A glucose concentration sensor and a method of manufacturing the same

Abstract

The embodiment of the present application provides a glucose concentration sensor and a preparation method thereof, the glucose concentration sensor comprises a substrate, a gallium nitride layer, an aluminum nitride layer, an organic functional group layer and a metal electrode layer; the substrate comprises at least one isosceles trapezoid structure; the isosceles trapezoid structure comprises a first side, a second side, a third side, a fourth side and a top surface; the gallium nitride layer is epitaxially grown on the first side and the second side, the aluminum nitride layer is laminated on the gallium nitride layer and the top surface, and the gallium nitride layer and the aluminum nitride layer laminated on the gallium nitride layer form a two-dimensional electron gas; the organic functional group layer is laminated on the upper surface of the aluminum nitride layer; and the metal electrode layer is laminated on the first region and the second region of the organic functional group layer and extends to the aluminum nitride layer. The glucose concentration sensor provided by the embodiment of the present application is simple in structure and easy to operate, can improve the detection sensitivity of the glucose concentration, and can also reduce the detection cost of the glucose concentration.

Description

Technical Field

[0001] This invention relates to the field of analytical detection technology, and in particular to a glucose concentration sensor and its preparation method. Background Technology

[0002] Glucose is the most widely distributed monosaccharide in nature. As the main energy source for living cells, glucose not only effectively enhances memory but also stimulates calcium absorption and promotes intercellular communication. However, an imbalance in blood glucose levels can trigger a series of diseases; for example, low glucose levels may lead to symptoms such as weakness, dizziness, and fatigue, while high glucose levels may lead to dehydration, diabetic nephropathy, and diabetic foot.

[0003] Currently, glucose concentration detection is mainly achieved through methods such as spectroscopy, fluorescence, and colorimetry.

[0004] However, methods such as spectroscopic, fluorescence, and colorimetric methods often suffer from high reagent costs, high equipment costs, complex equipment, cumbersome testing processes, and low sensitivity. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a glucose concentration sensor and its preparation method, so as to solve the problems of high testing cost, cumbersome testing process and low sensitivity of existing glucose concentration detection methods.

[0006] To solve the above problems, the present invention is achieved through the following technical solution:

[0007] This invention proposes a glucose concentration sensor, which includes a substrate, a gallium nitride layer, an aluminum nitride layer, an organic functional group layer, and a metal electrode layer;

[0008] The substrate includes at least one isosceles trapezoidal structure; adjacent isosceles trapezoidal structures are spaced apart by a first length; the isosceles trapezoidal structure includes a first side, a second side, a third side, a fourth side, and a top surface; the first side and the second side are the waists of the isosceles trapezoidal structure; the third side and the fourth side are opposite to each other and perpendicular to the top surface;

[0009] The gallium nitride layer is epitaxially distributed on the first side and the second side; the aluminum nitride layer is stacked on the upper surface of the gallium nitride layer and the top surface of the isosceles trapezoidal structure; the gallium nitride layer and the aluminum nitride layer stacked on the upper surface of the gallium nitride layer constitute a two-dimensional electron gas, which is used to obtain the electrical signal when the organic functional group layer and glucose molecules bind; the electrical signal is used to indicate the concentration of glucose molecules;

[0010] The organic functional group layer is stacked on the upper surface of the aluminum nitride layer; the organic functional group layer includes a first region near the third side and a second region near the fourth side, with a second length separating the first region and the second region;

[0011] The metal electrode layer includes a first electrode layer and a second electrode layer. The first electrode layer is stacked on the first region and extends along the plane of the third side to the aluminum nitride layer. The second electrode layer is stacked on the second region and extends along the plane of the fourth side to the aluminum nitride layer.

[0012] This invention also proposes a method for preparing a glucose concentration sensor, the method comprising:

[0013] Obtain a substrate; the substrate includes at least one isosceles trapezoidal structure, with a first length interval between adjacent isosceles trapezoidal structures; the isosceles trapezoidal structure includes a first side surface, a second side surface, a third side surface, a fourth side surface, and a top surface; the first side surface and the second side surface are the waists of the isosceles trapezoidal structure; the third side surface and the fourth side surface are opposite to each other and perpendicular to the top surface;

[0014] Gallium nitride layers are epitaxially grown on the first side and the second side;

[0015] An aluminum nitride layer is grown on the upper surface of the gallium nitride layer and the top surface of the isosceles trapezoidal structure. The gallium nitride layer and the aluminum nitride layer stacked on the upper surface of the gallium nitride layer constitute a two-dimensional electron gas. The two-dimensional electron gas is used to obtain the electrical signal when the organic functional group layer and glucose molecules bind. The electrical signal is used to indicate the concentration of glucose molecules.

[0016] A first solution is spin-coated onto the upper surface of the aluminum nitride layer, and the first solution spin-coated onto the aluminum nitride layer is dried to obtain an organic functional group layer; the organic functional group layer includes a first region near the third side and a second region near the fourth side, with a second length spaced between the first region and the second region;

[0017] A first electrode layer is deposited in the region corresponding to the organic functional group layer and the aluminum nitride layer in the plane containing the first region and the third side, and a second electrode layer is deposited in the region corresponding to the organic functional group layer and the aluminum nitride layer in the plane containing the second region and the fourth side, to obtain a glucose concentration sensor; the first electrode layer and the second electrode layer constitute the metal electrode layer of the glucose concentration sensor.

[0018] Compared with the prior art, the embodiments of the present invention have the following advantages:

[0019] The glucose concentration sensor provided in this embodiment of the invention includes a substrate, a gallium nitride layer, an aluminum nitride layer, an organic functional group layer, and a metal electrode layer. The substrate includes at least one isosceles trapezoidal structure, with adjacent isosceles trapezoidal structures spaced apart by a first length. The two-dimensional electron gas and the organic functional group layer, sequentially stacked on each isosceles trapezoidal structure, have a large specific surface area, increasing the contact probability between glucose molecules and the organic functional group layer, thus improving the detection efficiency of the glucose concentration sensor. The gallium nitride layer is epitaxially located on the first and second sides of the isosceles trapezoidal structure. The aluminum nitride layer is stacked on the upper surface of the gallium nitride layer and the top surface of the isosceles trapezoidal structure, such that the gallium nitride layer and the aluminum nitride layer stacked on the upper surface of the gallium nitride layer constitute a two-dimensional electron gas, and the organic functional group layer is stacked on the upper surface of the aluminum nitride layer. In this invention, a first electrode layer of a metal electrode layer is stacked on the first region of the organic functional group layer and extends along the plane of the third side of the isosceles trapezoidal structure to the aluminum nitride layer. A second electrode layer of the metal electrode layer is stacked on the second region and extends along the plane of the fourth side to the aluminum nitride layer. The electron concentration of the two-dimensional electron gas layer is sensitive to weak electrical signals, allowing for real-time acquisition of weak electrical signals before and after the specific binding of the organic functional group layer and glucose molecules. These signals are then output through the metal electrode layer, thereby lowering the detection limit of glucose concentration and improving the sensitivity of the glucose concentration sensor. Furthermore, directly stacking the organic functional group layer on the surface of the aluminum nitride layer shortens the distance between the organic functional group layer and the two-dimensional electron gas, further improving the sensitivity of the glucose concentration sensor. The glucose concentration sensor provided in this embodiment has a simple structure and is easy to operate. While improving the detection sensitivity of glucose concentration, it also reduces the detection cost of glucose concentration.

[0020] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention. Attached Figure Description

[0021] Figure 1 This is a top view schematic diagram of a glucose concentration sensor provided in an embodiment of the present invention;

[0022] Figure 2 This is a cross-sectional view of a glucose concentration sensor along the thickness direction provided in an embodiment of the present invention.

[0023] Figure 3 This is a flowchart illustrating the steps of a method for preparing a glucose concentration sensor according to an embodiment of the present invention.

[0024] Figure 4 This is a graph showing the relationship between the current value output by a glucose concentration sensor and the glucose concentration, provided in an embodiment of the present invention.

[0025] Explanation of reference numerals in the attached figures:

[0026] 10-Substrate; 20-Two-dimensional electron gas; 30-Organic functional group layer; 40-Metal electrode layer; 21-Gallium nitride layer; 22-Aluminum nitride layer; 41-First electrode layer; 42-Second electrode layer; 01-First side surface; 02-Second side surface; 03-Third side surface; 04-Fourth side surface; 05-Top surface; 06-Polar surface; 07-Semi-polar surface. Detailed Implementation

[0027] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0028] The following description, in conjunction with the accompanying drawings, details a glucose concentration sensor and its preparation method provided in this application through specific embodiments and application scenarios.

[0029] Reference Figure 1 and Figure 2 , Figure 1 This is a top view schematic diagram of a glucose concentration sensor according to an embodiment of the present invention. Figure 2 Is Figure 1 A cross-sectional view of the glucose concentration sensor along its thickness at the O-O' line. Figure 1 and Figure 2As shown, the glucose concentration sensor of this embodiment includes a substrate 10, a gallium nitride (GaN) layer 21, an aluminum nitride (AlN) layer 22, an organic functional group layer 30, and a metal electrode layer 40. The substrate 10 includes at least one isosceles trapezoidal structure, with a first length l1 between adjacent isosceles trapezoidal structures. The isosceles trapezoidal structure includes a first side surface 01, a second side surface 02, a third side surface 03, a fourth side surface 04, and a top surface 05. The first side surface 01 and the second side surface 02 are the waists of the isosceles trapezoidal structure; the third side surface 03 and the fourth side surface 04 are opposite each other and perpendicular to the top surface 05. A gallium nitride (GaN) layer 21 is epitaxially distributed on the first side surface 01 and the second side surface 02. An aluminum nitride (A) layer 22 is stacked on the upper surface of the GaN layer 21 and the top surface 05 of the isosceles trapezoidal structure. The GaN layer 21 and the Aluminum nitride layer 22 stacked on the upper surface of the GaN layer 21 constitute a two-dimensional electron gas (2DEG) 20. The 2DEG 20 is used to acquire the electrical signal when the organic functional group layer 30 binds to glucose molecules, and this electrical signal is used to indicate the concentration of glucose molecules. The organic functional group layer 30 is stacked on the upper surface of the Aluminum nitride layer 22. The organic functional group layer 30 includes a first region near the third side surface 03 and a second region near the fourth side surface 04, with a second length l2 between the first region and the second region. The metal electrode layer 40 includes a first electrode layer 41 and a second electrode layer 42. The first electrode layer 41 is stacked in the first region and extends along the plane of the third side surface 03 to the aluminum nitride layer 22. The second electrode layer 42 is stacked in the second region and extends along the plane of the fourth side surface 04 to the aluminum nitride layer 22.

[0030] In this substrate 10, a two-dimensional electron gas 20, an organic functional group layer 30, and a metal electrode layer 40 are formed on each isosceles trapezoidal structure. It can be understood that the gaps between adjacent isosceles trapezoidal structures in the substrate 10 are also isosceles trapezoidal structures, which can be called growth grooves and are used to form the two-dimensional electron gas 20.

[0031] The first length l1 between adjacent isosceles trapezoidal structures is the length between adjacent bases of the adjacent isosceles trapezoidal structures, and the third length l3 between the organic functional group layers 30 on adjacent isosceles trapezoidal structures is greater than 0, that is, the organic functional group layers on adjacent isosceles trapezoidal structures need to ensure that they do not contact each other. For example, the first isosceles trapezoidal structure and the second isosceles trapezoidal structure are adjacent isosceles trapezoidal structures in the substrate 10. The first isosceles trapezoidal structure includes a first base and a second base, and the second isosceles trapezoidal structure includes a third base and a fourth base. The second base of the first isosceles trapezoidal structure and the third base of the second isosceles trapezoidal structure are adjacent. Therefore, the first length l1 between the first isosceles trapezoidal structure and the second isosceles trapezoidal structure is the distance between the second base and the third base. It should be noted that the base of the isosceles trapezoidal structure is the base corresponding to the waist of the isosceles trapezoidal structure.

[0032] It is understood that each isosceles trapezoidal structure includes four sides and a top surface 05. The first side 01 is opposite to the second side 02 and is the waist of the isosceles trapezoidal structure. The third side 03 is opposite to the fourth side 04 and is the side outside the waist of the isosceles trapezoidal structure. In this embodiment of the invention, the third side 03 and the fourth side 04 are both perpendicular to the top surface 05 of the isosceles trapezoidal structure.

[0033] In the organic functional group layer 30, the first region is the area extending from the edge near the third side surface 03 towards the center of the organic functional group layer 30, and the second region is the area extending from the edge near the fourth side surface 04 towards the center of the organic functional group layer 30. The first region and the second region are separated by a second length l2, which is greater than 0. This means the first region and the second region must not contact each other to avoid short circuits caused by contact between the first electrode layer 41 stacked in the first region and the second electrode layer 42 stacked in the second region. The first width of the first region along the direction from the edge near the third side surface to the center of the organic functional group layer is 5 μm to 500 μm, and the second width of the second region along the direction from the edge near the fourth side surface to the center of the organic functional group layer is the same as the first width, also 5 μm to 500 μm.

[0034] In this embodiment of the invention, the two-dimensional electron gas 20 covers the first side 01 and the second side 02 of the isosceles trapezoidal structure, and the organic functional group layer 03 is stacked on the entire upper surface of the two-dimensional electron gas 20. The metal electrode layer 40 is only stacked on the first region near the third side 03 and the second region near the fourth side 04 of the organic functional group layer 30. This allows the glucose concentration sensor to transmit electrical signals through the metal electrode layer 40 while ensuring sufficient contact between the surface of the organic functional group layer 30 and glucose molecules. Based on the electrical signal obtained by the two-dimensional electron gas 20 when the organic functional group layer 30 binds to glucose molecules, the concentration of glucose molecules is determined.

[0035] Specifically, when glucose molecules and organic functional group layer 30 specifically bind to form an electrical signal, two-dimensional electron gas 20 acquires the electrical signal and transmits it through metal electrode layer 40 to an electrical signal receiving device connected to glucose concentration sensor. The user can view the electrical signal from the electrical signal receiving device and determine the specific concentration of glucose molecules based on the electrical signal.

[0036] Among them, a two-dimensional electron gas 20 is a system in which the movement of an electron group in one direction (such as the z direction) is restricted to a very small range by using physical methods such as quantum confinement, while it can move freely in the other two directions (such as the x and y directions). If the electron density in the two-dimensional electron system is high, it is called a two-dimensional electron gas 20.

[0037] In this embodiment of the invention, the material of the two-dimensional electron gas 20 may include, but is not limited to, aluminum nitride / gallium nitride, aluminum gallium nitride (AlGaN) / gallium nitride, etc.

[0038] A glucose molecule can be any glucose molecule in a liquid; for example, a glucose molecule can be a glucose molecule in blood or a glucose solution. An electrical signal can be a current value or a voltage value.

[0039] In this embodiment of the invention, when the resistance of the glucose concentration sensor is constant, the concentration of glucose molecules is positively correlated with the current value and the concentration of glucose molecules is positively correlated with the voltage value.

[0040] Before using a glucose concentration sensor to detect glucose molecule concentration, multiple sets of target liquids with known glucose molecule concentrations can be measured using the glucose concentration sensor to determine the correlation between glucose molecule concentration and electrical signal. During the glucose concentration detection process using the glucose concentration sensor, the glucose molecule concentration can be determined based on the predetermined correlation and the electrical signal acquired by the two-dimensional electron gas 20.

[0041] In this embodiment of the invention, the two-dimensional electron gas 20 is obtained by combining gallium nitride and aluminum nitride. An aluminum nitride layer 22 coats the upper surface of the gallium nitride layer 21, forming the two-dimensional electron gas 20 at the interface between the aluminum nitride layer 22 and the gallium nitride layer 21. The glucose concentration sensor provided by this embodiment uses the two-dimensional electron gas 20, formed by the heterojunction interface of the gallium nitride layer 21 and the aluminum nitride layer 22, to capture the electrical signal when the organic functional group layer 30 specifically binds to glucose molecules. This achieves the purpose of detecting the concentration of glucose molecules. Furthermore, the gallium nitride grown by this method has low stress and high crystal quality, reducing the scattering effect of defects in the first side surface 01 and the second side surface 02 on the two-dimensional electron gas 20, improving the mobility of the two-dimensional electron gas 20, and thus improving the accuracy and sensitivity of the glucose concentration sensor in detecting the concentration of glucose molecules.

[0042] The substrate 10 is a silicon (Si) substrate, and the first side surface 01 and the second side surface 02 are the 111 crystal plane of the Si substrate. The metal electrode layer 40 may include one or more of titanium (Ti), aluminum (Al), nickel (Ni), gold (Au), platinum (Pt), molybdenum (Mo), iridium (Ir), tantalum (Ta), niobium (Nb), cobalt (Co), and tungsten (W).

[0043] Addressing the issues of high testing costs, cumbersome testing processes, and low sensitivity in existing glucose concentration detection methods, this invention provides a glucose concentration sensor comprising a substrate 10, a gallium nitride layer 21, an aluminum nitride layer 22, an organic functional group layer 30, and a metal electrode layer 40. The substrate 10 includes at least one isosceles trapezoidal structure, with adjacent isosceles trapezoidal structures spaced apart by a first length. The two-dimensional electron gas 20 and the organic functional group layer 30, sequentially stacked on each isosceles trapezoidal structure, have a large specific surface area, increasing the contact probability between glucose molecules and the organic functional group layer 30, thus improving the detection efficiency of the glucose concentration sensor. The gallium nitride layer 21 is epitaxially located on the first side 01 and the second side 02 of the isosceles trapezoidal structure. The aluminum nitride layer 22 is stacked on the upper surface of the gallium nitride layer 21 and the top surface 05 of the isosceles trapezoidal structure, such that the gallium nitride layer 21 and the aluminum nitride layer 22 stacked on the upper surface of the gallium nitride layer 21 constitute a two-dimensional electron gas. 20. An organic functional group layer 30 is stacked on the upper surface of an aluminum nitride layer 22. A first electrode layer 41 of a metal electrode layer 40 is stacked on the first region of the organic functional group layer 30 and extends to the aluminum nitride layer 22 along the plane of the third side 03 of the isosceles trapezoidal structure. A second electrode layer 42 of the metal electrode layer 40 is stacked on the second region and extends to the aluminum nitride layer 22 along the plane of the fourth side 04. The electron concentration of the two-dimensional electron gas layer 20 is sensitive to weak electrical signals. It can acquire weak electrical signals before and after the specific binding of the organic functional group layer 30 and glucose molecules in real time, and output electrical signals through the metal electrode layer 40, thereby reducing the detection limit of glucose concentration and improving the sensitivity of the glucose concentration sensor. Furthermore, by directly stacking the organic functional group layer 30 on the surface of the two-dimensional electron gas 20, the distance between the organic functional group layer 30 and the two-dimensional electron gas 20 can be shortened, further improving the sensitivity of the glucose concentration sensor. The glucose concentration sensor provided in this embodiment of the invention not only improves the detection sensitivity and efficiency of glucose concentration, but also simplifies operation and reduces the detection cost of glucose concentration.

[0044] Optionally, refer to Figure 1 The gallium nitride layer 21 includes a polar surface 06 and a semi-polar surface 07; wherein, the polar surface 06 is a surface parallel to the first side surface 01 or the second side surface 02, and the semi-polar surface 07 is a surface in the gallium nitride layer 21 other than the polar surface 06.

[0045] The glucose concentration sensor provided in this embodiment of the invention has a gallium nitride layer 21 with one polar surface 06 and two semi-polar surfaces 07. Compared with the first direction perpendicular to the semi-polar surface 07, the gallium nitride layer 21 grows faster in the second direction perpendicular to the polar surface 06. During the growth process, the stress of the gallium nitride layer 21 can be well released, resulting in fewer defects at the heterojunction interface between the gallium nitride layer 21 and the aluminum nitride layer 22, and higher crystal quality. This can greatly improve the mobility of the two-dimensional electron gas 20 formed by the heterojunction interface between the gallium nitride layer 21 and the aluminum nitride layer 22, making the glucose concentration sensor more sensitive in the process of detecting the concentration of glucose molecules.

[0046] It is understandable that, when the growth rate of the gallium nitride layer 21 in the second direction perpendicular to the polar surface 06 is greater than the growth rate in the first direction perpendicular to the semi-polar surface 07, the cross-sectional shape of the gallium nitride layer 21 epitaxially grown on the first side surface 01 and the second side surface 02 along the thickness direction of the glucose concentration sensor is as follows: Figure 1 The isosceles trapezoid shown.

[0047] Optionally, in some embodiments, the thickness of the gallium nitride layer 21 is from 1 μm to 10 μm. For example, the thickness of the gallium nitride layer 21 can be one or any two of the following: 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm and 10 μm.

[0048] The thickness of the gallium nitride layer 21 is the distance from the surface of the gallium nitride layer 21 parallel to the first side surface 01 (i.e., the polar surface 06) to the first side surface 01.

[0049] Optionally, in some embodiments, the thickness of the aluminum nitride layer 22 is from 15 nm to 30 nm. For example, the thickness of the aluminum nitride layer 22 can be one or any two of the following values: 15 nm, 18 nm, 20 nm, 22 nm, 24 nm, 26 nm, 28 nm, 30 nm, 32 nm and 35 nm.

[0050] The thickness of the aluminum nitride layer 22 is the distance between the surface of the aluminum nitride layer 22 that is stacked with the gallium nitride layer 21 and the surface that is stacked with the organic functional group layer 30.

[0051] Optionally, in some embodiments, the organic functional group layer 30 is any one of glucose carbon quantum dot chitosan molecularly imprinted film, borate-functionalized carbon quantum dot molecularly imprinted film, and reduced graphene-nano copper molecularly imprinted film.

[0052] Optionally, in some embodiments, the height of each isosceles trapezoidal structure in the substrate 10 is from 1 μm to 5 μm, for example, it can be a range of one or any two of 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm.

[0053] The height of the isosceles trapezoidal structure refers to the distance between the plane formed by the base sides of each isosceles trapezoidal structure and the top surface 05 of the isosceles trapezoidal structure.

[0054] It should be noted that, in this embodiment of the invention, the heights of each isosceles trapezoidal structure in the substrate 10 are equal.

[0055] Optionally, in some embodiments, the thickness of the substrate 10 is from 2 μm to 200 μm; for example, the thickness of the substrate 10 can be a range of one or any two of 1 μm, 20 μm, 40 μm, 60 μm, 80 μm, 100 μm, 120 μm, 140 μm, 160 μm, 180 μm and 200 μm.

[0056] The thickness of substrate 10 is the distance between the bottom surface of substrate 10 and the top surface 05 of the isosceles trapezoidal structure.

[0057] Optionally, in some embodiments, the thickness of the organic functional group layer 30 is from 200 nm to 1000 nm; for example, the thickness of the organic functional group layer 30 can be a range of one or any two of 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm and 1000 nm.

[0058] Optionally, in some embodiments, the thickness of the metal electrode layer 40 is from 50 nm to 1000 nm; for example, the thickness of the metal electrode layer 40 can be a range of one or any two of 50 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm and 1000 nm.

[0059] It is understood that the first electrode layer 41 and the second electrode layer 42 in the metal electrode layer 40 have the same thickness, and the thickness of the first electrode layer 41 and the second electrode layer 42 is 50nm to 1000nm.

[0060] This invention also provides a method for preparing any of the aforementioned glucose concentration sensors. (Refer to...) Figure 3 The diagram illustrates a flowchart of a method for preparing a glucose concentration sensor according to an embodiment of the present invention, the method comprising steps S101 to S105:

[0061] Step S101: Obtain the substrate.

[0062] The substrate includes at least one isosceles trapezoidal structure, with a first length interval between adjacent isosceles trapezoidal structures; the isosceles trapezoidal structure includes a first side, a second side, a third side, a fourth side, and a top surface; the first side and the second side are the waists of the isosceles trapezoidal structure; the third side and the fourth side are opposite to each other and perpendicular to the top surface.

[0063] In this step, the substrate is a silicon substrate, and at least one isosceles trapezoidal structure is pre-prepared on the substrate to meet the needs of preparing a gallium nitride layer in subsequent step S102, an aluminum nitride layer in step S103, an organic functional group layer in step S104, and a metal electrode layer in step S105.

[0064] The thickness of the substrate can be from 1 μm to 200 μm; the height of the isosceles trapezoidal structure in the substrate is from 1 μm to 5 μm.

[0065] Step S102: Epitaxially grow gallium nitride layers on the first side and the second side.

[0066] Step S103: An aluminum nitride layer is grown on the upper surface of the gallium nitride layer and the top surface of the isosceles trapezoidal structure.

[0067] The gallium nitride layer and the aluminum nitride layer stacked on the upper surface of the gallium nitride layer constitute a two-dimensional electron gas; the two-dimensional electron gas is used to acquire the electrical signal when the organic functional group layer and glucose molecules bind; the electrical signal is used to indicate the concentration of glucose molecules. The material of the two-dimensional electron gas 20 may include, but is not limited to, aluminum nitride / gallium nitride, aluminum gallium nitride / gallium nitride, etc.

[0068] In this embodiment of the invention, the two-dimensional electron gas is formed by the heterojunction interface of the gallium nitride layer and the aluminum nitride layer. In the process of preparing the two-dimensional electron gas, gallium nitride layers can be grown on the first and second sides of the isosceles trapezoidal structure by selective epitaxial growth technology in step S102, and then aluminum nitride layers can be grown on the upper surface of the gallium nitride layer and the top surface of the isosceles trapezoidal structure in step S103, thereby forming a two-dimensional electron gas at the heterojunction interface of the gallium nitride layer and the aluminum nitride layer.

[0069] Trimethylgallium (Ga(CH3)3) can be used as the gallium precursor, trimethylaluminium (C3H9Al) as the aluminum precursor, and ammonia (NH3) as the nitrogen precursor. Specifically, before step S102, the substrate obtained in step S101 can be placed in a metal-organic chemical vapor deposition (MOCVD) reactor; in step S102, the vaporized gases of trimethylgallium and ammonia are introduced into the MOCVD reactor to selectively grow gallium nitride layers on the first and second sides of the isosceles trapezoidal structure; in step S103, the vaporized gases of trimethylaluminium and ammonia are introduced into the MOCVD reactor to grow aluminum nitride layers on the upper surface of the gallium nitride layer and the top surface of the isosceles trapezoidal structure.

[0070] It is understandable that the first and second sides of the isosceles trapezoidal structure are the same crystal plane, while the third and fourth sides are different from the first and second sides. The crystal planes corresponding to the first and second sides are favorable for gallium nitride growth. Therefore, in step S102, the gallium nitride layer will preferentially grow on the first and second sides. During the preferential growth of the gallium nitride layer on the first and second sides, the stress can be well released. Compared with conventional thin film structures, the heterojunction structure prepared by this method has higher interface crystal quality and fewer defects, which can improve the mobility of two-dimensional electron gas and make the glucose concentration sensor more sensitive to the detection of glucose molecule concentration.

[0071] The gallium nitride layer includes a polar surface and a semi-polar surface; the polar surface is the surface parallel to the first or second side surface, and the semi-polar surface is the surface in the gallium nitride layer other than the polar surface. In the two-dimensional electron gas, the thickness of the gallium nitride layer is 1 μm to 10 μm, and the thickness of the aluminum nitride layer is 15 nm to 30 nm.

[0072] Step S104: Spin-coat the first solution onto the upper surface of the aluminum nitride layer, and dry the first solution spin-coated onto the aluminum nitride layer to obtain an organic functional group layer; the organic functional group layer includes a first region near the third side and a second region near the fourth side, with a second length spaced between the first region and the second region.

[0073] Specifically, in the organic functional group layer, the first region is the region extending from the edge near the third side of the organic functional group layer towards the center of the organic functional group layer, and the second region is the region extending from the edge near the fourth side of the organic functional group layer towards the center of the organic functional group layer. The first region and the second region are separated by a second length, which is greater than 0. That is, the first region and the second region need to be ensured not to contact each other to avoid short circuits caused by contact between the first electrode layer deposited in the first region and the second electrode layer deposited in the second region in step S104.

[0074] The first solution is a precursor solution corresponding to a pre-prepared organic functional group layer; the thickness of the organic functional group is 200 nm to 1000 nm.

[0075] In this embodiment of the invention, the organic functional group layer is any one of glucose carbon quantum dot chitosan molecularly imprinted film, borate-functionalized carbon quantum dot molecularly imprinted film, and reduced graphene-nano copper molecularly imprinted film.

[0076] Specifically, when the organic functional group layer is a glucose carbon quantum dot chitosan molecularly imprinted film, the first solution is an ethanol solution of the glucose carbon quantum dot chitosan molecularly imprinted polymer. When the first solution is an ethanol solution of the glucose carbon quantum dot chitosan molecularly imprinted polymer, the preparation method of the first solution includes the following steps A11 to A14:

[0077] Step A11: Synthesize carbon quantum dot (CDs) nanomaterials using carbon source as material. Mix the carbon quantum dot nanomaterials with a chitosan (CS) solution with good film-forming properties in a first ratio to obtain a first solution.

[0078] The first ratio is 1:7 to 1:3.

[0079] Step A12: The first solution is applied to the surface of the glassy carbon electrode (GCE), and the glassy carbon electrode is placed in an oven for drying to obtain CDs-CS / GCE.

[0080] The drying temperature ranges from 10℃ to 100℃, and the drying time ranges from 10 min to 60 min.

[0081] Step A13: Using 3-aminophenylboronic acid (APBA) as a functional monomer and glucose as a template molecule, glucose carbon quantum dot chitosan molecularly imprinted polymer (MIP) was synthesized on CDs-CS / GCE using a three-electrode system.

[0082] Specifically, firstly, 3-aminophenylboronic acid and glucose are mixed in equal proportions (ranging from 0.8:1 to 1.2:1) to obtain a second solution; then, the second solution is coated onto CDs-CS / GCE; finally, a voltage of 1V to 10V is applied to the CDs-CS / GCE coated with the second solution using any three of the four electrodes (gold, platinum, silver, and copper) for 1 to 10 minutes to obtain a glucose carbon quantum dot chitosan molecularly imprinted polymer.

[0083] Step A14: The glucose carbon quantum dot chitosan molecularly imprinted polymer is ultrasonically cleaned in an ethanol solution to obtain a glucose carbon quantum dot chitosan molecularly imprinted film.

[0084] The duration of ultrasonic cleaning is 5 min to 30 min.

[0085] When the organic functional group layer is a boric acid-functionalized carbon quantum dot molecularly imprinted film, the first solution is an ethanol solution of the boric acid-functionalized carbon quantum dot molecularly imprinted polymer. When the first solution is an ethanol solution of the boric acid-functionalized carbon quantum dot molecularly imprinted polymer, the preparation method of the first solution includes the following steps A21 to A26:

[0086] Step A21: Dissolve sodium citrate (Na3C6H5O7·2H2O) and aminophenylboronic acid (PBA) as precursors in 40 mL of distilled water to obtain the third solution.

[0087] The mass ratio of sodium citrate to aminophenylboronic acid is 1.2:1 to 2:1.

[0088] Step A22: Adjust the pH of the third solution to neutral, and continuously introduce nitrogen gas into the neutral third solution to remove dissolved oxygen.

[0089] The method for adjusting the pH of the third solution to neutral is to add sodium hydroxide (NaOH) and / or potassium hydroxide (KOH) to the third solution. The flow rate of nitrogen gas is in the range of 10 sccm to 200 sccm; the duration of nitrogen gas introduction is in the range of 1 min to 30 min.

[0090] Step A23: Heat the third solution using a reaction vessel, and then cool the third solution to room temperature after the heating treatment.

[0091] The heating treatment temperature is between 100℃ and 300℃, and the heating treatment duration is between 1 hour and 12 hours.

[0092] Step A24: Centrifuge the third solution cooled to room temperature, and then freeze-dry the third solution after centrifugation to obtain solid borate functionalized carbon quantum dots (APBA-CDs).

[0093] The purpose of centrifuging the third solution after it has been cooled to room temperature is to remove the precipitate from the third solution.

[0094] The centrifugation speed is 500 rpm / min to 3000 rpm / min, and the centrifugation time is 1 min to 30 min.

[0095] Step A25: Using APBA-CDs as a carrier, boric acid functionalized carbon quantum dot molecularly imprinted polymers are obtained by sol-gel polymerization under the action of methyl orthosilicate (TMOS) and phenyltriethoxysilane (TEOS).

[0096] Specifically, firstly, APBA-CDs, methyl orthosilicate, and phenyltriethoxysilane are mixed in a second ratio to obtain a fourth solution; then, the fourth solution is kept at a temperature using a muffle furnace to obtain a first mixture; finally, the first mixture is allowed to stand at room temperature for 24 to 48 hours to obtain a boric acid-functionalized carbon quantum dot molecularly imprinted polymer.

[0097] The second ratio is 1.5:1:1 to 2:1:1; the temperature of the heat preservation treatment is 10℃ to 300℃, and the duration of the heat preservation treatment is 1 hour to 10 hours.

[0098] Step A26: The boric acid-functionalized carbon quantum dot molecularly imprinted polymer is ultrasonically cleaned in an ethanol solution to obtain a boric acid-functionalized carbon quantum dot molecularly imprinted film.

[0099] The duration of ultrasonic cleaning is 5 min to 30 min.

[0100] When the organic functional group layer is a reduced graphene-copper nanoparticle-imprinted film, the first solution is an ethanol solution of the reduced graphene-copper nanoparticle-imprinted polymer. When the first solution is an ethanol solution of the reduced graphene-copper nanoparticle-imprinted polymer, the preparation method of the first solution includes the following steps A31 to A35:

[0101] Step A31: Graphene oxide (GO) is dispersed in N,N-dimethylformamide (DMF) and subjected to ultrasonic treatment to obtain a dispersion.

[0102] The mass ratio of graphene oxide to N,N-dimethylformamide is 1:3 to 1:8; the duration of ultrasonic treatment is 10 min to 60 min.

[0103] Step A32: Drop the dispersion onto the surface of the glassy carbon electrode and air dry it at room temperature to obtain a graphene oxide modified electrode (GO-GCE).

[0104] The thickness of the dispersion is 1 mm to 200 mm.

[0105] Step A33: Treat GO-GCE in a mixed solution of copper sulfate and sodium citrate to obtain rGO-CuNPs-GCE.

[0106] Step A34: Using glucose as a template molecule and p-aminobenzoic acid as a functional monomer, rGO-CuNPs-GCE is prepared by electropolymerization to obtain a reduced graphene-nano copper molecularly imprinted polymer.

[0107] Specifically, firstly, glucose and para-aminobenzoic acid are mixed in a third ratio to obtain a fifth solution; then, the fifth solution is kept at a constant temperature using a muffle furnace to obtain a second mixture, which is then naturally cooled to room temperature; next, the second mixture, cooled to room temperature, is added to rGO-CuNPs-GCE, and any one of gold / platinum / silver / copper is used as an electrode. A voltage of 1V to 10V is applied to the rGO-CuNPs-GCE containing the second mixture for 1min to 10min to obtain a reduced graphene-nano copper molecularly imprinted polymer.

[0108] The third ratio is 0.8:1 to 1.2:1; the temperature of the heat preservation treatment is 10℃ to 200℃, and the duration of the heat preservation treatment is 1 hour to 10 hours.

[0109] Step A35: The reduced graphene-copper nanomolecular imprinted polymer is ultrasonically cleaned in an ethanol solution to obtain a reduced graphene-copper nanomolecular imprinted film.

[0110] The duration of ultrasonic cleaning is 5 min to 30 min.

[0111] Step S105: Deposit a first electrode layer in the region corresponding to the organic functional group layer and the aluminum nitride layer in the plane containing the first region and the third side, and deposit a second electrode layer in the region corresponding to the organic functional group layer and the aluminum nitride layer in the plane containing the second region and the fourth side to obtain a glucose concentration sensor.

[0112] The first electrode layer and the second electrode layer constitute the metal electrode layer of the glucose concentration sensor; the thickness of the metal electrode layer is 50 nm to 1000 nm; it is understood that the thickness of the first electrode layer and the second electrode layer in the metal electrode layer is equal, and the thickness of both the first electrode layer and the second electrode layer is 50 nm to 1000 nm; for example, when the first electrode layer is the positive electrode of the glucose concentration sensor, the second electrode layer is the negative electrode of the glucose concentration sensor; when the first electrode layer is the negative electrode of the glucose concentration sensor, the second electrode layer is the positive electrode of the glucose concentration sensor.

[0113] In this step, the first electrode layer and the second electrode layer can be deposited using methods such as electroplating, electrophoresis, molecular deposition, and atomic deposition to obtain a glucose concentration sensor.

[0114] The first and second electrode layers are used to transmit the electrical signals acquired by the two-dimensional electron gas to an electrical signal receiving device connected to the glucose concentration sensor, so that users can view and analyze the electrical signals from the electrical signal receiving device.

[0115] Specifically, when glucose molecules and organic functional groups specifically bind to form an electrical signal, a two-dimensional electron gas acquires the electrical signal and transmits it through a first electrode layer and a second electrode layer to an electrical signal receiving device connected to a glucose concentration sensor. The user can view the electrical signal from the electrical signal receiving device and determine the concentration of glucose molecules based on the electrical signal.

[0116] The method for fabricating a glucose concentration sensor provided in this invention is based on a substrate comprising at least one isosceles trapezoidal structure. A two-dimensional electron gas and an organic functional group layer are sequentially fabricated on the isosceles trapezoidal structure of the substrate, resulting in a large specific surface area. This increases the contact probability between glucose molecules and the organic functional group layer, thereby improving the detection efficiency of the glucose concentration sensor. Gallium nitride (GaN) layers are epitaxially grown on the first and second sides of the isosceles trapezoidal structure, and aluminum nitride (ANU) layers are grown on the upper surface of the GaN layers and the top surface of the isosceles trapezoidal structure. The GaN layers and the ANU layer stacked on the upper surface of the GaN layers constitute a two-dimensional electron gas. An organic functional group layer is fabricated on the upper surface of the ANU layer, stacked on the upper surface of the ANU layer. In the first region and the second... A first electrode layer is deposited in the region corresponding to the organic functional group layer and the aluminum nitride layer on the plane containing the three sides, and a second electrode layer is deposited in the region corresponding to the organic functional group layer and the aluminum nitride layer on the plane containing the second and fourth sides, thus obtaining a glucose concentration sensor. The electron concentration of the two-dimensional electron gas layer is sensitive to weak electrical signals, and the weak electrical signals before and after the specific binding of the organic functional group layer and glucose molecules can be acquired in real time. The electrical signals are then output through the metal electrode layer, thereby reducing the detection limit of glucose concentration and improving the sensitivity of the glucose concentration sensor. Furthermore, directly stacking the organic functional group layer on the surface of the two-dimensional electron gas can shorten the distance between the organic functional group layer and the two-dimensional electron gas, further improving the sensitivity of the glucose concentration sensor. The glucose concentration sensor prepared by the method provided in this embodiment of the invention not only improves the detection sensitivity and efficiency of glucose concentration, but also simplifies the operation and reduces the detection cost of glucose concentration.

[0117] Optionally, in some embodiments, the temperature at which the gallium nitride layer is epitaxially grown on the first and second sides is between 1000°C and 1050°C; for example, the temperature for epitaxial growth of gallium nitride can be a range of one or any two of 1000°C, 1010°C, 1020°C, 1030°C, 1040°C, and 1050°C.

[0118] Optionally, in some embodiments, the pressure for epitaxially growing gallium nitride layers on the first and second sides is from 100 mbar to 500 mbar; for example, the pressure for epitaxially growing gallium nitride can be a range of one or both of 100 mbar, 200 mbar, 300 mbar, 400 mbar, and 500 mbar.

[0119] Optionally, in some embodiments, the duration of epitaxial growth of gallium nitride layers on the first and second sides is from 100s to 1000s; for example, the duration of epitaxial growth of gallium nitride can be a range of one or any two of 100s, 200s, 300s, 400s, 500s, 600s, 700s, 800s, 900s, and 1000s.

[0120] Optionally, in some embodiments, the temperature at which the aluminum nitride layer is grown on the upper surface of the gallium nitride layer and the top surface of the isosceles trapezoidal structure is 1000°C to 1050°C; for example, the temperature for growing the aluminum nitride layer can be a range of one or any two of 1000°C, 1010°C, 1020°C, 1030°C, 1040°C, and 1050°C.

[0121] Optionally, in some embodiments, the pressure for growing the aluminum nitride layer on the upper surface of the gallium nitride layer and the top surface of the isosceles trapezoidal structure is from 10 mbar to 200 mbar; for example, the pressure for growing the aluminum nitride layer can be a range of one or any two of 10 mbar, 20 mbar, 40 mbar, 60 mbar, 80 mbar, 100 mbar, 120 mbar, 140 mbar, 160 mbar, 180 mbar, and 200 mbar.

[0122] Optionally, in some embodiments, the time for growing the aluminum nitride layer on the upper surface of the gallium nitride layer and the top surface of the isosceles trapezoidal structure is from 10s to 100s; for example, the time for growing the aluminum nitride layer can be a range of one or any two of 10s, 20s, 30s, 40s, 50s, 60s, 70s, 80s, 90s, and 100s.

[0123] Optionally, in some embodiments, step S101, obtaining the substrate, includes steps S1011 to S1012:

[0124] Step S1011: Under constant temperature conditions, anisotropic etching is performed on any one surface of the original substrate using an alkaline solution to obtain an original substrate including at least one isosceles trapezoidal structure.

[0125] The constant temperature condition is between 10℃ and 60℃, for example, it can be one or any two of 10℃, 20℃, 30℃, 40℃, 50℃, and 60℃; the anisotropic etching process duration is between 10min and 30min, for example, it can be one or any two of 10min, 15min, 20min, 25min, and 30min; the alkaline solution concentration is between 20wt.% and 50wt.%, for example, it can be one or any two of 20wt.%, 30wt.%, 40wt.% and 50wt.%.

[0126] In this step, the alkaline solution may include, but is not limited to, potassium hydroxide solution and sodium hydroxide solution.

[0127] Step S1012: Clean the original substrate, which includes at least one isosceles trapezoidal structure, using hydrofluoric acid solution to obtain the substrate.

[0128] The concentration of the hydrofluoric acid solution is 10 wt.% to 30 wt.%, for example, it can be one or any two of 10 wt.%, 15 wt.%, 20 wt.%, 25 wt.%, and 30 wt.%; the cleaning time is 1 min to 10 min, for example, it can be one or any two of 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, and 10 min.

[0129] In this embodiment of the invention, cleaning the original substrate, which includes at least one isosceles trapezoidal structure, with a hydrofluoric acid solution can produce an oxide-free hydrogen passivated surface in the substrate. The glucose concentration sensor prepared based on the substrate with the oxide-free hydrogen passivated surface can improve the concentration of crystal defects in each functional layer of the glucose concentration sensor and improve the crystal quality.

[0130] Optionally, in some embodiments, step S104, which involves depositing a first electrode layer in the region corresponding to the organic functional group layer and the aluminum nitride layer in the plane containing the first region and the third side, and depositing a second electrode layer in the region corresponding to the organic functional group layer and the aluminum nitride layer in the plane containing the second region and the fourth side, to obtain a glucose concentration sensor, includes steps S1041 to S1043:

[0131] Step S1041: Evaporate the target metal with an electron beam to deposit a first electrode layer in the region corresponding to the organic functional group layer and the aluminum nitride layer in the plane containing the first region of the organic functional group layer and the third side surface.

[0132] Step S1042: Evaporate the target metal with an electron beam to deposit a second electrode layer in the region corresponding to the organic functional group layer and the aluminum nitride layer in the plane containing the second region of the organic functional group layer and the fourth side surface.

[0133] Step S1043: Anneal the first electrode layer and the second electrode layer to obtain a glucose concentration sensor.

[0134] The annealing process is conducted in a nitrogen atmosphere; the annealing temperature is between 500°C and 1000°C, for example, it can be one or any two of the following values: 500°C, 600°C, 700°C, 800°C, 900°C, and 1000°C; the annealing duration is between 10s and 100s, for example, it can be one or any two of the following values: 10s, 20s, 30s, 40s, 50s, 60s, 70s, 80s, 90s, and 100s.

[0135] The target metal can be one or more of titanium, aluminum, nickel, gold, platinum, molybdenum, iridium, tantalum, niobium, cobalt, and tungsten.

[0136] For example, when the target metals are titanium, aluminum, nickel, and gold, in step S1041, a titanium layer, an aluminum layer, a nickel layer, and a gold layer can be sequentially deposited in the regions corresponding to the organic functional group layer and the aluminum nitride layer in the plane containing the first region and the third side surface, to obtain a first electrode layer comprising sequentially stacked titanium, aluminum, nickel, and gold layers. The thickness of the titanium layer is 10 nm to 30 nm, the aluminum layer is 100 nm to 300 nm, the nickel layer is 10 nm to 30 nm, and the gold layer is 10 nm to 100 nm. It should be noted that when the first electrode layer includes at least one metal layer, the sum of the thicknesses of all metal layers is 50 nm to 1000 nm.

[0137] When the target metals are titanium, aluminum, nickel, and gold, in step S1042, titanium, aluminum, nickel, and gold layers are sequentially deposited in the regions corresponding to the organic functional group layer and the aluminum nitride layer in the plane containing the second region and the fourth side surface, resulting in a second electrode layer comprising sequentially stacked titanium, aluminum, nickel, and gold layers. The thickness of the titanium layer is 10 nm to 30 nm, the aluminum layer is 100 nm to 300 nm, the nickel layer is 10 nm to 30 nm, and the gold layer is 10 nm to 100 nm. It should be noted that when the second electrode layer includes at least one metal layer, the sum of the thicknesses of all metal layers is 50 nm to 1000 nm.

[0138] To make the inventive objectives, technical solutions, and beneficial effects of this invention clearer, the invention is further described below with reference to embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0139] The present invention will be described in detail below through embodiments.

[0140] Example 1

[0141] (1) Obtaining the substrate:

[0142] First, under constant temperature conditions, anisotropic etching is performed on the surface of the original silicon substrate using an alkaline solution to obtain an original silicon substrate including at least one isosceles trapezoidal structure; then, the original silicon substrate including at least one isosceles trapezoidal structure is cleaned using hydrofluoric acid solution to obtain a silicon substrate.

[0143] The isotropic conditions were maintained at 40°C, the anisotropic etching process lasted 18 minutes, the alkaline solution concentration was 40 wt.%, the hydrofluoric acid solution concentration was 20 wt.%, and the cleaning time was 5 minutes. The silicon substrate included four isosceles trapezoidal structures, with a 20 μm interval between adjacent isosceles trapezoidal structures. Each isosceles trapezoidal structure included a first side, a second side, a third side, a fourth side, and a top surface. The first and second side were the waists of the isosceles trapezoidal structure. The third and fourth side were opposite each other and perpendicular to the top surface. The height of the isosceles trapezoidal structure was 3 μm, and the thickness of the silicon substrate was 100 μm.

[0144] (2) Preparation of two-dimensional electron gas:

[0145] First, a silicon substrate is placed into an MOCVD reactor. Then, a gaseous mixture of trimethylgallium and ammonia is introduced into the MOCVD reactor to epitaxially grow gallium nitride layers on the first and second sides of the isosceles trapezoidal structure of the silicon substrate. Next, a gaseous mixture of trimethylaluminum and ammonia is introduced into the MOCVD reactor to grow aluminum nitride layers on the upper surface of the gallium nitride layer and the top surface of the isosceles trapezoidal structure. The gallium nitride layer and the aluminum nitride layer stacked on the upper surface of the gallium nitride layer form a two-dimensional electron gas. The two-dimensional electron gas is used to obtain the electrical signal when organic functional group layers and glucose molecules bind, and this electrical signal is used to indicate the concentration of glucose molecules.

[0146] The gallium nitride (GaN) layer has a thickness of 5 μm, and the aluminum nitride (AN) layer has a thickness of 20 nm. The GaN layer includes a polar surface and a semi-polar surface, where the polar surface is parallel to either the first or second side surface, and the semi-polar surface is the surface outside the polar surface in the GaN layer. The epitaxial growth temperature of the GaN layer is 1020 °C, the epitaxial growth pressure is 400 mbar, and the epitaxial growth time is 800 s. The growth temperature of the AN layer is 1050 °C, the growth pressure is 75 mbar, and the growth time is 90 s.

[0147] (3) Preparation of organic functional group layers:

[0148] A first solution is spin-coated onto the upper surface of an aluminum nitride layer, and the first solution spin-coated onto the aluminum nitride layer is dried to obtain an organic functional group layer. The organic functional group layer includes a first region near the third side and a second region near the fourth side, with a 10 μm gap between the first and second regions. The first region has a first width of 100 μm along the direction from its edge near the third side to the center of the organic functional group layer, and the second region has a second width of 100 μm along the direction from its edge near the fourth side to the center of the organic functional group layer. The first solution is an ethanol solution of glucose carbon quantum dot chitosan molecularly imprinted polymer, and the organic functional group layer is a glucose carbon quantum dot chitosan molecularly imprinted film. The thickness of the organic functional group layer is 500 nm.

[0149] (4) Preparation of glucose concentration sensor:

[0150] First, the target metal is evaporated by electron beam. A first electrode layer is deposited in the region corresponding to the organic functional group layer and the aluminum nitride layer in the plane containing the first and third sides of the organic functional group layer. A second electrode layer is deposited in the region corresponding to the organic functional group layer and the aluminum nitride layer in the plane containing the second and fourth sides of the organic functional group layer. Then, the first and second electrode layers are annealed to obtain a glucose concentration sensor. The first and second electrode layers constitute the metal electrode layer of the glucose concentration sensor. The target metal includes titanium, aluminum, nickel, and gold. The metal electrode layer consists of a titanium layer, an aluminum layer, a nickel layer, and a gold layer stacked sequentially. The thickness of the titanium layer is 25 nm, the thickness of the aluminum layer is 150 nm, the thickness of the nickel layer is 25 nm, and the thickness of the gold layer is 50 nm. The annealing environment is a nitrogen atmosphere, the annealing temperature is 800 °C, and the annealing time is 30 s.

[0151] Example 2

[0152] The difference between Example 2 and Example 1 is that in step (1), the temperature of the isothermal condition is 10°C, the duration of the anisotropic etching process is 30 min, and the concentration of the alkaline solution is 50 wt.%.

[0153] Example 3

[0154] The difference between Example 3 and Example 1 is that in step (1), the temperature of the isothermal condition is 60°C, the duration of the anisotropic etching process is 10 min, and the concentration of the alkaline solution is 20 wt.%.

[0155] Example 4

[0156] The difference between Example 4 and Example 1 is that in step (1), the concentration of hydrofluoric acid solution is 10 wt.% and the cleaning time is 10 min.

[0157] Example 5

[0158] The difference between Example 5 and Example 1 is that in step (1), the concentration of hydrofluoric acid solution is 30 wt.% and the cleaning time is 1 min.

[0159] Example 6

[0160] The difference between Example 6 and Example 1 is that in step (1), the height of the isosceles trapezoidal structure is 1 μm and the thickness of the silicon substrate is 2 μm.

[0161] Example 7

[0162] The difference between Example 7 and Example 1 is that in step (1), the height of the isosceles trapezoidal structure is 5 μm and the thickness of the silicon substrate is 200 μm.

[0163] Example 8

[0164] The difference between Example 8 and Example 1 is that in step (2), the thickness of the gallium nitride layer is 1 μm; the temperature for growing the gallium nitride layer is 1000℃; the pressure for growing the gallium nitride layer is 100 mbar; and the growth time of the gallium nitride layer is 100 s.

[0165] Example 9

[0166] The difference between Example 9 and Example 1 is that in step (2), the thickness of the gallium nitride layer is 10 μm; the temperature for growing the gallium nitride layer is 1050 °C; the pressure for growing the gallium nitride layer is 500 mbar; and the growth time of the gallium nitride layer is 1000 s.

[0167] Example 10

[0168] The difference between Example 10 and Example 1 is that in step (2), the thickness of the aluminum nitride layer is 15 nm; the temperature for growing the aluminum nitride layer is 1000 °C; the pressure for growing the aluminum nitride layer is 10 mbar; and the growth time of the aluminum nitride layer is 10 s.

[0169] Example 11

[0170] The difference between Example 11 and Example 1 is that in step (2), the thickness of the aluminum nitride layer is 30 nm; the temperature for growing the aluminum nitride layer is 1030 °C; the pressure for growing the aluminum nitride layer is 200 mbar; and the growth time of the aluminum nitride layer is 100 s.

[0171] Example 12

[0172] The difference between Example 12 and Example 1 is that in step (3), the thickness of the organic functional group layer is 200 nm.

[0173] Example 13

[0174] The difference between Example 13 and Example 1 is that in step (3), the thickness of the organic functional group layer is 1000 nm.

[0175] Example 14

[0176] The difference between Example 14 and Example 1 is that in step (3), the first solution is an ethanol solution of boric acid functionalized carbon quantum dot molecularly imprinted polymer, and the organic functional group layer is a boric acid functionalized carbon quantum dot molecularly imprinted film.

[0177] Example 15

[0178] The difference between Example 15 and Example 1 is that in step (3), the first solution is an ethanol solution of reduced graphene-nano copper molecularly imprinted polymer, and the organic functional group layer is a reduced graphene-nano copper molecularly imprinted film.

[0179] Example 16

[0180] The difference between Example 16 and Example 1 is that in step (4), the target metal is titanium; the metal electrode layer is a titanium layer with a thickness of 50 nm.

[0181] Example 17

[0182] The difference between Example 17 and Example 1 is that, in step (4), the target metal also includes platinum, molybdenum, iridium, tantalum, niobium, and cobalt; the metal electrode layer includes a titanium layer, an aluminum layer, a nickel layer, a gold layer, a platinum layer, a molybdenum layer, an iridium layer, a tantalum layer, a niobium layer, and a cobalt layer stacked sequentially. The thickness of the titanium layer is 30 nm, the thickness of the aluminum layer is 300 nm, the thickness of the nickel layer is 30 nm, the thickness of the gold layer is 100 nm, the thickness of the platinum layer is 50 nm, the thickness of the molybdenum layer is 200 nm, the thickness of the iridium layer is 40 nm, the thickness of the tantalum layer is 150 nm, the thickness of the niobium layer is 30 nm, and the thickness of the cobalt layer is 70 nm.

[0183] Example 18

[0184] The difference between Example 18 and Example 1 is that in step (4), the annealing temperature is 500°C and the annealing time is 100s.

[0185] Example 19

[0186] The difference between Example 19 and Example 1 is that in step (4), the annealing temperature is 1000℃ and the annealing time is 10s.

[0187] Comparative Example

[0188] The difference between the comparative example and Example 1 is as follows:

[0189] In step (1), the original silicon substrate is ultrasonically cleaned with deionized water under constant temperature conditions to obtain a silicon substrate; the ultrasonic cleaning time is 30 min.

[0190] In step (2), after loading the silicon substrate into the MOCVD reactor, firstly, nitrogen (N2), trimethylaluminum, and trimethylindium (In(CH3)3) are introduced into the MOCVD reactor to generate an indium aluminum nitride (InAlN) buffer layer on any surface of the silicon substrate; then, gallium and nitrogen are introduced into the MOCVD reactor to grow an intrinsic gallium nitride layer on the upper surface of the InAlN buffer layer; then, a P-type gallium nitride layer is grown on the upper surface of the intrinsic gallium nitride layer; finally, gallium, nitrogen, and Trimethylaluminum was introduced into an MOCVD reactor to grow an intrinsic aluminum gallium nitride layer on the upper surface of a p-type gallium nitride layer. The InAlN buffer layer had a thickness of 250 nm. The intrinsic gallium nitride layer was grown at 750 °C, under a pressure of 100 mbar for 90 min, resulting in a thickness of 3 μm. The p-type gallium nitride layer was grown at 500 °C for 200 s, resulting in a thickness of 5 μm. The intrinsic aluminum gallium nitride layer was grown at 800 °C for 80 min, resulting in a thickness of 5 μm.

[0191] In step (3), a first solution is spin-coated onto the upper surface of the intrinsic aluminum gallium nitride layer, and the first solution spin-coated onto the upper surface of the intrinsic aluminum gallium nitride layer is dried to obtain an organic functional group layer.

[0192] In step (4), the target metal is evaporated by electron beam, a first electrode layer is deposited in the first region of the organic functional group layer, and a second electrode layer is deposited in the second region of the organic functional group layer to obtain a glucose concentration sensor.

[0193] The glucose concentration sensors prepared in Examples 1, 14, 15, and the comparative example were used to detect the glucose concentration in liquids containing glucose molecules. The detection results are as follows: Figure 4 As shown.

[0194] Reference Figure 4 The glucose concentration sensor prepared in Example 1 was used to detect the glucose concentration in a liquid containing glucose molecules. The current value output by the glucose concentration sensor increased with the increase of glucose concentration, and the linear correlation coefficient R1 between the current value output by the glucose concentration sensor and the glucose concentration was [missing value]. 2 The linearity is 0.996, which shows good linearity.

[0195] The glucose concentration sensor prepared in Example 14 was used to detect the glucose concentration in a liquid containing glucose molecules. The current value output by the glucose concentration sensor increased with the increase of glucose concentration, and the linear correlation coefficient R² between the current value output by the glucose concentration sensor and the glucose concentration was [missing value]. 2 The linearity is 0.998, which shows good linearity.

[0196] The glucose concentration sensor prepared in Example 15 was used to detect the glucose concentration in a liquid containing glucose molecules. The current value output by the glucose concentration sensor increased with the increase of glucose concentration, and the linear correlation coefficient R3 between the current value output by the glucose concentration sensor and the glucose concentration was [missing value]. 2 The linearity is 0.992, which shows good linearity.

[0197] However, when using the glucose concentration sensor prepared in the comparative example to detect glucose concentration in liquids containing glucose molecules, there was no significant correlation between the current value output by the glucose concentration sensor and the glucose concentration. Furthermore, the linear correlation coefficient R4 between the current value output by the glucose concentration sensor and the glucose concentration was not significant. 2 With a linearity of only 0.721, the glucose concentration sensor prepared based on the comparative example has poor reliability in detecting glucose concentration in liquids containing glucose molecules.

[0198] In summary, the glucose concentration sensor provided in this embodiment of the invention outputs a current value that increases with the increase of glucose concentration, and the linear correlation coefficient between the output current value and the glucose concentration is above 0.99, demonstrating good linearity. Based on the glucose concentration sensor provided in this embodiment of the invention, the glucose concentration of liquids containing glucose molecules can be detected with high reliability. During the testing process, the relationship between the current value and the glucose concentration can be determined based on the linear correlation between the output current value and the glucose concentration. In subsequent testing, the glucose concentration can be determined based on the output current value and the relationship expression. Moreover, the glucose concentration sensor provided in this embodiment of the invention has a simple structure and is easy to operate, improving the detection sensitivity and reliability of glucose concentration while reducing the detection cost.

[0199] The above provides a detailed description of a glucose concentration sensor and its preparation method provided by the present invention. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A glucose concentration sensor, characterized in that, The glucose concentration sensor includes a substrate, a gallium nitride layer, an aluminum nitride layer, an organic functional group layer, and a metal electrode layer. The substrate includes at least one isosceles trapezoidal structure; adjacent isosceles trapezoidal structures are spaced apart by a first length; the isosceles trapezoidal structure includes a first side, a second side, a third side, a fourth side, and a top surface; the first side and the second side are the waists of the isosceles trapezoidal structure; the third side and the fourth side are opposite to each other and perpendicular to the top surface; The gallium nitride layer is epitaxial on the first side and the second side; the aluminum nitride layer is stacked on the upper surface of the gallium nitride layer and the top surface of the isosceles trapezoidal structure; the gallium nitride layer and the aluminum nitride layer stacked on the upper surface of the gallium nitride layer constitute a two-dimensional electron gas, which is used to obtain the electrical signal when the organic functional group layer and glucose molecules are bound. The electrical signal is used to indicate the concentration of glucose molecules; the gallium nitride layer includes a polar surface and a semi-polar surface; the polar surface is a surface parallel to the first side or the second side, and the semi-polar surface is a surface in the gallium nitride layer other than the polar surface; the growth rate of the gallium nitride layer in the direction perpendicular to the polar surface is greater than the growth rate in the direction perpendicular to the semi-polar surface; The organic functional group layer is stacked on the upper surface of the aluminum nitride layer; the organic functional group layer includes a first region near the third side and a second region near the fourth side, with a second length separating the first region and the second region; The metal electrode layer includes a first electrode layer and a second electrode layer. The first electrode layer is stacked on the first region and extends along the plane of the third side to the aluminum nitride layer. The second electrode layer is stacked on the second region and extends along the plane of the fourth side to the aluminum nitride layer.

2. The glucose concentration sensor according to claim 1, characterized in that, The thickness of the gallium nitride layer is 1 μm to 10 μm; the thickness of the aluminum nitride layer is 15 nm to 30 nm.

3. The glucose concentration sensor according to claim 1, characterized in that, The organic functional group layer is any one of glucose carbon quantum dot chitosan molecularly imprinted film, borate-functionalized carbon quantum dot molecularly imprinted film, and reduced graphene-nano copper molecularly imprinted film.

4. The glucose concentration sensor according to claim 1, characterized in that, The height of the isosceles trapezoidal structure is 1 μm to 5 μm.

5. The glucose concentration sensor according to claim 1, characterized in that, The thickness of the substrate is 1 μm to 200 μm; the thickness of the organic functional group layer is 200 nm to 1000 nm; and the thickness of the metal electrode layer is 50 nm to 1000 nm.

6. A method for preparing a glucose concentration sensor, characterized in that, The method includes: Obtain a substrate; the substrate includes at least one isosceles trapezoidal structure, with a first length interval between adjacent isosceles trapezoidal structures; the isosceles trapezoidal structure includes a first side surface, a second side surface, a third side surface, a fourth side surface, and a top surface; the first side surface and the second side surface are the waists of the isosceles trapezoidal structure; the third side surface and the fourth side surface are opposite to each other and perpendicular to the top surface; Gallium nitride layers are epitaxially grown on the first side and the second side; An aluminum nitride layer is grown on the upper surface of the gallium nitride layer and the top surface of the isosceles trapezoidal structure. The gallium nitride layer and the aluminum nitride layer stacked on the upper surface of the gallium nitride layer constitute a two-dimensional electron gas. The two-dimensional electron gas is used to acquire the electrical signal when the organic functional group layer and glucose molecules bind. The electrical signal is used to indicate the concentration of glucose molecules. The gallium nitride layer includes a polar surface and a semi-polar surface. The polar surface is a surface parallel to the first side or the second side, and the semi-polar surface is a surface in the gallium nitride layer other than the polar surface. The growth rate of the gallium nitride layer in the direction perpendicular to the polar surface is greater than the growth rate in the direction perpendicular to the semi-polar surface. A first solution is spin-coated onto the upper surface of the aluminum nitride layer, and the first solution spin-coated onto the aluminum nitride layer is dried to obtain an organic functional group layer; the organic functional group layer includes a first region near the third side and a second region near the fourth side, with a second length spaced between the first region and the second region; A first electrode layer is deposited in the region corresponding to the organic functional group layer and the aluminum nitride layer in the plane containing the first region and the third side, and a second electrode layer is deposited in the region corresponding to the organic functional group layer and the aluminum nitride layer in the plane containing the second region and the fourth side, to obtain a glucose concentration sensor; the first electrode layer and the second electrode layer constitute the metal electrode layer of the glucose concentration sensor.

7. The method according to claim 6, characterized in that, The temperature for epitaxially growing gallium nitride layers on the first and second sides is 1000°C to 1050°C, the pressure is 100 mbar to 500 mbar, and the duration is 100 s to 1000 s.

8. The method according to claim 6, characterized in that, The temperature for growing the aluminum nitride layer on the upper surface of the gallium nitride layer and the top surface of the isosceles trapezoidal structure is 1000°C to 1050°C, the pressure is 10 mbar to 200 mbar, and the duration is 10 s to 100 s.

9. The method according to claim 6, characterized in that, The acquisition of the substrate includes: Under isothermal conditions, anisotropic etching is performed on any surface of the original substrate using an alkaline solution to obtain an original substrate including at least one isosceles trapezoidal structure; the isothermal conditions are from 10°C to 60°C, the anisotropic etching time is from 10 min to 30 min, and the concentration of the alkaline solution is from 20 wt.% to 50 wt.%. The original substrate, comprising at least one isosceles trapezoidal structure, is cleaned using a hydrofluoric acid solution to obtain a substrate; the concentration of the hydrofluoric acid solution is 10 wt.% to 30 wt.%, and the cleaning time is 1 min to 10 min.

10. The method according to claim 6, characterized in that, A glucose concentration sensor is obtained by depositing a first electrode layer in the region corresponding to the organic functional group layer and the aluminum nitride layer in the plane containing the first region and the third side surface, and depositing a second electrode layer in the region corresponding to the organic functional group layer and the aluminum nitride layer in the plane containing the second region and the fourth side surface, comprising: The target metal is evaporated by electron beam, and a first electrode layer is deposited in the region corresponding to the organic functional group layer and the aluminum nitride layer in the plane containing the first region of the organic functional group layer and the third side surface. The target metal is evaporated by electron beam, and a second electrode layer is deposited in the region corresponding to the organic functional group layer and the aluminum nitride layer in the plane containing the second region of the organic functional group layer and the fourth side surface. The first electrode layer and the second electrode layer are annealed to obtain a glucose concentration sensor; the annealing environment is a nitrogen environment, the annealing temperature is 500℃ to 1000℃, and the annealing time is 10s to 100s.

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