scholarly journals Micropipette-Based Microfluidic Device for Monodisperse Microbubbles Generation

Micromachines ◽  
2018 ◽  
Vol 9 (8) ◽  
pp. 387
Author(s):  
Carlos Toshiyuki Matsumi ◽  
Wilson José da Silva ◽  
Fábio Kurt Schneider ◽  
Joaquim Miguel Maia ◽  
Rigoberto E. M. Morales ◽  
...  
Keyword(s):  
Electric Fields ◽  
Microfluidic Device ◽  
Soft Lithography ◽  
Low Cost ◽  
Characteristic Curve ◽  
Microfluidic Devices ◽  
Average Diameter ◽  
Internal Diameter ◽  
Medical Diagnostic ◽  
Average Size

Microbubbles have various applications including their use as carrier agents for localized delivery of genes and drugs and in medical diagnostic imagery. Various techniques are used for the production of monodisperse microbubbles including the Gyratory, the coaxial electro-hydrodynamic atomization (CEHDA), the sonication methods, and the use of microfluidic devices. Some of these techniques require safety procedures during the application of intense electric fields (e.g., CEHDA) or soft lithography equipment for the production of microfluidic devices. This study presents a hybrid manufacturing process using micropipettes and 3D printing for the construction of a T-Junction microfluidic device resulting in simple and low cost generation of monodisperse microbubbles. In this work, microbubbles with an average size of 16.6 to 57.7 μm and a polydispersity index (PDI) between 0.47% and 1.06% were generated. When the device is used at higher bubble production rate, the average diameter was 42.8 μm with increased PDI of 3.13%. In addition, a second-order polynomial characteristic curve useful to estimate micropipette internal diameter necessary to generate a desired microbubble size is presented and a linear relationship between the ratio of gaseous and liquid phases flows and the ratio of microbubble and micropipette diameters (i.e., Qg/Ql and Db/Dp) was found.

scholarly journals A rapid-prototyped moulding system towards optimised scalable fabrication of elastomeric microfluidic devices

2021 ◽  
Author(s):  
Christine Poon ◽  
Albert Fahrenbach
Keyword(s):  
3D Printing ◽  
Microfluidic Device ◽  
Lean Manufacturing ◽  
Soft Lithography ◽  
Low Cost ◽  
Microfluidic Devices ◽  
Petri Dish ◽  
Device Fabrication ◽  
Alternative Techniques ◽  
Optimisation Techniques

3D printing and makerspace technologies are increasingly explored as alternative techniques to soft lithography for making microfluidic devices, and for their potential to segue towards scalable commercial fabrication. Here we considered the optimal application of current benchtop 3D printing for microfluidic device fabrication through the lens of lean manufacturing and present a straightforward but robust rapid prototyped moulding system that enables easy estimation of more precise quantities of polydimethylsiloxane (PDMS) required per device to reduce waste and importantly, making devices with better defined depths and volumes for (i) modelling gas exchange and (ii) fabrication consistency as required for quality-controlled production. We demonstrate that this low-cost moulding step can enable a 40 – 300% reduction in the amount of PDMS required for making individual devices compared to the established method of curing approximately 30 grams of PDMS prepolymer overlaid on a 4” silicon wafer master in a standard plastic petri dish. Other process optimisation techniques were also investigated and are recommended as readily implementable changes to current laboratory and foundry-level microfluidic device fabrication protocols for making devices either out of PDMS or other elastomers. Simple calculators are provided as a step towards more streamlined, software controlled and automated design-to-fabrication workflows for both custom and scalable lean manufacturing of microfluidic devices.

scholarly journals A rapid-prototyped moulding system towards optimised scalable fabrication of elastomeric microfluidic devices

2021 ◽  
Author(s):  
Christine Poon ◽  
Albert Fahrenbach
Keyword(s):  
3D Printing ◽  
Microfluidic Device ◽  
Lean Manufacturing ◽  
Soft Lithography ◽  
Low Cost ◽  
Microfluidic Devices ◽  
Petri Dish ◽  
Device Fabrication ◽  
Alternative Techniques ◽  
Optimisation Techniques

3D printing and makerspace technologies are increasingly explored as alternative techniques to soft lithography for making microfluidic devices, and for their potential to segue towards scalable commercial fabrication. Here we considered the optimal application of current benchtop 3D printing for microfluidic device fabrication through the lens of lean manufacturing and present a straightforward but robust rapid prototyped moulding system that enables easy estimation of more precise quantities of polydimethylsiloxane (PDMS) required per device to reduce waste and importantly, making devices with better defined depths and volumes for (i) modelling gas exchange and (ii) fabrication consistency as required for quality-controlled production. We demonstrate that this low-cost moulding step can enable a 40 – 300% reduction in the amount of PDMS required for making individual devices compared to the established method of curing approximately 30 grams of PDMS prepolymer overlaid on a 4” silicon wafer master in a standard plastic petri dish. Other process optimisation techniques were also investigated and are recommended as readily implementable changes to current laboratory and foundry-level microfluidic device fabrication protocols for making devices either out of PDMS or other elastomers. Simple calculators are provided as a step towards more streamlined, software controlled and automated design-to-fabrication workflows for both custom and scalable lean manufacturing of microfluidic devices.

A Very Low-Cost, Labor-Efficient, and Simple Method to Block Scattered Ultraviolet Light in PDMS Microfluidic Devices by Inserting Aluminum Foil Strips

2018 ◽  
Vol 11 (1) ◽  
Author(s):  
Shuo Wang ◽  
Peter Shankles ◽  
Scott Retterer ◽  
Yong Tae Kang ◽  
Chang Kyoung Choi
Keyword(s):  
Soft Lithography ◽  
Uv Light ◽  
Low Cost ◽  
Microfluidic Devices ◽  
Aluminum Foil ◽  
Material Synthesis ◽  
Simple Method ◽  
Micro Particles ◽  
Complex Shapes ◽  
The Cost

Abstract Opto-microfluidic methods have advantages for manufacturing complex shapes or structures of micro particles/hydrogels. Most of these microfluidic devices are made of polydimethylsiloxane (PDMS) by soft lithography because of its flexibility of designing and manufacturing. However, PDMS scatters ultraviolet (UV) light, which polymerizes the photocrosslinkable materials at undesirable locations and clogs the microfluidic devices. A fluorescent dye has previously been employed to absorb the scattered UV light and shift its wavelength to effectively solve this issue. However, this method is limited due to the cost of the materials (tens of dollars per microchip), the time consumed on synthesizing the fluorescent material and verifying its quality (two to three days). More importantly, significant expertise on material synthesis and characterization is required for users of the opto-microfluidic technique. The cost of preliminary testing on multiple iterations of different microfluidic chip designs would also be excessive. Alternatively, with a delicate microchannel design, we simply inserted aluminum foil strips (AFS) inside the PDMS device to block the scattered UV light. By using this method, the UV light was limited to the exposure region so that the opto-microfluidic device could consistently generate microgels longer than 6 h. This is a nearly cost- and labor-free method to solve this issue.

scholarly journals Low Cost Micro Milling Machine for Prototyping Plastic Microfluidic Devices

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 707 ◽  
Author(s):  
Md Mubarak Hossain ◽  
Tanzilur Rahman
Keyword(s):  
Developing Countries ◽  
Microfluidic Device ◽  
Low Cost ◽  
Microfluidic Devices ◽  
Micro Milling ◽  
Biological Research ◽  
Milling Machine ◽  
Plastic Materials ◽  
Milling Machines

Micro-milling is one of the commonly used methods of fabrication of microfluidic devices necessary for cell biological research and application. Commercial micro-milling machines are expensive, and researchers in developing countries can’t afford them. Here, we report the design and the development of a low-cost (<130 USD) micro milling machine and asses the prototyping capabilities of microfeatures in plastic materials. We demonstrate that the developed machine can be used in fabricating the plastic based microfluidic device.

Chemotaxis of Mesenchymal Stem Cells in a Microfluidic Device

2012 ◽  
Vol 1498 ◽  
pp. 67-72
Author(s):  
Ruth Choa ◽  
Manav Mehta ◽  
Kangwon Lee ◽  
David Mooney
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Microfluidic Device ◽  
Soft Lithography ◽  
Center Of Mass ◽  
Cell Movement ◽  
Microfluidic Devices ◽  
Chemokine Gradient ◽  
Long Time ◽  
Stable Linear

ABSTRACTAdult bone marrow derived mesenchymal stem cells (MSCs) represent an important source of cells for tissue regeneration. Control of MSC migration and homing is still unclear. The goal of this study was to identify potent chemoattractants for MSCs and characterize MSC chemotaxis using a microfluidic device as a model system and assay platform. The three chemokines compared in this study were CXCL7, CXCL12, and AMD 3100.Microfluidic devices made of polydimethysiloxane (PDMS) were fabricated by soft lithography techniques and designed to generate a stable linear chemokine gradient. Cell movements in response to the gradient were captured by timelapse photos and tracked over 24 hours. Chemokine potency was measured via several chemotaxis parameters including: velocity in the direction of interest (V), center of mass (Mend), forward migration indice (YFMI). The migratory paths of the cells were mapped onto a displacement plot and compared.The following results were measured in the direction of interest (towards higher concentrations of chemokine): For velocity, only cells exposed to CXCL12 had a statistically significant (p=.014) average velocity (V=0.19 ± 0.07 um/min) when compared to the control condition (V=0.06 ±0 .04 um/min). For the center of mass, where the displacement of cells from their starting positions were compared, again only CXCL12 (Mend= 53.9 ± 10.8 um) stimulated statistically significant (p = .013) displacement of cells compared to the control condition (Mend = 19.3 ± 16.1 um). For the forward migration index, the efficiency of cell movement was measured. Indices in both the CXCL12 (YFIM = 0.19 ± 0.08) and CXCL7 (YFIM = 0.09 ±0.03) conditions were statistically significant (p = .023 for CXCL12 and p = .035 for CXCL7) when compared with the control index (YFIM = .04 ± .02).This study demonstrated the use of microfluidic devices as a viable platform for chemotaxis studies. A stable linear chemokine gradient was maintained over a long time scale to obtain cell migration results. CXCL12 was quantitatively determined to be the most potent chemoattractant in this research; these chemoattractive properties promote its use in future developments to control MSC homing.

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.

Method for Characterization of Passive Mechanical Filtration of Particles in Digital Microfluidic Devices

2014 ◽  
Author(s):  
Peter D. Dunning ◽  
Pierre E. Sullivan ◽  
Michael J. Schertzer
Keyword(s):  
Microfluidic Device ◽  
Vision System ◽  
Low Cost ◽  
Digital Microfluidics ◽  
Microfluidic Devices ◽  
Comb Filter ◽  
Enzyme Linked Immunosorbent Assay ◽  
Reaction Site ◽  
Digital Microfluidic

The ability to remove unbound biological material from a reaction site has applications in many biological protocols, such as those used to detect pathogens and biomarkers. One specific application where washing is critical is the Enzyme-Linked ImmunoSorbent Assay (ELISA). This protocol requires multiple washing steps to remove multiple reagents from a reaction site. Previous work has suggested that a passive mechanical comb filter can be used to wash particles in digital microfluidic devices. A method for the characterization of passive mechanical filtration of particles in Digital MicroFluidic (DMF) devices is presented in this work. In recent years there has been increased development of Lab-On-A-Chip (LOAC) devices for the automation and miniaturization of biological protocols. One platform for further research is in digital microfluidics. A digital microfluidic device can control the movement of pico-to nanoliter droplets of fluid using electrical signals without the use of pumps, valves, and channels. As such, fluidic pathways are not hardwired and the path of each droplet can be easily reconfigured. This is advantageous in biological protocols requiring the use of multiple reagents. Fabrication of these devices is relatively straight forward, since fluid manipulation is possible without the use of complex components. This work presents a method to characterize the performance of a digital microfluidic device using passive mechanical supernatant dilution via image analysis using a low cost vision system. The primary metric for performance of the device is particle retention after multiple passes through the filter. Repeatability of the process will be examined by characterizing performance of multiple devices using the same filter geometry. Qualitative data on repeatability and effectiveness of the dilution technique will also be attained by observing the ease with which the droplet disengages from the filter and by measuring the quantity of fluid trapped on the filter after each filtration step.

scholarly journals In situ thermal decomposition route: Preparation and characterization of nano nickel, cobalt, and copper oxides using an aromatic amine complexes as a low-cost simple precursor

2021 ◽  
Vol 23 (2) ◽  
pp. 47-53
Author(s):  
Moamen S. Refat ◽  
Soha F. Mohamed ◽  
Tariq A. Altalhi ◽  
Safyah B. Bakare ◽  
Ghaferah H. Al-Hazmi
Keyword(s):  
Thermal Decomposition ◽  
Lattice Structure ◽  
Low Cost ◽  
Average Diameter ◽  
Face Centered Cubic ◽  
Spinel Type ◽  
X Ray ◽  
Ft Ir ◽  
Xrd Patterns ◽  
Average Size

Abstract The main interest now is the development of metallic or inorganic-organic compounds to prepare nanoparticle materials. The use of new compounds could be beneficial and open a new method for preparing nanomaterials to control the size, shape, and size of the nanocrystals. In this article, the thermal decomposition of [M2(o-tol)2(H2O)8] Cl4 (where o-tol is ortho-tolidine compound, M = Ni2+, Co2+, Cu2+) new precursor complex was discussed in solid-state conditions. The thermal decomposition route showed that the synthesized three complexes were easily decomposed into NiO, Co3O4 and CuO nanoparticles. This decomposition was performed at low temperatures (~600°C) in atmospheric air without using any expensive and toxic solvent or complicated equipment. The obtained product was identified by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX). FT-IR, XRD and EDX analyses revealed that the NiO nanoparticles exhibit a face-centered-cubic lattice structure with a crystallite size of 9–12 nm. The formation of a highly pure spinel-type Co3O4 phase with cubic structure showed that the Co3O4 nanoparticles have a sphere-like morphology with an average size of 8–10 nm. The XRD patterns of the CuO confirmed that the monoclinic phase with the average diameter of the spherical nanoparticles was approximately 9–15 nm.

A Low Cost Fabrication Method for Electrowetting Assisted Desiccation of Colloidal Droplets

2017 ◽  
Author(s):  
Xi Li ◽  
Kara L. Maki ◽  
Michael J. Schertzer
Keyword(s):  
Electric Fields ◽  
Contact Line ◽  
Elevated Temperatures ◽  
Low Cost ◽  
Contact Angle Hysteresis ◽  
Debye Length ◽  
Particle Diffusion ◽  
Colloidal Transport ◽  
Coffee Ring ◽  
Medical Diagnostic

When colloidal droplets evaporate, material is often deposited at the periphery in a coffee-ring pattern. An understanding of colloidal transport and deposition in evaporating droplets is critical for optimization of many medical diagnostic devices and printing processes. This phenomenon can also be used for nanoparticle self-assembly, containerless materials processing, and manufacturing of flexible electronics. The forces affecting colloidal transport can be categorized as (i) convective effects, (ii) particle diffusion, and (iii) boundary effects. Knowledge of fluid flow in an evaporating droplet is required to understand particle transport when convection effects dominate over particle diffusion. The evaporative radial flow identified by Deegan et al. [1] is the result of contact line pinning and high evaporation flux at the contact line. Hu and Larson later identified that dominance of thermal Marangoni recirculation within the droplet can suppress ring formations by convecting particles to the center of the deposition. Bhardwaj et al. [2] demonstrated that van der Walls and electrostatic forces can dominate colloidal transport and capture particles on the substrate to form uniform depositions. These effects are represented by the Derjaguin, Verwey, and Overbeek (DLVO) force. This force can attract or repel particles from the surface or other particles when they are separated by less than the Debye length. Attractive DLVO forces result in uniform depositions when they dominate over the evaporative and Marangoni flows in evaporating droplets. Particle capture on the substrate has also been achieved by antibodies-antigen reactions, or by leveraging magnetic and electrophoretic forces. Particles can also be captured on the interface of evaporating droplets. Li et al. [3] observed uniform colloidal monolayers when water droplets were evaporated at elevated temperatures. They argued that particles were being captured on the interface in these cases as the particle diffusion rate was smaller than the velocity of the collapsing interface. This work will find a low cost method for electrowetting assisted deposition and examine how electric fields can disrupt the interplay between convection, diffusion, and interface trapping in evaporating colloidal droplets. Application of AC and DC electric fields has the potential to suppress the coffee-ring effect by independently controlling the shape of the fluid interface, the contact angle hysteresis, and the motion of particles suspended in the droplet. This investigation will compare the interfacial evolution and deposition patterns left by evaporating protein laden droplets under AC and DC fields to examine their suitability for medical diagnostic applications.

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