Toshifumi Asano

Proposal of a new microreactor for vertical chemical operation

The authors proposed and fabricated a new microreactor stack which would be able to achieve a vertical fluid flow operation for the environment analysis, postgenome analysis, gene diagnosis, and screening of useful materials for medicine manufacture. This reactor is characterized as a simple structure with new aspects of the vertical fluid transportation using a proposed fluid filter with array of micro-through-bores. The deep x-ray lithography process using synchrotron radiation was used for the fabrication of the fluid filter. The feasibility of vertical liquid transportation was investigated using computational fluid dynamics analysis. It is indicated that the vertical liquid transportation is possible using the proposed fluid filter, and high efficiency mixing of liquid was also expected during transportation through the fluid filter. It was confirmed that the fluid flow velocity through the filter can be controlled by varying the load pressure around several kilopascals. A rapid enzyme reaction was s...

Novel Characteristics of Multifunctional Fluid Filters Fabricated by High-Energy Synchrotron Radiation Lithography

A new method using multifunctional fluid filters with through-capillary arrays for high throughput and large-scale integrated microfluidics is proposed. The method utilizes a liquids surface tension and fluid flows perpendicular to a substrate using a fluid filter. Utilizing this method, we can minimize the space consumption of microchannels, and enhance the flexibility of channel design, because these are not extant on the surface of substrates as in traditional microfluidics, but are through-capillary arrays passing through the substrates. In addition, the passive multifunctional characteristics of the fluid filter are favorable for the integration of microfluidics. Therefore, the integration number can be increased from the previous order of hundreds to thousands or more. We conducted a computational fluid dynamics (CFD) analysis to examine the feasibility of vertical fluid flow operation; the multifunctionality of the fluid filter as a microvalve, a microchannel and a micromixer was estimated. The fabrication of the fluid filter by deep X-ray lithography and the vertical fluid flow operation were successfully conducted and the high-throughput properties of the vertical fluid flow were demonstrated.

A New Micro-Chemical Reactor Using Fluid Filters for Vertical Fluid Flow Operation

We proposed and fabricated a new chemical reactor with a vertical fluid flow operation for the environment analysis, post-genome analysis, gene diagnosis, and screening of useful materials for medicine manufacture. This reactor is characterized as a simple structure with new aspects of the vertical fluid transportation induced using a fluid filter with micro-through bores. The deep X-ray lithography process using synchrotron radiation was used for the fabrication of such a fluid filter. Computational fluid dynamics (CFD) simulation results revealed that fluid can be sustained on the surface of the fluid filter and easily transported by pneumatic operation. It was confirmed that the fluid flow velocity through the filter can be controlled by varying the loaded pressure around several kPa. It was demonstrated that the proposed chemical reactor has a good vertical fluid flow operation performance.

Immunoassay Using Microfluid Filters Constructed by Deep X-Ray Lithography

Microfluid filters were fabricated, which possessed 2,100 cylindrical through-bores (φ40 μm) in 200 μm-thickness polymethylmethacrylate (PMMA) sheets (φ3 mm), by deep X-ray lithography using synchrotron radiation. To evaluate the microfluid filters as a device for an immunoassay, we bound the goat anti-mouse immunogloblin G (IgG) antibody to the surface of the filters, and set the filters between reaction vessels stacked vertically in a microreactor. An enzyme-linked immunosorbent assay (ELISA) of mouse IgG using the goat anti-mouse IgG/horseradish-peroxidase (HRP) conjugate indicated that mouse IgG could be quantitatively detected in the range of 0–100 ng/ml, demonstrating the applicability of vertical microfluidic operation to the immunoassay.

Organelle Optogenetics: Direct Manipulation of Intracellular Ca2+ Dynamics by Light

As one of the ubiquitous second messengers, the intracellular Ca2+, has been revealed to be a pivotal regulator of various cellular functions. Two major sources are involved in the initiation of Ca2+-dependent signals: influx from the extracellular space and release from the intracellular Ca2+ stores such as the endoplasmic/sarcoplasmic reticulum (ER/SR). To manipulate the Ca2+ release from the stores under high spatiotemporal precision, we established a new method termed “organelle optogenetics.” That is, one of the light-sensitive cation channels (channelrhodopsin-green receiver, ChRGR), which is Ca2+-permeable, was specifically targeted to the ER/SR. The expression specificity as well as the functional operation of the ER/SR-targeted ChRGR (ChRGRER) was evaluated using mouse skeletal myoblasts (C2C12): (1) the ChRGRER co-localized with the ER-marker KDEL; (2) no membrane current was generated by light under whole-cell clamp of cells expressing ChRGRER; (3) an increase of fluorometric Ca2+ was evoked by the optical stimulation (OS) in the cells expressing ChRGRER in a manner independent on the extracellular Ca2+ concentration ([Ca2+]o); (4) the ΔF/F0 was sensitive to the inhibitor of sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) and (5) the store-operated Ca2+ entry (SOCE) was induced by the OS in the ChRGRER-expressing cells. Our organelle optogenetics effectively manipulated the ER/SR to release Ca2+ from intracellular stores. The use of organelle optogenetics would reveal the neuroscientific significance of intracellular Ca2+ dynamics under spatiotemporal precision.

A new micro chemical reactor stack for vertical fluid flow operation

The advantages of micro reactors for the chemical synthesis, discovery and catalyst development of substances are generally recognized today. The significant properties of microreactors such as low energy consumption, high selectivity, yields, short response times and pathways for the chemical reactions will lead to the ecological and economical process engineering. Such properties result from the large surface area to volume ratios, high gradients of temperature, pressure, and concentration of reagent solutions. The possibility to integrate a large number of micro units within a finite small space develop several major fields of application such as fine chemicals, combinatorial synthesis, high throughput screening using reactor units operated in parallel and in serial with different functions. The standard structure of the conventional micro rectors, however, expand on two dimensional substrate. From the point of micro integration and cost downing, such structure has a finite restriction. We proposed and fabricated a new chemical reactor which can operate vertically in stacked structures according to demanded chemical functions such as reaction, isolation, and purification. A variety of three-dimensional microfabrication processes brought by LIGA process using Synchrotron radiation allows new type of vertical microreactors and their components. This reactor is characterized as the simple structure with no valve and no pumping units and new aspect of the chemical reaction evoked by the use of the micro fluid filters. We have investigated the vertical fluid transport properties and the chemical properties.