Using thermoplastic polymers as substrate material is an attractive approach to develop low-cost, disposable microfluidic devices. This study investigates a simple and rapid polymer replication method of fabricating microchannels by a hot roller embossing process. The hot roller embosser used in this study was modified from a commercially available film laminator, and the roller micromold was fabricated by spin coating an SU-8 layer on a flexible copper sheet. A straight microchannel measuring 5 cm long, 200 lm wide, and 41.4 lm deep was used to evaluate the imprinting performance on cyclic olefin copolymer and polyvinylchloride film. This study also investigates the effects of hot roller embossing temperature, rolling speed, and embossing pressure on the microchannel depth and geometry transfer efficiency.

Mass spectrometry (MS) interfacing technology provides the means for incorporating microfluidic processing with post MS analysis. In this study, we propose a simple piezo-ring-on-chip microfluidic device for the controlled spraying of MALDI-MS targets. This device uses a low-cost, commercially-available ring-shaped piezoelectric acoustic atomizer (piezo-ring) directly integrated into a polydimethylsiloxane microfluidic device to spray the sample onto the MS target substrate. The piezo-ring-on-chip microfluidic device's design, fabrication, and actuation, and its pulsatile pumping effects were evaluated. The spraying performance was examined by depositing organic matrix samples onto the MS target substrate by using both an automatic linear motion motor, and manual deposition. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) was performed to analyze the peptide samples on the MALDI target substrates. Using our technique, model peptides with 10 M concentration can be successfully detected. The results also indicate that the piezo-ring-on-chip approach forms finer matrix crystals and presents better MS signal uniformity with little sample consumption compared to the conventional pipetting method.

SUMMARYMicrofluidic devices using droplets make it possible to perform high-throughput screening of single-cell samples through encapsulating cells into droplets. In conventional encapsulation methods, devices have T-junction and flow-focusing geometry for droplet generation. Using those techniques, it is difficult to achieve uniform distribution of cells, or to place single cells in droplets. Moreover, in screening samples, it is necessary to have a mechanism to hold the droplets at one place for a long time. However, it is somewhat difficult to add such a function to conventional devices. Thus, we propose a new single-cell encapsulation method using triangular microwells. In this approach, each single cell is isolated, encapsulated, and held in one place by triangular microwells. This approach has the benefit that the droplet size can be regulated by the size of the microwells. In addition, optimization of encapsulation is easier than in conventional methods because the flow rate of the oil phase does not affect the encapsulation. C⃝ 2016 Wiley Periodicals, Inc. Electron Comm Jpn, 99(2): 55-63, 2016; Published online in Wiley Online Library (wileyonlinelibrary.com).

We use a simple, low-cost electroless etching and deposition process to create a localized silver nanoparticle decorated surface porous silicon (LocAg-PS). The LocAg-PS surface exhibits self-align and sample condensation capabilities for SERS analysis.