Flow measurement device and method based on microchannel groove inner vortex cell flow

Abstract

The application discloses a flow measuring device and method based on micro-channel groove inner vortex flow, and belongs to the flow measuring device field. In the measuring device, the fluid main channel is of a rectangular structure, the circular micro-groove is of an arc structure formed by the intersection of the circular shape and the fluid main channel, the circular micro-groove is communicated with the fluid main channel at the intersection position, and a particle and a second-phase insoluble liquid supplement channel is arranged to input the second-phase insoluble liquid and single tracer particles into the circular micro-groove; the fluid main channel is communicated with the to-be-measured fluid, the to-be-measured fluid drives the tracer particles to form secondary flow, and a micro light sensing sensor detects the motion frequency of the tracer particles to calculate the flow of the to-be-measured fluid. Through the technical scheme of the application, the detection of different fluid flows is realized, has considerable resolution, is suitable for the particle tracking speed measurement without pollution for the to-be-measured sample which is not suitable for the tracer particles, the device structure is simple, easy to manufacture, compact and portable, and is suitable for large-scale production.

Description

Technical Field

[0001] This invention relates to the field of flow measurement device technology, and in particular to a flow measurement device based on vortex flow in a microchannel groove and a flow measurement method based on vortex flow in a microchannel groove. Background Technology

[0002] Microfluidics is a technology that uses microchannels and micro-flow paths to control minute amounts of liquids. It enables high-precision, high-throughput, highly automated, and low-consumption experimental operations at the microscale, and is widely used in biomedicine, chemical analysis, and environmental monitoring. Flow sensors are a crucial component of microfluidic systems, enabling the measurement of flow rates of microfluidics within microfluidic chips. Conveniently and accurately acquiring real-time flow parameters of microfluidics within microfluidic chips is essential for their practical applications. The application of micro-flow rates in the biomedical field is particularly urgent in the field of fluid measurement.

[0003] Due to an incomplete understanding of the flow mechanisms in microfluidic systems and a lag in their application, most current micro / nano liquid flow measurement devices still employ methods based on macroscopic flow measurement principles, such as volumetric methods, differential pressure methods, and mass methods, only scaled down. However, because the scale of micro / nano liquid flow is reduced, its flow range is typically only a few microliters or even nanoliters per minute, and traditional macroscopic measurement principles have certain limitations at the micro / nano scale. In recent years, some research institutions have proposed new micro-flow measurement devices. For example, Guan Zhijian et al. proposed an active piston liquid flow standard device, but its fixed photoelectric switch calibration method has limitations in measuring minute flow rates. The German Federal Institute of Physics and Technology developed a small flow standard device with a flow range of 1 mL / min to 2000 mL / min and an uncertainty of 0.1% to 0.2%. However, this device still cannot measure minute flow rates to meet the needs of microfluidic systems. The French Industrial Technology Research Center designed a small flow measurement standard device that can calibrate a flow range of 1 mL / h to 10 L / h with an uncertainty of 0.1%, but this device is bulky, cumbersome to operate, and lacks practical applicability and widespread applicability. The Zhejiang Provincial Institute of Metrology designed an electrically driven piston-type liquid small flow measurement standard calibration system for the biomedical field. This system uses a piston cylinder as the measuring vessel. The flow measurement system uses a stepper motor to drive a piston cylinder to generate a fluid source. The piston cylinder, in conjunction with a grating ruler, forms the flow measurement system. The flow rate is measured by calculating the volume of fluid discharged by the piston within a certain measurement time. This device can measure flow rates ranging from 0.1 to 1000 mL / h, but its accuracy is not high, with an expanded uncertainty of only 0.5% to 1.0%. In research laboratories, mature large-scale equipment is usually used to measure flow rates and velocities in microfluidic systems, such as micron-level particle imaging velocimetry (μPIV) and particle tracking velocimetry (PTV). However, there are still many obstacles to overcome in terms of accuracy and real-time performance of microfluidic flow measurement. These include the high cost of large-scale microfluidic flow measurement equipment, the need for post-processing to reflect microfluidic flow rates in real time, the complexity of experimental operations, and the need to introduce other tracer substances.

[0004] In summary, existing microfluidic velocimetry technologies cannot effectively measure the flow rate of microfluidic samples that are restricted from containing tracer particles, and they cannot detect low flow rates, nor can they achieve real-time measurement or require complex professional measuring instruments. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a flow measurement device and method based on vortex flow within a microchannel groove. Employing an indirect measurement method, it utilizes the shear force between two immiscible liquids. The flow of the microfluidic sample within the main fluid channel induces vortex flow in the second phase of the immiscible liquid within the circular microchannel. By leveraging the linear relationship between the periodic rotational motion period of tracer particles along the vortex lines under vortex flow and the flow rate of the measured fluid within the main fluid channel, and by measuring the periodic motion frequency of the tracer particles using a miniature optical sensor, and the calibration linear relationship between the motion frequency and the main channel fluid flow rate, the flow rate of the main fluid channel can be calculated. This flow measurement device and method overcomes the limitations of other macroscopic sensors in miniaturization and integration, enabling the detection of different flow velocities within the main fluid channel with considerable resolution. It offers advantages such as low cost, ease of manufacture, high dynamic response speed, and no need for complex professional measuring instruments. It is particularly suitable for pollution-free particle tracking and velocimetry of samples unsuitable for tracer particles, demonstrating broad applicability in the field of microfluidics. The device is simple in structure, easy to manufacture, compact, and portable, making it suitable for large-scale production.

[0006] To achieve the above objectives, the present invention provides a flow measurement device based on vortex flow within a microchannel groove, comprising: a chip body structure, a bottom plate, a main fluid channel, a circular microgroove, a particle and a second-phase immiscible solution replenishment channel, and a micro-photosensor;

[0007] The bottom plate is fixed to the bottom of the chip body structure, and the fluid main channel, the circular micro-groove and the micro-photosensor are provided on the chip body structure under the support of the bottom plate;

[0008] The main fluid channel is a rectangular structure formed on the surface of the chip body structure, and the circular microgroove is an arc-shaped structure formed by the intersection of a circle and the main fluid channel. The circular microgroove is connected to the main fluid channel at the intersection.

[0009] The edge of the circular microgroove is provided with a connecting channel for replenishing the particles and the second phase immiscible solution. The particle and second phase immiscible solution replenishment channel is used to input the second phase immiscible solution and a single tracer particle into the circular microgroove.

[0010] The fluid to be tested is introduced into the main fluid channel, and the fluid to be tested can drive the second phase immiscible solution to form a secondary flow with the tracer particles therein;

[0011] The miniature photosensitive sensor is disposed on the outer edge of the circular micro-groove. The miniature photosensitive sensor detects the motion frequency of the tracer particles and calculates the flow rate of the fluid to be measured based on the motion frequency of the tracer particles.

[0012] In the above technical solution, preferably, the main fluid channel is intersected by a preset number of circular microgrooves, each group of circular microgrooves is connected to an independent channel for replenishing the particles and the second phase immiscible solution, and each group of circular microgrooves is provided with a corresponding micro photosensitive sensor.

[0013] In the above technical solution, preferably, a replenishment channel valve is provided on the replenishment channel of the particles and the second phase immiscible solution, and the opening and closing of the replenishment channel valve is controlled to control the process of introducing the second phase immiscible solution and / or the tracer particles into the circular microgroove.

[0014] In the above technical solution, preferably, the micro-photosensor includes a transmitter and a receiver, the transmitter and the receiver being respectively disposed on both sides of the circular microgroove, the transmitter and the receiver cooperating to measure the frequency of the tracer particles undergoing periodic circular rotational motion in the circular microgroove along with the second phase-immiscible liquid.

[0015] In the above technical solution, preferably, the circular microgroove intersects with the main fluid channel at one-fifth of the circular diameter.

[0016] In the above technical solution, preferably, the chip body structure and the lower substrate are made of polydimethylsiloxane (PDMS), and the chip body structure and the lower substrate are fixed by oxygen ion bonding.

[0017] In the above technical solution, preferably, the main fluid channel and the circular microgroove are groove structures formed on the main structure of the chip. The two ends of the main fluid channel are respectively provided with holes for the liquid to be tested inlet and the liquid to be tested outlet, forming the fluid flow area in the working process of the microfluidic chip. The micro photosensitive sensor is embedded in the reserved groove of the main structure of the chip.

[0018] In the above technical solution, preferably, the diameter of the circular microgroove is 500 micrometers, the depth is 500 micrometers, and the spacing between adjacent circular microgrooves is at least 1000 micrometers.

[0019] This invention also proposes a flow measurement method based on vortex flow within a microchannel groove, applicable to the flow measurement device based on vortex flow within a microchannel groove disclosed in any of the above technical solutions, comprising:

[0020] The fluid to be tested is input into the main fluid channel, so that the fluid to be tested flows stably in the main fluid channel;

[0021] The motion frequency f of tracer particles in a circular microgroove that undergo periodic circular rotational motion with the second phase immiscible solution is detected by a miniature optical sensor.

[0022] The flow rate Q of the fluid to be tested is calculated according to the formula Q = (fb) / k, where k and b are the linear coefficient and constant between the flow rate of the fluid to be tested and the motion frequency of the tracer particles, respectively.

[0023] In the above technical solution, preferably, the flow measurement method based on vortex flow within a microchannel groove further includes:

[0024] The flow rate of the fluid under test is calculated by using the average value of the motion frequency of the corresponding tracer particles detected by the miniature photosensitive sensors in a preset number of groups;

[0025] The second phase immiscible solution and / or the tracer particles are replenished into the circular microgroove through the particle and second phase immiscible solution replenishment channel to achieve long-term flow monitoring.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] 1. This invention is based on a low-cost, direct particle tracking method, which can be applied to microfluidic flow measurement applications where tracer particles are not suitable.

[0028] 2. This invention can be used under low flow rate conditions where other sensors cannot detect flow rates. The lowest measurable flow rate can reach 200 nL / min. The fluid flow rate in the main channel of the sensor has a good linear relationship with the particle motion in the side cavity, and it has considerable resolution. The periodic motion frequency of the tracer particles has a high linearity and goodness of fit R with the fluid flow rate in the main channel. 2 =0.93, which meets the accuracy requirements for microfluidic flow measurement.

[0029] 3. The side channel parameter observed is the frequency of the periodic motion of the tracer particles. Optical microscopes and cameras are omitted. A miniature light sensor is integrated on the chip. When a particle passes directly through a point on the chip, the sensor will detect it, making the flow measurement device more compact and portable.

[0030] 4. Simple structure, easy to manufacture; low cost, suitable for large-scale production. Attached Figure Description

[0031] Figure 1 This is a schematic diagram illustrating the measurement principle of a flow measurement device based on vortex flow within a microchannel groove, as disclosed in one embodiment of the present invention.

[0032] Figure 2This is a schematic diagram of the flow measurement device based on vortex flow in a microchannel groove, as disclosed in one embodiment of the present invention.

[0033] Figure 3 for Figure 2 An enlarged structural schematic diagram of part A disclosed in the illustrated embodiment;

[0034] Figure 4 This is a schematic diagram of the two-dimensional simulation results of the flow of the fluid under test in the main fluid channel and the second phase immiscible solution in the circular microgroove, as disclosed in an embodiment of the present invention.

[0035] Figure 5 This is a schematic diagram showing the fitting relationship between the fluid flow rate Q of the main fluid channel and the periodic rotational motion frequency f of the tracer particles in the circular microgroove, as disclosed in one embodiment of the present invention.

[0036] Figure 6 This is a schematic diagram of the calibration experiment method for a flow measurement device based on vortex flow in a microchannel groove, as disclosed in one embodiment of the present invention.

[0037] Figure 7 This is a schematic flowchart of a flow measurement method based on vortex flow within a microchannel groove, as disclosed in one embodiment of the present invention.

[0038] In the diagram, the correspondence between the components and the reference numerals is as follows:

[0039] 1. Chip main structure, 2. Bottom plate, 3. Fluid main channel, 31. Liquid inlet to be measured, 32. Liquid outlet to be measured, 4. Circular microgroove, 5. Particle and second-phase immiscible liquid replenishment channel, 6. Miniature photosensitive sensor, 61. Transmitter, 62. Receiver, 7. Replenishment channel valve, 8. Liquid to be measured, 9. Second-phase immiscible liquid, 10. Miniature photosensitive sensor circuitry. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] The present invention will now be described in further detail with reference to the accompanying drawings:

[0042] like Figures 1 to 3As shown, a flow measurement device based on vortex flow in a microchannel groove according to the present invention includes: a chip body structure 1, a bottom plate 2, a main fluid channel 3, a circular microgroove 4, a particle and second-phase immiscible solution replenishment channel 5, and a micro photosensitive sensor 6.

[0043] The bottom plate 2 is fixed to the bottom of the chip body structure 1. With the support of the bottom plate 2, a fluid main channel 3, a circular micro groove 4 and a micro light sensor 6 are set on the chip body structure 1.

[0044] The main fluid channel 3 is a rectangular structure formed on the surface of the chip body structure 1. The circular microgroove 4 is an arc-shaped structure formed by the intersection of a circle and the main fluid channel 3. The circular microgroove 4 and the main fluid channel 3 are connected at the intersection.

[0045] The edge of the circular microgroove 4 is provided with a connected particle and second phase immiscible solution replenishment channel 5, which is used to input the second phase immiscible solution 9 and a single tracer particle into the circular microgroove 4.

[0046] The fluid to be tested 8 is introduced into the main fluid channel 3. The fluid to be tested 8 can drive the second phase immiscible liquid 9 and the tracer particles therein to form a secondary flow.

[0047] A miniature light sensor 6 is disposed on the outer edge of a circular micro-groove 4. The miniature light sensor 6 detects the motion frequency of the tracer particles and calculates the flow rate of the fluid to be measured 8 based on the motion frequency of the tracer particles.

[0048] In this embodiment, an indirect measurement method is employed. Utilizing the shear force between two immiscible liquids, the flow of the microfluidic under test within the main channel induces the flow of a second-phase immiscible fluid within the microgrooves on the sidewalls, thereby generating vortex flow. Under the influence of vortex flow, particles within the grooves move along the vortex lines, exhibiting periodic rotational motion. The particle rotation period has a linear relationship with the flow rate of the microfluidic under test within the main channel. A miniature photosensitive sensor 6 integrated on a chip measures the frequency of the periodic motion of particles within the vortex cells of the second-phase immiscible fluid, and a calibrated linear relationship between the frequency and the flow rate of the fluid in the main channel is obtained. Therefore, the flow rate of the main fluid channel 3 can be calculated by measuring the rotation frequency of the tracer particles.

[0049] Specifically, the flow device and method of the present invention overcome the shortcomings of other macroscopic sensors that cannot be miniaturized and integrated, realize the detection of different flow rates of fluid in the main fluid channel 3, and have considerable resolution. It has the advantages of low cost, easy manufacturing, high dynamic response speed, and no need for complex professional measuring instruments. It is especially suitable for achieving pollution-free particle tracking and velocity measurement for test samples that are not suitable for tracer particles. It has wide applicability in the field of microfluidics technology, meets the needs of actual measurement, and the device has a simple structure, is easy to manufacture, compact and portable, and is suitable for large-scale production.

[0050] In the implementation process, a single tracer particle and a second immiscible liquid 9 are introduced into the circular microgroove 4 through the particle and second-phase immiscible liquid replenishment channel 5. The test fluid 8 is then input into the main fluid channel 3. The second-phase immiscible liquid 9 is non-miscible with the test fluid 8. The main fluid channel 3 serves as the flow channel for the test fluid 8, and the circular microgroove 4 serves as the flow cavity for the second-phase immiscible liquid 9. During the flow of the test fluid 8, it comes into contact with the second-phase immiscible liquid within the circular microgroove 4. Due to the shear force between the two immiscible liquids, the flow of the test fluid 8 causes a secondary flow in the second-phase immiscible liquid 9 containing the tracer particle. The tracer particle undergoes a circular periodic flow within the circular microgroove 4 following the secondary flow of the second-phase immiscible liquid 9, forming a vortex flow.

[0051] When the fluid to be measured 8 is in a stable flow state, the secondary flow state of the second phase immiscible liquid 9 has a considerable linearity with the flow rate of the fluid to be measured. The flow rate of the fluid to be measured 8 can be obtained by processing the data detected by the periodic motion frequency of the tracer particles by the micro photosensitive sensor 6 integrated on the chip main structure 1.

[0052] This indirect measurement method can solve the problem that tracer particles are not suitable for various microfluidic samples. Utilizing the principle of vortex flow in the circular microgroove 4 of the microchannel, the second-phase immiscible solution 9 and a single tracer particle in the circular microgroove 4 can indirectly measure the fluid flow rate in the main fluid channel 3 of the linear reaction without contaminating the fluid to be measured 8. Moreover, it can be used under low flow rate conditions that cannot be detected by some other sensors, and the lowest measurable flow rate can reach 200 nL / min.

[0053] When a tracer particle passes directly through a point on the chip, the miniature photosensitive sensor 6 will detect it. The observed side channel parameter is the frequency of the tracer particle's periodic motion. Therefore, complex auxiliary equipment such as optical microscopes and CCDs can be eliminated, making the flow measurement device and microfluidic chip more compact and portable.

[0054] Furthermore, the circular micro-groove 4 at the intersection of the main fluid channel 3 is a circular groove, and the secondary flow vortex formed in the circular groove is more stable than that in other shapes such as rectangular or triangular grooves. The stable secondary flow in the circular micro-groove 4 makes the measured data more accurate.

[0055] In the above embodiment, preferably, the main fluid channel 3 is intersected by a predetermined number of circular microgrooves 4, each group of circular microgrooves 4 is connected to an independent particle and second phase immiscible solution replenishment channel 5, and each group of circular microgrooves 4 is provided with a corresponding micro photosensitive sensor 6.

[0056] During implementation, the spacing of the circular microgrooves 4 is set without causing mutual interference, and the number of circular microgrooves 4 is selected according to the length of the main fluid channel 3. Based on the rotation frequency of the tracer particles detected by the miniature photosensitive sensors 6 set at the edges of multiple sets of circular microgrooves 4, the flow rate of the fluid to be measured in different areas of the main fluid channel 3 can be determined, thereby improving the accuracy and stability of the flow rate measurement of the fluid to be measured 8.

[0057] In the above embodiment, preferably, a replenishment channel valve 7 is provided on the particle and second phase immiscible solution replenishment channel 5. The opening and closing of the replenishment channel valve 7 is controlled to control the process of introducing the second phase immiscible solution 9 and / or tracer particles into the circular microgroove 4. Opening the replenishment channel valve 7 can replenish the tracer particles and / or second phase immiscible solution 9 required for measuring the fluid flow rate.

[0058] In the above embodiment, preferably, the miniature photosensor 6 includes a transmitter 61 and a receiver 62. The transmitter 61 and the receiver 62 are respectively disposed on both sides of the circular microgroove 4 and are respectively connected to the miniature photosensor circuit 10. The transmitter 61 sends a signal, and based on the signal received by the receiver 62, it is determined whether the tracer particle has passed through a certain point on the signal transmission path. Based on the analysis of the received signal, the frequency of the tracer particle's periodic circular rotational motion with the second phase immiscible solution 9 in the circular microgroove 4 can be measured.

[0059] In the above embodiment, preferably, the circular microgroove 4 intersects with the main fluid channel 3 at one-fifth of its circular diameter, so as to ensure that the second-phase immiscible liquid 9 in the circular microgroove 4 will not be washed away due to too much contact with the test fluid 8, nor will it only undergo low-velocity Brownian motion due to too little contact with the test fluid 8; the particles in the circular microgroove 4 and the second-phase immiscible liquid 9 are immiscible with the liquid in the main fluid channel 3, so the tracer particles and the second-phase immiscible liquid 9 in the circular microgroove 4 will not contaminate the test fluid 8 if they are washed away.

[0060] In the above embodiment, preferably, the chip body structure 1 and the lower substrate 2 are made of polydimethylsiloxane (PDMS). The chip body structure 1 and the lower substrate 2 are fixed together by oxygen ion bonding. The lower substrate 2 is placed at the bottom of the chip body structure 1 to support the chip body structure 1 and provide flow space. Since the chip body structure 1 is made of flexible PDMS material, the miniature photosensor 6 is directly embedded in a reserved groove in the chip body structure 1. The reserved groove is 50 μm smaller than the size of the miniature photosensor 6, so the miniature photosensor 6 can be stably fixed without much fixing. The miniature photosensor circuitry 10 is arranged from the upper surface of the chip body structure 1, forming a main circuit to transmit the signal.

[0061] In the above embodiments, preferably, the main fluid channel 3 and the circular microgroove 4 are groove structures formed on the chip body structure 1. The two ends of the main fluid channel 3 are respectively provided with holes for the liquid to be tested inlet 31 and the liquid to be tested outlet 32, forming a fluid flow area in the working process of the microfluidic chip.

[0062] In the above embodiments, preferably, the diameter of the circular microgrooves 4 is 500 micrometers, the depth is 500 micrometers, and the spacing between adjacent circular microgrooves 4 is at least 1000 micrometers to ensure that the vortex flow formed by adjacent circular microgrooves 4 does not interfere with each other. When the length of the fluid main channel 3 is approximately 15 mm, preferably, it is a rectangle with a cross-section of 900 μm × 500 μm, with 7 circular microgrooves 4 provided on one side wall. The height of 500 μm is a typical value for the fluid main channel 3, and having the same height as the circular microgrooves 4 simplifies the manufacturing process.

[0063] According to the flow measurement device based on vortex flow in a microchannel groove disclosed in the above embodiment, during implementation, a two-dimensional simulation of the flow in the circular microgroove 4 was performed using CFD software. The simulation results are as follows: Figure 4 As shown, the sample fluid 8 drives the second phase immiscible liquid 9 in the circular microgroove 4 to achieve secondary flow, forming a vortex in the circular microgroove 4, and the tracer particles make periodic circular motion in the second phase immiscible liquid 9.

[0064] The flow sensing and measurement mechanism for low-flow-rate microfluidics in this invention is as follows: the microfluidic sample flows in the main fluid channel 3. Due to the shear force between the liquids, the microfluidic sample drives the secondary flow of the second-phase immiscible liquid 9 in the circular microgroove 4. The periodic flow frequency of the second-phase immiscible liquid 9 has a linear relationship with the flow rate of the microfluidic sample. The flow rate of the microfluidic sample can be calculated by measuring the periodic motion frequency of the tracer particles in the second-phase immiscible liquid 9 through the micro photosensitive sensor 6.

[0065] To verify this theory, an experiment was conducted using a syringe pump to introduce a fluid at a known flow rate into the flow measurement device. The particle frequencies of the photosensitive sensor within different grooves at specific flow rates were recorded, as shown in Table 1. The average values ​​of the periodic particle motion frequencies at specific flow rates were then plotted as a fitting graph, as shown below. Figure 5 As shown, it is evident that the periodic motion frequency of the tracer particles within the second-phase immiscible solution 9 exhibits a considerably high linearity and goodness of fit with the fluid flow rate of the main fluid channel 3, R. 2 =0.93(R) 2 The value of is between 0 and 1, and the closer it is to 1, the better the model fits.

[0066] Table 1. Particle frequencies of the photosensitive sensors in different grooves at specific flow rates.

[0067]

[0068] like Figure 6 As shown, the present invention also proposes a flow measurement method based on vortex flow within a microchannel groove, applicable to the flow measurement device based on vortex flow within a microchannel groove disclosed in any of the above embodiments, comprising:

[0069] The fluid to be tested, 8, is input into the main fluid channel 3, so that the fluid to be tested, 8, flows stably in the main fluid channel 3.

[0070] The motion frequency f of tracer particles that undergo periodic circular rotational motion with the second phase immiscible solution 9 in the circular microgroove 4 is detected by the miniature light sensor 6.

[0071] The flow rate Q of the fluid 8 to be measured is calculated according to the formula Q=(fb) / k, where k and b are the linear coefficient and constant between the flow rate of the fluid 8 to be measured and the motion frequency of the tracer particles, respectively.

[0072] In the above embodiments, preferably, the flow measurement method based on vortex flow within microchannel grooves further includes:

[0073] The flow rate of the fluid to be measured 8 is calculated by using the average value of the motion frequency of the corresponding tracer particles detected by a preset number of miniature optical sensors 6.

[0074] The second-phase immiscible solution 9 and / or tracer particles are replenished into the circular microgroove 4 through the particle and second-phase immiscible solution replenishment channel 5 to achieve long-term flow monitoring.

[0075] According to the flow measurement device and method based on vortex flow in microchannel grooves disclosed in the above embodiments, the flow measurement device needs to be calibrated before flow measurement and detection, as shown in the appendix. Figure 7 The required experimental setup includes:

[0076] A flow measurement device based on vortex flow in a microchannel groove is used to measure the flow rate of the fluid to be measured, 8.

[0077] Injection pumps are used to deliver fluid at specific flow rates to microfluidic chips;

[0078] Waste liquid collection bottle, used to collect waste liquid flowing through the chip.

[0079] The specific calibration steps are as follows:

[0080] 1. After setting the specific flow rate of the syringe pump, connect it to a flow measurement device, and connect the outlet to a waste liquid bottle;

[0081] 2. After the fluid flow in the main fluid channel 3 of the flow measurement device stabilizes, start recording the frequency of tracer particles passing through the test point in the circular micro-groove 4 detected by the miniature optical sensor 6 in the flow measurement device.

[0082] 3. Record the data for the injection pump at six input flow rates: 10 μL / min, 20 μL / min, 30 μL / min, 40 μL / min, 50 μL / min, and 60 μL / min. Record these data in Table 2. The first row of the table shows the injection pump flow rate Q, which is set by adjusting the injection pump. The second row shows the sequence number n of the seven circular micro-grooves 4 distributed on the main fluid channel 3. The third row shows the periodic motion frequency f of the tracer particles within the seven circular micro-grooves 4 on the main fluid channel 3 at the corresponding specific flow rate. Note that because the tracer particles pass through the test point twice during one periodic motion within the circular micro-grooves 4, the stable frequency needs to be divided by 2 when filling in the third row of the table to obtain the periodic motion frequency f of the tracer particles within the seven circular micro-grooves 4 on the main fluid channel 3 at the specific flow rate. The fourth row shows the average value y of the periodic motion frequency of the tracer particles at the specific flow rate, which is calculated based on the data in the third row.

[0083] Table 2

[0084]

[0085] 4. To fit a straight line y = kQ + b to the 6 data points (Q1, y1), (Q2, y2), ..., (Q6, y6) using the least squares method, and to find k and b, we first need to calculate the average of the x and y coordinates of the data points. and Then, based on the principle of least squares, we can obtain the following formula:

[0086]

[0087]

[0088] There is a strong linear relationship between the flow rate of the syringe pump and the motion frequency of the tracer particles in the second-phase immiscible liquid 9 of the flow measurement device. Furthermore, when the flow rate setting is changed, a new stagnant flow is established within a few seconds. Therefore, by measuring the motion frequency of the tracer particles in the second-phase immiscible liquid 9, the flow velocity of the microfluidic sample liquid can be calculated, and thus the flow rate can be calculated.

[0089] In actual measurement, to measure the flow rate (velocity) of the fluid to be measured, the fluid to be measured, the flow rate measuring device, and the waste liquid collection bottle are required.

[0090] 8. The fluid to be measured;

[0091] A flow measurement device used to measure the flow rate of a fluid to be measured.

[0092] Waste liquid collection bottle, used to collect the test fluid flowing through the chip 8.

[0093] The working process of this device is as follows:

[0094] 1. Connect the fluid to be measured, 8, to the inlet of the flow measurement device, and connect the outlet to the waste liquid bottle;

[0095] 2. After the fluid flow stabilizes, record the frequencies detected by the seven miniature photosensitive sensors 6 in the flow measurement device. Divide the frequency values ​​by two to obtain the periodic motion frequency f of the tracer particles. Fill in Table 3 with the serial numbers n of the different circular microgrooves 4 corresponding to the seven motion frequencies f:

[0096] Table 3

[0097]

[0098] 3. Based on the linear relationship y = kQ + b between the main fluid channel and the periodic motion frequency of the tracer particles obtained during calibration, the formula is used:

[0099] Q=(yb) / k

[0100] The flow rate Q of the fluid to be measured in the main channel is calculated.

[0101] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A flow measurement device based on microchannel recessed vortex cell flow for microfluidic flow measurement in a microfluidic chip, characterized in that, include: The chip's main structure includes a bottom plate, a main fluid channel, circular microgrooves, a supplementary channel for particles and a second-phase immiscible solution, and a miniature photosensor. The bottom plate is fixed to the bottom of the chip body structure, and the fluid main channel, the circular micro-groove and the micro-photosensor are provided on the chip body structure under the support of the bottom plate; The main fluid channel is a rectangular structure formed on the surface of the chip body structure. The circular microgroove is an arc-shaped structure formed by the intersection of a circle and the main fluid channel. The circular microgroove intersects with the main fluid channel at one-fifth of the circle's diameter, and the circular microgroove and the main fluid channel are connected at the intersection. The edge of the circular microgroove is provided with a connecting channel for replenishing the particles and the second phase immiscible solution. The particle and second phase immiscible solution replenishment channel is used to input the second phase immiscible solution and a single tracer particle into the circular microgroove. The fluid to be tested is introduced into the main fluid channel, and the fluid to be tested can drive the second phase immiscible solution to form a secondary flow with the tracer particles therein; The miniature photosensitive sensor is disposed on the outer edge of the circular micro-groove. The miniature photosensitive sensor detects the motion frequency of the tracer particles and calculates the flow rate of the fluid to be measured based on the motion frequency of the tracer particles.

2. The flow measurement device based on vortex flow within a microchannel groove according to claim 1, characterized in that, The main fluid channel is intersected by a predetermined number of circular microgrooves. Each group of circular microgrooves is connected to an independent channel for replenishing the particles and the second phase immiscible solution. Each group of circular microgrooves is equipped with a corresponding micro-photosensor.

3. The flow measurement device based on vortex flow within a microchannel groove according to claim 2, characterized in that, A replenishment channel valve is provided on the replenishment channel of the particles and the second phase immiscible solution. The opening and closing of the replenishment channel valve is controlled to control the process of introducing the second phase immiscible solution and / or the tracer particles into the circular microgroove.

4. The flow measurement device based on vortex flow within a microchannel groove according to claim 2, characterized in that, The miniature photosensitive sensor includes a transmitter and a receiver, which are respectively disposed on both sides of the circular microgroove. The transmitter and the receiver cooperate to measure the frequency of the tracer particles undergoing periodic circular rotational motion in the circular microgroove along with the second phase-immiscible solution.

5. The flow measurement device based on vortex flow within a microchannel groove according to claim 1, characterized in that, The chip body structure and the lower substrate are made of polydimethylsiloxane (PDMS), and the chip body structure and the lower substrate are fixed together by oxygen ion bonding.

6. The flow measurement device based on vortex flow within a microchannel groove according to claim 5, characterized in that, The main fluid channel and the circular microgroove are groove structures formed on the main structure of the chip. The two ends of the main fluid channel are respectively provided with holes for the liquid to be tested inlet and the liquid to be tested outlet, forming the fluid flow area during the operation of the microfluidic chip. The micro photosensitive sensor is embedded in the reserved groove of the main structure of the chip.

7. The flow measurement device based on vortex flow within a microchannel groove according to claim 1, characterized in that, The circular microgrooves have a diameter of 500 micrometers and a depth of 500 micrometers, and the spacing between adjacent circular microgrooves is at least 1000 micrometers.

8. A flow measurement method based on vortex flow within a microchannel groove, characterized in that, The flow measurement device based on vortex flow within a microchannel groove, as described in any one of claims 1 to 7, comprises: The fluid to be tested is input into the main fluid channel, so that the fluid to be tested flows stably in the main fluid channel; The motion frequency of tracer particles in a circular microgroove, which undergo periodic circular rotation along with the second-phase immiscible solution, is detected by a miniature optical sensor. f ; According to the formula Q=(fb) / k The flow rate of the fluid to be measured was calculated. Q ,in, k and b These are the linear coefficient and constant between the flow rate of the fluid under test and the motion frequency of the tracer particles, respectively.

9. The flow measurement method based on vortex flow within a microchannel groove according to claim 8, characterized in that, Also includes: The flow rate of the fluid under test is calculated by using the average value of the motion frequency of the corresponding tracer particles detected by the miniature photosensitive sensors in a preset number of groups; The second phase immiscible solution and / or the tracer particles are replenished into the circular microgroove through the particle and second phase immiscible solution replenishment channel to achieve long-term flow monitoring.

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