Eui Don Han

Passive contact guidance of fibroblast cells using consecutive trapezoidal micropatterns

Cell migration on micropatterned substrates is a complex process regulated by cell-substrate interactions. This paper presents a passive method for guiding the migration of NIH 3T3 fibroblasts using consecutive trapezoidal micropatterns, made of a biocompatible photopolymer (OrmoComp®), to provide tapered micro-features on the cells. The cell migration paths measured from our platforms quantitatively address the dependence of the migratory behavior of the cells on the tapered micro-features. Most of the cells on the micropatterns have moved in a converging direction rather than in a diverging one; migration speed on the micropatterns has been noticeably faster than that on flat substrates.

Blood Separation Device Based on Microstructures in Microchannels

In this paper, plasma extraction device based on microstructure in microchannels was presented. Also, we analyzed the blood flow according to blood transportation methods for application of blood separation. The microchannels for blood separation were designed blood cell channel, plasma channel and separation channel. The separation channel to separate the plasma was performed the role of micro filter based. The overall shape of microchannels was designed to spiral shape. Spiral microchannel was designed for prevention of blood cell cross-over from blood cell channel to plasma channel and clogging. Microchannels were made of polymethylsiloxane which is optically transparent. Blood sample was diluted with phosphate buffered saline at the ratio of 1:3. Characteristics of blood cell flow through microchannel, also, were observed with respect to two different blood transportation methods including pushing by syringe pump and pulling by vacuum pump. As results, blood flow driven by vacuum pump (pulling) was slower than that driven by syringe pump (pushing), but almost no blood cell was crossover from blood cell channel to plasma channel in pulling transportation method.

Fabrication of high-aspect-ratio aluminum oxyhydroxide nanopillars for anti-reflection surfaces

This study presents the anti-reflection characteristics of high-aspect-ratio aluminum oxyhydroxide nanopillars prepared by the hydrothermal synthesis method from a nanoporous alumina substrate. Three different alumina-based nanostructures, including nanolens, short-nanopillar, and long-nanopillar were prepared, and the center-to-center distance of the nanostructures was fixed as 380 ± 50 nm. The diameter of the nanopillars was 140 ± 30 nm, and the aspect ratios of the short and long nanopillars were 1.5 and 4.0, respectively. From visual investigation, the surfaces of fabricated aluminum oxyhydroxide nanopillars appear black, although they did not have any black color. The anti-reflection characteristics of high aspect ratio aluminum oxyhydroxide nanopillars were compared with those of an alumina nanolens array. According to the experimental results, the high-aspect-ratio aluminum oxyhydroxide nanopillar array demonstrated remarkable anti-reflection characteristics, with 0.18% reflectance at an incident angle of 15°.