Biosensor and preparation method thereof

Abstract

The invention provides a biosensor and a preparation method thereof, the biosensor comprises a substrate, a superlattice conducting layer, a source electrode, a drain electrode and a packaging layer, the substrate and the superlattice conducting layer are stacked from bottom to top, the source electrode and the drain electrode are arranged on the substrate and oppositely arranged at two end parts of the superlattice conducting layer, and the packaging layer is arranged on the substrate. The packaging layer is arranged on the superlattice conducting layer and covers the source electrode and the drain electrode, the upper surface, located above the superlattice conducting layer, of the packaging layer is provided with an opening extending to the upper surface of the superlattice conducting layer, and an exposed isolation pool is formed on the upper surface of the superlattice conducting layer; the superlattice conductive layer comprises a metal nitride layer, a carbon nanomaterial layer and a conductive metal nanomaterial layer, the metal nitride layer, the carbon nanomaterial layer and the conductive metal nanomaterial layer are stacked from bottom to top, and the metal nitride layer is made of boron nitride. The superlattice conducting layer is arranged as the sensing layer, so that the biosensor has better conductivity and higher sensitivity.

Description

Technical Field

[0001] The present invention belongs to the technical field of biosensors, and more particularly relates to a biosensor and a preparation method thereof. Background Art

[0002] A biosensor is an instrument device that converts biological signals into physical signals such as photoelectric signals and displays them. Biosensors are not only applied in the field of biotechnology, but also widely used in technical fields such as environmental monitoring, medical diagnosis, and disease prevention. Currently, with the application of graphene and carbon nanotubes in sensing biological signals, biosensors have gradually overcome the problem of low sensitivity. However, for biosensors realized with graphene and carbon nanotubes as key sensing materials, due to their one-electron-layer thickness, they are very easy to be damaged during large-scale mass production, resulting in defects, poor conductivity, insufficient stability, and the sensitivity can only reach the pM level. Therefore, they cannot be used in some scenarios that require high sensitivity and high stability, greatly limiting their applications. Summary of the Invention

[0003] Based on the technical problems existing in the prior art, the present invention provides a biosensor and a preparation method thereof, aiming to solve the technical problems of poor conductivity, insufficient stability, and low sensitivity of biosensors in the prior art.

[0004] To achieve the above object, according to one aspect of the present invention, there is provided a biosensor, including a substrate, a superlattice conductive layer, a source electrode, a drain electrode, and a packaging layer. The substrate and the superlattice conductive layer are stacked from bottom to top. The source electrode and the drain electrode are disposed on the substrate and are relatively disposed at two ends of the superlattice conductive layer. The packaging layer is disposed on the superlattice conductive layer and covers the source electrode and the drain electrode. Among them, an opening extending to the upper surface of the superlattice conductive layer is provided on the upper surface of the packaging layer located above the superlattice conductive layer, and an exposed isolation pool is formed on the upper surface of the superlattice conductive layer; the superlattice conductive layer includes a metal nitride layer, a carbon nanomaterial layer, and a conductive metal nanomaterial layer. The metal nitride layer, the carbon nanomaterial layer, and the conductive metal nanomaterial layer are stacked from bottom to top, and the material of the metal nitride layer is boron nitride.

[0005] Optionally, the material of the substrate is one of silicon, diamond, sapphire, quartz, polyethylene terephthalate, and polyimide.

[0006] Optionally, the material of the carbon nanomaterial layer is single-layer graphene or carbon nanotubes.

[0007] Optionally, the material of the conductive metal nanomaterial layer is nano silver, nano gold, or gold quantum dots.

[0008] Optionally, the materials of the source electrode and the drain electrode are metal or alloy.

[0009] Optionally, the metal is one of titanium, platinum, gold, and chromium.

[0010] Optionally, the alloy is a titanium alloy, a platinum alloy, a gold alloy, or a chromium alloy.

[0011] Optionally, the material of the encapsulation layer is one of silicon oxide, silicon nitride, polyethylene terephthalate, polyimide, and polydimethylsiloxane.

[0012] According to another aspect of the present invention, there is provided a method for preparing a biosensor as described above, including the following steps: Step S1. Transfer boron nitride onto a substrate to form a metal nitride layer; Step S2. Transfer carbon nanomaterials onto the metal nitride layer, and then obtain a patterned carbon nanomaterial layer through a photolithography process and an oxygen plasma etching process; Step S3. Deposit conductive metal nanomaterials on the carbon nanomaterial layer to form a deposited conductive metal nanomaterial layer, such that the conductive metal nanomaterial layer is combined with the carbon nanomaterial layer and the metal nitride layer to form a superlattice conductive layer; Step S4. After cleaning and removing the photoresist on the surface of the superlattice conductive layer, perform a source-drain electrode process to fabricate a source electrode and a drain electrode in a specified area; Step S5. Perform encapsulation above the superlattice conductive layer, the source electrode, and the drain electrode to form an encapsulation layer, and open an opening extending to the upper surface of the superlattice conductive layer on the upper surface of the encapsulation layer located above the superlattice conductive layer, so that an exposed isolation pool is formed on the upper surface of the superlattice conductive layer, and the preparation of the biosensor is completed.

[0013] Compared with the prior art, the beneficial effects of the biosensor and the preparation method thereof provided by the present invention are as follows: (1) The biosensor of the present invention has a superlattice conductive layer as the sensing layer, and the superlattice conductive layer is formed by combining a metal nitride layer, a conductive metal nanomaterial layer, and a carbon nanomaterial layer, so that the biosensor has better conductivity and higher carrier mobility, and thus higher sensitivity.

[0014] (2) The superlattice conductive layer as the sensing layer has better stability and consistency compared with traditional nanomaterials, and is more suitable for mass production. Description of the Drawings

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0016] Figure 1 Structural schematic diagram of the biosensor provided by an embodiment of the present invention; Figure 2 Structural schematic diagram of the superlattice conductive layer provided by an embodiment of the present invention; Figure 3 Schematic diagram of the implementation process of the biosensor provided by an embodiment of the present invention; Figure 4 Test schematic diagram of the biosensor provided by an embodiment of the present invention.

[0017] The label details related to the above-mentioned drawings are as follows: 10. Substrate; 20. Superlattice conductive layer; 201. Metal nitride layer; 202. Carbon nanomaterial layer; 203. Conductive metal nanomaterial layer; 30. Source electrode; 40. Drain electrode; 50. Encapsulation layer; 60. Isolation pool; 70. Test solution; 80. Silver chloride electrode; 90. Power supply. Detailed implementation manners

[0018] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0019] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element. Without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0020] It should be understood that the orientation or positional relationship indicated by the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present invention.

[0021] In addition, the terms "first" and "second" are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means more than two, unless otherwise specifically defined.

[0022] As described in the background art, currently, with the application of graphene and carbon nanotubes to sensing biological signals, biosensors have gradually overcome the problem of too low sensitivity. However, for biosensors realized with graphene and carbon nanotubes as key sensing materials, due to their thickness of one electron layer, they are very easily damaged during large-scale production, resulting in defects, poor conductivity, and a sensitivity that can only reach the pM level. Therefore, they cannot be used in some scenarios that require high sensitivity and high stability, greatly limiting their applications.

[0023] See Figure 1 and Figure 2 As shown in

[0024] Applying the above technical solution of the present invention, the biosensor is provided with a superlattice conductive layer 20 as the sensing layer. The superlattice conductive layer 20 is composed of a metal nitride layer 201, a conductive metal nanomaterial layer 203 and a carbon nanomaterial layer 202, so that the biosensor has better conductivity and higher carrier mobility, improving the sensitivity of the biosensor. At the same time, as the sensing layer, the superlattice conductive layer 20 has better stability and consistency compared with traditional nanomaterials, and is more suitable for mass production.

[0025] In some embodiments of the present invention, the material of the substrate 10 is one of silicon, diamond, sapphire, quartz, polyethylene terephthalate (PET) and polyimide (PI).

[0026] In some embodiments of the present invention, the material of the carbon nanomaterial layer 202 is single-layer graphene or carbon nanotubes.

[0027] In some embodiments of the present invention, the material of the conductive metal nanomaterial layer 203 is nano silver, nano gold or gold quantum dots.

[0028] In some embodiments of the present invention, the materials of the source electrode 30 and the drain electrode 40 are metal or alloy.

[0029] In some embodiments of the present invention, the metal is one of titanium (Ti), platinum (Pt), gold (Au) and chromium (Cr).

[0030] In some embodiments of the present invention, the alloy is titanium alloy, platinum alloy, gold alloy or chromium alloy.

[0031] In some embodiments of the present invention, the material of the encapsulation layer 50 is one of silicon oxide, silicon nitride, polyethylene terephthalate (PET), polyimide (PI) and polydimethylsiloxane (PDMS).

[0032] See Figure 3 As shown, another aspect of the present invention provides a preparation method of the biosensor as described above, including the following steps: Step S1. Transfer boron nitride onto the substrate 10 to form a metal nitride layer 201; In some embodiments of the present invention, the material of the substrate 10 in step S1 is one of silicon, diamond, sapphire, quartz, polyethylene terephthalate (PET) and polyimide (PI).

[0033] For example, transfer the boron nitride two-dimensional material grown by CVD (chemical vapor deposition) onto the substrate 10.

[0034] Step S2. Transfer the carbon nanomaterials onto the metal nitride layer 201, and then obtain the patterned carbon nanomaterial layer 202 through photolithography and oxygen plasma etching processes; In some embodiments of the present invention, the carbon nanomaterials are single-layer graphene or carbon nanotubes.

[0035] For example, transfer one of the nanomaterials such as single-layer graphene or carbon nanotubes onto the metal nitride layer 201, implement the patterned mask through photolithography, and then implement the patterning of the nanomaterials through oxygen plasma etching. Step S3. Deposit the conductive metal nanomaterials on the carbon nanomaterial layer 202 to deposit the conductive metal nanomaterial layer 203, so that the conductive metal nanomaterial layer 203 is combined with the carbon nanomaterial layer 202 and the metal nitride layer 201 to form the superlattice conductive layer 20; In some embodiments of the present invention, the conductive metal nanomaterials are silver nanoparticles, gold nanoparticles or gold quantum dots.

[0036] For example, deposit silver nanoparticles on the patterned graphene through a chemical method to obtain the superlattice conductive layer 20.

[0037] Step S4. After cleaning and removing the photoresist on the surface of the superlattice conductive layer 20, perform the source-drain electrode process to fabricate the source electrode 30 and the drain electrode 40 in the specified area; In some embodiments of the present invention, implement the patterned mask of the source-drain metal photoresist through photolithography, deposit the metal electrode, and finally realize the metal electrode in the specified area on the device through lift-off.

[0038] Step S5. Perform encapsulation above the superlattice conductive layer 20, the source electrode 30 and the drain electrode 40 to form the encapsulation layer 50, and open an opening extending to the upper surface of the superlattice conductive layer 20 on the upper surface of the encapsulation layer 50 located above the superlattice conductive layer 20, so that an exposed isolation pool 60 is formed on the upper surface of the superlattice conductive layer 20, and the preparation of the biosensor is completed.

[0039] In some embodiments of the present invention, materials such as silicon oxide, silicon nitride, polyethylene terephthalate, polyimide, polydimethylsiloxane, etc. are selected for encapsulation to form the isolation pool 60.

[0040] The present invention also provides a testing method for the biosensor, see Figure 4 for the test wiring as shown.

[0041] Before the test, functionalization needs to be performed on the superlattice conductive layer 20. During the test, drop the test solution 70 into the isolation pool 60 with a dropper and press Figure 4Apply power. If there are corresponding organisms in the test solution 70, it will cause a slight change in the surface charge of the superlattice conductive layer 20. After being amplified by the field effect transistor, the biological signal can be measured from the test electrical signal. In practical applications, for example, when it is necessary to test whether a patient is infected with a certain virus, it is only necessary to functionalize the superlattice conductive layer 20 surface with antibodies related to the virus. During the test, extract the patient's body fluid for testing. If the virus exists in the patient's body, when dropping the patient's body fluid onto the biosensor, measure the electrical signal of the test sensor. By observing the electrical signal, it can be directly and quickly determined whether the patient is negative or positive for the virus.

[0042] In summary, implementing a biosensor and its preparation method provided in this embodiment has at least the following beneficial technical effects: (1) By setting the superlattice conductive layer 20 as the sensing layer, the superlattice conductive layer 20 is composed of a metal nitride layer 201, a conductive metal nanomaterial layer 203 and a carbon nanomaterial layer 202, making the biosensor have better electrical conductivity and higher carrier mobility, thus improving the sensitivity of the biosensor; (2) As the sensing layer, the superlattice conductive layer 20 has better stability and consistency compared with traditional nanomaterials and is more suitable for mass production.

[0043] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A biosensor, characterized in that: The invention comprises a substrate, a superlattice conductive layer, a source electrode, a drain electrode and a packaging layer, wherein the substrate and the superlattice conductive layer are stacked from bottom to top, the source electrode and the drain electrode are arranged on the substrate and are arranged opposite to each other at two ends of the superlattice conductive layer, the packaging layer is arranged on the superlattice conductive layer and covers the source electrode and the drain electrode, wherein the upper surface of the packaging layer located above the superlattice conductive layer is provided with an opening extending to the upper surface of the superlattice conductive layer, and an exposed isolation pool is formed on the upper surface of the superlattice conductive layer; The superlattice conductive layer comprises a metal nitride layer, a carbon nanomaterial layer and a conductive metal nanomaterial layer, wherein the metal nitride layer, the carbon nanomaterial layer and the conductive metal nanomaterial layer are stacked from bottom to top, and the material of the metal nitride layer is boron nitride.

2. The biosensor according to claim 1, characterized in that The material of the substrate is one of silicon, diamond, sapphire, quartz, polyethylene terephthalate and polyimide.

3. The biosensor according to claim 1, characterized in that The material of the carbon nanomaterial layer is single-layer graphene or carbon nanotube.

4. The biosensor according to claim 3, characterized in that The material of the conductive metal nanomaterial layer is nanosilver, nanogold or gold quantum dots.

5. The biosensor according to claim 1, characterized in that The source electrode and the drain electrode are made of metal or alloy.

6. The biosensor according to claim 5, characterized in that The metal is one of titanium, platinum, gold and chromium.

7. The biosensor according to claim 5, characterized in that The alloy is a titanium alloy, a platinum alloy, a gold alloy or a chromium alloy.

8. The biosensor according to claim 1, characterized in that The material of the encapsulation layer is one of silicon oxide, silicon nitride, polyethylene terephthalate, polyimide and polydimethylsiloxane.

9. A method for preparing a biosensor according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step S1. transferring boron nitride to a substrate to form a metal nitride layer; Step S2. transferring the carbon nanomaterial onto the metal nitride layer, and then obtaining a patterned carbon nanomaterial layer by photolithography and oxygen plasma etching; Step S3. depositing a conductive metal nanomaterial on the carbon nanomaterial layer to form a conductive metal nanomaterial layer, so that the conductive metal nanomaterial layer is combined with the carbon nanomaterial layer and the metal nitride layer to form a superlattice conductive layer; Step S4. After cleaning and removing the glue from the surface of the superlattice conductive layer, a source-drain electrode process is performed to prepare a source electrode and a drain electrode in a specified area; Step S5. Encapsulation is performed above the superlattice conductive layer, the source electrode and the drain electrode to form a packaging layer, and an opening extending to the upper surface of the superlattice conductive layer is opened on the upper surface of the packaging layer above the superlattice conductive layer, so that an exposed isolation pool is formed on the upper surface of the superlattice conductive layer, thereby completing the preparation of the biosensor.

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