Microfluidic device with reflective compound cavity

Abstract

The utility model discloses a micro -flow device with reflection type composite cavity, including single -mode optical fiber and its one side fixed connection's reflection type composite cavity structure, reflection type composite cavity structure includes capillary tube and inside sealed sleeve of first optical fiber, connecting pipe and side hole optical fiber in proper order, and side hole optical fiber is connected as liquid outlet to waste liquid pool, wherein, the fusion joint of first optical fiber, connecting pipe forms first interface, and the fusion joint of connecting pipe and side hole optical fiber forms second interface, and side hole optical fiber is equipped with two independent micropore passageway, and the axis of connecting pipe is equipped with the cavity that penetrates, and the two symmetrical micro -flow passageways are formed between first optical fiber and capillary tube, and the connection of two micro -flow passageways one end all with micro -injection pump, and the other end is communicated with two micropore passageways through the cavity. The utility model discloses through cleaning also can be repeatedly used, and the versatility is strong, avoided the problem that the resource waste of frequently replacing sensor causes, and the structure does not have electronic components, and it is not easy to be interfered with environment.

Description

Technical Field

[0001] This utility model relates to the field of fiber optic sensing and microfluidics technology, specifically to a microfluidic device with a reflective composite cavity. Background Technology

[0002] Fiber optic microfluidic sensing technology has become an important development direction in recent years in fields such as biochemical detection, environmental monitoring, and medical diagnosis. It combines the high sensitivity and anti-electromagnetic interference characteristics of fiber optic sensors with the advantages of microfluidic technology, such as low sample consumption, high integration, and parallel processing, showing great application potential.

[0003] However, these traditional sensors generally lack efficient integrated microfluidic channels, often requiring the entire sensor head to be immersed in the liquid to be measured. This approach results in high sample consumption, slow and inefficient sample introduction and cleaning processes, making it difficult to achieve rapid and continuous detection of trace samples, and is also susceptible to environmental interference. The industry urgently needs an integrated sensing solution that combines robust structure, low-cost manufacturing, high sensitivity, and true microfluidic functionality. Utility Model Content

[0004] This utility model addresses the problems in the prior art by disclosing a microfluidic device with a reflective composite cavity. The device is formed by sequentially fusing a first optical fiber, a connecting tube, and a side-hole optical fiber, then sealing them with an external capillary tube. This composite cavity structure is then combined with a single-mode optical fiber and a micro-injection pump. The connection method is simple, requiring no additional accessories for assembly, effectively reducing the problem of increased defect rates due to numerous accessories. It can also be reused after cleaning and can test various liquids, exhibiting strong versatility and avoiding the waste of resources caused by frequent sensor replacements, while also saving costs. Furthermore, the structure of this application has no electronic components, making it less susceptible to environmental interference.

[0005] This utility model is achieved through the following technical solution: This invention first provides a microfluidic device with a reflective composite cavity, including a single-mode optical fiber for connecting an optical modem and a reflective composite cavity structure fixedly connected to one side. The reflective composite cavity structure includes a capillary tube and a first optical fiber, a connecting tube, and a side-hole optical fiber sequentially sealed inside it. The side-hole optical fiber serves as a liquid outlet connected to a waste liquid tank. The first interface is formed at the fusion splice of the first optical fiber and the connecting tube. The fusion splice between the connecting tube and the edge-hole optical fiber forms a second interface. The edge-hole fiber has two independent micro-pore channels. A through cavity is provided at the axis of the connecting pipe; Two symmetrical microfluidic channels are formed between the first optical fiber and the capillary tube. One end of each of the two microfluidic channels is connected to a pipeline for injecting the liquid to be tested into a micro-injection pump, and the other end is connected to two micropore channels through a cavity to form a reflective composite cavity.

[0006] As a further improvement, the first optical fiber is a cylinder with a core wrapped around it. The outer wall of the cylinder has two symmetrically positioned grooves. After the capillary tube is sleeved on the outside of the first optical fiber, the grooves become flow channels. The flow channels are sealed and connected to the micro-injection pump.

[0007] As a further improvement, the first optical fiber is a one-piece molded structure.

[0008] As a further improvement, the connecting pipe is a hollow cylindrical structure, with the hollow part forming a cavity, and the cross-section of the cavity is figure-eight shaped or gourd shaped.

[0009] As a further improvement, the maximum internal diameter of the cavity is L3 and the minimum internal diameter is L4, the maximum external diameter of the first optical fiber is L1 and the minimum external diameter is L2, and the following conditions are met: L1 > L4, L3 > L2.

[0010] As a further improvement, the capillary tube is internally fitted with the fusion splice of the first optical fiber and the connecting tube, the fusion splice of the first optical fiber and the single-mode optical fiber, and the connection between the tubing of the micro-injection pump and the flow channel. Both ends of the capillary tube are sealed with UV glue.

[0011] As a further improvement, the edge-hole fiber includes independently configured micro-pore channels and a first fiber core, wherein the micro-pore channels are the first micro-pore channel and the second micro-pore channel.

[0012] As a further improvement, the first micropore channel, the second micropore channel, and the first fiber core are parallel to each other, and the first micropore channel and the second micropore channel are symmetrical about the first fiber core.

[0013] As a further improvement, the first micropore channel and the second micropore channel are at the same distance from the first fiber core, and are set at an angle to the first fiber core, with the angle ranging from 5° to 20°.

[0014] As a further improvement, the length of the edge-hole fiber is 5 cm, the outer diameter is 125 micrometers, the diameter of the first fiber core is 9 micrometers, the maximum diameter of each micro-hole channel is 25 micrometers, and the distance from the center of the micro-hole channel to the first fiber core is 25 micrometers.

[0015] The features and beneficial effects of this utility model are as follows: (1) The structure of this utility model is simple. After the first optical fiber, the connecting tube and the side hole optical fiber are fused together in sequence, the external capillary tube is sealed to form a reflective composite cavity structure. Then, it can be used with a single-mode optical fiber and a micro-injection pump. The connection method is simple and no additional accessories are required for assembly, which effectively reduces the problem of increased failure rate caused by many accessories. This device can be used with an optical modem, computer and light source. By monitoring the movement of the wavelength of the input beam in real time, it can achieve high sensitivity and real-time measurement of the refractive index of the liquid. When detecting different liquids, the optical modem, computer and light source can be reused. This device can also be reused after cleaning. Moreover, it can test a variety of liquids and has strong versatility. It avoids the problem of wasting resources caused by frequently replacing sensors and saves costs. The structure of this application is particularly suitable for laboratories or testing rooms for biochemical detection, environmental monitoring and medical diagnosis.

[0016] (2) The liquid inlet and waste liquid outlet of this application are on both sides of the reflective composite cavity structure, which makes the liquid flow direction singular and distinguishes the two from the distance. Especially when used in the laboratory, it effectively avoids the situation of liquid confusion.

[0017] (3) The working principle of this utility model for testing the refractive index of liquids is simple, and it can be reused after cleaning. It can also test a variety of liquids, making it highly versatile. This avoids the problem of wasting resources caused by frequently replacing sensors and saves costs.

[0018] (4) This utility model has no electronic components and is less susceptible to external electromagnetic interference. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the microfluidic device with a reflective composite cavity as described in an embodiment of the present invention; Figure 2 This is a schematic diagram of the reflective composite cavity described in an embodiment of the present invention; Figure 3 This is a schematic diagram of the first optical fiber according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the connecting pipe described in an embodiment of the present utility model; Figure 5 This is a schematic diagram illustrating the working principle of the microfluidic device with a reflective composite cavity described in an embodiment of the present invention.

[0021] Explanation of reference numerals in the attached figures: 1. Single-mode optical fiber; 2. First optical fiber; 21. First groove; 22. Second groove; 3. Connecting tube; 31. Cavity; 4. Side-hole optical fiber; 41. First micro-pore channel; 42. Second micro-pore channel; 43. First fiber core; 5. Capillary tube; 6. Micro-injection pump; 7. Waste liquid tank; 8. First interface; 9. Second interface; A. Optical signal path; B. Flow path of the liquid under test. Detailed Implementation

[0022] To facilitate understanding of this utility model, a more comprehensive description of this utility model will be provided below, along with embodiments of this utility model, but this does not limit the scope of this utility model.

[0023] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0024] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0025] Existing sensors, due to their structural limitations, require the entire sensor head to be immersed in the liquid being tested during microfluidic detection. After testing, the sensor is either unusable or easily damaged during cleaning. Therefore, we designed a microfluidic device with a reflective composite cavity. This device, used in conjunction with an optical modulator / demodulator, spectrometer, and light source, achieves high-sensitivity, real-time measurement of the liquid's refractive index by monitoring the movement of the wavelength of the input light beam. The optical modulator / demodulator, spectrometer, and light source can all be reused when testing different liquids. The device itself can also be reused after cleaning. Furthermore, it can test a variety of liquids, offering strong versatility and avoiding the resource waste caused by frequent sensor replacements, while also saving costs. The structure of this application is particularly suitable for laboratories or testing facilities used in biochemical detection, environmental monitoring, and medical diagnostics.

[0026] A microfluidic device with a reflective composite cavity, such as Figures 1 to 5 As shown, This includes a single-mode fiber 1 for connecting an optical modem and a reflective composite cavity structure with a fixed connection on one side. The reflective composite cavity structure includes a capillary tube 5 and a first optical fiber 2, a connecting tube 3, and a side-hole optical fiber 4, which are sequentially sealed and sleeved inside the capillary tube. The side-hole optical fiber 4 serves as a liquid outlet connected to the waste liquid tank 7. The fusion joint between the etched-edge optical fiber 2 and the connecting tube 3 forms the first interface 8, and the fusion joint between the connecting tube 3 and the etched-edge optical fiber 4 forms the second interface 9. The edge-hole fiber 4 has two independent micro-pore channels. A through cavity 31 is provided at the axis of the connecting pipe 3; Two symmetrical microfluidic channels are formed between the first optical fiber 2 and the capillary tube 5. One end of each of the two microfluidic channels is connected to a pipeline for injecting the liquid to be tested into a micro-injection pump 6, and the other end is connected to two micropore channels through the cavity 31 to form a reflective composite cavity.

[0027] This application features a simple structure and connection method, requiring no additional accessories for assembly, effectively reducing the problem of increased defect rates caused by numerous parts. The structure uses a single type of raw material, avoiding the waste of warehouse storage space and the risk of material misplacement caused by diverse raw materials, thus reducing production costs. In this application's structure, the inlet and outlet liquids are located on opposite sides of the reflective composite cavity structure, ensuring a single flow direction for the liquids and clearly distinguishing them by distance. This effectively prevents liquid mixing, especially in laboratory applications.

[0028] In one embodiment, the single-mode fiber 1 is a standard single-mode fiber with an outer diameter of 125 micrometers, an inner diameter of 9 micrometers, and a length ranging from 100 to 200 micrometers, preferably 150 micrometers. The standard single-mode fiber guides light from the light source to the sensing probe in a single mode with low loss, and efficiently transmits the interference reflection signal generated at the probe back to the optical modem. This stable transmission ensures that the sensing signal has a high signal-to-noise ratio and contrast, which is the basis for high-precision measurement.

[0029] The optical modem, model HYPERION si155, integrates a light source, detector, signal processing, and data processing units. This greatly simplifies system setup, lowers the operational threshold, and makes the system more stable and reliable.

[0030] The micro-injection pump 6 is a Lange LSP01-2A integrated injection pump. It can precisely control the push and pull of liquids at submicron or even nanometer levels, ensuring that the sample can completely and stably fill the cavity without causing leakage or damage to sensitive optical interfaces due to excessive injection.

[0031] In one embodiment, the first optical fiber 2, the connecting tube 3, and the side-hole optical fiber 4 are all made of pure quartz glass to provide excellent chemical inertness, thermal stability, and optical transparency.

[0032] In one embodiment, the first optical fiber 2 is a cylinder with a core wrapped around its center. The outer wall of the cylinder has two symmetrically positioned grooves, namely a first groove 21 and a second groove 22. After the first optical fiber 2 is externally sleeved with the capillary tube 5, the groove becomes a flow channel, and the flow channel is sealed to the micro-injection pump 6.

[0033] Preferably, after the tubing of the micro-injection pump 6 is inserted into the flow channel, it is bonded to the flow channel (by adhesive).

[0034] In one embodiment, the groove of the first optical fiber 2 is formed by etching with a hydrofluoric acid solution.

[0035] In another embodiment, the first optical fiber 2 is an integrally formed structure with a length of 150 micrometers and an outer diameter of 125 micrometers.

[0036] In another embodiment, the connecting tube 3 is a hollow cylindrical structure, with a cavity 31 formed in the hollow part. The cross-section of the cavity 31 is B-shaped, figure-eight-shaped, or gourd-shaped. The formed cavity 31 allows the light signals entering the cavity 31 to interact strongly, thereby obtaining a highly sensitive detection signal.

[0037] The maximum inner diameter of cavity 31 is L3 and the minimum inner diameter is L4. The maximum outer diameter of the first optical fiber 2 is L1 and the minimum outer diameter is L2. In order to ensure the stability of the fusion splicing of the first optical fiber 2 and the connecting tube 3, and to ensure that the liquid flow is not affected after the fusion splicing, the following conditions must be met: L1 > L4, L3 > L2.

[0038] In one embodiment, L1 is 70 micrometers, L2 is 25 micrometers, L3 is 90 micrometers, and L4 is 35 micrometers.

[0039] In one embodiment, the edge-hole fiber 4 includes a micro-hole channel and a first fiber core 41, which are respectively independently arranged, wherein the micro-hole channels are a first micro-hole channel 41 and a second micro-hole channel 42.

[0040] In one embodiment, the first micropore channel 41, the second micropore channel 42, and the first fiber core 43 are parallel to each other, and the first micropore channel 41 and the second micropore channel 42 are symmetrical about the first fiber core 43.

[0041] In another embodiment, the first micropore channel 41 and the second micropore channel 42 are at the same distance from the first fiber core 43 and are set at an angle to the first fiber core 43. Preferably, the angle is in the range of 5°-20°, which allows the liquid that enters to be quickly discharged under the action of gravity under the condition that the measurement requirements can be met, avoiding the use of additional driving force and thus saving other energy.

[0042] In one embodiment, the side-hole fiber 4 is 5 cm long and has an outer diameter of 125 μm. The first core 41 has a diameter of 9 μm, the maximum diameter of each micro-aperture is 25 μm, and the distance from the center of the micro-aperture to the first core 43 is 25 μm. Selecting a 5 cm long side-hole fiber ensures that the portion of the optical signal transmitted through the second interface is completely lost, avoiding a third reflection and the formation of interference signals.

[0043] The capillary 5 has an inner diameter of about 1 mm. It isolates the sensing area from the external environment, allowing the liquid to be tested to flow through the capillary 2 first and then enter the reflective composite cavity. This avoids the liquid being tested directly scouring the weld point, thereby extending the service life.

[0044] In one embodiment, the capillary tube 5 is internally connected to the first optical fiber 2 and its fusion splice with the connecting tube 3, the fusion splice with the single-mode optical fiber 1, the tubing of the micro-injection pump 6, and the flow channel connection. At the same time, both ends of the capillary tube 5 are sealed with UV glue to prevent liquid leakage.

[0045] The working principle of a microfluidic device with a reflective composite cavity is as follows: The light emitted by the broadband light source is transmitted through single-mode fiber 1 and then through the first fiber 2. When the beam reaches the first interface 8, a portion of the light A is reflected back and returns to the single-mode fiber 1 along the original path. Another portion of the light B is transmitted into the cavity 31 of the connecting tube 3 and continues to propagate to the second interface 9. At the second interface 9, a portion of the light B1 is reflected again and returns along the cavity 31. Another portion of the light B2 is transmitted into the side-hole fiber 4. However, the transmission of the portion of light B2 in the 5 cm long side-hole fiber 4 will result in a large loss and will not produce any interfering reflection signal. The portion of light A reflected by the first interface 8 and the portion of light B1 reflected back from the second interface 9 continue to propagate in the first fiber 2 and the single-mode fiber 1, but there is an optical path difference between them. When these two beams are finally received by the optical modem, they will meet and superimpose, forming an interference spectrum. When the liquid to be tested enters the flow channel between the connecting tube 2 and the capillary tube 2 through the micro-injection pump 6, the phase of the interference spectrum will change due to the change in the refractive index of the medium in the flow channel, which manifests as a wavelength shift in the interference valley. By monitoring the movement of this wavelength in real time, highly sensitive, real-time measurement of the refractive index of liquids can be achieved.

[0046] The device proposed in this application for testing the refractive index of liquids has a simple working principle and structure. It can be reused after cleaning and can test a variety of liquids, making it highly versatile. This avoids the problem of wasting resources caused by frequent sensor replacements and saves costs.

[0047] It should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A microfluidic device with a reflective composite cavity, characterized in that: The device includes a single-mode optical fiber for connecting an optical modem and a reflective composite cavity structure fixedly connected to one side. The reflective composite cavity structure includes a capillary tube and a first optical fiber, a connecting tube, and a side-hole optical fiber sequentially sealed inside it. The side-hole optical fiber serves as an outlet connected to a waste liquid tank. The first interface is formed at the fusion splice of the first optical fiber and the connecting tube. The fusion splice between the connecting tube and the edge-hole optical fiber forms a second interface. The edge-hole fiber has two independent micro-pore channels. A through cavity is provided at the axis of the connecting pipe; Two symmetrical microfluidic channels are formed between the first optical fiber and the capillary tube. One end of each of the two microfluidic channels is connected to a pipeline for injecting the liquid to be tested into a micro-injection pump, and the other end is connected to two micropore channels through a cavity to form a reflective composite cavity.

2. The microfluidic device with a reflective composite cavity according to claim 1, characterized in that: The first optical fiber is a cylinder with a fiber core wrapped around it. The outer wall of the cylinder has two symmetrically positioned grooves. After the capillary tube is sleeved on the outside of the first optical fiber, the grooves become flow channels. The flow channels are sealed and connected to the micro-injection pump.

3. A microfluidic device with a reflective composite cavity according to claim 2, characterized in that: The first optical fiber is a one-piece molded structure.

4. A microfluidic device with a reflective composite cavity according to claim 2, characterized in that: The connecting pipe is a hollow cylindrical structure, with the hollow part forming a cavity. The cross-section of the cavity is figure-eight shaped or gourd shaped.

5. A microfluidic device with a reflective composite cavity according to claim 4, characterized in that: The maximum internal diameter of the cavity is L3 and the minimum internal diameter is L4. The maximum external diameter of the first optical fiber is L1 and the minimum external diameter is L2, and the following conditions are met: L1 > L4 and L3 > L2.

6. A microfluidic device with a reflective composite cavity according to claim 2, characterized in that: The capillary tube is internally fitted with the fusion splice of the first optical fiber and the connecting tube, the fusion splice of the first optical fiber and the single-mode optical fiber, and the connection between the tubing of the micro-injection pump and the flow channel. Both ends of the capillary tube are sealed with UV glue.

7. A microfluidic device with a reflective composite cavity according to claim 1, characterized in that: The edge-hole fiber includes independently configured micro-pore channels and a first fiber core, wherein the micro-pore channels are the first micro-pore channel and the second micro-pore channel.

8. A microfluidic device with a reflective composite cavity according to claim 7, characterized in that: The first micropore channel, the second micropore channel, and the first fiber core are parallel to each other, and the first micropore channel and the second micropore channel are symmetrical about the first fiber core.

9. A microfluidic device with a reflective composite cavity according to claim 7, characterized in that: The first micropore channel and the second micropore channel are at the same distance from the first fiber core, and are set at an angle to the first fiber core, with the angle ranging from 5° to 20°.

10. A microfluidic device with a reflective composite cavity according to claim 7, characterized in that: The fiber with the edge aperture is 5 cm long, has an outer diameter of 125 μm, a first core diameter of 9 μm, a maximum diameter of 25 μm for each micro-aperture channel, and a distance of 25 μm from the center of the micro-aperture channel to the first core.

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