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Polymer microchannel chips (dimension of the channel, 20 µm (depth) × 100 µm (width)) integrated with dual microband electrodes were fabricated by an imprinting method, and their characteristic electrochemical responses were elucidated in detail. A silicon micromachined template fabricated by photolithography and dry etching techniques was used for imprinting. An aqueous solution of a ferrocene derivative was brought into the microchannel by pressure-driven flow, and the electrode responses were studied on the basis of voltammetry and chronoamperometry. A linear sweep voltammetry of 1-hydroxyethylferrocene (FeCp-0H) in water demonstrated that the electrode responses in the microchannel chip were best characterized by one-dimensional diffusion along the channel length, reflecting the structural dimension of the channel. In generation-collection mode experiments, furthermore, a collection efficiency as high as ∼90% was attained in the microchannel owing to both restricted space and characteristics of solution flow in the channel. It was confirmed that diffusion and solution flow made molecular transport very efficient in the microchannel. The experimental results were also compared with those predicted by computer simulations. [ABSTRACT FROM AUTHOR]

Applies the solvation dynamics measurements to an ion-exchange resin using Nile Blue A (NB) as a fluorescence probe. Fluorescence lifetime of NB in the resin; Roles of 'bound water' molecules on the water structures; Effects of the counterion of the ion-exchange group on the solvation processes.

Features the development of a laser-trapping microspectroscopy system combined with a fluid manifold for the manipulation and analysis of `single' microparticles. Microparticles introduced to a flow cell set on a microscope stage; Flow rate and particle size dependencies of the trapped microparticle; Adsorption rate of Rhodamine B.

Studies the fluorescence dynamics of Rhodamine B (RhB) and excitation energy transfer from RhB to Malachite Green (MG) in cation-exchange resin particles. Suggestion of a strong biding of the dye to the ion-exchange group of the resin; Use of fractal dimension analysis to determine the apparent structural dimension.

An external reflection (ER) spectrometric device was developed to directly measure adsorbates at the supercritical carbon dioxide (SC-CO2)-water interface. The aggregation of diprotonated species of 5,10,15,20-tetraphenyl-21H,23H-porphinetetrasulfonic acid (H4tpps2-) at the positively charged SC-CO2-water interface, prepared by adsorption by the cetyltrimethylammonium ion (CTA+), was studied using this device. Orientations of the H4tpps2-) monomers and J-aggregates at the SC-CO2-water interface were assessed using s- and p-polarized external reflection (ER) spectra. It appeared that the porphyrin plane of the H4tpps2-) monomer was nearly parallel to the SC-CO2-water interface, and that the long axis of the rod-like H4tpps2-) J-aggregate was also nearly parallel to the interface. Dependence of the ER spectra on CTA+ concentration and CO2 pressure were investigated, and the interfacial CTA+ concentration was found to cause changes in the interfacial H4tpps2-) species present. Increasing the CO2 pressure changed the interfacial species from the H4tpps2-) monomer to the H4tpps2-) J-aggregate because the interfacial CTA+ concentration increased as the pressure increased. This suggests that the interfacial chemical species can be changed by controlling the pressure and temperature of the SC-CO2. This is the first report of direct measurements of the chemical species at the SC-CO2-water interface, as far as we know. [ABSTRACT FROM AUTHOR]

Examines the fabrication of nanometer-sized channels on fused-silica substrates by fast atom beam etching and hydrofluoric acid bonding methods. Demonstration of a liquid introduction method using capillary action; Analysis of liquid velocity by surface energy and macroscale hydrodynamics; Measurement of rhodamine and sulforhodamine.

Background: Gel-type autologous chondrocyte (Chondron™) implantations have been used for several years without using periosteum or membrane. This study involves evaluations of the clinical results of Chondron™ at many clinical centers at various time points during the postoperative patient follow-up. Methods: Data from 98 patients with articular cartilage injury of the knee joint and who underwent Chondron™ implantation at ten Korean hospitals between January 2005 and November 2008, were included and were divided into two groups based on the patient follow-up period, i.e. 13~24-month follow-up and greater than 25-month follow-up. The telephone Knee Society Score obtained during telephone interviews with patients, was used as the evaluation tool. Results: On the tKSS-A (telephone Knee Society Score-A), the score improved from 43.52 ± 20.20 to 89.71 ± 13.69 (P < 0.05), and on the tKSS-B (telephone Knee Society Score-B), the score improved from 50.66 ± 20.05 to 89.38 ± 15.76 (P < 0.05). The total improvement was from 94.18 ± 31.43 to 179.10 ± 24.69 (P < 0.05). Conclusion: Gel-type autologous chondrocyte implantation for chondral knee defects appears to be a safe and effective method for both decreasing pain and improving knee function. [ABSTRACT FROM AUTHOR]

By using characteristics of titania nanoparticles, a patterning and tuning method of microchannel surface wettability was developed for microfluid control. Titania modification of a microchannel provided a nanometer-sized surface roughness and the subsequent hydrophobic treatment made the surface superhydrophobic. Photocatalytic decomposition of the coated hydrophobic molecules was used to pattern the surface wettability which was tuned in the range from superhydrophobic to superhydrophilic under controlled photoirradiation. Four-step wettability-based Laplace valves working as passive stop valves (6.8–12.5 kPa pressure barrier) were prepared by using the patterned and tuned surface. As a demonstration, a batch operation system consisting of two sub-nL dispensers and a reaction chamber was constructed. Fundamental liquid manipulations required for the batch operation were successfully conducted, including liquid measurement (390 and 770 pL), transportation, injection into the chamber, and retention in the chamber. To verify the quantitative operation, the system was applied to a fluorescence quenching experiment as an example of volumetric analyses. The present method provides flexible patterning in a wide range of tuned wettability surfaces in microchannels even after channel fabrication and it can be applied to various two- or multi-phase microfluidic systems. [ABSTRACT FROM AUTHOR]