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Diabetes mellitus (DM) is a chronic disease affecting nearly 400 million people worldwide. In order to manage the disease, patients need to monitor the blood glucose level by puncturing the finger several times a day, which is uncomfortable and inconvenient. We present here a potential non-invasive monitoring method based on the velocity of ultrasonic waves generated in glucose solution by the photoacoustic principal, which can recognize the glucose concentration down to 20mg/dL. In order to apply this method to warm bodies, we carefully designed the experiment and performed measurements from 30 °C to 50 °C to generate a set of calibration curves, which may be used by engineers to build devices. Most importantly, we have theoretically explained the relationship between the compressibility and the glucose concentration. Our results show that the compressibility of solution decreases with the glucose concentration, which clarified the controversy between theory and experiment results in the literature. The derived formula is generally validity, which can be used to nondestructively measure solution concentration for other types of solutions using photoacoustic principle. [ABSTRACT FROM AUTHOR]

In this paper, we present a novel rapid-prototyping process for out-of-cleanroom microfabrication of three-dimensional multilayer microfluidic structures with a 10 µm resolution, referred to as the Direct Projection on Dry-film Photoresist (DP2). A commercially available digital projector is customized to function as a direct mask generation and photo exposure system, while easy-processing photosensitive dry films are used as the microfluidic constructs. Multilayer alignments among maskless-patterned layers are reliably achieved by using a Software Alignment technique with less than 10 µm precision, which eliminates the use of mechanical travelling stage. The bonding between different layers of dry film, simply enabled by a plasma-assisted thermal lamination, offers an easy implementation for suspended multilayer microstructures. Development of a complex microfluidic chip from computer layout can thus be accomplished within an hour in a regular chemical or biological lab environment using this approach. [ABSTRACT FROM AUTHOR]

With the major advances in soft lithography and polymer materials, use of microfluidic devices has attracted tremendous attention recently. A simple and fast micromachining process is highly in demand to prototype such a device efficiently and economically. In this paper, we first reported an out-of-cleanroom printing-based integrated microfabrication process, referred to as the lab-on-a-print(LOP), for rapid-prototyping three-dimensional microfluidics. Using this lab-on-a-printprocess, we demonstrated the potential to accomplish an entire design-to-fabrication cycle within an hour, including about 70 µm resolution of direct-lithography patterning, well-controlled polyimide wet etching, three-dimensional pattern alignment and multilayer wax thermal-fusion packaging. A microfluidic gradient generator was prepared and tested for validation of the lab-on-a-printmicrofabrication process. [ABSTRACT FROM AUTHOR]

An optimization strategy combining computational fluid dynamics (CFD) with multiobjective evolutionary algorithm (MOEA) for dual-impeller design in an aerated tank was proposed to maximize the overall effective gas holdup and minimize the power consumption with six geometrical variables. The nondominated sorting genetic algorithm-II (NSGA-II) was applied to construct a Pareto front from numerous design points with greatly reduced computation. The measurement of local gas holdup and power consumption by dual electric conductivity probe and torque sensor was utilized to verify the CFD model and evaluate the optimal design. The optimal design with a pitched concave blade disk turbine as the lower impeller and a down-pumping pitched blade turbine as the upper impeller exhibited the best gas dispersion performance with efficient energy savings. This approach has the potential to greatly enhance the efficiency of industrial stirred reactors. [ABSTRACT FROM AUTHOR]

In this paper, we introduce a novel microfluidic combinatorial synthesis platform, referred to as Microfluidic Print-to-Synthesis (MPS), for custom high-throughput and automated synthesis of a large number of unique peptides in a microarray format. The MPS method utilizes standard Fmoc chemistry to link amino acids on a polyethylene glycol (PEG)-functionalized microdisc array. The resulting peptide microarrays permit rapid screening for interactions with molecular targets or live cells, with low nonspecific binding. Such combinatorial peptide microarrays can be reliably prepared at a spot size of 200 µm with 1 mm center-tocenter distance, dimensions that require only minimal reagent consumption (less than 30 nL per spot per coupling reaction). The MPS platform has a scalable design for extended multiplexibility, allowing for 12 different building blocks and coupling reagents to be dispensed in one microfluidic cartridge in the current format, and could be further scaled up. As proof of concept for the MPS platform, we designed and constructed a focused tetrapeptide library featuring 2560 synthetic peptide sequences, capped at the N-terminus with 4-[(N'-2-methylphenyl)ureido]phenylacetic acid. We then used live human T lymphocyte Jurkat cells as a probe to screen the peptide microarrays for their interaction with a4ß1 integrin overexpressed and activated on these cells. Unlike the one-bead-one-compound approach that requires subsequent decoding of positive beads, each spot in the MPS array is spatially addressable. Therefore, this platform is an ideal tool for rapid optimization of lead compounds found in nature or discovered from diverse combinatorial libraries, using either biochemical or cell-based assays. [ABSTRACT FROM AUTHOR]

Directional dithering of a laser beam potentially limits the detection accuracy of a laser triangulation displacement probe. A theoretical analysis indicates that the measurement accuracy will linearly decrease as the laser dithering angle increases. To suppress laser dithering, a scheme for reduction of the influence of laser beam directional dithering in a laser triangulation displacement probe, which consists of a collimated red laser, a laser beam pointing control setup, a receiver lens, and a charge-coupled device, is proposed in this paper. The laser beam pointing control setup is inserted into the source laser beam and the measured object and can separate the source laser beam into two symmetrical laser beams. Hence, at the angle at which the source laser beam dithers, the positional averages of the two laser spots are equal and opposite. Moreover, a virtual linear function method is used to maintain a stable average of the positions of the two spots on the imaging side. Experimental results indicate that with laser beam pointing control, the estimated standard deviation of the fitting error decreases from 0.3531mm to 0.0100mm, the repeatability accuracy can be lowered from ±7mm to ±5 μm, and the nonlinear error can be reduced from ±6% FS (full scale) to ±0.16% FS. [ABSTRACT FROM AUTHOR]