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

Abstract

The invention discloses a micro-fluidic panel, a mercury ion concentration detection device based on gallium nitride and a preparation method thereof, and relates to the technical field of ion concentration detection.The micro-fluidic panel comprises a serpentine channel, the head end of the serpentine channel is connected with a reaction tank, and the tail end of the serpentine channel is connected with a first channel and a second channel; the first channel flows through the gate region of the semiconductor structure; magnetic parts are arranged at the joints of the serpentine channel, the first channel and the second channel and are used for shunting positive ions and negative ions in a solution. An electrochemical method is adopted, thymine bases on the surface of the aptamer are combined with mercury ions, a stable T-Hg-T compound is formed on the surface of the sensor, charge distribution on the surface of a grid electrode of a GaN device is changed, two-dimensional electron gas concentration change and source-drain current change are caused, and the sensing device is not provided with a reference electrode, simple in structure and convenient to operate. The detected drain current is sensitive to the surface charge change of the device. The detection sensitivity is 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 mercury ion concentration detection device, and a preparation method thereof. Background Art

[0002] Heavy metals are increasingly used in industrial production and have since become a key driver of social progress. For example, lead, cadmium, and mercury play a vital role in battery manufacturing, alloy production, and other fields. However, the serious environmental and health hazards of heavy metals have been recognized. These heavy metals often leach into water bodies through industrial wastewater, causing pollution. Mercury ions are also highly toxic. Even slight excesses can interfere with the function of enzymes and proteins in the human body, affecting normal cell activity and leading to cell damage and necrosis. Long-term exposure to mercury ions can cause damage to the nervous system and kidney disease. Therefore, strict control of mercury ion emissions is necessary to reduce their environmental and human hazards. Current technologies for measuring heavy metal content in water can be categorized into three main categories: spectroscopic analysis, electrochemical analysis, and biochemical analysis. Spectroscopic analysis requires large equipment and is relatively accurate, but lacks flexibility. Electrochemical analysis, on the other hand, utilizes equipment that is increasingly miniaturized and integrated. In the electrochemical sensor method, by fixing specific recognition elements on the electrode surface, sensors with high sensitivity to specific heavy metal ions can be designed and manufactured, thereby achieving rapid and effective detection of heavy metal ions in the environment.

[0003] Microfluidics technology focuses on the precise manipulation of fluids at the micron scale. Microfluidic chips integrate microstructures such as microchannels, microreaction cells, microvalves, and micropumps for precise manipulation of trace fluids. Microfluidic chip technology is being widely used in the field of water quality testing due to its advantages such as low sample and reagent consumption, high-speed analysis, multi-parameter integrated detection, automation, integration, and portability. By optimizing the microchannel design, this technology can quickly capture and separate trace heavy metal ions, significantly reducing the detection threshold. Combined with electrochemical, optical, or fluorescence sensing technology, it can also achieve high-specificity and high-precision heavy metal ion detection. In addition, the miniaturization and portability of microfluidic chips also enable on-site real-time monitoring, which is suitable for multiple scenarios such as environmental monitoring, food safety, and industrial wastewater treatment. Summary of the Invention

[0004] In view of the above problems in the prior art, the present invention is proposed.

[0005] 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 serpentine channel, a head end of which is connected to a reaction pool, and a tail end is connected to a first channel and a second channel respectively; the first channel flows through the gate area of the semiconductor structure; a magnetic part is provided at the connection between the serpentine channel, the first channel and the second channel for diverting positive ions and negative ions in the solution.

[0006] As a preferred solution of the microfluidic panel of the present invention, at least one filtering unit is connected in series on the serpentine channel.

[0007] As a preferred solution of the microfluidic panel of the present invention, the reaction pool is connected to the first liquid inlet and the second liquid inlet respectively, and the middle of the serpentine channel is further connected to the third liquid inlet.

[0008] In a second aspect, the present invention also provides a mercury ion concentration detection device, which includes the above-mentioned microfluidic panel, and also includes a buffer layer and a two-dimensional electron gas layer stacked in sequence; the two-dimensional electron gas layer includes an intrinsic layer, an isolation layer and a barrier layer stacked in sequence; the surface of the barrier layer is provided with a groove, and the surface of the groove is coated with a specific recognition layer; when the liquid to be tested flows through the specific recognition layer, its surface charge will change.

[0009] As a preferred solution of the gallium nitride-based mercury ion concentration detection device of the present invention, the specific recognition layer includes a graphene / metal platinum nanoparticle complex and an aptamer coated on the surface of the groove.

[0010] As a preferred solution of the gallium nitride-based mercury ion concentration detection device described in the present invention, the buffer layer is 1 to 10,000 nm thick; the intrinsic layer is made of GaN with a thickness of 10 to 6,000 nm; the barrier layer is made of AlGaN with a thickness of 10 to 25 nm; and the isolation layer is made of AlN with a thickness of 1 nm.

[0011] As a preferred solution of the gallium nitride-based mercury ion concentration detection device of the present invention, it further includes a source and a drain arranged on the top of the intrinsic layer, and a gate region arranged on the top of the groove, and the gate region is partially placed in the groove.

[0012] As a preferred solution of the gallium nitride-based mercury ion concentration detection device described in the present invention, it further includes a bottom plate and a top plate, the buffer layer and the two-dimensional electron gas layer are embedded in the bottom plate, and the microfluidic panel is located between the bottom plate and the top plate.

[0013] In a third aspect, the present invention also provides a method for preparing a gallium nitride-based mercury ion concentration detection device, which is suitable for preparing the above-mentioned gallium nitride-based mercury ion concentration detection device, and the method includes: forming a buffer layer on the surface of a substrate; forming an intrinsic layer on the surface of the buffer layer; forming an isolation layer on the surface of the intrinsic layer; forming a barrier layer on the surface of the isolation layer; opening a groove on the surface of the barrier layer and coating a specific recognition layer on its surface; and covering a microfluidic panel on the coated specific recognition layer.

[0014] As a preferred solution of the method for preparing the gallium nitride-based mercury ion concentration detection device of the present invention, the material of the specific recognition layer is a graphene / metal platinum nanoparticle composite material.

[0015] The present invention has the following beneficial effects: Using an electrochemical method, the thymine bases on the aptamer surface bind to mercury ions to form a stable T-Hg-T complex on the sensor surface. This alters the charge distribution on the gate surface of the GaN device, leading to changes in the two-dimensional electron gas concentration and source-drain current. The sensor device lacks a reference electrode, resulting in a simple structure, and the detected drain current is sensitive to changes in device surface charge. Furthermore, the graphene / metal nanocomposite provides more surface active sites, facilitating aptamer fixation and adsorption of more complexes, thereby improving detection sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] 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.

[0017] Figure 1 A cross-sectional view of a mercury ion concentration detection device based on gallium nitride.

[0018] Figure 2 A top view of the microfluidic panel. DETAILED DESCRIPTION

[0019] 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.

[0020] 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.

[0021] 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.

[0022] Reference Figure 1 and Figure 2 , which is the first embodiment of the present invention, provides a microfluidic panel. The microfluidic panel M includes a serpentine channel 1. The head end of the serpentine channel 1 is connected to the reaction pool 2, and the tail end is connected to the first channel 1-1 and the second channel 1-2, respectively. In other words, the serpentine channel 1 is divided into two branches. The first channel 1-1 flows through the gate region 14 of the semiconductor structure.

[0023] A magnetic part 3 is placed at the connection between the serpentine channel 1, the first channel 1-1 and the second channel 1-2. The magnetic part 3 can be a small magnet, which is used to divert the positive and negative ions in the solution in the serpentine channel 1. The positive ions enter the first channel 1-1, and the negative ions enter the second channel 1-2.

[0024] The ends of the first channel 1-1 and the second channel 1-2 are connected to a first liquid outlet 1-1-1 and a second liquid outlet 1-2-1, respectively. The reaction tank 2 is also connected to a first liquid inlet 5 and a second liquid inlet 6, respectively. A third liquid inlet 7 is also connected to the middle of the serpentine channel 1.

[0025] When the microfluidic panel M is used for mercury ion concentration testing, ethylenediaminetetraacetic acid buffer and the water to be tested are introduced into the first liquid inlet 5 and the second liquid inlet 6 respectively, and mixed and precipitated in the reaction tank 2. When the mixed solution is about to pass through the third liquid inlet, acetic acid-sodium acetate buffer is introduced into the third liquid inlet 7. The acetic acid-sodium acetate buffer can resist the pH changes caused by the addition of a small amount of acid or alkali in the unknown solution and the chemical reactions that may occur in the serpentine channel 1 through its buffering effect, so that the environmental pH in the serpentine channel 1 remains relatively stable. It can interact with the surface of the serpentine channel 1 and reduce the nonspecific adsorption of biomolecules on the wall of the serpentine channel 1. In addition, the buffer provides appropriate ionic strength, optimizes the interaction between the sensor surface and mercury ions, and suppresses the interference of other metal ions or impurities on the test results, thereby improving the specificity of the detection. The tortuous structure of the serpentine channel 1 allows the ethylenediaminetetraacetic acid buffer and the water to be tested to be fully mixed.

[0026] There are three filter units 4 in series in the serpentine channel 1. The filter units 4 can filter the solution. When the solution flows into the serpentine channel 1, the first channel 1-1 and the second channel 1-2, the magnetic element 3 will separate the positive and negative ions in the solution. 2+It will enter the first channel 1-1. When it flows through the gate region 14, the graphene / metal platinum nanocomposite layer modified with the aptamer near the gate region 14 will specifically recognize the mercury ions: when the Hg+ ions bind to the thymine bases on the surface of the aptamer, it will cause the charge on the electrode surface to change, and the current value will be proportional to the Hg 2+ The concentration is linear. Specifically, the nitrogen atom in the thymine molecule forms a coordination bond with the mercury ion. This coordination effect enables thymine to effectively bind to the mercury ion, thereby forming a stable T-Hg-T complex on the sensor surface. Usually, an aptamer such as a DNA oligonucleotide containing thymine is fixed on the electrode surface. When Hg 2+ When present, it coordinates with thymine in DNA, causing the DNA to transform from a flexible single-stranded structure to a relatively rigid double-stranded structure, thereby changing the charge distribution on the electrode surface. 2+ The current value output by the solution is used to establish a standard curve for the detection device.

[0027] As an optional embodiment, the present invention also provides a gallium nitride-based mercury ion concentration detection device, which includes the above-mentioned microfluidic panel M and a semiconductor structure device, which includes a buffer layer 9 and a two-dimensional electron gas layer 10 stacked in sequence on a substrate 17, wherein the two-dimensional electron gas layer 10 includes an intrinsic layer 10-1, an isolation layer 10-2 and a barrier layer 10-3 stacked in sequence on the surface of the substrate 17; the surface of the barrier layer 10-3 is provided with a groove, and the surface of the groove is coated with a specific recognition layer 11.

[0028] Preferably, the specific recognition layer 11 includes a graphene / metal platinum nanoparticle complex and an aptamer coated on the surface of the groove, and the aptamer surface has thymine bases. The nitrogen atom in the thymine molecule forms a coordination bond with the mercury ion. This coordination effect enables thymine to effectively bind to the mercury ion, thereby forming a stable T-Hg-T complex on the sensor surface. Usually, the aptamer, such as a DNA oligonucleotide containing thymine, is fixed to the electrode surface. When Hg2+ is present, it coordinates with the thymine in the DNA, causing the DNA to transform from a flexible single-stranded structure to a relatively rigid double-stranded analog complex, thereby changing the charge distribution on the electrode surface.

[0029] Preferably, the buffer layer has a thickness of 1 to 10,000 nm; the intrinsic layer 10-1 is made of GaN with a thickness of 10 to 6,000 nm; the barrier layer 10-3 is made of AlGaN with a thickness of 10 to 25 nm; and the isolation layer 10-2 is made of AlN with a thickness of 1 nm.

[0030] Specifically, a source 12 and a drain 13 are provided on the top of the intrinsic layer 10 - 1 , and a gate region 14 is provided on the top of the groove, and a portion of the gate region 14 is placed in the groove.

[0031] The semiconductor device structure is embedded in the bottom plate 15 , and the microfluidic panel M is disposed between the bottom plate 15 and the top plate 16 .

[0032] As an optional embodiment, the present invention further provides a method for preparing a device for detecting mercury ion concentration based on gallium nitride, the method comprising:

[0033] Step 1: growing a buffer layer 9 on the surface of the substrate 17 by a metal organic chemical vapor epitaxy process, the buffer layer 9 including a GaN buffer layer or an AlGaN buffer layer; and growing a heterostructure layer on the buffer layer.

[0034] Step 2: On the temporary device obtained in step 1, apply a layer of AZ4210 photoresist with a thickness of 1-2 μm at a spin speed of 3000 rpm, and then place it on a hot plate at 100°C for pre-baking for 2 minutes. Etch the AlGaN barrier layer 10-3 using ICP etching technology. After completing the mesa etching, define the ohmic contact area on the active area using photolithography technology, then place it in the photolithography machine for exposure for 4 seconds, and then place it on the hot plate for post-baking;

[0035] The device is then placed in a developer to develop the ohmic electrode areas for the source and drain. Electron beam evaporation or sputtering is used to sequentially grow Ti / Al / Ni / Au from bottom to top on the defined ohmic contact areas, forming source 12 and drain 13. The device is then placed in a nitrogen environment for rapid thermal annealing, and any residual photoresist at the bottom is removed. A layer of passivation material is then grown using PECVD.

[0036] Step 3: Coat a layer of AZ4210 photoresist with a thickness of 1 to 2 μm on the temporary device obtained in step 2 at a spin speed of 3000 rpm, perform exposure using a photomask, and develop the exposed photoresist using a developer TMAH to expose the gate region 14 to be etched.

[0037] A mixed gas of Cl2 and BCl3 is then used in an inductively coupled plasma etching system to etch a recessed structure in the gate region 14. A layer of Ni / Au metal is then deposited on both sides and the bottom of the recess using PECVD. The Ni / Au gate electrode forms a good Schottky contact with the AlGaN barrier layer 10-3.

[0038] Step 4: Coat the graphene / metal platinum nanoparticle composite material on the gate region 14 etched in step 3, and fix the aptamer on the surface of the composite material by covalent bonding or electrostatic adsorption to obtain a third temporary device.

[0039] Step 5: Cover the temporary device obtained in Step 4 with a microchannel layer of matching dimensions. This layer is patterned using photolithography, then etched using ICP to form the channels. The mold is then cast, cured, and peeled off to form the microfluidic panel M. The filter membrane is cut to the appropriate size and placed in the slot reserved for the filter membrane during the microfluidic channel design, forming the filter unit 4. Photoresist covers part of the source electrode 12 and part of the drain electrode 13. The main channel passes through the recessed gate region 14. Small magnets are embedded in the surface of the channel diversion area, and holes are drilled at the inlet and outlet ends.

[0040] Step 6: Plasma-treat the surface of the microchannel layer and encapsulate the microfluidic channels by bonding or hot pressing. After encapsulation, the pre-set upper and lower fluid channels are connected to the electrode leads to create the final device.

[0041] It should be understood that the principle of the aptamer-modified graphene / metal platinum nanocomposite layer specifically recognizing mercury ions is that when Hg 2+ When ions bind to the thymine bases on the surface of the aptamer, the surface charge of the electrode changes, and the current value is similar to that of Hg 2+ The concentration is linear. Specifically, the nitrogen atom in the thymine molecule forms a coordination bond with the mercury ion. This coordination effect enables thymine to effectively bind to the mercury ion, thereby forming a stable T-Hg-T complex on the sensor surface. Usually, an aptamer such as a DNA oligonucleotide containing thymine is fixed on the electrode surface. When Hg 2+ When present, it coordinates with thymine in DNA, causing the DNA to transform from a flexible single-stranded structure to a relatively rigid double-stranded analog complex, thereby changing the charge distribution on the electrode surface.

[0042] Furthermore, the preparation steps of the graphene / metal platinum nanoparticle composite in step 4 include:

[0043] An appropriate amount of ultrasonically treated graphite oxide and a platinum precursor were dissolved in 30 ml of deionized water and stirred to mix; then 2 ml of sodium citrate solution, 5 ml of anhydrous ethanol, and an appropriate amount of sodium borohydride were added. The stirred solution was heated at 180°C for 5 hours, centrifuged, washed with distilled water and ethanol several times, and dried in a vacuum oven at 60°C for 12 hours to obtain a graphene / platinum nanoparticle composite.

[0044] Furthermore, the step of modifying the groove gate includes:

[0045] An appropriate amount of synthesized graphene / platinum nanoparticle complex is placed in deionized water and ultrasonically mixed to form a particle-free uniform suspension. A small amount of the solution is dropped on the surface of the groove, covered with a glass cover and dried in a drying area. The aptamer is then fixed to the surface of the composite material through covalent bonds or electrostatic adsorption.

[0046] As an optional embodiment, the present invention also provides a mercury ion concentration detection device based on gallium nitride for Hg 2+ The detection method comprises the following steps:

[0047] Step 1: Add different concentrations of Hg2 + The standard buffer solution is sequentially introduced into the serpentine channel 1 and then into the first channel 1-1. Different drain bias voltages are applied to the source 12 and drain 13 of the device to measure the IV characteristic curve of the GaN device. + The current value output by the solution is used to establish a standard curve for the detection device.

[0048] Step 2: Pre-irradiate the test water with UV light for 30 seconds. Add appropriate amounts of EDTA buffer and test water to the two inlets, respectively, and allow them to mix and precipitate in the reaction tank. Just as the mixed solution is about to pass through the third inlet, add acetic acid-sodium acetate buffer.

[0049] Step 3: When the mixed solution passes through the groove structure, measure its output current value under the same conditions. Compare the output current with the standard curve and determine the Hg2 in the test solution based on the matching current value. + concentration.

[0050] 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 (M), characterized in that: include, A serpentine channel (1), the head end of which is connected to a reaction pool (2), and the tail end of which is respectively connected to a first channel (1-1) and a second channel (1-2); the first channel (1-1) flows through a gate region (14) of a semiconductor structure; A magnetic member (3) is provided at the connection between the serpentine channel (1), the first channel (1-1) and the second channel (1-2) for diverting positive ions and negative ions in the solution.

2. The microfluidic panel (M) according to claim 1, characterized in that: At least one filter unit (4) is connected in series on the serpentine channel (1).

3. The microfluidic panel (M) according to claim 1 or 2, characterized in that: The reaction pool (2) is connected to the first liquid inlet (5) and the second liquid inlet (6) respectively, and the middle of the serpentine channel (1) is also connected to the third liquid inlet (7).

4. A mercury ion concentration detection device based on gallium nitride, characterized in that: A microfluidic panel (M) according to any one of claims 1 to 3, further comprising a buffer layer (9) and a two-dimensional electron gas layer (10) stacked in sequence; The two-dimensional electron gas layer (10) comprises an intrinsic layer (10-1), an isolation layer (10-2), and a barrier layer (10-3) stacked in sequence; a surface of the barrier layer (10-3) is provided with a groove, and the surface of the groove is coated with a specific recognition layer (11); When the liquid to be tested flows through the specific recognition layer (11), its surface charge will change.

5. The gallium nitride-based mercury ion concentration detection device according to claim 4, characterized in that: The specific recognition layer (11) comprises a graphene / metal platinum nanoparticle complex and an aptamer coated on the surface of the groove, and the surface of the aptamer has a thymine base.

6. The gallium nitride-based mercury ion concentration detection device according to claim 5, characterized in that: The thickness of the buffer layer is 1 to 10000 nm; the material of the intrinsic layer (10-1) is GaN, with a thickness of 10 to 6000 nm; the material of the barrier layer (10-3) is AIGaN, with a thickness of 10 to 25 nm; the material of the isolation layer (10-2) is AIN, with a thickness of 1 nm.

7. The gallium nitride-based mercury ion concentration detection device according to claim 6, characterized in that: It also includes a source electrode (12) and a drain electrode (13) arranged on the top of the intrinsic layer (10-1), and a gate region (14) arranged on the top of the groove, wherein a portion of the gate region (14) is placed in the groove.

8. The gallium nitride-based mercury ion concentration detection device according to claim 7, characterized in that: It also includes a bottom plate (15) and a top plate (16), wherein the buffer layer (9) and the two-dimensional electron gas layer (10) are both embedded in the bottom plate (15), and the microfluidic panel (M) is located between the bottom plate (15) and the top plate (16).

9. A method for preparing a mercury ion concentration detection device based on gallium nitride, characterized in that: Suitable for preparing the mercury ion concentration detection device according to any one of claims 4 to 8, the method comprising: forming a buffer layer (9) on the surface of a substrate (17); forming an intrinsic layer (10-1) on the surface of the buffer layer (9); forming an isolation layer (10-2) on the surface of the intrinsic layer (10-1); forming a barrier layer (10-3) on the surface of the isolation layer (10-2); A groove is formed on the surface of the barrier layer (10-3), and a specific recognition layer (11) is coated on the surface; The microfluidic panel (M) is covered on the coating specific recognition layer (11).

10. The method for preparing a mercury ion concentration detection device based on gallium nitride according to claim 9, characterized in that: The material of the specific recognition layer (11) is a graphene / metal platinum nanoparticle composite material.

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