| 研究課題/領域番号 |
21K03884
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| 研究機関 | 沖縄科学技術大学院大学 |
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研究代表者 |
HAWARD Simon 沖縄科学技術大学院大学, マイクロ・バイオ・ナノ流体ユニット, グループリーダー (20812986)
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| 研究期間 (年度) |
2021-04-01 – 2024-03-31
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| キーワード | microfluidics / extensional flow / viscoelastic fluid / rheology |
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| 研究実績の概要 |
In FY2021 we have been endeavoring to fabricate a three-dimensional (3D) microfluidic device to impose uniaxial and biaxial extensional flows. Devices have been fabricated in glass by selective laser-induced etching, based on designs produced by a numerical optimization procedure. The fabricated devices have been imaged using x-ray micro-tomography, and the geometry of the fabrication has been compared to the target design. After several design/fabrication iterations, we achieved production of a highly precise geometry.
The fabricated device has been tested by measuring the velocity fields for Newtonian flow and comparing the results against numerical predictions in uniaxial and biaxial extension. Excellent agreement has been obtained.
Simultaneously to fabricating the microfluidic device, polymer solutions for viscoelastic flow experiments (to be conducted in FY2022) have been formulated. The 3D nature of the microfluidic device means that, for flow visualization, the solvent must have the same refractive index as the glass device. This is achieved with a mixture of 89.6% glycerol and 10.4% water. Conveniently, poly(acrylamide) readily dissolves in such a solvent. Viscoelastic poly(acrylamide) solutions with concentration in the range 0.005 to 0.04 wt% have been formulated and have been characterized by standard rheometrical methods to determine the shear viscosity and relaxation time.
Experiments are proceeding to determine the extensional viscosities of the poly(acrylamide) solutions in a pre-existing planar extensional flow microfluidic device.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
The project is progressing very well and on course with the proposed time-line. It was expected that the design and fabrication of the microfluidic device would be very complex and challenging. That was indeed the case, but with perseverance the task was successfully accomplished.
At the conclusion of FY2021, we have largely completed the tasks set out for the first year of our proposed research plan. We have fabricated a unique microfluidic device for the generation of uniaxial and biaxial extensional flows with controllable extensional rate. We also have a series of viscoelastic polymer solutions that will enable us to combine flow visualization and pressure drop measurements in order to quantify the extensional viscosity.
Pressure drop experiments to measure the planar extensional viscosity in a pre-existing (and well-characterized) two-dimensional (2D) microfluidic device are already underway and the results so far appear encouraging.
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| 今後の研究の推進方策 |
We are in a strong position to achieve the research objectives targeted in the second year of this project. In FY2022, first we will complete the measurements of the planar extensional viscosity of our polymer solutions in our 2D microfluidic device. Subsequently, we will test the polymer solutions in our new 3D microfluidic device using flow velocimetry to confirm the flow field, and specifically the extensional rates achieved in uniaxial and biaxial elongation. We will also measure the uniaxial and biaxial extensional viscosities in our new 3D device by making pressure drop measurements.
We aim to compare the extensional flow response of the polymer solutions in uniaxial, planar and biaxial extension in terms of extensional viscosity as a function of the imposed strain rate, and also non-dimensionalized in terms of the Trouton ratio and Weissenberg number. We anticipate that a comparison of the viscoelastic flow response in uniaxial, planar and biaxial extension will lead to significant new insights into polymer solution rheology.
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| 次年度使用額が生じた理由 |
There is a very small amount to be used next fiscal year due to slight underspend (just 673 JPY)
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