Microfluidic panel, gallium nitride-based manganese ion detection device and preparation method of gallium nitride-based manganese ion detection device

Abstract

The invention discloses a micro-fluidic panel, a gallium nitride-based manganese ion detection device and a preparation method thereof, and relates to the field of ion concentration detection.The micro-fluidic panel comprises a first two-way switching valve which is connected with a sample inlet, a leacheate inlet and the first end of a quantitative microtube; the second two-way switching valve is respectively connected with the second end of the quantitative microtube, the waste sample port and the cation exchange column; when a sample enters the quantitative microtube for the first time, the first two-way switching valve and the second two-way switching valve are adjusted, so that the sample is temporarily sealed in the quantitative microtube and enters the cation exchange column along with leacheate. Compared with a traditional detector, the signal-to-noise ratio of a detection signal can be increased, the device has the advantages of trace detection, quick response and the like, and the device with the modified grid is combined with a chip ion chromatography principle to elute manganese ions by utilizing a cation exchange column, so that the selectivity and the sensitivity of non-inhibition type ion chromatography are greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of ion concentration detection, and in particular to a microfluidic panel, a gallium nitride-based manganese ion detection device, and a preparation method thereof. Background Art

[0002] Microfluidics, also known as lab-on-a-chip, has ushered in an era of large-scale, precise manipulation of micro- and nano-biological particles, providing new approaches and methods for accurate, rapid, and intelligent disease detection and monitoring. The materials commonly used in microfluidic chips make them inexpensive, safe, and hygienic. The characteristic cross-sectional dimensions of the microchannels within microfluidic chips are small, ranging from tens to hundreds of micrometers, requiring small sample volumes. The chips often offer high throughput and rapid detection speeds, enabling rapid sample testing.

[0003] Given that conventional detection technologies find it difficult to achieve micro-quantification of samples, microfluidic chips are tiny in size and have fast reaction speeds. With their micron-scale channel structure, they achieve nanoliter or even picoliter sample consumption, leading the trend of the times. A handheld laboratory based on microfluidic technology can integrate conventional laboratory functions onto a chip of several square centimeters. Since its advent, it has been widely used in biological detection, chemical synthesis, medical detection and other fields due to its advantages such as miniaturization, high throughput, low reagent usage, and easy integration with other equipment. Among various liquids, the demand for metal ion detection is particularly prominent. However, most existing metal ion sensors still use a sampling method, which is relatively slow to detect liquids that change at any time. They cannot reflect the changes in metal ions in the solution in real time, and cannot control the damage caused by pollution in the first place. The microfluidic chip system is composed of a network of microchannels, and controllable fluids run through the entire system, which can meet the needs of on-site real-time monitoring of fluids in various liquids of water quality.

[0004] Non-suppressive ion chromatography often has problems such as high background noise, resulting in unclear peaks. Using titanium dioxide-modified GaN microfluidic chips as new electrical signal detection devices within a suitable pH range will greatly improve the sensitivity and accuracy of detection targets compared to traditional electrode detectors, while reducing the dead volume during detection. In addition, less column material and eluent are used, and the overall device cost is low. Summary of the Invention

[0005] In view of the above problems in the prior art, the present invention is proposed.

[0006] Therefore, the problem to be solved by the present invention is how to improve the sensitivity and accuracy of detecting targets.

[0007] In order to solve the above technical problems, in the first aspect, the present invention provides the following technical solutions: a microfluidic panel, comprising a first two-way switching valve, which is respectively connected to the sample inlet, the eluent inlet and the first end of the quantitative microtube; a second two-way switching valve, which is respectively connected to the second end of the quantitative microtube, the waste sample port and the cation exchange column; when the sample enters the quantitative microtube for the first time, the first two-way switching valve and the second two-way switching valve are adjusted so that the sample is temporarily sealed in the quantitative microtube and enters the cation exchange column together with the eluent.

[0008] As a preferred solution of the microfluidic panel of the present invention, a filter is further provided between the sample inlet and the first two-way switching valve for filtering the sample.

[0009] As a preferred solution of the microfluidic panel of the present invention, the tail end of the cation exchange column is further connected to a waste liquid port, and a lead port is further provided between the cation exchange column and the waste liquid port.

[0010] As a preferred solution of the microfluidic panel of the present invention, the cation exchange column is a carboxylic acid-based cation resin or a sulfonic acid-based cation resin.

[0011] In a second aspect, the present invention also provides a gallium nitride-based manganese ion detection device, comprising a sensor, wherein the sensor includes a functionalized layer stacked on a gate surface; the microfluidic panel is arranged on the surface of the functionalized layer, and the sample in the microfluidic panel can flow through the functionalized layer.

[0012] As a preferred solution of the gallium nitride-based manganese ion detection device of the present invention, it includes a substrate, a buffer layer, an epitaxial layer and a cap layer stacked in sequence from bottom to top, and the gate is located on the surface of the cap layer.

[0013] As a preferred solution of the gallium nitride-based manganese ion detection device described in the present invention, the epitaxial layer includes an AlGaN epitaxial layer and a GaN epitaxial layer, the buffer layer is made of GaN, and the cap layer is made of GaN.

[0014] As a preferred solution of the gallium nitride-based manganese ion detection device described in the present invention, it further includes a source and a drain, the source and the drain are respectively in Schottky contact with the epitaxial layer, and the cap layer is in ohmic contact with the gate.

[0015] In a third aspect, the present invention also provides a method for preparing a manganese ion detection device based on gallium nitride, which is suitable for preparing the above-mentioned manganese ion detection device. The preparation method includes providing a substrate; forming a buffer layer and an epitaxial layer on the substrate in sequence; forming a source, a drain and a gate on the surface of the epitaxial layer respectively; and forming a functionalized layer on the surface of the gate, wherein the functionalized layer can adsorb metal ions.

[0016] As a preferred solution of the gallium nitride-based manganese ion detection device of the present invention, the material of the functionalized layer (3) is titanium dioxide.

[0017] The beneficial effects of the present invention are as follows: the present invention constructs a gallium nitride microfluidic chip comprising a GaN buffer layer, a GaN epitaxial layer, an AlGaN epitaxial layer, and a GaN cap layer. By setting an electrode microsensor, the nano-titanium dioxide surface functionalized layer is used to adsorb the ions to be measured on the gate surface to control the concentration of 2DEG and control the electrical signal to detect the metal ion value. Compared with traditional detectors, the present invention can not only improve the signal-to-noise ratio of the detection signal, but also has the advantages of trace detection, rapid response, and suitability for meeting the needs of instant portable environments. The GaN device after gate modification combines the chip ion chromatography principle with the use of a cation exchange column to elute manganese ions, thereby greatly improving the selectivity and sensitivity of non-suppressed ion chromatography. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 Schematic diagram of the microfluidic panel structure.

[0020] Figure 2 Schematic diagram of the structure of the manganese ion detection device based on gallium nitride. DETAILED DESCRIPTION

[0021] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0022] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0023] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it individually or selectively refer to an embodiment that is mutually exclusive of other embodiments.

[0024] Example 1

[0025] Reference Figure 1 and Figure 2 , which is the first embodiment of the present invention, provides a microfluidic panel 1. The microfluidic panel 1 includes a first two-way switching valve 1-1 and a second two-way switching valve 1-5.

[0026] Specifically, the first two-way switching valve 1-1 has three ports: a first end connected to the sample inlet 1-2, a second end connected to the eluent inlet 1-3, and a third end connected to the first end of the quantitative microtube 1-4. Preferably, a filter 1-8 is further connected between the sample inlet 1-2 and the first two-way switching valve 1-1. The filter 1-8 is filled with a multi-layer filter membrane or a neutral microporous filter material.

[0027] Furthermore, a first end of the second two-way switching valve 1-5 is connected to the waste port 1-6, a second end is connected to the second end of the quantitative microtube 1-4, and a third end is connected to the first end of the cation exchange column 1-7.

[0028] Furthermore, a waste liquid port 1-9 is connected to the second end, ie, the tail end, of the cation exchange column 1-7, and a lead port 1-10 is provided between the cation exchange column 1-7 and the waste liquid port 1-9 for connecting electrodes.

[0029] After the sample passes through the cation exchange columns 1-7, it flows through the gate 2 of the sensor device.

[0030] As an optional embodiment, the present invention also provides a manganese ion detection device based on gallium nitride, which includes a sensor, and the sensor includes a functionalized layer 3 stacked on the surface of the gate 2. After the sample in the microfluidic panel 1 in the previous embodiment flows out from the cation exchange column 1-7, it will flow through the functionalized layer 3 on the surface of the gate 2.

[0031] Specifically, the sensor also includes a substrate 4, a buffer layer 5, an epitaxial layer 6, and a cap layer 7 stacked in ascending order, with the gate 2 located on the surface of the cap layer 7. The epitaxial layer 6 includes an AlGaN epitaxial layer 6-1 and a GaN epitaxial layer 6-2. The buffer layer 5 is made of GaN, and the cap layer 7 is made of GaN.

[0032] Preferably, the thickness of the AlGaN epitaxial layer 6 - 1 and the buffer layer 5 is 2-50 nm, the thickness of the GaN epitaxial layer 6 - 2 is 1-10000 nm, and the thickness of the cap layer 7 is 1-3 nm.

[0033] The sensor also includes a source electrode 8 and a drain electrode 9, each forming Schottky contacts with the epitaxial layer 6. A cap layer 7 forms an ohmic contact with the gate 2. The source and drain electrodes 8 and 9 are made of one or more combinations of titanium, aluminum, nickel, and gold. The gate 2 is made of one or more combinations of gold, nickel, and platinum. The gold layer on the gate 2 is 5-100 nm thick, while the functionalized layer 3 is 1-20 nm thick. The cation exchange columns 1-7 are made of carboxylic acid-based or sulfonic acid-based cation resins.

[0034] The working principle of this device is:

[0035] First, adjust the first two-way switching valve 1-1 and the second two-way switching valve 1-3 to connect the eluent inlet 1-3, the quantitative microtube 1-4, the cation exchange column area 1-7, the sensor area, and the waste port 1-9. A mixture of tartaric acid and dipicolinic acid or hydrochloric acid is introduced, controlling the eluent pH to approximately 3-6 at a flow rate of 10 μL / min to 1 mL / min. The mixed eluent then completely saturates the cation exchange column area 1-7.

[0036] Then, the first two-way switching valve 1-1 and the second two-way switching valve 1-3 are adjusted to connect the sample inlet 1-2, the filter 1-8, the quantitative microtube 1-4, and the waste sample port 1-6. Air is first pumped in to empty and clean the current path, and then the sample is pumped in to allow the sample to enter the quantitative microtube 1-4. The valve is adjusted again to close the sample inlet 1-2 to connect the eluent inlet 1-3, the quantitative microtube 1-4, the cation exchange column area 1-7, the sensor area, and the waste liquid port 1-9. The eluent is introduced to pass through this path to reach the sensor area to detect the magnitude of the source and drain output current, and the chemical sensor model is used to obtain the concentration to be measured based on the current magnitude. The source and drain voltages are set according to the electrical parameters of the detection device. Samples with different manganese ion gradient concentrations can be configured for testing, a standard curve is determined, and then the manganese ion content of the sample is calculated.

[0037] The specific method for detecting manganese ion concentration is:

[0038] S1: First, place the device into the standard eluent without sample concentration and wait for a while for the reading to stabilize;

[0039] S2: Setting the voltage of the source 8 and the drain 9 according to the electrical parameters;

[0040] S3: Passing a test solution with different concentration gradients of manganese ions into the gallium nitride microfluidic chip, and obtaining a standard peak spectrum of manganese ions using a non-suppressed ion chromatography model based on the magnitude of the source-drain output current of the test solution;

[0041] Furthermore, by monitoring the source-drain output current in the test solution and measuring the manganese ion concentration, it was discovered that in this combination, the adsorption of metal ions by functionalized layer 3 (nano-titanium dioxide) leads to an increase in Vg on the surface of the HEMT device. According to the equation, an increase in Vg leads to an increase in the 2DEG density and Id. As the concentration of introduced heavy metal ions increases, more ions combine to form complexes during their retention time, leading to an increase in the positive charge on the gate surface and a significant increase in Id. Conversely, for the complexed metal anions, Id is significantly reduced.

[0042]

[0043] (where n s is the two-dimensional electron gas density, q and V(x) are the electron charge and channel potential, respectively, ε n , μ, d, W, and L are the dielectric constant of the barrier layer, the mobility of electrons in the 2DEG, the distance between the surface and the 2DEG, and the width and length of the gate contact, respectively. Voff, Vg, Vds, and Vt are the off voltage, gate voltage, drain voltage, and threshold voltage, respectively.

[0044]

[0045] Among them, C x is the concentration of the target ion in the unknown sample; A x is the peak area (or peak height) of the target ion in the unknown sample; A s is the peak area (or peak height) of the target ion in the standard solution; C s is the concentration of the target ion in the standard solution.

[0046] S4: Response time, sensitivity, and rate of change of the measuring device.

[0047] It should be understood that ion exchange is based on the principle of reversible exchange between ions in the mobile phase and ions on the stationary phase (ion exchange resin). When sample ions enter the chromatographic column, they are separated based on the differences in their affinity for the stationary phase. In non-suppressed ion chromatography, the separated ions enter the detector directly, where quantification is achieved by measuring the change in current.

[0048] It should be understood that the exchange process of manganese ions:

[0049] Diffusion stage: When a solution containing manganese ions (Mn2+) comes into contact with an ion exchange resin, the manganese ions first diffuse from the bulk of the solution to the surface of the resin particles. They then diffuse from the surface of the resin particles into the pores within the resin, ultimately reaching the active groups within the resin. This process is influenced by factors such as the solution's flow rate, temperature, and the resin's pore structure.

[0050] Equilibrium stage: As the exchange reaction proceeds, manganese ions in the solution are continuously adsorbed by the resin, while exchangeable ions on the resin continuously enter the solution. When the adsorption rate and desorption rate are equal, the ion exchange reaches equilibrium. At this point, the concentration of manganese ions in the solution and the amount of manganese ions adsorbed on the resin no longer change, achieving dynamic equilibrium.

[0051] Coordination exchange reaction: Taking carboxylic acid-based cation exchange resin as an example, when manganese ions diffuse near the carboxylic acid group, they react with the carboxylic acid group to form a stable chelate. At the same time, the exchangeable ions (usually hydrogen ions H+ or other cations) originally bound to the active group are released into the solution, completing the ion exchange process. The reaction formula can be simply expressed as:

[0052]

[0053] Where R represents the skeleton of the ion exchange resin.

[0054] Elution: Carboxylic acid-based cation exchange resins bind to manganese ions through coordination bonds. During elution with an acid solution, hydrogen ions disrupt the coordination bonds between the resin and the manganese ions. These hydrogen ions compete with the carboxylic acid groups for binding sites, causing the manganese ions to dissociate from the resin and enter the solution. This reaction, which drives the manganese ions away from the resin, allows elution. As elution proceeds, the manganese ions are gradually displaced, leaving the eluate containing a large amount of manganese ions.

[0055] As an optional embodiment, the present invention also provides a method for preparing a manganese ion detection device based on gallium nitride, the preparation method comprising:

[0056] P1: A buffer layer 5, a GaN epitaxial layer 6-2, and an AlGaN epitaxial layer 6-1 are sequentially grown on a substrate 4 using an MOCVD method. Each layer is subjected to chemical mechanical polishing to smooth the surface, thereby obtaining a first temporary device.

[0057] P2: AZ4210 was dropped onto the surface of the first temporary device obtained in P1 at a speed of 3000 rpm for 15 s.

[0058] Use a hot plate to bake at 100°C for 6 minutes; expose the first temporary device after the glue is thrown off, and perform base film treatment on it;

[0059] Mesa etch: SiCl4 = 4 sccm; Pressure = 0.5 Pa; Power = 100 / 50 W, Time: 10 minutes, reaching 126 nm; Power = 100 / 20 W; Time: 2 minutes, reaching 7 nm; Etch target depth: 1330 Å; PMGI SF6, 2000 rpm, 40 seconds, thickness 0.35 μm; Hot plate 200°C, 5 minutes; EPI621, 2500 rpm, 30 seconds, thickness 0.6 μm; Finally, hot plate 90°C, 1 minute.

[0060] The ohmic electrode regions of the source and drain are developed using a photoresist, and a Ti layer and an Al layer are sequentially grown on the ohmic electrode regions from bottom to top using an evaporation coating method to form a source electrode 9 and a drain electrode 8. After stripping, rapid thermal annealing is performed at 850°C for 60 seconds to form an ohmic contact between the Ti metal and the AlGaN layer. The photoresist is then removed to obtain a second temporary device.

[0061] P3: The second temporary device obtained in P2 is protected with photoresist to protect the source 8 and drain 9. After exposure and development, the area where the cap layer 7 needs to be grown is exposed. The cap layer 7 is grown on the AlGaN epitaxial layer 6-1 using the MOCVD method to obtain the third temporary device.

[0062] P4: The third temporary device obtained in P3 is subjected to photoresist washing, and the photoresist is exposed and developed again to expose the gate 2 portion. A gold single-element gate is obtained by magnetron sputtering and the photoresist is removed to obtain the fourth temporary device;

[0063] P5: Spin-coat the fourth temporary device obtained in P4 with photoresist, expose and develop to expose the gate 2 portion, and use physical vapor deposition to deposit a nano-titanium dioxide layer, i.e., functionalized layer 3, on the Au gate to obtain the fifth temporary device and remove the resist;

[0064] P6: Embed the fifth temporary device obtained in P5 into a PMMA backing plate with matching dimensions to obtain the sixth temporary device;

[0065] P7: Attach the microfluidic panel 1 to the sixth temporary device obtained in P6, package the chip, and connect the upper and lower channels and electrode leads of the reserved PMMA board to obtain the final device.

[0066] In summary, the beneficial effects of the present invention are:

[0067] By constructing a gallium nitride microfluidic chip including a GaN buffer layer, a GaN epitaxial layer, an AlGaN epitaxial layer, and a GaN cap layer, and setting an electrode microsensor, the metal ion value is detected by controlling the concentration of 2DEG by adsorbing the ions to be measured on the gate surface using a nano-titanium dioxide surface functional layer and controlling the electrical signal. Compared with traditional detectors, the present invention not only improves the signal-to-noise ratio of the detection signal, but also has the advantages of trace detection, rapid response, and suitability for meeting the needs of instant portable environments. The GaN device with modified gate is combined with the principle of chip ion chromatography to elute manganese ions using a cation exchange column, which greatly improves the selectivity and sensitivity of non-suppressed ion chromatography.

[0068] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A microfluidic panel (1), characterized in that: include, a first two-way switching valve (1-1), which is respectively connected to the sample inlet (1-2), the eluent inlet (1-3) and the first end of the quantitative microtube (1-4); a second two-way switching valve (1-5), which is respectively connected to the second end of the quantitative microtube (1-4), the waste port (1-6) and the cation exchange column (1-7); When the sample first enters the quantitative microtube (1-4), the first two-way switching valve (1-1) and the second two-way switching valve (1-5) are adjusted so that the sample is temporarily sealed in the quantitative microtube (1-4) and enters the cation exchange column (1-7) together with the eluent.

2. The microfluidic panel (1) according to claim 1, characterized in that: A filter (1-8) is also provided between the sample inlet (1-2) and the first two-way switching valve (1-1) for filtering samples.

3. The microfluidic panel (1) according to claim 2, characterized in that: The tail end of the cation exchange column (1-7) is also connected to a waste liquid port (1-9), and a lead-in port (1-10) is provided between the cation exchange column (1-7) and the waste liquid port (1-9).

4. The microfluidic panel (1) according to claim 3, characterized in that: The cation exchange column (1-7) is a carboxylic acid type cation resin or a sulfonic acid type cation resin.

5. A manganese ion detection device based on gallium nitride, characterized in that: The sensor comprises a functionalized layer (3) stacked on the surface of a gate (2); The microfluidic panel (1) according to any one of claims 1 to 4 is arranged on the surface of the functionalized layer (3), and the sample in the microfluidic panel (1) can flow through the functionalized layer (3).

6. The gallium nitride-based manganese ion detection device according to claim 5, wherein: It comprises a substrate (4), a buffer layer (5), an epitaxial layer (6) and a cap layer (7) stacked in sequence from bottom to top, and the gate (2) is located on the surface of the cap layer (7).

7. The gallium nitride-based manganese ion detection device according to claim 6, wherein: The epitaxial layer (6) comprises an AlGaN epitaxial layer (6-1) and a GaN epitaxial layer (6-2), the buffer layer (5) is made of GaN, and the cap layer (7) is made of GaN.

8. The gallium nitride-based manganese ion detection device according to claim 7, wherein: It also includes a source electrode (8) and a drain electrode (9), wherein the source electrode (8) and the drain electrode (9) are in Schottky contact with the epitaxial layer (6), and the cap layer (7) is in ohmic contact with the gate electrode (2).

9. A method for preparing a manganese ion detection device based on gallium nitride, characterized in that: Suitable for preparing the manganese ion detection device as claimed in any one of claims 5 to 8, the preparation method comprising: providing a substrate (4); forming a buffer layer (5) and an epitaxial layer (6) in sequence on the substrate (4); forming a source electrode (8), a drain electrode (9) and a gate electrode (2) on the surface of the epitaxial layer (6); A functionalized layer (3) is formed on the surface of the gate (2), and the functionalized layer (3) is capable of adsorbing metal ions.

10. The method for preparing a gallium nitride-based manganese ion detection device according to claim 8, wherein: The material of the functionalized layer (3) is titanium dioxide.

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