Showing 4 results for Microfluidics
Volume 13, Issue 4 (1-2023)
Abstract
Stem cells are characterized by their capacity for self-renewal and their ability to differentiate into specific cell types under the influence of their microenvironment. It is known that matrix chemistry controls stem cell differentiation. Single cell encapsulations of the Mesenchymal stem cells into a semi-permeable microgel, allows a greater control of the stem cell fate. In this study, a chip for single-cell encapsulation was designed and fabricated using microfluidic technology. By using microfluidic chip, human bone marrow mesenchymal stem cells (hBMSCs) are encapsulated inside alginate and alginate-poly-l lysine (PLL) microgels. The results of long-term viability of MSCs inside alginate-PLL microgels, shows a significant increase compared to alginate microgels. Mesenchymal stem cell proliferation in alginate-PLL microgels also increased significantly on days 14 and 21. It seems that PLL improves cell adhesion and function by creating a positively charged matrix. Microscopic studies indicate that the morphology of the cells inside the microgels is spherical. However, the average diameter and volume of cells in microgels containing PLL are smaller than others, which indicates more proliferation and space limitation inside the microgels. Therefore, single cell alginate-PLL microgels provide a suitable substrate in clinical studies for tissue engineering, organ transplantation and cell therapy.
M. Arvahi , S.gh. Masoudi , A. Mohammadi ,
Volume 19, Issue 4 (4-2019)
Abstract
Microfluidic chips in the last two decades have had significant advances in the analysis of interfacial tension phenomenon due to their many advantages. To analyze interfacial tension phenomena, droplet flow in microchannels can be used. In this study, water-n-hexane interfacial tension in the presence of surface-active agents was measured, using microfluidic tensiometry. For this purpose, a glass microfluidic flow-focusing junction was fabricated for generating n-hexane droplets within an aqueous phase. The dependence of droplet size on the concentration of surfactants has been investigated. A theoretical equation was developed, considering force balance on the droplet generation in the microfluidic device, giving a relation between the interfacial tension and the generated droplet sizes. By standardizing the microfluidic chips with the aid of a system, whose interfacial tension is known (hexane normal and tween 20 in distilled water), interfacial tension can be measured with measuring the size of produced droplets for other systems that can form droplets in the microchannel. In this study, the microfluidic device and the relation were employed to measure the interfacial tension in the presence of either of sodium dodecyl sulphate (SDS) or Cetyl trimethylammonium bromide (CTAB) surfactants. It was found that the measured interfacial tensions deviate less than 10% compared to those measured with a commercially available ring method.
Alireza Barani, Peiman Mosaddegh, Shaghayegh Haghjooy Javanmard, Shahrokh Sepehrirahnama,
Volume 21, Issue 10 (10-2021)
Abstract
These days, investigation on using acoustofluidic microchannels in separation of microparticles and cells is under consideration. Working under optimum efficiency, these microchannels should be designed and manufactured truly. In this work, a new methodology for designing and manufacturing of acoustofluidic microchannels are explained. Then, a metallic microchannel with 2-nodes of pressure wave based on this method was developed. For mass production purpose, a low cost and reliable method which is CNC micromachining is used. Also, to conduct the heat generated by the wave, this microchannel was made out of aluminum and then polishing technique is applied. Then, the performance of this microchannel in agglomerating of human blood cells and BT-20 breast cancer cells to nodal lines was experimentally studied. The results showed that the applied design and manufacturing technique are suitable. Although some tests were performed to find temperature rise of microchannel due to damping effect, it was found that true design method and also using metals with high thermal conductivity can prevent the temperature increase to the point beyond which living cells will be hurt.
Saeed Pourahmadian, Mohamad Ali Bijarchi,
Volume 24, Issue 7 (6-2024)
Abstract
The compound droplets resulting from water-in-oil-in-water emulsions have many applications, including in the food, pharmaceutical and cosmetic industries. Investigating the effective parameters in the production of these droplets plays an important role in their controlled production. In this numerical study, the production of compound droplets in a three-phase axisymmetric glass capillary microfluidic device is investigated. The structure of this system consists of two co-flow and one flow-focusing devices. In this study, the volume of fluid (VOF) method is used to solve the governing equations in different phases. 5 dimensionless parameters are selected to check the effect of each component on the diameter, the generation frequency, and the breakup length of the compound droplets. This study has successfully predicted the formation of compound droplets in the droplet regime. The simulation results show that with increasing the ratio of inner nozzle diameter to outer tube diameter, the core diameter enhances and the shell thickness decreases. By decreasing the angle of the inner nozzle tip, the drop regime changes to the jet regime. By increasing the contact angle of the middle phase with respect to the outer phase in the outer tube wall from 90 to 120 degrees, the frequency of droplet generation increases by 22%. The results of this study can be used for applications such as 3D cell culture.
