Electrolyte additives, applied voltage, and wiping speed were investigated to elucidate the optimum conditions for electropolishing of stainless steel(SUS304)using a wiping method with an electrolyte-solution-impregnated felt wiper cathode. Adding a viscosity improver and a surfactant to the electrolyte solution(mixed acid of 98% sulfuric acid and 85% phosphoric acid(1 : 3, v/v))reduced the evolution of pits on the electropolished SUS304 surfaces caused by the wiping method, but it reduced the polishing rate. Conditions of higher applied voltage and lower wiping speed led to an increased polishing rate and decreased pit evolution on the SUS304 surface. Electropolishing by the wiping method using the electrolyte containing the viscosity improver and 8 V of applied voltage and 10 mm s-1 wiping speed produced extremely smooth and high-gloss surfaces. Analysis by glow discharge optical emission spectroscopy revealed that the depth profile of the surface composition had a Cr-rich layer formed on the electropolished SUS304 surface by the wiping method. The pitting potential of SUS304 surface shifted to a more positive value after electropolishing using the wiping method. That value was comparable to that obtained after conventional electropolishing.
Human mesenchymal stem cells were cultured using poly(dimethylsiloxane)substrates with regularly arrayed wrinkle microstructures formed by partially depositing diamond-like carbon thin films. The optimal design pattern for development of more interconnections of cells within a shorter period was found to be square-shaped areas of 50 μm size arranged at the intervals of 50 - 100 μm in a grid-like pattern.