Micro-fluidic chip and micro-fluidic chip module with temperature control integrated Tesla valve

Abstract

The invention discloses a micro-fluidic chip and a micro-fluidic chip module of a temperature control integrated Tesla valve. According to the micro-fluidic chip, the forward Tesla valve flow channel with the one-way conduction characteristic is arranged to be connected with a sample liquid inlet and a reagent liquid inlet respectively, and fluid backflow pollution is prevented; efficient mixing of a sample and a reagent is realized by utilizing a multi-stage reverse Tesla valve uniform mixing runner; and a gettering trap is arranged to eliminate bubble interference. Furthermore, the micro-fluidic chip is integrated with a semiconductor temperature control device, and the temperature of the reaction liquid in the chip is kept constant through feedback control. The device is especially suitable for rapid and accurate detection of indexes such as ammonia nitrogen in water, and has the advantages of high mixing efficiency, strong anti-interference capability and accurate and stable detection result.

Description

Technical Field

[0001] This invention relates to the field of microfluidic chip technology, specifically to a microfluidic chip for detecting indicators such as ammonia nitrogen in water and a module integrating temperature control function. Background Technology

[0002] Traditional water quality testing methods (such as Nessler's reagent method and salicylic acid spectrophotometry) are typically performed in laboratories, which suffers from cumbersome procedures, high reagent consumption, long testing cycles, and difficulty in rapid on-site testing. Microfluidic chip technology, due to its advantages of integration and low sample and reagent consumption, has been introduced into the field of water quality testing. However, existing microfluidic chips for testing still face the following technical challenges: low mixing efficiency of multiple fluid streams; backflow and cross-contamination easily occur between different inlets due to differences in flow rates; bubbles generated during the reaction process affect optical detection accuracy; and environmental temperature fluctuations affect the efficiency and stability of the colorimetric reaction, thus limiting detection sensitivity and accuracy. Summary of the Invention

[0003] The present invention aims to overcome the shortcomings of the prior art and provide a microfluidic chip and its module with high mixing efficiency, prevention of solution backflow and cross-contamination, and precise temperature control.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] Firstly, this invention provides a microfluidic chip whose flow channel structure integrates forward and reverse Tesla valves, achieving directional backflow prevention and efficient active mixing of fluids. The sample and two reagents enter through the forward Tesla valve channel with unidirectional flow guidance characteristics, and then sequentially pass through two stages of reverse Tesla valve mixing channels for thorough mixing and reaction. Finally, air bubbles are removed by a degassing trap, and the mixture is temporarily stored in a storage tank for later testing. This design effectively solves problems such as uneven mixing, backflow contamination, and air bubble interference.

[0006] Secondly, this invention provides a microfluidic chip module with an integrated Tesla valve for temperature control. Based on the aforementioned microfluidic chip, it integrates a precise temperature control system based on a semiconductor cooling chip. This system monitors the outlet liquid temperature in real time and controls the cooling or heating power of the semiconductor cooling chip accordingly. This ensures that the reaction solution inside the chip (such as an ammonia-nitrogen colorimetric reaction system) is always in an optimal and constant temperature environment (e.g., 30℃-40℃), thereby significantly improving the reaction speed, colorimetric stability, and the repeatability and accuracy of the detection results.

[0007] The beneficial effects of this invention are as follows:

[0008] 1. The forward Tesla valve flow channel design effectively prevents backflow and cross-contamination of different fluids due to pressure differences.

[0009] 2. By utilizing the vortex and secondary flow generated within the flow channel of the reverse Tesla valve, the mixing efficiency of micro-fluids is greatly improved, and the reaction time is shortened.

[0010] 3. The unique degassing trap design eliminates bubbles generated during the reaction, preventing them from interfering with subsequent optical detection.

[0011] 4. The integrated semiconductor temperature control device can accurately maintain the temperature required for the reaction, overcome the influence of ambient temperature fluctuations, and ensure that the reaction proceeds efficiently and stably. It is especially suitable for temperature-sensitive colorimetric reaction systems, such as the rapid and accurate detection of ammonia nitrogen in water. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the flow channel structure (T-type connection) of the microfluidic chip of the present invention in Embodiment 1.

[0013] Figure 2 This is a schematic diagram of the flow channel structure (Y-type connection) of the microfluidic chip of the present invention in Embodiment 1.

[0014] Figure 3 This is a schematic diagram of the flow path of a series positive Tesla valve.

[0015] Figure 4 This is a schematic diagram of the flow channel of a series reverse Tesla valve.

[0016] Figure 5 A schematic diagram of the geometric parameters of a Tesla valve unit designed for optimization.

[0017] Figure 6 A schematic diagram of a liquid baffle installed in the mixing channel of a reverse Tesla valve.

[0018] Figure 7 This is an exploded structural diagram of the temperature-controlled integrated microfluidic chip module of the present invention.

[0019] In the diagram: 11. Sample inlet; 12. Reagent A inlet; 13. Reagent B inlet; 14. Outlet; 15. Degassing trap; 16. Storage tank; 21. Forward Tesla valve sample backflow prevention channel; 22. Forward Tesla valve reagent A backflow prevention channel; 23. Forward Tesla valve reagent B backflow prevention channel; 24. First-stage reverse Tesla valve mixing channel; 25. Second-stage reverse Tesla valve mixing channel; 26. First Y-type connector; 27. Second Y-type connector; 28. First T-type connector; 29. ​​Second T-type connector; 31. Thermal pad; 32. Thermal plate; 33. Thermal insulation cotton; 34. Cooling fan; 341. Housing; 342. Fan blade; 343. Air outlet baffle; 35. Support platform; 36. Semiconductor chip; 37. Heat sink. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0021] Example 1: Microfluidic Chip

[0022] like Figure 1 or Figure 2 As shown, this embodiment provides a microfluidic chip for detecting ammonia nitrogen in water. The chip includes a sample inlet 11, two reagent inlets (reagent A inlet 12 and reagent B inlet 13), and an outlet 14. The sample inlet 11 is connected to the sample backflow prevention channel 21 of a forward Tesla valve, and the reagent A and B inlets are respectively connected to the reagent A backflow prevention channel 22 and the reagent B backflow prevention channel 23 of a forward Tesla valve.

[0023] During operation, the water sample and reagent A flow through channels 21 and 22 respectively, and then converge via the first Y-type connector 26 or the first T-type connector 28, entering the mixing channel 24 of the first-stage reverse Tesla valve. In the reverse Tesla valve structure (such as...) Figure 4 Under the intense turbulence generated (as shown), the two are rapidly and thoroughly mixed, completing the first step of the reaction (e.g., generating chloramine). Subsequently, the mixture and reagent B, delivered via flow channel 23, merge through the second Y-type connector 27 or the second type connector 29 and enter the second-stage reverse Tesla valve mixing flow channel 25 for the second step of mixing and colorimetric reaction.

[0024] The colorimetric reaction solution then flows into the degassing trap 15, where air bubbles are captured and eliminated. The degassed solution is then briefly stored in the storage tank 16 to allow the colorimetric reaction to stabilize completely. Finally, the solution can be drawn out through the outlet 14 and sent to the detection cell for absorbance measurement. Each inlet uses a forward Tesla valve flow path, ensuring that even if the flow rates in each branch are different, the fluid will not flow backward to other inlets, avoiding reagent contamination and cross-interference.

[0025] Furthermore, the inventors discovered that the structural parameters of the Tesla valve unit have a significant impact on mixing efficiency and bubble removal. For example... Figure 5 As shown, by optimizing the included angle (α) of the Y-shaped bifurcation of the Tesla valve to be between 30° and 60° (such as 45°), and making the width (W1, W2) and length (L1, L2) of the flow channels on both sides after the bifurcation unequal, the flow characteristics of the fluid in the valve can be significantly improved, effectively avoiding bubble retention while achieving efficient mixing.

[0026] To verify the above optimization effect, a comparative experiment was conducted. The table below lists some of the comparative parameters and the corresponding observation results of "whether air bubbles exist in the flow channel":

[0027] Experimental results show that, within the included angle range, and in combination with the differentiated design of the width and length of the flow channels on both sides, an unexpected technical effect of avoiding bubble retention can be achieved.

[0028] In addition, such as Figure 6 As shown, liquid baffles can be added to the mixing channel 24 of the first-stage reverse Tesla valve and / or the mixing channel 25 of the second-stage reverse Tesla valve to further disturb the flow field and enhance the mixing effect.

[0029] Example 2: Microfluidic chip module with integrated temperature control Tesla valve

[0030] like Figure 7 As shown, this embodiment integrates the microfluidic chip described in Embodiment 1 with a precision temperature control device to form a fully functional detection module.

[0031] The core of the temperature control device is a semiconductor chip (thermoelectric cooler) 36. A heat-conducting plate 32 and a heat-conducting pad 31 are sequentially attached to its working surface. The heat-conducting pad 31 then makes close contact with the bottom of the microfluidic chip, forming an efficient heat conduction path. Thermal insulation cotton 33 is filled around the semiconductor chip 36 to reduce heat exchange with the environment. A heat sink 37 is attached to its non-working surface, and a cooling fan 34 supported by a support platform 35 is located below it to dissipate the heat generated during operation.

[0032] The temperature control process is as follows: A temperature sensor (such as a thermocouple or platinum resistance thermometer) located near the liquid outlet 14 monitors the temperature of the outflowing liquid in real time and transmits the signal to the temperature controller. The temperature controller dynamically adjusts the direction and magnitude of the current input to the semiconductor chip 36 based on the difference between the set temperature (e.g., 35°C) and the actual measured value. When heating is required, a forward current is applied, causing the working surface of the semiconductor chip 36 to heat up; when cooling is required, a reverse current is applied, causing the working surface to cool down. Through this closed-loop control, the temperature of the internal reaction system of the chip can be precisely stabilized within a preset range.

[0033] When used for on-site detection of ammonia nitrogen in water, the integrated temperature control function ensures that the salicylic acid spectrophotometric colorimetric reaction is always carried out at the optimal temperature. Compared with traditional portable devices without temperature control, this module significantly reduces errors caused by ambient temperature fluctuations, making color development faster (reaction time can be shortened to less than 10 minutes) and more stable, thereby greatly improving the accuracy and reliability of the detection.

[0034] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A microfluidic chip, characterized in that, include: A sample inlet (11) is connected to a sample flow channel; Two reagent inlets, namely reagent A inlet (12) and reagent B inlet (13). The reagent A inlet (12) is connected to a positive Tesla valve reagent A backflow prevention channel (22); The reagent B inlet (13) is connected to a positive Tesla valve reagent B backflow prevention channel (23). The sample flow channel and the positive Tesla valve reagent A backflow prevention flow channel (22) converge and connect to the first-stage reverse Tesla valve mixing flow channel (24). The forward Tesla valve reagent B backflow prevention channel (23) and the first-stage reverse Tesla valve mixing channel (24) converge and connect to the second-stage reverse Tesla valve mixing channel (25). The outlet of the second-stage reverse Tesla valve mixing channel (25) is sequentially connected to the degassing trap (15), the liquid storage tank (16), and the liquid outlet (14).

2. The microfluidic chip as described in claim 1, characterized in that, The sample flow channel and the positive Tesla valve reagent A backflow prevention flow channel (22) are connected to the first-stage reverse Tesla valve mixing flow channel (24) after converging through a Y-type connector (26) or a T-type connector (28).

3. The microfluidic chip as described in claim 2, characterized in that, The sample flow channel is a positive Tesla valve sample backflow prevention flow channel (21).

4. The microfluidic chip as described in claim 3, characterized in that, The forward Tesla valve sample backflow prevention channel (21), the forward Tesla valve reagent A backflow prevention channel (22), the forward Tesla valve reagent B backflow prevention channel (23), the first-stage reverse Tesla valve mixing channel (24), and the second-stage reverse Tesla valve mixing channel (25) are all composed of several Tesla valve units connected in series.

5. The microfluidic chip as described in claim 4, characterized in that, The included angle of the Y-shaped bifurcation constituting the Tesla valve unit is 30° to 60°, and the width and length of the flow channels on both sides of the Y-shaped bifurcation are different.

6. The microfluidic chip as described in claim 4 or 5, characterized in that, Liquid baffles are provided in the first-stage reverse Tesla valve mixing channel (24) and / or the second-stage reverse Tesla valve mixing channel (25).

7. A microfluidic chip module with an integrated temperature-controlled Tesla valve, characterized in that, It includes a microfluidic chip as described in any one of claims 1-6, and a temperature control device for maintaining a constant temperature of the microfluidic chip during operation.

8. The microfluidic chip module with temperature-controlled integrated Tesla valve as described in claim 7, characterized in that, The temperature control device includes: a thermometer for collecting the temperature of the liquid at the outlet (14) of the microfluidic chip; a semiconductor chip (36) whose working surface is thermally coupled to the microfluidic chip; and a temperature controller electrically connected to the thermometer and the semiconductor chip (36). The temperature controller changes the direction and intensity of the current input to the semiconductor chip (36) to control its working surface to cool or heat, thereby maintaining the temperature of the solution inside the microfluidic chip at a preset constant temperature.

9. The microfluidic chip module with temperature-controlled integrated Tesla valve as described in claim 8, characterized in that, The temperature control device also includes a thermal pad (31) and a thermal plate (32); the thermal pad (31) is disposed between the bottom of the microfluidic chip and the thermal plate (32); the thermal plate (32) is in contact with the working surface of the semiconductor chip (36).

10. The microfluidic chip module with temperature-controlled integrated Tesla valve as described in claim 9, characterized in that, The temperature control device also includes heat insulation cotton (33), heat sink (37) and cooling fan (34); the heat insulation cotton (33) covers the semiconductor chip (36); the heat sink (37) is attached to the non-working surface of the semiconductor chip (36); the cooling fan (34) is used to dissipate heat from the heat sink (37); The temperature control device also includes a support platform; the support platform is used to support the cooling fan, and the middle part of the support platform is a hollow structure.

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