1. Preparing the microfluidic flow cell
NOTE: For this protocol, a commercial microfluidic flow cell will be utilized. By using a commercial product that is designed for light penetration from an optical microscope, any challenges regarding brightfield illumination of the media will be minimized.
<ol>
	<li>Start preparing the microfluidic flow cell by covering the outlet with parafilm to seal one end of the channel so that the empty flow cell may be packed with polymeric pow...

<ol>
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B., Chen, G., Su, C., Li, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transport+and+retention+of+colloids+in+porous+media:+Does+shape+really+matter.">Transport and retention of colloids in porous media: Does shape really matter.</a> Environmental Science and Technology. 47 (15), 8391-8398 (2013).</li><li>Ochiai, N., Kraft, E. L., Selker, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methods+for+colloid+transport+visualization+in+pore+networks.">Methods for colloid transport visualization in pore networks.</a> Water Resources Research. 42 (12), (2006).</li><li>Rottman, J., Sierra-Alvarez, R., Shadman, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Real-time+monitoring+of+nanoparticle+retention+in+porous+media.">Real-time monitoring of nanoparticle retention in porous media.</a> Environmental Chemistry Letters. 11 (1), 71-76 (2013).</li><li>Xing, Y., Chen, X., Chen, X., Zhuang, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Colloid-mediated+transport+of+pharmaceutical+and+personal+care+products+through+porous+media.">Colloid-mediated transport of pharmaceutical and personal care products through porous media.</a> Scientific Reports. 6 (1), 1-10 (2016).</li><li>Dathe, A., 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=Functional+models+for+colloid+retention+in+porous+media+at+the+triple+line.">Functional models for colloid retention in porous media at the triple line.</a> Environmental Science and Pollution Research. 21 (15), 9067-9080 (2014).</li><li>Zhang, T., 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=Investigation+of+nanoparticle+adsorption+during+transport+in+porous+media.">Investigation of nanoparticle adsorption during transport in porous media.</a> SPE Journal. 20 (4), 667-677 (2015).</li><li>Zhang, Q., Karadimitriou, N. K., Hassanizadeh, S. M., Kleingeld, P. J., Imhof, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Study+of+colloids+transport+during+two-phase+flow+using+a+novel+polydimethylsiloxane+micro-model.">Study of colloids transport during two-phase flow using a novel polydimethylsiloxane micro-model.</a> Journal of Colloid and Interface Science. 401, 141-147 (2013).</li><li>Health and environmental effects of particulate matter (PM). EPA Available from: <a target="_blank" href="https://www.epa.gov/pm-pollution/health-and-environmental-effects-particulate-matter-pm">https://www.epa.gov/pm-pollution/health-and-environmental-effects-particulate-matter-pm</a> (2021)</li><li>Bridge, J. W., Banwart, S. A., Heathwaite, A. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Noninvasive+quantitative+measurement+of+colloid+transport+in+mesoscale+porous+media+using+time+lapse+fluorescence+imaging.">Noninvasive quantitative measurement of colloid transport in mesoscale porous media using time lapse fluorescence imaging.</a> Environmental Science &amp; Technology. 40 (19), 5930-5936 (2006).</li><li>ASTMInternational. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Standard+test+methods+for+determining+loose+and+tapped+bulk+densities+of+powders+using+a+graduated+cylinder.">Standard test methods for determining loose and tapped bulk densities of powders using a graduated cylinder.</a> ASTMInternational. , (2018).</li><li>Donovan, K. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Microfluidic investigations of capillary flow and surface phenomena in porous polymeric media for 3D printing. , (2019).</li><li>. 34;Try Tracker Online.&amp;#34; Tracker Video Analysis and Modeling Tool for Physics Education Available from: <a target="_blank" href="https://physlets.org/tracker/">https://physlets.org/tracker/</a> (2022)</li><li>Janssen, P. H. M., Depaifve, S., Neveu, A., Francqui, F., Dickhoff, B. H. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impact+of+powder+properties+on+the+rheological+behavior+of+excipients.">Impact of powder properties on the rheological behavior of excipients.</a> Pharmaceutics. 13 (8), 1198 (2021).</li><li>Boschini, F., Delaval, V., Traina, K., Vandewalle, N., Lumay, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Linking+flowability+and+granulometry+of+lactose+powders.">Linking flowability and granulometry of lactose powders.</a> International Journal of Pharmaceutics. 494 (1), 312-320 (2015).</li><li>Yablokova, G., 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=Rheological+behavior+of+&#946;-Ti+and+NiTi+powders+produced+by+atomization+for+SLM+production+of+open+porous+orthopedic+implants.">Rheological behavior of &#946;-Ti and NiTi powders produced by atomization for SLM production of open porous orthopedic implants.</a> Powder Technology. 283, 199-209 (2015).</li><li>Lumay, G., Fiscina, J., Ludewig, F., Vandewalle, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Influence+of+cohesive+forces+on+the+macroscopic+properties+of+granular+assemblies.">Influence of cohesive forces on the macroscopic properties of granular assemblies.</a> AIP Conference Proceedings. 1542, 995 (2013).</li><li>Lumay, G., 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=Effect+of+relative+air+humidity+on+the+flowability+of+lactose+powders.">Effect of relative air humidity on the flowability of lactose powders.</a> Journal of Drug Delivery Science and Technology. 35, 207-212 (2016).</li></ol>

The protocol that is provided is highly dependent on the material characteristics of the particles that are chosen. Material properties impacting flow include particle size distribution2,3,4,5,11,21, particle surface roughness11, chemical properties at the particle surface2...

Inkjet-based binder jetting into powder media represents an important technology in additive manufacturing (3D printing). The binder jetting process begins with the deposition of functional fluids into powder media using a scanning inkjet printing process. Specifically, an inkjet print head translates over the powder surface, depositing the liquid binding agent onto a powder surface, and thereby forming a solid part in a layer-by-layer fashion1. Inkjet-based binder jetting technologies generally include sand, metal powders, and polymeric powders. However, to expand the materials&#39; space in binder jetting, a fundamental approach to investigating fluid-powder and powder-powder interactions, tribology, powder packing density, and particle aggregation is required. Specifically, for fluid-powder interactions, a critical need exists for the ability to image fluid flow through powder beds in real-time. This promises to be a powerful tool for researchers to include as a characterization technique and potentially as a screening method for different combinations of fluids and powders2,3,4, as well as more complex systems, such as concrete 3D-printing systems that utilize particle-bed methods.
The development of novel imaging techniques of molecular and colloidal transport, including nanoparticles, is an active area of investigation in microfluidic and millifluidic studies. Probing intermolecular interactions by imaging techniques can be challenging, as little work has been done to probe these types of interactions under the conditions of unsaturated and unsteady fluid flow. Many of the studies that are reported in the literature have focused on a saturated, pre-wetted, porous media, such as glass bead5,6,7,8,9,10,11,12 and soils13,14,15,16,17,18. This technique provides a non-invasive approach, resulting in high temporal and spatial resolution2,3,4,19. Furthermore, the developed technique provides a novel method for characterizing and quantifying nano-scale and micron-scale particle transport in a variety of porous media, focusing on polymeric powders.
The proposed technique utilizes a mobile device to record unsaturated, unsteady fluidic transport through porous polymeric media with particle dimensions that are representative of the powders used in 3D printing systems that utilize fluidic powder-bed fusion technologies. This technique is advantageous as the flow cells are cost-effective, reusable, small, and easily handled, illustrating the dominant aspects of frugal science. The ability to implement these simple experiments into a field study is very straightforward, eliminating the complications, cost, and time that are required in optical microscopy. Given the ease of creating the setup, the access to quick results, and the minimal number of sample requirements, this technique is an optimal platform for diagnostic screening.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>&#181;-Slide I Luer</td>
			<td>ibidi</td>
			<td>80191</td>
			<td>Microfluidic flow cell</td>
		</tr>
		<tr>
			<td>Beaker</td>
			<td>Southern Labware</td>
			<td>BG1000-800</td>
			<td>Glassware</td>
		</tr>
		<tr>
			<td>CALIBRE 301-58 LT Natural Polycarbonate Resin</td>
			<td>TRINSEO LLC</td>
			<td>CALIBRETM 301-58 LT</td>
			<td>Natural polycarbonate resin</td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Sigma Aldrich</td>
			<td>1.00983</td>
			<td>Solvent</td>
		</tr>
		<tr>
			<td>Fume Hood</td>
			<td>Kewaunee</td>
			<td>Supreme Air LV Fume Hoods</td>
			<td>Used with 92 FPM at 18&#34; opening</td>
		</tr>
		<tr>
			<td>iPhone 7 plus</td>
			<td>Apple</td>
			<td></td>
			<td>Camera</td>
		</tr>
		<tr>
			<td>Opaque 3D printed material</td>
			<td></td>
			<td></td>
			<td>The CAD drawing is provided in the supplemental file</td>
		</tr>
		<tr>
			<td>ORGASOL&#160; 2002 ES 6 NAT 3</td>
			<td>ARKEMA</td>
			<td>A12135</td>
			<td>Polyamide powder</td>
		</tr>
		<tr>
			<td>Pipet</td>
			<td>VWR</td>
			<td>10754-268</td>
			<td>Disposable Transfer Pipet</td>
		</tr>
		<tr>
			<td>Pipette</td>
			<td>Globe Scientific Inc.</td>
			<td>3301-200</td>
			<td>Pipette that can hold 125 &#181;L of fluid</td>
		</tr>
		<tr>
			<td>Polystyrene</td>
			<td>Advanced Laser Materials, LLC.</td>
			<td>PS200</td>
			<td>Polystyrene for sintering</td>
		</tr>
		<tr>
			<td>Tracker</td>
			<td></td>
			<td></td>
			<td>Video analysis and modeling tool</td>
		</tr>
		<tr>
			<td>VariQuest 100 White Light Model 3-3700</td>
			<td>FOTODYNE</td>
			<td>&#160;3-3700</td>
			<td>White light</td>
		</tr>
		<tr>
			<td>Water</td>
			<td></td>
			<td></td>
			<td>Distilled water</td>
		</tr>
	</tbody>
</table>

frugal imaging technique of capillary flow through three-dimensional polymeric printing powders

The development of novel imaging techniques of molecular and colloidal transport, including nanoparticles, is an area of active investigation in microfluidic and millifluidic studies. With the advent of three-dimensional (3D) printing, a new domain of materials has emerged, thereby increasing the demand for novel polymers. Specifically, polymeric powders, with average particle sizes on the order of a micron, are experiencing a growing interest from academic and industrial communities. Controlling material tunability at the mesoscopic to microscopic length scales creates opportunities to develop innovative materials, such as gradient materials. Recently, a need for micron-sized polymeric powders has been growing, as clear applications for the material are developing. Three-dimensional printing provides a high-throughput process with a direct link to new applications, driving investigations into the physio-chemical and transport interactions on a mesoscale. The protocol that is discussed in this article provides a non-invasive technique to image fluid flow in packed powder beds, providing high temporal and spatial resolution while leveraging mobile technology that is readily available from mobile devices, such as smartphones. By utilizing a common mobile device, the imaging costs that would normally be associated with an optical microscope are eliminated, resulting in a frugal-science approach. The proposed protocol has successfully characterized a variety of combinations of fluids and powders, creating a diagnostic platform for quickly imaging and identifying an optimal combination of fluid and powder.

In the section on analyzing data, the data for the time-lapsed images in Figure 3 illustrate the 75 wt% ethanol solution infiltrating the polycarbonate (PC) powder. Fluorescein was added to the solution to enhance the image quality for this publication. In the time-lapse images, the time-resolved process begins when the fluid is added to the inlet. Time, t, starts as soon as the fluid begins to penetrate the channel. The series of images demonstrates the progression of the fluid and...

Watch this Scientific Journal Video about Frugal Imaging Technique of Capillary Flow Through Three-Dimensional Polymeric Printing Powders at JoVE.com

Frugal Imaging Technique of Capillary Flow Through Three-Dimensional Polymeric Printing Powders

The proposed technique will provide a novel, efficient, frugal, and non-invasive approach for imaging fluidic flow through a packed powder bed, yielding high spatial and temporal resolution.

The development of novel imaging techniques of molecular and colloidal transport, including nanoparticles, is an area of active investigation in ...

The proposed technique is a novel, efficient, frugal and noninvasive approach to imaging fluidic flow through a packed powder bed yielding high spatial and temporal resolution. This technique is advantageous as the flow cells are cost effective, reusable, small and easily handled illustrating the dominant aspect of frugal science. Tapping the powders and confirming powder compaction is key to producing a reproducible diagnostic tool.To begin prepare the microfluidic flow cell by covering the outlet with perafoam to seal one end of the channel so that the empty flow cell may be packed with polymeric powder. Tape the metric paper ruler directly beneath the flow channel. Wave the microfluidic flow cell with the perafoam and the ruler attached.The mass of the flow cell is the unpacked flow cell mass. Use a plastic pipette to transfer the powder. While introducing the powder into the channel tap the flow cell at least five times to compact the powder.Continue packing until the powder reaches the beginning of the opening of the flow channel. Remove the powder present on the outer surface of the flow cell with a wipe soaked in alcohol. Once the powders are packed, visually inspect the flow cell for loosely packed powder.If the powder within the flow cell appears loosely packed, tap the flow cell five more times. If the powder packing appears consistent and compact, weigh the flow cell to measure the mass of the polymeric powder. To prevent flooding the camera detector with too much light, cover the light table with an opaque material such as a 3D printed cover in a black polylactic acid filament.Ensure that the material has an opening that is the size of the microchannel to allow light to illuminate the powder. To ensure that the camera on the mobile device can capture the contrast between the wet and dry powder, use the light table at a low to medium light intensity. Align the camera on the mobile device directly above the light table.Confirm that the camera is perpendicular to the top of the light table. After focusing the camera on the mobile device, select the record button. Add 125 microliters of fluid to the open inlet of the microchannel using a pipette.Record the flow for two minutes or until all the powder is wetted visibly. Transfer the video file from the mobile device to the computer for easy access. Once the software is installed, open the tracker software.From the file menu select open file to load the transferred video file on the desktop of the computer. To define the starting frame and the step size, click the clip settings icon. Then click on the calibration tool followed by new and select calibration stick.To zoom in on the ruler in the video, right click on the area to magnify and select zoom in from the list. Once appropriately magnified, define the beginning and end of one millimeter on the ruler taped to the microchannel and type 1 mm to define the distance. Click on the coordinate access tool.Set the origin for the x and y axis using the starting frame while doing the step. To create a point mass click on create. Then select point mouse.Use shift plus control to change the size of the rectangle. The initial point is where the inlet and the channel connect. Click on search next a couple of times to verify that the software is analyzing the correct area.If the software is functioning properly, click on search and wait for the software to finish analyzing the video. The open red circles on the plot represent the exact time and distance of the compiled information. In the interval from one to two seconds, the distance traveled by the fluid has doubled.During the interval from two to five seconds, the distance that the fluid has traveled also doubled. From five to 10 seconds, the fluid is still moving quickly. However, after 15 seconds the flow rate is slowing to a rate of approximately two millimeters every five seconds.The most important thing to remember when attending this procedure is to compact your powders. The procedure can be performed for ceramic and metallic powders and has high potential for geological field studies to track flow in pack pattern systems. This technique paved the way for researchers to explore chemically modified surfaces as well as fluids loaded with nanoparticles to observe particle attachment.

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1.1K Views.  South Dakota School of Mines & Technology. The proposed technique is a novel, efficient, frugal and noninvasive approach to imaging fluidic flow through a packed powder bed yielding high spatial and temporal resolution. This technique is advantageous as the flow cells are cost effective, reusable, small and easily handled illustrating the dominant aspect of frugal science. Tapping the powders and confirming powder compaction is key to producing a reproducible diagnostic tool.To begin prepare the microfluidic flow cell by coveri...