Optofluidic in situ maskless lithography of charge selective nanoporous hydrogel for DNA preconcentration

An optofluidic maskless photopolymerization process was developed for in situ negatively charged nanoporous hydrogel [poly-AMPS (2-acrylamido-2-methyl-1-propanesulfonic acid)] fabrication. The optofluidic maskless lithography system, which combines a high power UV source and digital mirror device, enables fast polymerization of arbitrary shaped hydrogels in a microfluidic device. The poly-AMPS hydrogel structures were positioned near the intersections of two microchannels, and were used as a cation-selective filter for biological sample preconcentration. Preconcentration dynamics as well as the fabricated polymer shape were analyzed in three-dimensions using fluorescein sample and a confocal microscope. Finally, single-stranded DNA preconcentration was demonstrated for polymerase chain reaction-free signal enhancement

Potentiometric Multichannel Cytometer Microchip for High-throughput Microdispersion Analysis

The parallelization of microfluidic cytometry is expected to lead to considerably enhanced throughput enabling point-of-care diagnosis. In this article, the development of a microfluidic potentiometric multichannel cytometer is presented. Parallelized microfluidic channels sharing a fluid path inevitably suffer from interchannel signal crosstalk that results from electrical coupling within the microfluidic channel network. By employing three planar electrodes within a single detection channel, we electrically decoupled each channel unit, thereby enabling parallel analysis by using a single cytometer microchip with multiple microfluidic channels. The triple-electrode configuration is validated by analyzing the size and concentration of polystyrene microbeads (diameters: 1.99, 2.58, 3, and 3.68 μm; concentration range: ∼2 × 10⁵ mL^–1 to ∼1 × 10⁷ mL^–1) and bacterial microdispersion samples (<i>Bacillus subtilis</i>, concentration range: ∼4 × 10⁵ CFU mL^–1 to ∼3 × 10⁶ CFU mL^–1). Crosstalk-free parallelized analysis is then demonstrated using a 16-channel potentiometric cytometer (maximum cross-correlation coefficients |<i>r</i>|: < 0.13 in all channel combinations). A detection throughput of ∼48 000 s^–1 was achieved; the throughout can be easily increased with the degree of parallelism of a single microchip without additional technical complexities. Therefore, this methodology should enable high-throughput and low-cost cytometry

Biomimetic microfingerprints for anti-counterfeiting strategies

An unclonable, fingerprint-mimicking anti-counterfeiting strategy is presented that encrypts polymeric particles with randomly generated silica film wrinkles. The generated wrinkle codes are as highly unique as human fingerprints and are technically irreproducible. Superior to previous physical unclonable functions, codes are tunable on demand and generable on various geometries. Reliable authentication of real-world products that have these microfingerprints is demonstrated using optical decoding methods. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim159621sciescopu

Liquid-capped encoded microcapsules for multiplex assay

Although droplet microfludics is a promising technology for handling a number of liquids of a single type of analyte, it has limitations in handling thousands of different types of analytes for multiplex assay. Here, we present a novel ???liquid-capped encoded microcapsule???, which is applicable to various liquid format assays. Various liquid drops can be graphically encoded and arrayed without repeated dispensing processes, evaporation, and the risk of cross-contamination. Millions of nanoliter-scale liquids are encapsulated within encoded microcapsules and self-assembled in microwells in a single dispensing process. The graphical code on the microcapsule enables identification of randomly assembled microcapsules in each microwell. We conducted various liquid phase assays including enzyme inhibitor screening, virus transduction, and drug-induced apoptosis tests. The results showed that our liquid handling technology can be utilized widely for various solution phase assays

Colour-barcoded magnetic microparticles for multiplexed bioassays

Encoded particles have a demonstrated value for multiplexed high-throughput bioassays such as drug discovery and clinical diagnostics(1,2). In diverse samples, the ability to use a large number of distinct identification codes on assay particles is important to increase throughput(3). Proper handling schemes are also needed to readout these codes on free-floating probe microparticles. Here we create vivid, free-floating structural coloured particles with multi-axis rotational control using a colour-tunable magnetic material and a new printing method(4). Our colour-barcoded magnetic microparticles offer a coding capacity easily into the billions with distinct magnetic handling capabilities including active positioning for code readouts and active stirring for improved reaction kinetics in microscale environments(5). A DNA hybridization assay is done using the colour-barcoded magnetic microparticles to demonstrate multiplexing capabilitiesclos

Programming magnetic anisotropy in polymeric microactuators

Polymeric microcomponents are widely used in microelectro-mechanical systems (MEMS) and lab-on-a-chip devices, but they suffer from the lack of complex motion, effective addressability and precise shape control(1,2). To address these needs, we fabricated polymeric nanocomposite microactuators driven by programmable heterogeneous magnetic anisotropy. Spatially modulated photopatterning(3) was applied in a shape-independent manner to microactuator components by successive confinement of self-assembled magnetic nanoparticles in a fixed polymer matrix. By freely programming the rotational axis of each component, we demonstrate that the polymeric microactuators can undergo predesigned, complex two- and three-dimensional motionclos