CN-122021451-A - Microfluidic pipeline design method for generating constant tensile force by utilizing variable-section pipeline

CN122021451ACN 122021451 ACN122021451 ACN 122021451ACN-122021451-A

Abstract

The invention provides a design method of a microfluidic pipeline for generating constant stretching force by utilizing a variable-section pipeline, which is characterized in that the microfluidic pipeline designed according to the invention forms a stretching strain rate field with uniform spatial distribution in a shrinkage area, and the problem that the stretching force is changed severely along with the position in the traditional linear shrinkage pipeline is solved. The structure ensures that the stretching force of the target object on different positions of the pipeline is basically kept constant, thereby greatly reducing the requirement on the positioning precision of the observation area, effectively eliminating the systematic error caused by the difference of sampling positions and obviously improving the accuracy of biomechanical characterization. On the basis of an ideal flow model, the invention further combines the channel depth-width ratio parameter, and compensates the flow distortion caused by the sidewall viscosity effect under the microscale through structural correction. The geometric optimization method based on the actual flow characteristics remarkably improves the spatial uniformity of the tensile force field, and is particularly suitable for the flow channel structures, such as shallow channels, which are easily affected by the three-dimensional boundary effect.

Inventors

LUO HAO
FENG ZHE
LIU YANAN
JING GUANGYIN
FENG WEI

Assignees

西北大学

Dates

Publication Date: 20260512
Application Date: 20260212

Claims (8)

1. A method of microfluidic pipeline design using variable cross-section tubing to produce a constant tensile force, the method comprising: Setting and obtaining basic structural parameters of a microfluidic pipeline and a target constant tensile strain rate, wherein the basic structural parameters at least comprise a starting cross-sectional area of a contraction area, a final cross-sectional area of the contraction area, a starting position of the contraction area, a final position of the contraction area and a channel height; Setting an axial flow rate along a centerline of the conduit to linearly increase with axial position according to a requirement for generating the target constant tensile strain rate in the constricted region; Keeping the channel height constant, and determining a basic width outline equation of the channel width changing along with the position according to the basic function; Based on the basic width profile equation, introducing a correction factor related to the channel depth-to-width ratio, and correcting the basic width profile equation to obtain an optimized width profile equation, wherein the correction is used for compensating central line flow velocity distribution distortion caused by fluid viscosity and wall effect under microscale so as to minimize the tensile strain rate fluctuation actually generated by a finally designed microfluidic pipeline in the contraction region; and manufacturing the microfluidic pipeline by adopting a micromachining process based on the optimized width profile equation, wherein the side wall of the shrinkage area of the microfluidic pipeline follows a hyperbolic nonlinear shrinkage track.
2. The method of claim 1, wherein the basis function The method comprises the following steps: In which, in the process, To be the starting cross-sectional area of the constriction region, To achieve a terminal cross-sectional area in the constricted region, In either position of the region of constriction, To shrink the total length of the pipe.
3. The method of claim 1, wherein the base width profile equation The method comprises the following steps: In which, in the process, 、 The width of the constriction region inlet and the constriction region outlet respectively, In either position of the region of constriction, To shrink the total length of the pipe.
4. The method of claim 1, wherein optimizing the width profile equation is: optimizing duct width The following implicit functional relationship must be satisfied: , In the formula, In order to optimize the width of the pipe, For the volume flow through the pipe, For a constant height of the channel, Peak flow rate for the centerline at the constricted inlet; The centerline peak flow at the outlet is contracted, In order to shrink the total length of the pipe, And (5) correcting factors for the cross-section flow velocity distribution.
5. The method of claim 1, wherein the modified target is to have a fluctuation amplitude of the actual tensile strain rate in the contracted region less than 5% relative to the target constant tensile strain rate.
6. The method of claim 1, wherein the microfluidic channel design method is applicable to pressure-driven newtonian fluids, viscoelastic fluids, or electroosmotic flow-driven microfluidic systems.
7. A microfluidic channel, characterized in that the geometric profile of the constriction region of the microfluidic channel is obtained with the design method according to any one of claims 1 to 6, such that a spatially position-independent constant tensile strain rate is produced on the centre line when fluid flows through the constriction region.
8. The microfluidic channel of claim 7, wherein the sidewall profile of the constriction region is in the form of a nonlinear hyperbola and has a tendency to widen near the outlet end due to viscosity modification.

Description

Microfluidic pipeline design method for generating constant tensile force by utilizing variable-section pipeline Technical Field The invention relates to the field of microfluidic pipeline design and hydrodynamic control, in particular to a microfluidic pipeline design method for generating constant tensile force by using a variable-section pipeline. Background In the fields of biomedical detection and micro-nano fluid research, deformation characterization of micro-nano scale objects such as cells, DNA molecules or polymers by using fluid-induced tensile force has become a common experimental means. Currently, the closest prior art in this field relies mainly on microfluidic channels of linear constriction geometry. However, in such a linearly constricted conduit, the channel width decreases linearly in the direction of flow, resulting in a significant non-linear characteristic of the change in flow velocity of the fluid in the constricted region. According to the basic principle of fluid mechanics, the tensile force and the tensile strain rate are in linear proportion, and the tensile strain rate is in direct proportion to the flow velocity gradient. In a linearly contracted pipe, the tensile strain rate can fluctuate dramatically depending on the spatial location of the object in the pipe. Thus, in linearly contracted pipes, the rate of tensile strain varies significantly with spatial position, i.e., the tensile forces experienced by the target object at different locations within the pipe are not uniform. That is, the non-uniform tensile force field brings significant technical limitations in practical application, namely, in order to accurately obtain key characterization parameters such as Young's modulus of cells, molecular relaxation time and the like, accurate positioning and capturing must be performed on specific spatial positions of the target object in the pipeline. Any deviation caused by different sampling positions can introduce systematic errors, and seriously affect the reliability and repeatability of the measurement result. Therefore, the development of a structural design method capable of generating a spatially uniform constant tensile force field in a microfluidic pipeline has important practical significance for improving the accuracy and experimental efficiency of biomechanical characterization under a micro-nano scale. Disclosure of Invention Aiming at the technical problems, the invention provides a design method of a microfluidic pipeline for generating constant tensile force by using a variable cross-section pipeline. In order to achieve the above object, the technical solution of the embodiment of the present invention is: in a first aspect, the present invention provides a microfluidic pipeline design method for generating a constant tensile force using a variable cross-section pipeline, the method comprising: Setting and obtaining basic structural parameters of a microfluidic pipeline and a target constant tensile strain rate, wherein the basic structural parameters at least comprise a starting cross-sectional area of a contraction area, a final cross-sectional area of the contraction area, a starting position of the contraction area, a final position of the contraction area and a channel height; Setting an axial flow rate along a centerline of the conduit to linearly increase with axial position according to a requirement for generating the target constant tensile strain rate in the constricted region; Keeping the channel height constant, and determining a basic width outline equation of the channel width changing along with the position according to the basic function; Based on the basic width profile equation, introducing a correction factor related to the channel depth-to-width ratio, and correcting the basic width profile equation to obtain an optimized width profile equation, wherein the correction is used for compensating central line flow velocity distribution distortion caused by fluid viscosity and wall effect under microscale so as to minimize the tensile strain rate fluctuation actually generated by a finally designed microfluidic pipeline in the contraction region; and manufacturing the microfluidic pipeline by adopting a micromachining process based on the optimized width profile equation, wherein the side wall of the shrinkage area of the microfluidic pipeline follows a hyperbolic nonlinear shrinkage track. In some embodiments, the functional relationshipThe method comprises the following steps: In which, in the process, To be the starting cross-sectional area of the constriction region, to achieve a terminal cross-sectional area in the constricted region,In either position of the region of constriction,To shrink the total length of the pipe. In some embodiments, the base width profile equationThe method comprises the following steps: In which, in the process, 、The width of the constriction region inlet and the constriction region outlet respectively,In either