Miniature PEPT tracer particle preparation device and method

Abstract

The invention discloses a miniature PEPT tracer particle preparation device and method.The device comprises control software, a multi-channel pressure pump, a liquid storage bottle, a flow meter, a micro-fluidic chip, an ultraviolet lamp and a collection bottle, the control software sets the multi-channel pressure pump to drive silicone oil in the liquid storage bottle and a mixture of a positron radioactive aqueous solution and UV curing glue; a water-in-oil two-phase flow system is formed in the micro-fluidic chip, a mixture of the positron radioactive aqueous solution and the UV curing adhesive is cured to form microsphere particles under the irradiation of ultraviolet light, and the micro PEPT tracer particles with positron radioactivity are obtained through rinsing. By controlling the input speeds of two liquids of the micro-fluidic chip, the preparation of the micro PEPT tracer particles with different sizes can be realized, and due to good flow field following performance, the tracer particles perform effective tracer characterization on micro solid particles and liquids in a multiphase flow, so that the PEPT technology realizes flow field measurement on micro solid phases and liquid phases.

Description

Technical Field

[0001] The invention belongs to the technical field of multiphase flow measurement, and in particular relates to a device and method for preparing micro PEPT tracer particles. Background Art

[0002] PEPT (positron emission particle tracer) technology is a new non-destructive and non-intrusive measurement technology for complex multiphase flows in industrial processes. It can image the three-dimensional dynamics of various liquid, powder and particle systems. PEPT technology can quickly and accurately track the movement of particles, and can obtain physical parameters such as particle trajectory, three-dimensional velocity field, turbulence field, density field and dispersion, and can be applied to the study of systems and flow phenomena of various scales, geometries and physical states.

[0003] The basic principle of PEPT is to use the gamma photon 3D imaging method to realize the position detection of radioactive tracer particles. Since the radioactive nuclides in the tracer particles are unstable, positron emission and positron annihilation events are very likely to occur, and gamma photons are radiated outward at the same time. Then the PEPT algorithm converts the gamma photon data captured by the detector in a short period of time into the position data of the tracer particles, that is, PEPT can measure the movement trajectory of the tracer particles.

[0004] Tracer particles are usually the key to determine whether PEPT technology can be successfully applied and measured in multiphase flow. They need to meet two basic requirements: (1) contain radioactive nuclides that can emit positrons and do not diffuse to the outside, and have a sufficiently high radioactivity so that the detector can capture enough gamma rays, so that PEPT can quickly and accurately locate the tracer particles; (2) have the same (or similar) physicochemical properties as the traced phase, so that it can correctly represent the kinetic characteristics of the substance being measured, rather than generating misleading data.

[0005] At present, the commonly used methods for preparing PEPT tracer particles are mainly direct and indirect methods. The direct method usually uses a cyclotron to directly bombard solid particles to achieve radioactive labeling, but it is only applicable to large-sized, high-temperature resistant, and oxygen-containing solid particles. The indirect method usually first uses adsorbent resin particles to absorb the radioactivity in the radioactive aqueous solution, and then places the resin particles in the solid particles by opening holes and backfilling to achieve radioactive labeling. However, it is difficult to use the above method for positron radioactive labeling of tiny solid particles and liquids. At present, there is still a lack of effective micro-tracer particle positron radioactive labeling methods, which greatly limits the application of PEPT in multiphase flow field measurements involving tiny solid particles or liquids. Therefore, establishing a method for preparing micro-PEPT tracer particles will help expand the application scope of PEPT technology and enhance the tracer characterization ability and multi-scale flow field detail capture ability of PEPT tracer particles. Summary of the invention

[0006] In view of the above problems, the object of the present invention is to provide a device and method for preparing micro PEPT tracer particles.

[0007] The specific technical solutions are as follows:

[0008] A micro PEPT tracer particle preparation device is characterized in that it comprises a multi-channel pressure pump, a first liquid storage bottle for placing silicone oil, a second liquid storage bottle for placing a mixture of a positron radioactive aqueous solution and a UV curing glue, and a microfluidic chip, the multi-channel pressure pump is respectively connected to the first liquid storage bottle and the second liquid storage bottle, the multi-channel pressure pump controls the pressure through control software, a first flow meter is provided on the outlet pipeline of the first liquid storage bottle, a second flow meter is provided on the outlet pipeline of the second liquid storage bottle, the first flow meter and the second flow meter are respectively connected to the multi-channel pressure pump signal feedback type, the outlet pipeline of the second liquid storage bottle is connected to the liquid input interface of the microfluidic chip, the outlet pipeline of the first liquid storage bottle is divided into two V-shaped pipelines, which are respectively connected to the liquid input interface of the microfluidic chip, and the outlet pipeline of the second liquid storage bottle and the liquid input interface of the microfluidic chip are 30 degrees, and the outlet of the microfluidic pipeline in the microfluidic chip is connected to a collecting bottle.

[0009] Furthermore, the microfluidic pipeline in the microfluidic chip is a long wavy channel, and an ultraviolet lamp is provided at the microfluidic chip.

[0010] A method for preparing micro PEPT tracer particles using the above device comprises the following steps:

[0011] 1) The output pressure value of each channel of the multi-channel pressure pump and the upper and lower flow rate limits of the first flowmeter and the second flowmeter are set in the control software, and the multi-channel pressure pump continuously inputs compressed air into the first liquid storage bottle and the second liquid storage bottle;

[0012] 2) The silicone oil in the first liquid storage bottle and the mixture of the positron-radioactive aqueous solution and the UV-curing adhesive in the second liquid storage bottle enter the channel under the driving of pressure, pass through the first flowmeter and the second flowmeter respectively, and enter the liquid input interface of the microfluidic chip;

[0013] 3) The first flow meter and the second flow meter measure the flow rate of the liquid in the two channels respectively, and feed the flow rate signal back to the multi-channel pressure pump. When the flow rate exceeds the preset upper limit, the multi-channel pressure pump will reduce the pressure value of the corresponding channel. When the flow rate is lower than the preset lower limit, the multi-channel pressure pump will increase the pressure value of the corresponding channel, so that the liquid flow rate of the two channels is maintained in a stable range, so as to ensure that discrete micro-droplets of uniform size are generated in the microfluidic chip;

[0014] 4) The liquid enters the microfluidic chip, and the mixture of the positron-radioactive aqueous solution and the UV-curable adhesive forms discrete microdroplets of uniform size in the continuous silicone oil, generating a liquid-liquid two-phase flow, which is then cured under ultraviolet light to become solid microspheres discretely distributed in the silicone oil, generating a solid-liquid two-phase flow;

[0015] 5) Solid microspheres discretely distributed in the silicone oil flow into the collection bottle from the output interface of the microfluidic chip.

[0016] Micro PEPT tracer particles can be obtained by rinsing the solid microspheres.

[0017] Furthermore, the flow rates of the two V-shaped pipelines for circulating silicone oil are the same, and at the liquid input port of the microfluidic chip, the flow rate ratio of the continuous phase silicone oil and the discrete phase positron radioactive aqueous solution to the UV curing glue is 5-20:1.

[0018] Furthermore, in step 4), the residence time of the micro-droplets under the irradiation of the ultraviolet lamp is 10-20 seconds to ensure reliable curing of the UV glue.

[0019] Furthermore, the flow rate v of the continuous phase c The diameter of the microdroplet d p The relationship between

[0020]

[0021] In the formula, v c is the flow velocity of the continuous phase, m / s; d p is the diameter of the microdroplet, m; γ represents the interfacial tension coefficient of the two phases, N / m; l CH1 represents the circumference of the pipe opening where the microdroplets are formed, m; C D represents the drag coefficient; ρ c is the density of the continuous phase, kg / m 3 .

[0022] The beneficial effects of the present invention are:

[0023] A method for preparing micro-PEPT tracer particles was established, which can produce positron-radioactive labeled tracer particles with good flow field following properties, enhance the tracing characterization ability of PEPT tracer particles and the multi-scale flow field detail capture ability of PEPT technology; by changing the pressure of each channel of the multi-channel pressure pump, the flow rate of the mixture of silicone oil, positron-radioactive aqueous solution and UV-curing glue can be adjusted respectively, so that the size of discrete micro-liquids in the microfluidic chip when they leave the channel mouth is different, and then the size of discrete micro-droplets and subsequent microspheres is regulated to obtain micro-PEPT tracer particles of different sizes. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1It is a schematic diagram of the device of the present invention;

[0025] Figure 2 It is a schematic diagram of the forces acting on the microfluidic chip of the present invention.

[0026] In the figure: 1. multi-channel pressure pump; 2. first liquid storage bottle; 3. second liquid storage bottle; 4. microfluidic chip; 5. first flow meter; 6. second flow meter; 7. control software; 8. collection bottle; 9. ultraviolet lamp. DETAILED DESCRIPTION

[0027] The present invention is further described below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited thereto.

[0028] like Figure 1 As shown, a micro PEPT tracer particle preparation device is characterized in that it includes a multi-channel pressure pump 1, a first liquid storage bottle 2 for placing silicone oil, a second liquid storage bottle 3 for placing a mixture of a positron radioactive aqueous solution and a UV curing glue, and a microfluidic chip 4, the multi-channel pressure pump 1 is connected to the first liquid storage bottle 2 and the second liquid storage bottle 3 respectively, the multi-channel pressure pump 1 controls the pressure through the control software 7, a first flow meter 5 is provided on the outlet pipeline of the first liquid storage bottle 2, a second flow meter 6 is provided on the outlet pipeline of the second liquid storage bottle 3, and the first flow meter 5 and The second flowmeter 6 is feedback-connected to the multi-channel pressure pump 1 respectively, the outlet pipeline of the second liquid storage bottle 3 is connected to the liquid input interface of the microfluidic chip 4, the outlet pipeline of the first liquid storage bottle 2 is divided into two V-shaped pipelines, which are respectively connected to the liquid input interface of the microfluidic chip 4, and the outlet pipeline of the second liquid storage bottle 3 and the liquid input interface of the microfluidic chip 4 are 30 degrees, the outlet of the microfluidic pipeline in the microfluidic chip 4 is connected to the collecting bottle 8, the microfluidic pipeline in the microfluidic chip 4 is a long wavy channel, and an ultraviolet lamp 9 is provided at the microfluidic chip 4.

[0029] like Figure 2 As shown, due to the tension between the continuous phase and the dispersed phase, the dispersed phase gathers at the liquid input interface of the microfluidic chip 4 to form tiny droplets. The force on the micro droplets in the axial direction of the pipeline includes the interfacial tension F ST and drag force F D , where the magnitude of the interfacial tension is related to the interfacial tension coefficient γ of the two phases and the circumference of the pipe opening where the microdroplet is formed l CH1 For two fixed liquids and devices, the interfacial tension coefficient γ, the circumference of the pipe opening where the microdroplets are formed l CH1 are all fixed constant values, so during the formation of microdroplets, the interfacial tension F ST Maintain a constant value, the drag force F DIt is the force that hinders the movement of the two phases due to the relative velocity between them. When the droplets flow out of the pipe, the peripheral fluid will produce a drag force on the droplets. It is related to the flow velocity, density and size of the continuous phase and can be expressed as C D represents the drag coefficient, ρ c is the density of the continuous phase, which is a fixed value here; v c is the flow velocity of the continuous phase, d p is the diameter of the micro-droplet. During the formation process, it can be approximately equivalent to being stationary at the pipe mouth, F ST Keep a constant value; while the droplet size d p is increasing, so F D Keep increasing until F D >F sT When the micro-droplets fall off, that is, the microspheres fall off after reaching a certain size, enter the continuous phase and continue to move with the continuous phase in the form of micro-sphere droplets, and solidify in the subsequent UV irradiation area to form solid micro-sphere particles. It should be noted that the feed rate v of the continuous phase in the whole process c It is a key parameter that directly affects the size of the final tracer particles. In the present invention, a flow meter is introduced to measure and feedback the two-phase flow rate, and the multi-channel pressure pump is accurately controlled to generate a relatively stable pressure, so that the speed of the discrete phase and the continuous phase entering the microfluidic chip remains stable, and tracer particles of uniform size are produced.

[0030] A method for preparing micro PEPT tracer particles comprises the following steps:

[0031] 1) The output pressure value of each channel of the multi-channel pressure pump 1, the upper and lower flow rate limits of the first flow meter 5 and the second flow meter 6 are set in the control software 7, and the multi-channel pressure pump 1 continuously inputs compressed air into the first liquid storage bottle 2 and the second liquid storage bottle 3;

[0032] 2) The silicone oil in the first liquid storage bottle 2 and the mixture of the positron-radioactive aqueous solution and the UV-curing adhesive in the second liquid storage bottle 3 enter the channel driven by pressure, pass through the first flow meter 5 and the second flow meter 6 respectively, and enter the liquid input interface of the microfluidic chip 4;

[0033] 3) The first flow meter 5 and the second flow meter 6 measure the flow rate of the liquid in the two channels respectively, and feed the flow rate signal back to the multi-channel pressure pump 1. When the flow rate exceeds the preset upper limit, the multi-channel pressure pump 1 will reduce the pressure value of the corresponding channel. When the flow rate is lower than the preset lower limit, the multi-channel pressure pump 1 will increase the pressure value of the corresponding channel, so that the flow rate of the liquid in the two channels is maintained in a stable range, so as to ensure that discrete micro-droplets of uniform size are generated in the microfluidic chip 4;

[0034] 4) The liquid enters the microfluidic chip 4, and the mixture of the positron-radioactive aqueous solution and the UV-curable adhesive forms discrete micro-droplets of uniform size in the continuous silicone oil, generating a liquid-liquid two-phase flow, and then solidifies under ultraviolet light to become solid micro-spheres discretely distributed in the silicone oil, generating a solid-liquid two-phase flow;

[0035] 5) The solid microspheres discretely distributed in the silicone oil flow into the collection bottle from the output interface of the microfluidic chip 4,

[0036] Micro PEPT tracer particles can be obtained by rinsing the solid microspheres.

[0037] Example

[0038] A small amount of surfactant can be added to the silicone oil as a continuous phase, and the mass ratio of the surfactant to the silicone oil is 1:99; the discrete phase is a mixture of a positron radioactive aqueous solution and a UV curing adhesive, and its positron radioactivity is not less than 1000MBq / mL.

[0039] Using a microfluidic chip 4 with a continuous phase and a discrete phase channel diameter of 100 μm, a p The PEPT tracer particles are 80 μm in diameter. Calculate, γ = 0.02N / m

[0040] l CH1 =1.57×10 -4 m,C D =119.6,ρ c =1000kg / m 3 The diameter of the pipe opening where the microdroplets are formed is 50 μm, and the continuous phase flow rate needs to be set to v c =180 mm / s (the two pipelines of the continuous phase have the same flow rate); and the discrete phase flow rate is set according to the ratio of the continuous phase to the discrete phase flow rate in the range of 5 to 20. In the control software 7, the pressure control parameters of the multi-channel pressure pump 1 are set so that the continuous phase flow rate is v c=180mm / s (corresponding to the measurement value of the first flowmeter 5 is 170μL / min, i.e., the total flow rate of the two continuous phase channels), and the upper and lower limits of the first flowmeter 5 are set to 141μL / min and 198μL / min respectively so that the continuous phase flow rate is controlled within the range of 150-210mm / s; the pressure control parameters of the multi-channel pressure pump 1 are set in the control software 7 so that the discrete phase flow rate is 20mm / s (corresponding to the measurement value of the second flowmeter 6 is 9μL / min, i.e., the total flow rate of the discrete phase channel), and the upper and lower limits of the second flowmeter 6 are set to 7μL / min and 12μL / min respectively so that the discrete phase flow rate is controlled within the range of 15-25mm / s. After the continuous phase and the discrete phase maintain a stable flow rate to enter the microfluidic chip 4 and form stable microdroplets, turn on the ultraviolet lamp 9 to irradiate the generated microdroplets to solidify them, and replace a new collection bottle after 20s to collect the formed solid microspheres.

[0041] The solid and liquid phases in the collection bottle were separated by using a filter, and then the solid microspheres were repeatedly rinsed with anhydrous alcohol and deionized water, respectively. Finally, the size, density, and radioactivity intensity of the obtained solid microspheres (PEPT tracer particles) were measured and evaluated.

[0042] The diameter of a single PEPT tracer particle is 80±10μm and the density is 1000±50kg / m 3 The positron radioactivity intensity of >100Bq was used as the quality standard for evaluation, and the qualified rate of the prepared PEPT tracer particles was above 70%.

Claims

1. A micro PEPT tracer particle preparation device, characterized in that: The invention comprises a multi-channel pressure pump (1), a first liquid storage bottle (2) for storing silicone oil, a second liquid storage bottle (3) for storing a mixture of a positron radioactive aqueous solution and a UV curing adhesive, and a microfluidic chip (4); the multi-channel pressure pump (1) is connected to the first liquid storage bottle (2) and the second liquid storage bottle (3) respectively; the multi-channel pressure pump (1) controls the pressure through control software (7); a first flow meter (5) is provided on the outlet pipeline of the first liquid storage bottle (2); a second flow meter (6) is provided on the outlet pipeline of the second liquid storage bottle (3); The first flow meter (5) and the second flow meter (6) are respectively connected to the multi-channel pressure pump (1) in a feedback manner; the outlet pipeline of the second liquid storage bottle (3) is connected to the liquid input interface of the microfluidic chip (4); the outlet pipeline of the first liquid storage bottle (2) is divided into two V-shaped pipelines, which are respectively connected to the liquid input interface of the microfluidic chip (4) and are 30 degrees apart from the outlet pipeline of the second liquid storage bottle (3) and the liquid input interface of the microfluidic chip (4); the outlet of the microfluidic pipeline in the microfluidic chip (4) is connected to the collecting bottle (8).

2. A micro PEPT tracer particle preparation device as claimed in claim 1, characterized in that: The microfluidic pipeline in the microfluidic chip (4) is a long wavy channel, and an ultraviolet lamp (9) is provided at the microfluidic chip (4).

3. A method for preparing micro PEPT tracer particles using the device as claimed in claim 2, characterized in that: The steps include: 1) setting the output pressure value of each channel of the multi-channel pressure pump (1) and the upper and lower flow rate limits of the first flow meter (5) and the second flow meter (6) in the control software (7), and the multi-channel pressure pump (1) continuously inputs compressed air into the first liquid storage bottle (2) and the second liquid storage bottle (3); 2) The silicone oil in the first liquid storage bottle (2) and the mixture of the positron-radioactive aqueous solution and the UV-curing adhesive in the second liquid storage bottle (3) enter the channel under the driving force of pressure, pass through the first flow meter (5) and the second flow meter (6), and enter the liquid input interface of the microfluidic chip (4); 3) The first flow meter (5) and the second flow meter (6) measure the flow rate of the liquid in the two channels respectively, and feed the flow rate signal back to the multi-channel pressure pump (1). When the flow rate exceeds a preset upper limit, the multi-channel pressure pump (1) will reduce the pressure value of the corresponding channel. When the flow rate is lower than a preset lower limit, the multi-channel pressure pump (1) will increase the pressure value of the corresponding channel, so that the flow rate of the liquid in the two channels is maintained within a stable range, so as to ensure that discrete micro-droplets of uniform size are generated in the microfluidic chip (4); 4) The liquid enters the microfluidic chip (4), and the mixture of the positron-radioactive aqueous solution and the UV-curable adhesive forms discrete microdroplets of uniform size in the continuous silicone oil, generating a liquid-liquid two-phase flow, and then solidifies under ultraviolet light to become solid microspheres discretely distributed in the silicone oil, generating a solid-liquid two-phase flow; 5) The solid microspheres discretely distributed in the silicone oil flow into a collection bottle from the output interface of the microfluidic chip (4), and the solid microspheres are rinsed to obtain micro PEPT tracer particles.

4. A method for preparing micro PEPT tracer particles as claimed in claim 3, characterized in that: The flow rates of the two V-shaped pipelines for circulating silicone oil are the same. At the liquid input port of the microfluidic chip (4), the flow rate ratio of the continuous phase silicone oil and the discrete phase positron radioactive aqueous solution to the UV curing glue is 5-20:

1.

5. A method for preparing micro PEPT tracer particles as claimed in claim 3, characterized in that: In step 4), the residence time of the micro droplets under the irradiation of the ultraviolet lamp is 10-20 seconds to ensure reliable curing of the UV glue.

6. A method for preparing micro PEPT tracer particles as claimed in claim 4, characterized in that: Flow rate of continuous phase v c The diameter of the microdroplet d p The relationship between In the formula, v c is the flow velocity of the continuous phase, m / s; d p is the diameter of the microdroplet, m; γ represents the interfacial tension coefficient of the two phases, N / m; l CH1 represents the circumference of the pipe opening where the microdroplets are formed, m; C D represents the drag coefficient; ρ c is the density of the continuous phase, kg / m 3 .

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