Characterization of liquid-core/liquid-cladding optical waveguides of a sodium chloride solution/water system by computational fluid dynamics.

A stable liquid/liquid optical waveguide (LLW) was formed using a sheath flow, where a 15% sodium chloride (NaCl) solution functioned as the core solution and water functioned as the cladding solution (15% NaCl/water LLW). The LLW was at least 200 mm in length. The concentration distributions of the liquid core and liquid cladding solutions in the LLW system were predicted by computational fluid dynamics (CFD) to validate the characteristics of the waveguide.

Viscosity and Wetting Property of Water Confined in Extended Nanospace Simultaneously Measured from Highly-Pressurized Meniscus Motion.

Understanding fluid and interfacial properties in extended nanospace (10-1000 nm) is important for recent advances of nanofluidics. We studied properties of water confined in fused-silica nanochannels of 50-1500 nm sizes with two types of cross-section: (1) square channel of nanoscale width and depth, and (2) plate channel of microscale width and nanoscale depth. Viscosity and wetting property were simultaneously measured from capillary filling controlled by megapascal external pressure.

Shape of the liquid-liquid interface in micro counter-current flows.

We investigated the shape of the liquid-liquid interface in micro counter-current flows formed within microchannels. The pressure balance at the interface was calculated based on the interface geometry. Although the shape should be an arc under laminar flow, a large deformation near the center of the microchannel was observed.

Microchip-based plasma separation from whole blood via axial migration of blood cells.

Highly efficient cell-free plasma separation from 200 µL of human whole blood was realized via axial migration of blood cells and cross-flow filtration in a microchip. Although various analyses of small volumes of blood have been reported, a large volume of blood is necessary for obtaining blood cells and plasma for the conventional plasma separation technique of centrifugation. A highly efficient plasma separation method using small volumes of blood without hemolysis is an important issue.

Development of a measurement technique for ion distribution in an extended nanochannel by super-resolution-laser-induced fluorescence.

Ion behavior confined in extended nanospace (10(1)-10(3) nm) is important for nanofluidics and nanochemistry with dominant surface effects. In this paper, we developed a new measurement technique of ion distribution in the nanochannel by super-resolution-laser-induced fluorescence. Stimulated emission depletion microscopy was used to achieve a spatial resolution of 87 nm higher than the diffraction limit.

Establishment of a confluent cardiomyocyte culture in a cylindrical microchannel.

We established a confluent cardiomyocyte culture method using an 800-µm diameter cylindrical microchannel in this report. This was realized by introducing cardiomyocytes 2 times before and after turning over a microchip. The optimum condition was starting the flowing medium 2.

Basic structure and cell culture condition of a bioartificial renal tubule on chip towards a cell-based separation microdevice.

Various separation processes have been integrated in microfluidics, such as capillary electrophoresis and chromatography, on a microchip. However, it is extremely difficult to separate a complicated biological system by conventional methods. Here, we report on a feasible structure and the culture condition of human renal proximal tubule epithelial cells (RPTECs), with the aim to construct a bioartificial renal tubule on a chip.

Experimental investigation of droplet acceleration and collision in the gas phase in a microchannel.

We developed a novel microfluidic system, termed a micro-droplet collider, by utilizing the spatial-temporal localized liquid energy to realize chemical processes, which achieved rapid mixing between droplets having a large volume ratio by collision. In this paper, in order to clarify the characteristics of the micro-droplet collider, dynamics of droplet acceleration, stationary motion and collision in the gas phase in a microchannel were experimentally investigated with visualized images using a microscope equipped with a high-speed camera. The maximum velocity of 450 mm s(-1) and acceleration of 1500 m s(-2) of a 1.

Extended-nano fluidic systems for analytical and chemical technologies.

Recently, integrated chemical systems have been further downscaled to the 10(1)-10(3) nm scale, which we call extended-nano space. The extended-nano space is a transient space from single molecules to bulk condensed phase, and fluidics and chemistry have not been explored. One of the reasons is the lack of research tools for the extended-nano space, because the space locates the gap between the conventional nanotechnology (10(0)-10(1) nm) and microtechnology (>1 microm).

Culture and leukocyte adhesion assay of human arterial endothelial cells in a glass microchip.

Cells are frequently exploited as processing components for integrated chemical systems, such as biochemical reactors and bioassay systems. By culturing vascular endothelial cells (ECs) in integrated chemical devices, vascular models have also been fabricated. Here, we utilized a thermally fused-glass microchip which is chemically and physically stable and favorable for optical detections, and cultured human arterial ECs (HAECs) in it.

Flow velocity profile of micro counter-current flows.

Flow velocity profiles of micro counter-current flow of aqueous and butylacetate phases in a microchannel having a width of 100 microm were measured by micro particle image velocimetry. In order to analyze the hydrodynamic characteristics of the counter-current flow, we derived a simple analytical model for the velocity profile. When flow rates of the aqueous and organic phases were 0.

Interaction between liposomes and RBC in microvessels in vivo.

Liposomes are phospholipid vesicles that can serve as carriers of biologically active agents in vitro and in vivo. Here, we describe the movement of liposomes suspended with blood flowing in capillaries. Liposomes were coated with a polymer to extend their lifespan in rat mesenteric blood vessels and detected by fluorescent staining.

Measurement of red cell velocity in microvessels using particle image velocimetry (PIV).

A new technique using particle image velocimetry (PIV) has been developed to evaluate the detailed velocity profiles of red cells flowing in microvessels. The microcirculation in rat mesentery was directly observed using high-speed videomicroscopy, and the images of red cells flowing in the mesenteric arterioles were recorded simultaneously with the arterial blood pressure. Based on the high-speed videomicroscopic images obtained, velocity vectors in single or branched arterioles were evaluated to obtain velocity profiles across the cross-section of arterioles.

Measurement of a velocity field in microvessels using a high resolution PIV technique.

Because endothelial cells are subject to flow shear stress, it is important to determine the velocity distribution in microvessels during studies of the mechanical interactions between the blood and the endothelium. Particle image velocimetry (PIV) is a quantitative method for measuring velocity fields instantaneously in experimental fluid mechanics. The authors have developed a high-resolution PIV technique that improves the dynamic flow range, spatial resolution, and measurement accuracy.

In vivo PIV measurement of red blood cell velocity field in microvessels considering mesentery motion.

As endothelial cells are subject to flow shear stress, it is important to determine the detailed velocity distribution in microvessels in the study of mechanical interactions between blood and endothelium. Recently, particle image velocimetry (PIV) has been proposed as a quantitative method of measuring velocity fields instantaneously in experimental fluid mechanics. The authors have developed a highly accurate PIV technique with improved dynamic range.