Toshiba Develops Hydrogen-generating Microreactor | The Free Library

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Japanese news service Nikkei recently reported that Toshiba Corporation has developed a hand-held microreactor designed to extract hydrogen from dimethyl ether (DME) and carbon-based fuels.

According to Nikkei, the microreactor is capable of producing approximately 200 cubic centimeters (cc) of hydrogen per minute from 200 cc of water and 50 cc of DME, providing enough fuel for a solid polymer fuel cell used to power a laptop computer.

Nikkei said the small size of the microreactor will enable the miniaturization of accompanying fuel cell systems.

SOURCE:  http://www.thefreelibrary.com/Toshiba+Develops+Hydrogen-generating+Microreactor.-a0143928349

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Microreactor Speeds Nanotech Particle Production by 500 Times | Science Daily

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Nov. 1, 2010 — Engineers at Oregon State University have discovered a new method to speed the production rate of nanoparticles by 500 times, an advance that could play an important role in making nanotechnology products more commercially practical.

The approach uses an arrayed microchannel reactor and a “laminated architecture” in which many sheets, each with thousands of microchannels in them, are stacked in parallel to provide a high volume of production and excellent control of the processes involved.

Applications could be possible in improved sensors, medical imaging, electronics, and even solar energy or biomedical uses when the same strategy is applied to abundant materials such as copper, zinc or tin.

A patent has been applied for, university officials say. The work, just published in the journal Nanotechnology, was done in the research group of Brian Paul, a professor in the OSU School of Mechanical, Industrial and Manufacturing Engineering.

“A number of new and important types of nanoparticles have been developed with microtechnology approaches, which often use very small microfluidic devices,” said Chih-hung Chang, a professor in the OSU School of Chemical, Biological and Environmental Engineering, and principal investigator on the study.

“It had been thought that commercial production might be as simple as just grouping hundreds of these small devices together,” Chang said. “But with all the supporting equipment you need, things like pumps and temperature controls, it really wasn’t that easy. Scaling things up to commercial volumes can be quite challenging.”

The new approach created by a research team of five engineers at OSU used a microreactor with the new architecture that produced “undecagold nanoclusters” hundreds of times faster than conventional “batch synthesis” processes that might have been used.

“In part because it’s faster and more efficient, this process is also more environmentally sensitive, using fewer solvents and less energy,” Chang said. “This could be very significant in helping to commercialize nanotech products, where you need high volumes, high quality and low costs.”

This research, Chang said, created nanoparticles based on gold, but the same concept should be applicable to other materials as well. By lowering the cost of production, even the gold nanoclusters may find applications, he said, because the cost of the gold needed to make them is actually just a tiny fraction of the overall cost of the finished product.

Nanoparticles are extraordinarily tiny groups of atoms and compounds that, because of their extremely small size and large surface areas, can have unusual characteristics that make them valuable for many industrial, electronic, medical or energy applications.

This work was supported by the Safer Nanomaterials and Nanomanufacturing Initiative of the Oregon Nanoscience and Microtechnologies Institute, or ONAMI. Funding was also provided by the Air Force Research Laboratory and the W.M. Keck Foundation.

SOURCE:  http://www.sciencedaily.com/releases/2010/11/101101130137.htm

Nanotechnology Increases Mineral Recovery | UPI

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Nanotechnology can offer a more efficient method to separate gold, silver, copper and other valuable materials from rock and ore, Canadian researchers say.

About 450 million tons of minerals are processed each year in a technique known as froth flotation, in which mineral ores are crushed into small particles and floated in water containing “collector” substances that can attach to the valuable particles and cause them to rise to the bubbling top of the water where they can be easily skimmed off.

Robert Pelton of McMaster University in Ontario and his colleagues say a new technology takes advantage of water-repelling nanoparticles as the “collectors,” an article in the American Chemical Society journal Langmuir reported.

In laboratory trials using glass beads to simulate mineral particles, the researchers found the nanoparticles attached so firmly to the beads that the flotation process produced a recovery rate of almost 100 percent.

CONCEPT: Microfluidic Electrolysis Cell | Science Direct

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Abstract

A single channel microfluidic electrolysis cell based on inexpensive materials and fabrication techniques is described. The cell is characterised using the electrochemistry of the Fe(CN)63−/Fe(CN)64− couple and its application in electrosynthesis is illustrated using the methoxylation reactions of N-formylpyrrolidine and 4-t-butyltoluene. It is shown that the reactions can be carried out with a good conversion in a single pass. The device, as described, allows the production of several mmol/hour of the methoxylated products.

Keywords

  • Microflow reactor;
  • Electrolysis cell;
  • Methoxylation reactions
Full-size image (50 K)

Fig. 1. Schematic illustration of the microflow reactor showing the essential components of the electrolysis cell. The diameter of the electrodes was 100 mm. The cell was sealed under compression by 11 stainless steel bolts placed in insulating tubes.

Full-size image (35 K)

Fig. 2. Schematic of the experimental set up, where 1 – the solvent bottle, 2 – pump, 3 – 5 ml sample loop, 4 – microreactor, and 5 – collection vial.

SOURCE:   http://www.sciencedirect.com/science/article/pii/S0013468611000971

Hiden CATLAB integrated micro-reactor sizes up | Chemistry Views

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The CATLAB integrated micro-reactor/mass spectrometer system is specifically optimised for continuous quantitative real-time analysis of catalytic activity and reaction components. The close-coupled mass spectrometer samples directly from the reactor zone for fastest response and precise process characterisation, providing overall response times of less than 0.5 seconds and with data accumulation rates at up to 500 data-points per second.
The latest brochure, just released, details new features to extend operational capability and ease of operation, with total system control now offered via the new LabView operating program with both fully automated and with manual operation. Operation is fully pre-programmable with total control of temperature, temperature ramp rate and of gas flow with up to 8 gas streams.
The quartz reactor and cartridge-style sample insertion system are now available with increased capacity for operation with sample volumes from 0.15 up to 2.5 mL, with the fast-response low thermal mass furnace operating to 1000C with ramp rates to 20C per minute. Applications include temperature programmed desorption(TPD), reduction(TPR), oxidation(TPO) and reaction(TPRx). Additionally the mass spectrometer module may be decoupled to provide standalone operation for general laboratory gas analysis applications.

SOURCE:  http://www.chemistryviews.org/details/advertorial/2548651/Hiden_CATLAB_integrated_micro-reactor_sizes_up.html

Microfluidic Valve Technology | Stanford University

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Soft Lithography is a microfabrication process in which a soft polymer (such as polydimethylsiloxane (PDMS) ) is cast onto a mold that contains a microfabricated relief or engraved pattern. Using this technique, membrane microvalves can be produced. This membrane microvalve is the fundamental component which enables liquids to be controlled on-chip and is the key to realizing microfluidic large scale integration.
A basic microfluidic device is composed of two elastomer layers. One layer contains channels for flowing liquids (flow layer), and the other layer contains channels that deflect the membrane valve into the flow channel and stop liquid flow when pressurized with air or liquid (control layer).


 Master Molds

Molds containing the relief of the desired microfluidic circuit are made using conventional photolithography. This entails first designing your desired microfluidic network in a CAD program and printing it onto a transparency film using a very high resolution printer. Next, an appropriate photosensitive polymer (photoresist) is spun onto a silicon wafer and ultraviolet light is exposed to the wafer through the overlaying mask. Finally, the wafers are developed to reveal the transferred microfluidic network pattern on the silicon wafer. Note: one mold is made for the control layer and one mold is made for the flow layer.


Photoresists and Geometry of channels:

A photoresist is a light-sensitive material used to form a patterned coating on a surface.

Photoresists are classified into two groups: positive resists and negative resists.

  • A positive resist is a type of photoresist in which the portion of the photoresist that is exposed to light becomes soluble to the photoresist developer. The portion of the photoresist that is unexposed remains insoluble to the photoresist developer.
  • A negative resist is a type of photoresist in which the portion of the photoresist that is exposed to light becomes insoluble to the photoresist developer. The unexposed portion of the photoresist is dissolved by the photoresist developer.

We use SU 8 series negative photoresist to create a rectangular type channels since after hard baking features have rectangular profile.
To make rounded channels we commonly use AZ  and SPR positive photoresists and they have  rounded profile after hard baking.


Single layer molds vs. multi layer molds:

Most commonly used are molds that have one layer of photoresist and all features are the same height.
Multi layer molds are made in cases when it is necessary to have features with different heights.

mold layers

Schematic of a multi-height (layer) mold showing 3 layers of different heights.

 

In this case, a second layer of photoresist is applied to the first one, and all the same basic mold making steps are repeated except exposure. Before exposing, it is necessary to align the first layer with the mask of the second layer.
In order to precisely position the mask of the second layer with the first layer mold, both masks for layers one and two should have alignment marks on them.
For a three layer mold the same steps are applied, and all 3 masks for those layers must have alignment marks in order to work.



PDMS Devices (Chips)

 

Types of devices

Push up

Push down

pushup_section.bmp

pushdown_section.bmp

Control lines pass under the flow channels. Pneumatic pressurization of the control line causes a membrane to deflect up into the flow structure, sealing the channel. Deep reaction chambers may be integrated into the flow layer (upwards). Control lines pass over the flow channels. Pneumatic/hydraulic pressure in the control lines flattens the membrane valve downwards to create a seal.
glasspushup_labled.JPG glasspushdown_labled.JPG

 

Steps to make devices: Push up device Push down device
Making Control layer Spinning PDMS on control mold to form a thin layer and bake Pour PDMS onto wafer to form a thick layer and bake
Making Flow layer Pour PDMS onto wafer to form a thick layer and bake Spinning PDMS on control mold to form a thin layer and bake
Aligning layers Align flow on control layer Align control on flow layer
Bonding layers Bake both layers Bake both layers
Bonding device to a substrate Bond the device to a substrate to seal the control layer Bond the device to a substrate to seal the flow layer

The following figure shows the basic fabrication process for this two-layer device (courtesy Dr. Carl Hansen):

processoverview_cropped.jpg
When a control channel and a flow channel cross, if the area of the intersection is large enough, a valve is created. The thin membrane separating the two channels deflects into the flow channel when the control channel is pressurized, creating a complete seal. The following picture shows a typical valve in the closed state (courtesy Dr. Carl Hansen):

http://thebigone.stanford.edu/foundry/images/index_clip_image002.jpg
Marc A. Unger, Hou-Pu Chou, Todd Thorsen, Axel Scherer, and Stephen Quake, “Monolithic Microfabricated Valves and Pumps by Multilayer Soft Lithography,” Science, vol. 288, no. 7, pp. 113-116, April 2000.
David C. Duffy, J. Cooper McDonald, Olivier J.A. Schueller, and George Whitesides, “Rapid Prototyping of Microfluidic Systems in Poly(dimethylsiloxane),” Analytical Chemistry, vol. 70, no. 23, pp. 4974-4984, December 1998.

 

SOURCE:  http://www.stanford.edu/group/foundry/Microfluidic%20valve%20technology.html

CONCEPT: Integrated Microfluidic Reactors | NIHMS

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Wei-Yu Lin, Yanju Wang, Shutao Wang, and Hsian-Rong Tseng
Department of Molecular and Medical Pharmacology, Crump institute for Molecular Imaging (CIMI),
Institute for Molecular Medicine (IMED), California NanoSystems Institute (CNSI), University of
California, Los Angeles, Los Angeles, CA, USA

Summary

Microfluidic reactors exhibit intrinsic advantages of reduced chemical consumption, safety, high surface-area-to-volume ratios, and improved control over mass and heat transfer superior to the macroscopic reaction setting. In contract to a continuous-flow microfluidic system composed of only a microchannel network, an integrated microfluidic system represents a scalable integration of a microchannel network with functional microfluidic modules, thus enabling the execution and automation of complicated chemical reactions in a single device. In this review, we summarize recent progresses on the development of integrated microfluidics-based chemical reactors for (i) parallel screening of in situ click chemistry libraries, (ii) multistep synthesis of radiolabeled imaging probes for positron emission tomography (PET), (iii) sequential preparation of individually addressable conducting polymer nanowire (CPNW), and (iv) solid-phase synthesis of DNA oligonucleotides.  These proof-of-principle demonstrations validate the feasibility and set a solid foundation for exploring a broad application of the integrated microfluidic system.

Keywords

Integrated microfluidics; Chemical screening, In situ click chemistry; Sequential synthesis, Positron emission tomography probes; Oligonucleotide synthesis; Conducting polymer nanowires

Published in final edited form as: Nano Today. 2009 December ; 4(6): 470–481. doi:10.1016/j.nantod.2009.10.007.

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