Observing Fluid Flow Through Carbon Nanotube Arrays and Nanoporous Membranes

2017 ◽  
Author(s):  
Anna Jensen ◽  
Michael G. Schrlau
Keyword(s):  
Fluid Flow ◽  
Fluid Transport ◽  
High Efficiency ◽  
Nanoporous Membranes ◽  
Intensity Measurements ◽  
Alumina Oxide ◽  
Cnt Arrays ◽  
3D Printed ◽  
Vertically Aligned ◽  
Flow Through

Arrays of carbon nanotubes (CNTs) have shown significant promise for delivering biomolecules into cells with high efficiency and low toxicity. In these applications, biomolecules are flowed from a large fluid reservoir, through the lumens of vertically-aligned, open-ended CNTs, and into cells cultured over top of the CNTs on the other side. Over the course of several transfection experiments, it was discovered that biomolecule delivery varied considerably depending on the type of biomolecule being delivered. It was also inferred that the number of CNTs the cells covered would affect the transfection rate. In this work, an experiment was designed and conducted to visually characterize fluid flow through these CNT arrays and other nanoporous membranes. The experiment utilizes a 3D printed flow device consisting of anodized alumina oxide (AAO) membranes and restricts flow to a predefined circular area. Flow data was taken by measuring the intensity of fluorescent dye as it diffused through the AAO membrane. The intensity measurements were then plotted as a function of time from which diffusion times constants were calculated. This work establishes a platform technique for visualizing fluid transport through AAO membranes, which can be applied to CNT arrays, and allow for the testing of the effects of other parameters on flow.

Hydraulic Conductivity in Trunk Xylem of Elm, Ulmus Americana

IAWA Journal ◽  
1985 ◽  
Vol 6 (4) ◽  
pp. 303-307 ◽  
Author(s):  
George S. Ellmore ◽  
Frank W. Ewers
Keyword(s):  
Fluid Flow ◽  
Hydraulic Conductivity ◽  
Fluid Transport ◽  
Growth Ring ◽  
Theoretical Calculations ◽  
Transport Pathway ◽  
Growth Rings ◽  
Ulmus Americana ◽  
Xylem Transport ◽  
Flow Through

The notion that most xylem transport in stems of ring-porous trees occurs in the outermost growth ring requires experimental support. Significance of this ring is challenged by workers who find tracer dyes appearing in 4 to 8 growth rings rather than in only the outermost increment. We test the hypothesis that the outermost growth ring is of overriding significance in fluid transport through stems of Ulmus, a ring-porous tree. Fluid flow through the outermost ring was quantified by removing that ring, calculating gravity flow rates (hydraulic conductivity at 10.13 kPa m-1 ), and by tracing the transport pathway through control and experimental stem segments. From measurements corroborating theoretical calculations based on Poiseuille's law, over 90% of fluid flow through the stem occurs through the outermost ring. Remaining rings combine to account for less than 10% of xylem transport. As a result of dependence upon transport in the most superficial xylem, ring-porous trees such as elm, oak, ash, and chestnut are particularly susceptible to xylem pathogens entering from the bark.

Facilitating Fluid Flow Through Carbon Nanotube Arrays Using 3D Printing

2017 ◽  
Author(s):  
Travis S. Emery ◽  
Anna Jensen ◽  
Koby Kubrin ◽  
Michael G. Schrlau
Keyword(s):  
Carbon Nanotube ◽  
3D Printing ◽  
Microfluidic Device ◽  
Low Cost ◽  
Microfluidic Devices ◽  
Nanotube Arrays ◽  
Nanotube Array ◽  
Cnt Arrays ◽  
3D Printed ◽  
Flow Through

Three-dimensional (3D) printing is a novel technology whose versatility allows it to be implemented in a multitude of applications. Common fabrication techniques implemented to create microfluidic devices, such as photolithography, wet etching, etc., can often times be time consuming, costly, and make it difficult to integrate external components. 3D printing provides a quick and low-cost technique that can be used to fabricate microfluidic devices in a range of intricate geometries. External components, such as nanoporous membranes, can additionally be easily integrated with minimal impact to the component. Here in, low-cost 3D printing has been implemented to create a microfluidic device to enhance understanding of flow through carbon nanotube (CNT) arrays manufactured for gene transfection applications. CNTs are an essential component of nanofluidic research due to their unique mechanical and physical properties. CNT arrays allow for parallel processing however, they are difficult to construct and highly prone to fracture. As a means of aiding in the nanotube arrays’ resilience to fracture and facilitating its integration into fluidic systems, a 3D printed microfluidic device has been constructed around these arrays. Doing so greatly enhances the robustness of the system and additionally allows for the nanotube array to be implemented for a variety of purposes. To broaden their range of application, the devices were designed to allow for multiple isolated inlet flows to the arrays. Utilizing this multiple inlet design permits distinct fluids to enter the array disjointedly. These 3D printed devices were in turn implemented to visualize flow through nanotube arrays. The focus of this report though, is on the design and fabrication of the 3D printed devices. SEM imaging of the completed device shows that the nanotube array remains intact after the printing process and the nanotubes, even those within close proximity to the printing material, remain unobstructed. Printing on top of the nanotube arrays displayed effective adhesion to the surface thus preventing leakage at these interfaces.

scholarly journals Fluid flow through 3D-printed particle beds: a new technique for understanding, validating, and improving predictability of permeability from empirical equations

2020 ◽  
Vol 134 (1) ◽  
pp. 1-40
Author(s):  
Sondre Gjengedal ◽  
Vegard Brøtan ◽  
Ole T. Buset ◽  
Erik Larsen ◽  
Olav Å. Berg ◽  
...  
Keyword(s):  
Porous Media ◽  
Fluid Flow ◽  
Flow Regime ◽  
Flow Behavior ◽  
Ct Imaging ◽  
3D Technology ◽  
Geometrical Properties ◽  
3D Printed ◽  
Flow Through ◽  
Forchheimer Flow

AbstractThe application of 3D technology for fabrication of artificial porous media samples improves porous media flow studies. The geometrical characteristics of a porous media pore channel: the channel shape, size, porosity, specific surface, expansion ratio, contraction ratio, and the tortuous pathway of the channel can be controlled through advanced additive manufacturing techniques (3D printing), computed tomography imagery (CT imaging) and image analysis methods. These 3D technologies have here been applied to construct and analyze four homogeneous porous media samples with predefined geometrical properties that are otherwise impossible to construct with conventional methods. Uncertainties regarding the geometrical properties are minimized because the 3D-printed porous media samples can be evaluated with CT imaging after fabrication. It is this combination of 3D technology that improves the data acquisition and data interpretation and contributes to new insight into the phenomenon of fluid flow through porous media. The effects of the individual geometrical properties on the fluid flow are then accounted for in permeability experiments in a Hassler flow cell. The results of the experimental work are used to test the theoretical foundation of the Kozeny–Carman equation and the extended version known as the Ergun equation. These equations are developed from analogies to the Hagen–Poiseuille flow equation. Based on the results from the laboratory experiments in this study, an analytical equation based on the analytical Navier–Stokes equations is presented as an alternative to the Hagen–Poiseuille analogy for porous media channels with non-uniform channel geometries. The agreement between experiment and the new equation reveals that the dissipating losses of mechanical energy in porous media flows are not a result of frictional shear alone. The mechanical losses are also a result of pressure dissipation that arise due to the non-uniformity of the channel geometry, which induced spatial variations to the strain rate field and induce acceleration of the velocity field in the flow through the porous medium. It is this acceleration that causes a divergence from linear flow conditions as the Stokes flow criterion (Re ≪ 1) is breached and causes the convective acceleration term to affect the flow behavior. The suggested modifications of theory and the presented experiments prove that the effects of surface roughness (1) do not alter the flow behavior in the Darcy flow regime or (2) in the Forchheimer flow regime. This implies that the flow is still laminar for the Forchheimer flow velocities tested.

Characterization of Capillary Flow Within a Homogenously Dispersed Array of Vertical Micropillars

2010 ◽  
Author(s):  
Conan Zhang ◽  
Carlos H. Hidrovo
Keyword(s):  
Fluid Flow ◽  
Analytical Solution ◽  
Analytical Model ◽  
Capillary Flow ◽  
Capillary Forces ◽  
Auxiliary Equipment ◽  
Geometric Conditions ◽  
Wick Structure ◽  
Vertically Aligned ◽  
Flow Through

When considering fluidic devices at the micron length scale, surface tension forces become dominant relative to body forces. Albeit smaller than mechanical and electrical pumps, capillary forces are commonly exploited as a mechanism to drive fluid flow. Unlike pumps, capillary driven flows are passive in nature and are not dependent on auxiliary equipment to drive fluid flow. Although beneficial from an energy standpoint, the lack of a supplementary driving potential causes the flow to be limited by the wick structure dimensions that generate the capillary forces. Subsequently, investigation into the contributions of the wick structure must be performed in order to optimize the fluid flow through a capillary structure. General capillary theory states that capillary forces increase inversely proportional to the pore radius. Consequently, arrays of vertically aligned nanopillars grown on silicon substrates are considered for fluid flow optimization due to their small pores. To simulate these nanopillars, an ab initio analysis was done on a homogenously dispersed array of vertically aligned pillars. An analytical solution to predict the maximum achievable capillary flow with respect to the structure dimensions was found through this method. Subsequently, this analytical solution can be used to produce a set of optimal geometric conditions that would induce the maximum capillary flow through a wick comprised of vertically aligned pillars. Experimental results are also presented to validate the analytical solution. Homogeneously dispersed cylindrical pillars were created on silicon wafers via reactive ion etching to reconstruct the geometry assumed by the analytical solution. The capillary limit was found for structures with varying geometric dimensions. By contrasting the empirical data with the values predicted by the analytical model, the validity of the analytical model was found to be in good agreement.

STABILITY OF COUPLE STRESS FLUID FLOW THROUGH A HORIZONTAL POROUS LAYER

2016 ◽  
Vol 19 (5) ◽  
pp. 391-404 ◽  
Author(s):  
B. M. Shankar ◽  
I. S. Shivakumara ◽  
Chiu-On Ng
Keyword(s):  
Fluid Flow ◽  
Porous Layer ◽  
Couple Stress ◽  
Couple Stress Fluid ◽  
Flow Through
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