed due to the dissolution of the anode material. Therefore, the use of high-voltage electric pulses leads to the increase of the inhomogeneity of the electric field at the electrode, which facilitates the occurrence of the electric breakdown of the liquid samples and causes non-equal treatment of each cell

Changes of the Electrode Surface Roughness Induced by High-Voltage Electric Pulses as Revealed by AFM

The changes of the surface topography of stainless-steel and aluminium electrodes occurring due to the action of electric pulses which are utilized for cell electroporation, have been studied by using atomic force microscopy. The surfaces of the polished stainless-steel electrodes were smooth - the average roughness was 13-17 nm and the total roughness 140-180 nm. The total roughness of the aluminium electrodes was about 320 nm. After the treatment of the chambers filled with 154 mM NaCl solution by a series of short (20-40 μs), high-voltage (4 kV) pulses with the total dissolution charge of 0.20-0.26 A s/$cm^{2}$, the roughness of the surface of the electrodes has increased, depending on the total amount of the electric charge that has passed through the unit area of the electrode. Up to a two- and threefold increase of the surface roughness of the stainless-steel and aluminium anodes respectively was observed due to the dissolution of the anode material. Therefore, the use of high-voltage electric pulses leads to the increase of the inhomogeneity of the electric field at the electrode, which facilitates the occurrence of the electric breakdown of the liquid samples and causes non-equal treatment of each cell

Spectroscopic Ellipsometry of Porphyrin Adsorbed in Porous Silicon

Aqueous solution of meso-tetra(4-sulfonatophenyl)porphine was deposited on electrochemically etched n-Si wafers. The morphology of the hybrid systems was investigated by scanning electron microscope and atomic force microscope techniques. The optical response of the hybrid systems was studied by spectroscopic ellipsometry in the range of 1-5 eV. Particular features in adsorption process were revealed for meso-tetra(4-sulfonatophenyl)porphine deposited on variously chemically treated Si substrates. It was found that porphyrin J-aggregates can be intercalated into large pores formed in a bulk n-Si as well as into nanopores of luminescent oxide layer