Name: capillary-based centrifugal microfluidic device for size-controllable formation of monodisperse microdroplets
Uploaded: 2016-02-22T15:00:00
Description: Watch this Scientific Journal Video about Capillary-based Centrifugal Microfluidic Device for Size-controllable Formation of Monodisperse Microdroplets at JoVE.com

This work was supported by the PRESTO "Design and Control of Cellular Functions" research area of the Japan Science and Technology Agency (JST), a Grant-in-Aid for Scientific Research of Innovative Areas "Molecular Robotics" (Project No. 24104002) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan, Grant-in-Aid for Young Scientists (A) (Project No. 24680033) and Scientific Research (B) (Project No. 26280097) from the Japan Society for the Promotion of Science (JSPS), and the Creative Design for Bioscience and Biotechnology course of the School of Bioscience and Biotechnology at Tokyo Tech.

1. Fabrication of a Capillary-based Microfluidic Device
<ol>
	<li>Set up of the holders 
	Note: The holder design is presented in Figure 2A.
	<ol>
		<li>Cut out each of the four discs of the holders (Figure 2A(i)-(iv)) from 2-mm-thick polyacetal plastic plate using a milling machine. Use the following dimensions for each of the four discs of the holder: (i) disc 1 diameter 8.5 mm, capillary hole (CH) diameter 1.3 mm, screw hole (SH) diameter 1.8 mm; (ii) disc 2 di...

<ol>
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F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Droplet-Based,+Composite+PDMS/Glass+Capillary+Microfluidic+System+for+Evaluating+Protein+Crystallization+Conditions+by+Microbatch+and+Vapor-Diffusion+Methods+with+On-Chip+X-Ray+Diffraction.">A Droplet-Based, Composite PDMS/Glass Capillary Microfluidic System for Evaluating Protein Crystallization Conditions by Microbatch and Vapor-Diffusion Methods with On-Chip X-Ray Diffraction.</a> Angew. Chem., Int. Ed. 43 (19), 2508-2511 (2004).</li><li>Nakano, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single-molecule+PCR+using+water-in-oil+emulsion.">Single-molecule PCR using water-in-oil emulsion.</a> J. Biotechnol. 102 (2), 117-124 (2003).</li><li>Diehl, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=BEAMing:+single-molecule+PCR+on+microparticles+in+water-in-oil+emulsions.">BEAMing: single-molecule PCR on microparticles in water-in-oil emulsions.</a> Nat. Methods. 3, 551-559 (2006).</li><li>He, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Selective+encapsulation+of+single+cells+and+subcellular+organelles+into+picoliter-+and+femtoliter-volume+droplets.">Selective encapsulation of single cells and subcellular organelles into picoliter- and femtoliter-volume droplets.</a> Anal. 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Sci. 59 (15), 3045-3058 (2004).</li><li>Anna, S. L., Bontoux, N., Stone, H. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Formation+of+dispersions+using+&amp;#34;flow-focusing&amp;#34;+in+microchannels.">Formation of dispersions using &amp;#34;flow-focusing&amp;#34; in microchannels.</a> Appl. Phys. Lett. 82, 364-366 (2003).</li><li>Takeuchi, S., Garstecki, P., Weibel, D. B., Whitesides, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+axisymmetric+flow-focusing+microfluidic+device.">An axisymmetric flow-focusing microfluidic device.</a> Adv. Mater. 17 (8), 1067-1072 (2005).</li><li>Thorsen, T., Roberts, R. W., Arnold, F. H., Quake, S. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamic+pattern+formation+in+a+vesicle-generating+microfluidic+device.">Dynamic pattern formation in a vesicle-generating microfluidic device.</a> Phys. Rev. Lett. 86 (18), 4163-4166 (2001).</li><li>Yamashita, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Generation+of+monodisperse+cell-sized+microdroplets+using+a+centrifuge-based+axisymmetric+co-flowing+microfluidic+device.">Generation of monodisperse cell-sized microdroplets using a centrifuge-based axisymmetric co-flowing microfluidic device.</a> J. Biosci. 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Using this device, the monodisperse W/O microdroplets were generated by Plateau-Rayleigh instability of a jet-flow17. Microscopic examination did not reveal the presence of satellite droplets. In the fabrication of the device, three critical steps are essential to successfully generate monodisperse W/O microdroplets. First, to supply a straight flow of oil containing surfactant and aqueous solution, the capillary holes of four discs must be arranged in a concentric pattern. Second, the inner capillary was care...

W/O microdroplets1-5 have many important applications for the study of biochemistry and bioengineering, including protein synthesis6, protein crystallization7, emulsion PCR8,9, cell encapsulation10, and construction of artificial cell-like systems5,6. To produce W/O microdroplets for these applications, important criteria are control of size and monodispersibility of the W/O microdroplets. Microfluidic devices for making monodisperse, size-controllable W/O microdroplets11 are based on the co-flowing method12,13, flow-focusing method14,15, and the T-junction method16 in microchannels. Although these methods produce highly monodisperse W/O microdroplets, the microfabrication process requires complicated handling and specialized techniques for the preparation of microchannels, and also requires a large amount of sample solution (at least several hundred &#181;l) because of the inevitable dead volume in the syringe pumps and tubes that conduct the sample solution to the microchannels. Thus, an easy-to-use and low-dead-volume method to generate monodisperse W/O microdroplets is needed.
This paper, along with videos of experimental procedures, describes a centrifugal capillary-based axisymmetric co-flowing microfluidic device17 for generating cell-sized, monodisperse W/O microdroplets (Figure 1). This simple method achieves size monodispersity and size controllability. It requires just a tabletop mini-centrifuge and a capillary-based axisymmetric co-flowing microfluidic device fixed in a sampling microtube. Our method needs only a very small volume (0.1 &#181;l), and does not waste any significant volume of the sample.

<table border="0" cellpadding="0" cellspacing="0" width="747">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">2-mm-thick polyacetal plastic plate</td>
			<td style="width:71px;">Tool</td>
			<td style="width:119px;">Nikkyo Technos, Co., Ltd. (Japan)</td>
			<td style="width:167px;">244-6432-08</td>
			<td style="width:175px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Milling machine</td>
			<td style="width:71px;">Tool</td>
			<td style="width:119px;">Roland DG Co., Ltd. (Japan)</td>
			<td>MDX-40A</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">End Mill RSE230-0.5*2.5</td>
			<td style="width:71px;">Tool</td>
			<td style="width:119px;">NS Tool Co., Ltd. (Japan)</td>
			<td>01-00644-00501</td>
			<td></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;">M2*40 screws</td>
			<td style="width:71px;">Tool</td>
			<td style="width:119px;">Jujo Synthetic Chemistry Labo. (Japan)</td>
			<td>0001-024</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Glass Capillry Puller</td>
			<td style="width:71px;">Tool</td>
			<td style="width:119px;">Narishige (Japan)</td>
			<td>PC-10</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Microforge</td>
			<td style="width:71px;">Tool</td>
			<td style="width:119px;">Narishige (Japan)</td>
			<td>MF-900</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Inner Glass Capillary</td>
			<td style="width:71px;">Tool</td>
			<td style="width:119px;">Narishige (Japan)</td>
			<td>G-1</td>
			<td></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Outer Glass Capillary</td>
			<td style="width:71px;">Tool</td>
			<td style="width:119px;">World Precision Instruments Inc. (USA)</td>
			<td>1B200-6</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">1.5 ml Sample tube</td>
			<td style="width:71px;">Tool</td>
			<td style="width:119px;">INA OPTIKA CO.,LTD (Japan)</td>
			<td>ST-0150F</td>
			<td></td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">Hexadecane</td>
			<td style="width:71px;">Reagent</td>
			<td style="width:119px;">Wako Pure Chemical Industries Ltd. (Japan)</td>
			<td>080-03685&#160;</td>
			<td></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Sorbitan monooleate (Span 80)</td>
			<td style="width:71px;">Reagent</td>
			<td style="width:119px;">Tokyo Chemical Industry Co., Ltd. (Japan)</td>
			<td>S0060</td>
			<td></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Milli Q system</td>
			<td style="width:71px;">Reagent</td>
			<td style="width:119px;">Merck Millipore Corporation (Germany)</td>
			<td>ZRQSVP030</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Swinging-out-type Mini-centrifuge</td>
			<td style="width:71px;">Tool</td>
			<td style="width:119px;">Hitech Co., Ltd. (Japan)</td>
			<td>ATT101</td>
			<td></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Digital Microscope</td>
			<td style="width:71px;">Tool</td>
			<td style="width:119px;">KEYENCE Corporation (Japan)</td>
			<td>VHX-2001</td>
			<td></td>
		</tr>
	</tbody>
</table>

capillary-based centrifugal microfluidic device for size-controllable formation of monodisperse microdroplets

Here, we demonstrate a simple method for the rapid production of size-controllable, monodisperse, W/O microdroplets using a capillary-based centrifugal microfluidic device. W/O microdroplets have recently been used in powerful methods that enable miniaturized chemical experiments. Therefore, developing a versatile method to yield monodisperse W/O microdroplets is needed. We have developed a method for generating monodisperse W/O microdroplets based on a capillary-based centrifugal axisymmetric co-flowing microfluidic device. We succeeded in controlling the size of microdroplets by adjusting the capillary orifice. Our method requires equipment that is easier-to-use than with other microfluidic techniques, requires only a small volume (0.1-1 &#181;l) of sample solution for encapsulation, and enables the production of hundreds of thousands number of W/O microdroplets per second. We expect this method will assist biological studies that require precious biological samples by conserving the volume of the samples for rapid quantitative analysis biochemical and biological studies.

In this study, we present a simple method for the generation of cell-sized W/O microdroplets by using a capillary-based centrifugal microfluidic device (Figure 1). The microfluidic device was composed of a capillary holder (Figure 2B), two glass capillaries (inner and outer glass capillaries in Figure 3C), and a microtube containing an oil including surfactant. We injected 0.1 &#181;l of sample solution into the inner glass capillary and ...

Watch this Scientific Journal Video about Capillary-based Centrifugal Microfluidic Device for Size-controllable Formation of Monodisperse Microdroplets at JoVE.com

Capillary-based Centrifugal Microfluidic Device for Size-controllable Formation of Monodisperse Microdroplets

Here, we demonstrate a simple production method for size-controllable, monodisperse, water-in-oil (W/O) microdroplets using a capillary-based centrifugal microfluidic device. This method requires only a small sample volume and enables high-yield production. We expect this method will be useful for rapid biochemical and cellular analyses.

Here, we demonstrate a simple method for the rapid production of size-controllable, monodisperse, W/O microdroplets using a capillary-based centrifugal ...

The overall goal of this procedure is to generate monodispersed water and oil microdroplets for biological studies using a capillary based centrifugal axi-symmetric co-flowing microfluidic device. This method can help produce monodispersed microdroplet for the biochemical field to advance the study of work in synthesis, single-molecule PCR, single encapsultation, and the simple modeling of living cells. The main advantages of this technique are that it is easy and adjustable.It requires less than a microliter of sample solution and it can produce monodispersed microdroplets of the required size. Demonstrating the procedure will be Morita, a postdoc from my laboratory. The capillary based microfluidic assembly begins with preparing the capillary holder.Begin with milling four discs from two millimeter thick polyacetyl plastic plates using a milling machine. The discs are used to form a column supported by rods and screws. Using M.2 screws, assemble the plates.First, from discs one and two, assemble the bottom of the holder. Then, shorten the screws by cutting them in the threaded sections. Connect three of the four holes to secure the two discs making a 0.9 centimeter stack.Similarly, assemble the top part of the holder from discs three and four. Use two of the holes in each plate to connect the plates. Make the stack 0.7 centimeters tall.Now, use a long screw to join the two empty holes in the top part of the holder with the two empty holes in the bottom part of the holder. The long screw should put a gap between the holders that is about two to three millimeters and the head of the screw should overhang the completed holder by about 2.2 centimeters. Each experiment uses a new set of capillaries fabricated from two capillaries.From a 90 millimeter capillary, make two inner capillaries using a glass cutter. Make two equally-sized sections. From a 150 millimeter capillary, make three inner capillary sections.Next, using a glass puller, sharpen each capillary section. Set the puller weight to its maximum and set the heat level to 60-70 degrees for the outer capillary or 70-80 for the inner capillary. Then, carefully sharpen the glass.Keep the length of the constricted parts of the capillaries within the advised limits. If the length of the tips is too long or short, adjust the heating element until the correct length is achieved. Now, prepare to cut the tips.First, use some clear tape to secure a capillary to a microscope stage. Overhang the tip under the objective. Second, using a platinum wire covered by glass beads, cut the tip off in three steps.First, put the capillary where the break should occur in contact with a cold bead. Second, heat the wire for one to two seconds. Then third, cut the tip off by cooling the platinum wire.This operation should be performed using a foot pedal control to heat the wire. Now, using a microforge, adjust the diameters of the capillary orifices. For the two outer glass capillaries, make their orifices 60 microns.For the three inner capillaries make orifices having diameters of five, 10 and 20 microns. To generate the microdroplets, first fill an outer glass capillary with an oil-containing surfactant such as hexadecane containing 2%sorbitin monooleate by weight. Load 10 microliters of the solution into the capillary.Then, secure the loaded copillary to the bottom part of the holder. Next, using capillary action, load about 0.1 microliters of aqueous solution into an inner glass capillary. Position the loaded inner capillary in the upper part of the holder.Now, insert the inner capillary across the holder and into the outer capillary. While observing the tip through a microscope, turn the long screw of the holder to slowly and carefully advance in the inner capillary into the outer capillary. Advance the inner capillary to where the outer capillary's diameter is between 100 and 150 microns.Now, introduce 100 microliters of the same oil with surfactant into the bottom of a 1.5 milliliter microtube. This will serve as a microdoplet collection tube. Carefully position the holder and capillaries into the loaded microtube.Make sure the outer capillary is not in contact with the solution in the microtube. Then, load the tube in to a tabletop swing-out type centrifuge. To generate the microdroplets, run the centrifuge at 1, 600 times gravity for one or two seconds.Then, remove the capillaries and holder from the tube and take an aliquot of the water-oil microdroplets collected in the tube. Eject the microdroplets onto a glass slide and image them for analysis. Using this protocol, various water-oil microdroplets where made from hexadecane containing 2%sorbitin monooleate.Droplets made using an inner pipette with an orifice diameter of five microns were measured to be 8.3 microns in diameter on average. Droplets made using an inner pipette with an orifice diameter of 10 microns were measured to be 12.7 microns in diameter on average. Droplets made using an inner pipette with a 20 microns orifice were about 17.9 microns in diameter.Thus, this method produces monodispersed microdroplets that have a diameter close to the size of the inner capillary orifice. After watching this video, you should have a good understanding of how to produce and control the size of monodispersed water and oil microdroplets for quantitative chemical experiments. Once mastered, this technique can be done in five to 10 minutes, if it is performed properly.

capillary-based-centrifugal-microfluidic-device-for-size-controllable

Research

JoVE Journal

Engineering

Indirect Fabrication of Lattice Metals with Thin Sections Using Centrifugal Casting

One of the typical methods to manufacture 3D lattice metals is the direct-metal additive manufacturing (AM) process such as Selective Laser Melting (SLM) and Electron Beam Melting (EBM). In spite of its potential processing capability, the direct AM method has several disadvantages such as high cost, poor surface finish of final products, limitation in material selection, high thermal stress, and anisotropic properties of parts. We propose a cost-effective method to manufacture 3D lattice metals. The objective of this study is to provide a detailed protocol on fabrication of 3D lattice metals having a complex shape and a thin wall thickness; e.g., octet truss made of Al and Cu alloys having a unit cell length of 5 mm and a cell wall thickness of 0.5 mm. An overall experimental procedure is divided into eight sections: (a) 3D printing of sacrificial patterns (b) melt-out of support materials (c) removal of residue of support materials (d) pattern assembly (e) investment (f) burn-out of sacrificial patterns (g) centrifugal casting (h) post-processing for final products. The suggested indirect AM technique provides the potential to manufacture ultra-lightweight lattice metals; e.g., lattice structures with Al alloys. It appears that the process parameters should be properly controlled depending on materials and lattice geometry, observing the final products of octet truss metals by the indirect AM technique.

An indirect additive manufacturing method combining a 3D printing of polymers with a centrifugal casting is outlined for manufacturing 3D octet truss metals (Al and Cu alloys) having a unit cell length of 5 mm with a wall thickness of 0.5 mm.

One of the typical methods to manufacture 3D lattice metals is the direct-metal additive manufacturing (AM) process such as Selective Laser Melting (SLM) ...

Solvent Bonding for Fabrication of PMMA and COP Microfluidic Devices

Thermoplastic microfluidic devices offer many advantages over those made from silicone elastomers, but bonding procedures must be developed for each thermoplastic of interest. Solvent bonding is a simple and versatile method that can be used to fabricate devices from a variety of plastics. An appropriate solvent is added between two device layers to be bonded, and heat and pressure are applied to the device to facilitate the bonding. By using an appropriate combination of solvent, plastic, heat, and pressure, the device can be sealed with a high quality bond, characterized as having high bond coverage, bond strength, optical clarity, durability over time, and low deformation or damage to microfeature geometry. We describe the procedure for bonding devices made from two popular thermoplastics, poly(methyl-methacrylate) (PMMA), and cyclo-olefin polymer (COP), as well as a variety of methods to characterize the quality of the resulting bonds, and strategies to troubleshoot low quality bonds. These methods can be used to develop new solvent bonding protocols for other plastic-solvent systems.

Solvent bonding is a simple and versatile method for fabricating thermoplastic microfluidic devices with high quality bonds. We describe a protocol to achieve strong, optically clear bonds in PMMA and COP microfluidic devices that preserve microfeature details, by a judicious combination of pressure, temperature, an appropriate solvent, and device geometry.

Thermoplastic microfluidic devices offer many advantages over those made from silicone elastomers, but bonding procedures must be developed for each ...

Scanning Light Scattering Profiler (SLPS) Based Methodology to Quantitatively Evaluate Forward and Backward Light Scattering from Intraocular Lenses

The scanning light scattering profiler (SLSP) methodology has been developed for the full-angle quantitative evaluation of forward and backward light scattering from intraocular lenses (IOLs) using goniophotometer principles. This protocol describes the SLSP platform and how it employs a 360&#176; rotational photodetector sensor that is scanned around an IOL sample while recording the intensity and location of scattered light as it passes through the IOL medium. The SLSP platform can be used to predict, non-clinically, the propensity for current and novel IOL designs and materials to induce light scatter. Non-clinical evaluation of light scattering properties of IOLs can significantly reduce the number of patient complaints related to unwanted glare, glistening, optical defects, poor image quality, and other phenomena associated with the unintended light scattering. Future studies should be conducted to correlate SLSP data with clinical results to help identify which measured light scatter is most problematic for patients that have undergone cataract surgery subsequent to IOL implantation.

Scanning Light Scattering Profiler SLPS Based Methodology to Quantitatively Evaluate Forward and Backward Light Scattering from Intraocular Lenses

This protocol describes the scanning light scattering profiler (SLSP) that enables the full-angle quantitative evaluation of forward and backward scattering of light from intraocular lenses (IOLs) using goniophotometer principles.

The scanning light scattering profiler (SLSP) methodology has been developed for the full-angle quantitative evaluation of forward and backward light ...

A 3D-printed Chamber for Organic Optoelectronic Device Degradation Testing

In this manuscript, we outline the manufacture of a small, portable, easy-to-use atmospheric chamber for organic and perovskite optoelectronic devices, using 3D-printing. As these types of devices are sensitive to moisture and oxygen, such a chamber can aid researchers in characterizing the electronic and stability properties. The chamber is intended to be used as a temporary, reusable, and stable environment with controlled properties (including humidity, gas introduction, and temperature). It can be used to protect air-sensitive materials or to expose them to contaminants in a controlled way for degradation studies. To characterize the properties of the chamber, we outline a simple procedure to determine the water vapor transmission rate (WVTR) using relative humidity as measured by a standard humidity sensor. This standard operating procedure, using a 50% infill density of polylactic acid (PLA), results in a chamber that can be used for weeks without any significant loss of device properties. The versatility and ease of use of the chamber allows it to be adapted to any characterization condition that requires a compact-controlled atmosphere.

Here, we present a protocol for the design, manufacture, and use of a simple, versatile 3D-printed and controlled atmospheric chamber for the optical and electrical characterization of air-sensitive organic optoelectronic devices.

In this manuscript, we outline the manufacture of a small, portable, easy-to-use atmospheric chamber for organic and perovskite optoelectronic devices, ...

A Modular Microfluidic Technology for Systematic Studies of Colloidal Semiconductor Nanocrystals

Colloidal semiconductor nanocrystals, known as quantum dots (QDs), are a rapidly growing class of materials in commercial electronics, such as light emitting diodes (LEDs) and photovoltaics (PVs). Among this material group, inorganic/organic perovskites have demonstrated significant improvement and potential towards high-efficiency, low-cost PV fabrication due to their high charge carrier mobilities and lifetimes. Despite the opportunities for perovskite QDs in large-scale PV and LED applications, the lack of fundamental and comprehensive understanding of their growth pathways has inhibited their adaptation within continuous nanomanufacturing strategies. Traditional flask-based screening approaches are generally expensive, labor-intensive, and imprecise for effectively characterizing the broad parameter space and synthesis variety relevant to colloidal QD reactions. In this work, a fully autonomous microfluidic platform is developed to systematically study the large parameter space associated with the colloidal synthesis of nanocrystals in a continuous flow format. Through the application of a novel translating three-port flow cell and modular reactor extension units, the system may rapidly collect fluorescence and absorption spectra across reactor lengths ranging 3 - 196 cm. The adjustable reactor length not only decouples the residence time from the velocity-dependent mass transfer, it also substantially improves the sampling rates and chemical consumption due to the characterization of 40 unique spectra within a single equilibrated system. Sample rates may reach up to 30,000 unique spectra per day, and the conditions cover 4 orders of magnitude in residence times ranging 100 ms - 17 min. Further applications of this system would substantially improve the rate and precision of the material discovery and screening in future studies. Detailed within this report are the system materials and assembly protocols with a general description of the automated sampling software and offline data processing.

Detailed herein are the operation and assembly protocols of a modular microfluidic screening platform for the systematic characterization of colloidal semiconductor nanocrystal syntheses. Through fully adjustable system arrangements, highly efficient spectra collection may be carried out across 4 orders of magnitude reaction time scales within a mass transfer-controlled sampling space.

Colloidal semiconductor nanocrystals, known as quantum dots (QDs), are a rapidly growing class of materials in commercial electronics, such as light ...

A Pipette-Tip Based Method for Seeding Cells to Droplet Microfluidic Platforms

Amongst various microfluidic platform designs frequently used for cellular analysis, droplet-microfluidics provides a robust tool for isolating and analyzing cells at the single-cell level by eliminating the influence of external factors on the cellular microenvironment. Encapsulation of cells in droplets is dictated by the Poisson distribution as a function of the number of cells present in each droplet and the average number of cells per volume of droplet. Primary cells, especially immune cells, or clinical specimens can be scarce and loss-less encapsulation of cells remains challenging. In this paper, we present a new methodology that uses pipette-tips to load cells to droplet-based microfluidic devices without the significant loss of cells. With various cell types , we demonstrate efficient cell encapsulation in droplets that closely corresponds to the encapsulation efficiency predicted by the Poisson distribution. Our method ensures loss-less loading of cells to microfluidic platforms and can be easily adapted for downstream single cell analysis, e.g., to decode cellular interactions between different cell types.

This article presents a protocol for seeding scarce population of cells using pipette-tips to droplet microfluidic devices in order to provide higher encapsulation efficiency of cells in droplets.

Amongst various microfluidic platform designs frequently used for cellular analysis, droplet-microfluidics provides a robust tool for isolating and ...

A Standard and Reliable Method to Fabricate Two-Dimensional Nanoelectronics

Two-dimensional (2D) materials have attracted huge attention due to their unique properties and potential applications. Since wafer scale synthesis of 2D materials is still in nascent stages, scientists cannot fully rely on traditional semiconductor techniques for related research. Delicate processes from locating the materials to electrode definition need to be well controlled. In this article, a universal fabrication protocol required in manufacturing nanoscale electronics, such as 2D quasi-heterojunction bipolar transistors (Q-HBT), and 2D back-gated transistors are demonstrated. This protocol includes the determination of material position, electron beam lithography (EBL), metal electrode definition, et al. A step by step narrative of the fabrication procedures for these devices are also presented. Furthermore, results show that each of the fabricated devices has achieved high performance with high repeatability. This work reveals a comprehensive description of process flow for preparing 2D nano-electronics, enables the research groups to access this information, and pave the way toward future electronics.

The article aims to introduce a standard and reliable fabrication procedure for the development of future low dimensional nanoelectronics.

Two-dimensional (2D) materials have attracted huge attention due to their unique properties and potential applications. Since wafer scale synthesis of 2D ...

Method Development for Contactless Resonant Cavity Dielectric Spectroscopic Studies of Cellulosic Paper

The current analytical techniques for characterizing printing and graphic arts substrates are largely ex situ and destructive. This limits the amount of data that can be obtained from an individual sample and renders it difficult to produce statistically relevant data for unique and rare materials. Resonant cavity dielectric spectroscopy is a non-destructive, contactless technique which can simultaneously interrogate both sides of a sheeted material and provide measurements which are suitable for statistical interpretations. This offers analysts the ability to quickly discriminate between sheeted materials based on composition and storage history. In this methodology article, we demonstrate how contactless resonant cavity dielectric spectroscopy may be used to differentiate between paper analytes of varying fiber species compositions, to determine the relative age of the paper, and to detect and quantify the amount of post-consumer waste (PCW) recycled fiber content in manufactured office paper.

A protocol for the non-destructive analysis of the fiber content and relative age of paper.

The current analytical techniques for characterizing printing and graphic arts substrates are largely ex situ and destructive. This limits the amount of ...

Ion-Exchange Membranes for the Fabrication of Reverse Electrodialysis Device

Reverse electrodialysis (RED) is an effective way to generate power by mixing two different salt concentrations in water using cation-exchange membranes (CEM) and anion-exchange membranes (AEM). The RED stack is composed of an alternating arrangement of the cation-exchange membrane and anion-exchange membrane. The RED device acts as a potential candidate for fulfilling the universal demand for future energy crises. Here, in this article, we demonstrate a procedure to fabricate a reverse electrodialysis device using laboratory-scale CEM and AEM for power production. The active area of the ion-exchange membrane is 49 cm2. In this article, we provide a step-by-step procedure for synthesizing the membrane, followed by the stack&#39;s assembly and power measurement. The measurement conditions and net power output calculation have also been explained. Furthermore, we describe the fundamental parameters that are taken into consideration for obtaining a reliable outcome. We also provide a theoretical parameter that affects the overall cell performance relating to the membrane and the feed solution. In short, this experiment describes how to assemble and measure RED cells on the same platform. It also contains the working principle and calculation used for estimating the net power output of the RED stack using CEM and AEM membranes.

We demonstrate the fabrication of a reverse electrodialysis device using a cation-exchange membrane (CEM) and anion-exchange membrane (AEM) for power generation.

Reverse electrodialysis (RED) is an effective way to generate power by mixing two different salt concentrations in water using cation-exchange membranes ...

Pneumatically Driven Microfluidic Platform for Micro-Particle Concentration

The present article introduces a method for fabricating and operating a pneumatic valve to control particle concentration using a microfluidic platform. This platform has a three-dimensional (3D) network with curved fluid channels and three pneumatic valves, which create networks, channels, and spaces through duplex replication with polydimethylsiloxane (PDMS). The device operates based on the transient response of a fluid flow rate controlled by a pneumatic valve in the following order: (1) sample loading, (2) sample blocking, (3) sample concentration, and (4) sample release. The particles are blocked by thin diaphragm layer deformation of the sieve valve (Vs) plate and accumulate in the curved microfluidic channel. The working fluid is discharged by the actuation of two on/off valves. As a result of the operation, all particles of various magnifications were successfully intercepted and disengaged. When this technology is applied, the operating pressure, the time required for concentration, and the concentration rate may vary depending on the device dimensions and particle size magnification.

The present protocol describes a pneumatic microfluidic platform that can be used for efficient microparticle concentration.

The present article introduces a method for fabricating and operating a pneumatic valve to control particle concentration using a microfluidic platform. ...