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 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.
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' 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.
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…
The authors have nothing to disclose.
None.
µ-Slide I Luer | ibidi | 80191 | Microfluidic flow cell |
Beaker | Southern Labware | BG1000-800 | Glassware |
CALIBRE 301-58 LT Natural Polycarbonate Resin | TRINSEO LLC | CALIBRETM 301-58 LT | Natural polycarbonate resin |
Ethanol | Sigma Aldrich | 1.00983 | Solvent |
Fume Hood | Kewaunee | Supreme Air LV Fume Hoods | Used with 92 FPM at 18" opening |
iPhone 7 plus | Apple | Camera | |
Opaque 3D printed material | The CAD drawing is provided in the supplemental file | ||
ORGASOL 2002 ES 6 NAT 3 | ARKEMA | A12135 | Polyamide powder |
Pipet | VWR | 10754-268 | Disposable Transfer Pipet |
Pipette | Globe Scientific Inc. | 3301-200 | Pipette that can hold 125 µL of fluid |
Polystyrene | Advanced Laser Materials, LLC. | PS200 | Polystyrene for sintering |
Tracker | Video analysis and modeling tool | ||
VariQuest 100 White Light Model 3-3700 | FOTODYNE | 3-3700 | White light |
Water | Distilled water |