Limits...
A "twisted" microfluidic mixer suitable for a wide range of flow rate applications.

Sivashankar S, Agambayev S, Mashraei Y, Li EQ, Thoroddsen ST, Salama KN - Biomicrofluidics (2016)

Bottom Line: The efficiency of mixing was calculated within the channel by acquiring intensities using ImageJ software.Results suggested that efficient mixing can be obtained when more than 3 units were consecutively placed.The geometry of the device, which has a length of 30 mm, enables the device to be integrated with micro total analysis systems and other lab-on-chip devices.

View Article: PubMed Central - PubMed

Affiliation: Computer, Electrical and Mathematical Science and Engineering Division (CEMSE), King Abdullah University of Science and Technology (KAUST) , Thuwal, Saudi Arabia.

ABSTRACT
This paper proposes a new "twisted" 3D microfluidic mixer fabricated by a laser writing/microfabrication technique. Effective and efficient mixing using the twisted micromixers can be obtained by combining two general chaotic mixing mechanisms: splitting/recombining and chaotic advection. The lamination of mixer units provides the splitting and recombination mechanism when the quadrant of circles is arranged in a two-layered serial arrangement of mixing units. The overall 3D path of the microchannel introduces the advection. An experimental investigation using chemical solutions revealed that these novel 3D passive microfluidic mixers were stable and could be operated at a wide range of flow rates. This micromixer finds application in the manipulation of tiny volumes of liquids that are crucial in diagnostics. The mixing performance was evaluated by dye visualization, and using a pH test that determined the chemical reaction of the solutions. A comparison of the tornado-mixer with this twisted micromixer was made to evaluate the efficiency of mixing. The efficiency of mixing was calculated within the channel by acquiring intensities using ImageJ software. Results suggested that efficient mixing can be obtained when more than 3 units were consecutively placed. The geometry of the device, which has a length of 30 mm, enables the device to be integrated with micro total analysis systems and other lab-on-chip devices.

No MeSH data available.


Related in: MedlinePlus

Mixing efficiency at different flow rates. (a) The flow of fluid in the tornado mixer at 1.0 ml/min. (b) The flow of fluid in the twisted mixer at 1.0 ml/min. Enlarged images of the selected sections are representative of the fluid flow within the channel.
© Copyright Policy - ccc - open
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4930447&req=5

f6: Mixing efficiency at different flow rates. (a) The flow of fluid in the tornado mixer at 1.0 ml/min. (b) The flow of fluid in the twisted mixer at 1.0 ml/min. Enlarged images of the selected sections are representative of the fluid flow within the channel.

Mentions: These micromixers can operate at low (1.0 μl/min) and high (1.0 ml/min) flow rates without disturbances in the mixing phenomenon. The flow quality is not negatively affected by the increasing flow rate, which would usually have an effect on lower mixing efficiency in the high flow rates.20 In order to demonstrate that the micromixers can operate with a wide range of flow rates, from 1.0 μl/min to 100.0 μl/min, a dye test was performed, and mixing was quantified using the above calculations. The mean grayscale values of the selected region were retrieved using ImageJ software. The mixing efficiency increased with the increase in units, which were arranged in a consecutive manner up to six units. After passing through the six units, the mixing phenomenon seemed to stabilize. The mixing of fluids in each unit at different flow rates is depicted in Fig. 6(a). The flow in the mixers was stable even at the high flow rates, while in some micromixers the mixing efficiency tended to be reduced in stability with the increasing flow rate.21 Steady flows were observed for flow rates from 1.0 to 1000.0 μl/min. The efficiency of mixing with the tornado mixer was also compared; the flow of fluids within the mixer is represented in Fig. 6(b). The additional channel within the mixer units provided lower resistance to the fluids passing through the mixer, and could therefore have been the reason for the low mixing efficiency. The fluid completely filled the units and the change in intensity of the color at 1.0 ml/min is shown in Fig. 6(c). At the higher flow rates, the molecules did not have sufficient time to mix through molecular diffusion; hence, the efficiency of mixing was greatly reduced compared to the low flow rates. In the present mixer, at 1.0 μl/min, the efficiency of the mixer was 0.80 after the first unit, as the diffusion of molecules had occurred and the fluids had traveled a relatively long distance to obtain that efficiency. It was also seen that the mixing efficiency of the tornado mixer increased slowly. However, despite the 3D configuration of the tornado chip, only its arcs are single layered, whereas the center-connecting channels are in two layers. It was here observed that the fluids tended to flow separately in the top and bottom layers, rather than swiftly up-and-down as observed in the twisted channel. This caused an error in the color intensity measurement, possibly due to the camera being unable to accurately obtain the true color intensity near the mid-plane region, where the majority of diffusion occurred. Consequently, the mixing efficiency of the tornado chip was expected to be undervalued; however, it remained lower than the efficiency of the twisted mixer. In examining the twisted mixer, it was obvious that with the addition of mixing units increased the mixing efficiency; after approximately five units, the mixing efficiency stabilized, indicating the fluids were well mixed (50% of each inlet), as observed in the simulation results. The splitting/recombining configuration of the microchannel generated vortices at moderate Re numbers; this may have been the reason for the high mixing efficiency of the twisted micromixers. A mixer that can operate at a wide range of flow rates could be integrated into a variety of applications that require high flow rates, such as microfluidic filtration,46 and applications that require low flow rates, such as cell cultures or vasculature on a chip.47 Therefore, this mixer is a possible device for the above applications.


A "twisted" microfluidic mixer suitable for a wide range of flow rate applications.

Sivashankar S, Agambayev S, Mashraei Y, Li EQ, Thoroddsen ST, Salama KN - Biomicrofluidics (2016)

Mixing efficiency at different flow rates. (a) The flow of fluid in the tornado mixer at 1.0 ml/min. (b) The flow of fluid in the twisted mixer at 1.0 ml/min. Enlarged images of the selected sections are representative of the fluid flow within the channel.
© Copyright Policy - ccc - open
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4930447&req=5

f6: Mixing efficiency at different flow rates. (a) The flow of fluid in the tornado mixer at 1.0 ml/min. (b) The flow of fluid in the twisted mixer at 1.0 ml/min. Enlarged images of the selected sections are representative of the fluid flow within the channel.
Mentions: These micromixers can operate at low (1.0 μl/min) and high (1.0 ml/min) flow rates without disturbances in the mixing phenomenon. The flow quality is not negatively affected by the increasing flow rate, which would usually have an effect on lower mixing efficiency in the high flow rates.20 In order to demonstrate that the micromixers can operate with a wide range of flow rates, from 1.0 μl/min to 100.0 μl/min, a dye test was performed, and mixing was quantified using the above calculations. The mean grayscale values of the selected region were retrieved using ImageJ software. The mixing efficiency increased with the increase in units, which were arranged in a consecutive manner up to six units. After passing through the six units, the mixing phenomenon seemed to stabilize. The mixing of fluids in each unit at different flow rates is depicted in Fig. 6(a). The flow in the mixers was stable even at the high flow rates, while in some micromixers the mixing efficiency tended to be reduced in stability with the increasing flow rate.21 Steady flows were observed for flow rates from 1.0 to 1000.0 μl/min. The efficiency of mixing with the tornado mixer was also compared; the flow of fluids within the mixer is represented in Fig. 6(b). The additional channel within the mixer units provided lower resistance to the fluids passing through the mixer, and could therefore have been the reason for the low mixing efficiency. The fluid completely filled the units and the change in intensity of the color at 1.0 ml/min is shown in Fig. 6(c). At the higher flow rates, the molecules did not have sufficient time to mix through molecular diffusion; hence, the efficiency of mixing was greatly reduced compared to the low flow rates. In the present mixer, at 1.0 μl/min, the efficiency of the mixer was 0.80 after the first unit, as the diffusion of molecules had occurred and the fluids had traveled a relatively long distance to obtain that efficiency. It was also seen that the mixing efficiency of the tornado mixer increased slowly. However, despite the 3D configuration of the tornado chip, only its arcs are single layered, whereas the center-connecting channels are in two layers. It was here observed that the fluids tended to flow separately in the top and bottom layers, rather than swiftly up-and-down as observed in the twisted channel. This caused an error in the color intensity measurement, possibly due to the camera being unable to accurately obtain the true color intensity near the mid-plane region, where the majority of diffusion occurred. Consequently, the mixing efficiency of the tornado chip was expected to be undervalued; however, it remained lower than the efficiency of the twisted mixer. In examining the twisted mixer, it was obvious that with the addition of mixing units increased the mixing efficiency; after approximately five units, the mixing efficiency stabilized, indicating the fluids were well mixed (50% of each inlet), as observed in the simulation results. The splitting/recombining configuration of the microchannel generated vortices at moderate Re numbers; this may have been the reason for the high mixing efficiency of the twisted micromixers. A mixer that can operate at a wide range of flow rates could be integrated into a variety of applications that require high flow rates, such as microfluidic filtration,46 and applications that require low flow rates, such as cell cultures or vasculature on a chip.47 Therefore, this mixer is a possible device for the above applications.

Bottom Line: The efficiency of mixing was calculated within the channel by acquiring intensities using ImageJ software.Results suggested that efficient mixing can be obtained when more than 3 units were consecutively placed.The geometry of the device, which has a length of 30 mm, enables the device to be integrated with micro total analysis systems and other lab-on-chip devices.

View Article: PubMed Central - PubMed

Affiliation: Computer, Electrical and Mathematical Science and Engineering Division (CEMSE), King Abdullah University of Science and Technology (KAUST) , Thuwal, Saudi Arabia.

ABSTRACT
This paper proposes a new "twisted" 3D microfluidic mixer fabricated by a laser writing/microfabrication technique. Effective and efficient mixing using the twisted micromixers can be obtained by combining two general chaotic mixing mechanisms: splitting/recombining and chaotic advection. The lamination of mixer units provides the splitting and recombination mechanism when the quadrant of circles is arranged in a two-layered serial arrangement of mixing units. The overall 3D path of the microchannel introduces the advection. An experimental investigation using chemical solutions revealed that these novel 3D passive microfluidic mixers were stable and could be operated at a wide range of flow rates. This micromixer finds application in the manipulation of tiny volumes of liquids that are crucial in diagnostics. The mixing performance was evaluated by dye visualization, and using a pH test that determined the chemical reaction of the solutions. A comparison of the tornado-mixer with this twisted micromixer was made to evaluate the efficiency of mixing. The efficiency of mixing was calculated within the channel by acquiring intensities using ImageJ software. Results suggested that efficient mixing can be obtained when more than 3 units were consecutively placed. The geometry of the device, which has a length of 30 mm, enables the device to be integrated with micro total analysis systems and other lab-on-chip devices.

No MeSH data available.


Related in: MedlinePlus