A double-rectangular-coil high-flux inductive oil detection device

Abstract

The application provides a double-rectangular-coil high-flux inductive oil detection device, which comprises a double-rectangular-coil microfluidic chip, a signal processing circuit and a data acquisition card, wherein the double-rectangular-coil microfluidic chip comprises an oil inlet, PDMS, a microfluidic channel, a glass slide, an oil outlet, a first rectangular excitation coil, a second rectangular excitation coil, a resonance capacitor and a thin piece of permalloy; the first excitation coil and the second excitation coil are connected in parallel on a waveform generator with a voltage of U in ; the resonance capacitor is connected in parallel with the first excitation coil and the second excitation coil, and the two ends of the resonance capacitor are connected with the signal processing circuit; an excitation signal U in is a sinusoidal signal sent by the waveform generator; an output induction signal U out is also a sinusoidal alternating current signal, which is converted into a direct current signal through the signal processing circuit, and finally converted into a digital signal and stored in a computer through the data acquisition card. The application can greatly improve the microfluidic channel flux of the microfluidic chip under the premise of almost no loss of detection accuracy and stable detection results.

Description

Technical Field

[0001] This invention relates to the field of oil detection technology, and more particularly to a high-throughput inductive oil detection device with dual rectangular coils. Background Technology

[0002] Microfluidic chip technology integrates basic operational units such as sample preparation, reaction, separation, and detection in biological, chemical, and medical analysis processes onto a single micrometer-scale chip, automating the entire analysis process. Oil detection and analysis technology, on the other hand, quantitatively and qualitatively analyzes the physicochemical properties and contaminant particles in oils (hydraulic oil, lubricating oil, etc.) within mechanical equipment. When small-diameter abrasive particles begin to appear in the oil, it indicates that the mechanical system has begun to wear, posing a safety hazard. If these abrasive particles are not detected and repaired in time before they reach a certain number and size, a vicious cycle will occur: the abrasive particles will accelerate the wear rate, and wear will produce more abrasive particles, eventually paralyzing the entire mechanical system. Therefore, timely and effective detection of oils in mechanical systems can effectively eliminate safety hazards and ensure the safe and stable operation of the mechanical system.

[0003] There are many methods for oil detection, with commonly used methods including acoustic, optical, and electrical detection. Electrical detection methods include inductive and capacitive methods. Compared to other methods, inductive detection offers advantages such as the ability to distinguish between different metal particles, high accuracy, high sensitivity, simple structure, and reliable performance. While microfluidic chip-based oil detection technology currently boasts very high accuracy, its small flow channel size has long been a technical challenge. The excessively small flow channel limits its application in practical mechanical systems, despite its high accuracy. Summary of the Invention

[0004] To address the aforementioned technical problem in existing microfluidic chip-based oil detection technologies where the detection throughput of the microchannel is relatively low due to chip characteristics, this invention provides a high-throughput inductive oil detection device with dual rectangular coils. This invention's dual rectangular coil sensor, while retaining the high precision advantages of microfluidic chips, offers significantly higher microchannel throughput.

[0005] The technical means employed in this invention are as follows:

[0006] A high-throughput inductive oil detection device with dual rectangular coils includes: a dual rectangular coil microfluidic chip, a signal processing circuit, and a data acquisition card, wherein:

[0007] The dual-rectangular coil microfluidic chip includes an oil inlet, PDMS, a microchannel, a glass substrate, an oil outlet, a first rectangular excitation coil, a second rectangular excitation coil, a resonant capacitor, and a thin sheet of permalloy. The first and second excitation coils are connected in parallel at a voltage of U. inOn the waveform generator, the resonant capacitor is connected in parallel with the first excitation coil and the second excitation coil, and the two ends of the resonant capacitor are connected to the signal processing circuit.

[0008] Excitation signal U in A sine wave is generated by a waveform generator, and the output induced signal U out It is also a sinusoidal AC signal, which is converted into a DC signal by a signal processing circuit, and finally converted into a digital signal by a data acquisition card and stored in a computer.

[0009] Furthermore, the method for fabricating the dual rectangular coil microfluidic chip includes:

[0010] The first rectangular excitation coil and the second rectangular excitation coil are arranged in the same vertical plane along the direction of gravity; a thin sheet of permalloy is inserted inside the first rectangular excitation coil and the second rectangular excitation coil to increase the magnetic field strength; the height of the 300μm interval between the first rectangular excitation coil and the second rectangular excitation coil is used as a microchannel, and a resonant capacitor is added in parallel with the first rectangular excitation coil and the second rectangular excitation coil to form a dual rectangular coil detection sensor.

[0011] The double rectangular coil detection sensor and the copper wire are fixed on the glass slide by passing copper wires through the interval positions, and then wrapped with a mold.

[0012] Mix PDMS and curing agent in a 10:1 ratio and remove air bubbles using a vacuum drying oven;

[0013] Pour PDMS into a mold and then place it in a vacuum drying oven to dry for 30 minutes to cure it.

[0014] After curing, the copper wire is pulled out, forming a microchannel, and the dual rectangular coil microfluidic chip is thus completed.

[0015] Furthermore, the first rectangular excitation coil and the second rectangular excitation coil have the same structure, both made of copper wire, and both have thin sheets of permalloy of the same size inserted inside.

[0016] Furthermore, the first rectangular excitation coil and the second rectangular excitation coil have 40 turns, a length of 350 μm, a width of 10 μm, and a height of 3 μm.

[0017] Furthermore, the signal processing circuit includes an electrically connected half-wave rectifier circuit, a low-pass filter circuit, a unidirectional lock-in amplifier circuit, and a post-filter circuit. The AC signal is converted into a DC signal after being processed by the half-wave rectifier circuit, the low-pass filter circuit, the unidirectional lock-in amplifier circuit, and the post-filter circuit in sequence.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. The dual rectangular coil high-throughput inductive oil detection device provided by the present invention utilizes a microfluidic chip-based oil detection device made of dual rectangular copper coils combined with a signal processing circuit to greatly improve the microchannel throughput of the microfluidic chip without losing detection accuracy and obtaining stable detection results.

[0020] 2. The dual rectangular coil high-throughput inductive oil detection device provided by the present invention greatly improves the microchannel throughput while ensuring the detection of 85μm copper particles and 70μm iron particles and stable detection results.

[0021] Based on the above reasons, this invention can be widely applied in fields such as oil detection. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a structural diagram of the dual rectangular coil microfluidic chip of the present invention.

[0024] Figure 2 This is a circuit diagram of the present invention.

[0025] Figure 3 The induced voltage of a single 85μm copper particle and a single 70μm iron particle provided in the embodiments of the present invention.

[0026] In the diagram: 1. Oil inlet; 2. PDMS; 3. Microfluidic channel; 4. Glass substrate; 5. Oil outlet; 6. First rectangular excitation coil; 7. Resonant capacitor; 8. Second rectangular excitation coil; 9. Thin sheet permalloy; 10. Three-coil microfluidic chip circuit; 11. Signal processing circuit; 12. Data acquisition card; 13. Half-wave rectifier circuit; 14. Low-pass filter circuit; 15. Unidirectional phase-locked amplifier circuit; 16. Post-filter circuit. Detailed Implementation

[0027] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0028] 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, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. 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.

[0029] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0030] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0031] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms 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 on the scope of protection of this invention. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0032] For ease of description, spatial relative terms such as "above," "over," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation besides the orientation of the device as described in the figures. For example, if the device in the figures is inverted, a device described as "above" or "above" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0033] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0034] This invention provides a high-throughput inductive oil detection device with dual rectangular coils, comprising: a dual rectangular coil microfluidic chip, a signal processing circuit 11, and a data acquisition card 12, wherein:

[0035] like Figure 1 As shown, the dual rectangular coil microfluidic chip includes an oil inlet 1, PDMS 2, a microchannel 3, a glass substrate 4, an oil outlet 5, a first rectangular excitation coil 6, a second rectangular excitation coil 8, a resonant capacitor 7, and a thin sheet of permalloy 9. Figure 2 As shown, the first excitation coil 6 and the second excitation coil 8 are connected in parallel at a voltage of U. in On the waveform generator, the resonant capacitor 7 is connected in parallel with the first excitation coil 6 and the second excitation coil 8, and the two ends of the resonant capacitor 7 are connected to the signal processing circuit 11; in this embodiment, the resonant capacitor 7 is a 44NF through-hole capacitor.

[0036] Excitation signal U in A sine wave is generated by a waveform generator, and the output induced signal U out It is also a sinusoidal AC signal, which is converted into a DC signal by the signal processing circuit 11, and finally converted into a digital signal by the data acquisition card 12 and stored in the computer.

[0037] In a preferred embodiment of the present invention, the signal processing circuit 11 includes an electrically connected half-wave rectifier circuit 13, a low-pass filter circuit 14, a unidirectional lock-in amplifier circuit 15, and a post-filter circuit 16. The AC signal is sequentially processed by the half-wave rectifier circuit 13, the low-pass filter circuit 14, the unidirectional lock-in amplifier circuit 15, and the post-filter circuit 16, and then converted into a DC signal. Figure 2 As shown, M1 and M2 are parallel excitation coils, and C1 is a resonant capacitor. The excitation signal U... in A sine wave is generated by a waveform generator, and the output induced signal U out It is also a sinusoidal AC signal, which is converted into a DC signal by the signal processing circuit 11, and finally converted into a digital signal by the data acquisition card 12 and stored in the computer.

[0038] In a specific implementation, as a preferred embodiment of the present invention, the method for fabricating the dual rectangular coil microfluidic chip includes:

[0039] S1. Fabrication of a dual rectangular coil detection sensor:

[0040] S11. Arrange the first rectangular excitation coil 6 and the second rectangular excitation coil 8 in the same vertical plane along the direction of gravity;

[0041] S12. Insert a thin sheet of permalloy 9 inside the first rectangular excitation coil 6 and the second rectangular excitation coil 8 to increase the magnetic field strength;

[0042] S13. The height of the 300μm interval between the first rectangular excitation coil 6 and the second rectangular excitation coil 8 is taken as the microchannel 3.

[0043] S13. Add a resonant capacitor 7 in parallel with the first rectangular excitation coil 6 and the second rectangular excitation coil 8 to form a dual rectangular coil detection sensor;

[0044] S2. Fabrication of a dual rectangular coil microfluidic chip:

[0045] S21. Pass the copper wire along the interval position, fix the double rectangular coil detection sensor and the copper wire on the glass slide 4, and wrap it with a mold.

[0046] S22. Mix PDMS2 and curing agent in a ratio of 10:1, and remove air bubbles using a vacuum drying oven;

[0047] S23. Pour PDMS2 into the mold and then place it in a vacuum drying oven to dry for 30 minutes to cure it.

[0048] S24. After curing, the copper wire is pulled out, forming microchannel 3, and the dual rectangular coil microfluidic chip is completed.

[0049] In a specific implementation, as a preferred embodiment of the present invention, the first rectangular excitation coil 6 and the second rectangular excitation coil 8 have the same structure, both made of copper wire with a diameter of 70μm, and both the first rectangular excitation coil 6 and the second rectangular excitation coil 8 have thin sheets of permalloy 9 of the same size inserted inside.

[0050] In a specific implementation, as a preferred embodiment of the present invention, the first rectangular excitation coil 6 and the second rectangular excitation coil 8 have 40 turns, a length of 350 μm, a width of 10 μm, and a height of 3 μm.

[0051] Example

[0052] Lubricating oil is injected into the flow channel through the oil inlet. Once the oil seeps out from the outlet, the injection is stopped. Then, iron abrasive particles (70μm in size) and copper particles (85μm in size), accurately measured beforehand using a microscope, are placed sequentially into the oil inlet before the lubricating oil is injected into the flow channel. The test is considered complete when the particles completely pass through the detection area and flow out of the flow channel. Figure 3 As shown, when a single iron particle passes through the rectangular dual-coil sensor, its output signal exhibits a peak that is symmetrical about the center point. Similarly, when a single copper particle passes through the dual-rectangular-coil microfluidic chip, its output signal also exhibits a trough, and the signal is symmetrical about the center point. Figure 3 In the diagram, the troughs represent the waveform of copper particles, and the peaks represent the waveform of iron particles.

[0053] In addition, in order to greatly increase the microchannel throughput and solve the problem of the microchannel being too small in microfluidic chips, the present invention has three microchannels with a diameter of 300μm and identical detection effect. Compared with the single-channel structure, the microchannel throughput of the detection device of the present invention is increased by a full three times.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-throughput inductive oil detection device with dual rectangular coils, characterized in that, include: The microfluidic chip with dual rectangular coils, the signal processing circuit (11), and the data acquisition card (12) are as follows: The dual rectangular coil microfluidic chip includes an oil inlet (1), PDMS (2), a microchannel (3), a glass substrate (4), an oil outlet (5), a first rectangular excitation coil (6), a second rectangular excitation coil (8), a resonant capacitor (7), and a thin sheet of permalloy (9). The first excitation coil (6) and the second excitation coil (8) are connected in parallel at a voltage of U in On the waveform generator, the resonant capacitor (7) is connected in parallel with the first excitation coil (6) and the second excitation coil (8), and the two ends of the resonant capacitor (7) are connected to the signal processing circuit (11). The first rectangular excitation coil (6) and the second rectangular excitation coil (8) are arranged in the same vertical plane along the direction of gravity; a thin sheet of permalloy (9) is inserted inside the first rectangular excitation coil (6) and the second rectangular excitation coil (8) to increase the magnetic field strength; the height of the first rectangular excitation coil (6) and the second rectangular excitation coil (8) is 300μm apart as a microchannel (3), and a resonant capacitor (7) is added in parallel with the first rectangular excitation coil (6) and the second rectangular excitation coil (8) to form a double rectangular coil detection sensor; stimulus signal U in A sine wave signal is generated by a waveform generator, and the output is the induced signal. U out It is also a sinusoidal AC signal, which is converted into a DC signal by the signal processing circuit (11), and finally converted into a digital signal by the data acquisition card (12) and stored in the computer.

2. The high-throughput inductive oil detection device with dual rectangular coils according to claim 1, characterized in that, The method for fabricating the dual rectangular coil microfluidic chip includes: The double rectangular coil detection sensor and the copper wire are fixed on the glass slide (4) by passing the copper wire through the interval position, and then wrapped with a mold. Mix PDMS (2) with curing agent at a ratio of 10:1 and remove air bubbles using a vacuum drying oven; Pour PDMS (2) into the mold and then put it into a vacuum drying oven to dry for 30 minutes to cure it; After curing, the copper wire is pulled out, thus forming a microchannel (3), and the dual rectangular coil microfluidic chip is thus completed.

3. The high-throughput inductive oil detection device with dual rectangular coils according to claim 1, characterized in that, The first rectangular excitation coil (6) and the second rectangular excitation coil (8) have the same structure, both made of copper wire, and both have thin sheets of permalloy (9) of the same size inserted inside.

4. The high-throughput inductive oil detection device with dual rectangular coils according to claim 3, characterized in that, The first rectangular excitation coil (6) and the second rectangular excitation coil (8) have 40 turns, a length of 350 μm, a width of 10 μm, and a height of 3 μm.

5. The high-throughput inductive oil detection device with dual rectangular coils according to claim 1, characterized in that, The signal processing circuit (11) includes an electrically connected half-wave rectifier circuit (13), a low-pass filter circuit (14), a unidirectional lock-in amplifier circuit (15), and a post-filter circuit (16). The AC signal is processed by the half-wave rectifier circuit (13), the low-pass filter circuit (14), the unidirectional lock-in amplifier circuit (15), and the post-filter circuit (16) in sequence and then converted into a DC signal.

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