Nucleic acid sensing device and preparation method thereof

Abstract

The invention discloses a nucleic acid sensing device and a preparation method thereof, a grid electrode of an electrochemical transistor is modified by specially designed nucleic acid, and through the excellent inherent amplification capability of OECT, the specific recognition of 0.1 nM level of a specific nucleic acid fragment can be realized; the OECT has the advantages of low cost and easiness in manufacturing, and only the grid needs to be modified, so that large-scale manufacturing and popularization can be realized in a resource limited area; due to the fact that the grid electrode is independently designed, detection and replacement of modified nucleic acid can be conveniently carried out, dissociation of nucleic acid crosslinked on the gold grid can be achieved only by heating the gold grid to 97 DEG C, and then rapid replacement of a detection target can be achieved by reusing ssDNA / ssRNA modification needing to be detected.

Description

Technical Field

[0001] The present invention relates to the field of biological detection technology, and in particular to a nucleic acid sensor device and a preparation method thereof. Background Art

[0002] Nucleic acid detection devices with high sensitivity are extremely important for the screening of genetic diseases and tumor detection. Currently, common high-sensitivity detection technologies require relatively complex processes and related equipment, which are difficult to popularize in areas with limited resources. Most high-sensitivity detection equipment requires a long detection time and has high requirements for testers, who need to master relatively complex techniques.

[0003] Therefore, it is necessary to develop a nucleic acid sensor device and a preparation method thereof to solve the above problems. Summary of the invention

[0004] The purpose of the present invention is to design a nucleic acid sensor device and a preparation method thereof in order to solve the above problems.

[0005] The present invention achieves the above-mentioned purpose through the following technical solutions: The nucleic acid sensor device includes: a substrate, a drain electrode, a semiconductor layer, a source electrode, a DNA modification layer, and a gate electrode arranged in sequence from bottom to top. The encapsulation layer is used to encapsulate the substrate, the drain electrode, the semiconductor layer, the source electrode, the DNA modification layer, and the gate electrode to expose the working part of the semiconductor layer.

[0006] Furthermore, the drain and the source are both metal films, and the metal films are divided into two-layer structures, wherein the first film layer close to the substrate is chromium or ITO or a metal oxide film, and the second film layer above the first film layer is gold.

[0007] Preferably, the thickness of the source electrode and the drain electrode is 50 to 100 nm.

[0008] Preferably, the semiconductor layer is made of at least one of poly-gDPP-g2T, gDPP-ttt, P3HT, and PEDOT:PSS.

[0009] Preferably, the gate is an Au thin film.

[0010] Preferably, the encapsulation layer is at least one of Az2035 photoresist, Su-8 photoresist, and 1,4-bis(trifluoromethyl)phenyl-2,5-difluorophenylene.

[0011] Preferably, the DNA modification layer 1 is a paired nucleic acid sequence designed based on the nucleic acid to be identified, and the 5' end thereof is modified with a thiol group.

[0012] A method for preparing a nucleic acid sensor device comprises the following steps: Step 1: Clean the silicon wafer substrate with detergent, deionized water, acetone, and isopropyl alcohol, and then dry it to prepare a base; Step 2: Spin-coating Az2035 photoresist on the substrate, then annealing, drying, exposing under a photolithography machine, and then drying again, using MIF300 to develop, patterning the photoresist, thereby preparing a patterned photoresist layer; Step 3: Fully evaporate Cr and Au layers on the patterned photoresist layer; evaporate Cr and Au layers on the gate at the same time; Step 4: Soak the entire evaporated silicon wafer substrate in acetone to strip the photoresist and prepare the drain electrode; Step 5: Spin-coat a semiconductor layer on the drain electrode, then cross-link with ultraviolet light, develop with chloroform after cross-linking, and then blow dry with nitrogen to prepare the semiconductor layer; Step 6: Au is fully evaporated on the dried semiconductor layer, and then photoresist is fully spin-coated, pre-baked, and photoresist patterning is achieved by exposure and development using a photolithography machine, and then baked again after exposure, and developed using MIF300; then the fully evaporated Au on the top is etched using a diluted gold etching solution to achieve patterning of the top electrode, and the surface photoresist is washed off with acetone to achieve the preparation of the source electrode; Step 7: Spin-coat the photoresist AZ2035 on the source electrode again, pre-bake at 110° for 60 seconds, use a photolithography machine to expose, bake again at 110° for 60 seconds, use MIF300 to develop to achieve patterning, and prepare the encapsulation layer; Step 8: Add thiol-modified ssDNA onto the gate to achieve gate modification. The ssDNA is in liquid form dissolved in TE buffer to achieve a DNA modification layer.

[0013] Furthermore, in step 5, the semiconductor layer is prepared by mixing gDPP-TTT, cellouse, and dtfDA dissolved in chloroform and by dynamic spinning.

[0014] The beneficial effects of the present invention are: 1. In the present invention, the gate of the electrochemical transistor is modified with specially designed nucleic acids, and the excellent inherent amplification ability of OECT can achieve specific recognition of specific nucleic acid fragments at the 0.1nM level.

[0015] 2. In the present invention, since OECT has the advantages of low cost and easy manufacturing, and it only requires modification of the gate, it can be manufactured and promoted on a large scale in resource-limited areas.

[0016] 3. Since the gate is designed independently, the replacement of the detected and modified nucleic acids can be easily performed. The gold grid only needs to be heated to 97 degrees to dissociate the nucleic acids cross-linked thereon, and then the ssDNA / ssRNA modification to be detected can be reused to achieve rapid replacement of the detection target. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic diagram of the structure of a nucleic acid sensor device; Figure 2 This is a comparison diagram of the source-drain current of Example 1 when the recognition target DNA is added for modification in steady state; Figure 3 It is a comparison diagram of the turn-on voltage and the on-state current of Example 1 (the control group of Example 2), Example 2 (the experimental group), Example 3 (the experimental group) and Example 4 (the control group of Example 3).

[0018] Legend: 1-DNA modification layer, 2-semiconductor layer, 3-substrate, 4-encapsulation layer, 5-gate; 6-source; 7-drain. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0022] In the description of the present invention, it should be understood that the terms "upper", "lower", "inside", "outside", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are directions or positional relationships in which the product of the invention is usually placed when in use, or are directions or positional relationships commonly understood by those skilled in the art. These directions or positional relationships are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0023] Furthermore, the terms “first”, “second”, etc. are merely used for distinguishing descriptions and should not be understood as indicating or implying relative importance.

[0024] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms such as "setting" and "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings.

[0026] like Figure 1 As shown, the nucleic acid sensor device includes, arranged from bottom to top, a substrate 3, a drain electrode 7, a semiconductor layer 2, a source electrode 6, a DNA modification layer 1, and a gate 5. The encapsulation layer is used to encapsulate the substrate 3, the drain electrode 7, the semiconductor layer 2, the source electrode 6, the DNA modification layer 1, and the gate 5 to expose the working part of the semiconductor layer.

[0027] The drain and source are both metal films, which are divided into two-layer structures, wherein the first film layer close to the substrate is chromium or ITO or metal oxide film, which is used for adhesion and strength support, and the second film layer above the first film layer is gold, which is used for modification and provides good conductive effect. The present invention preferably uses chromium film as the adsorption and strength support layer, which has high strength, good conductivity, and good adhesion effect on gold.

[0028] The thickness of the source and drain electrodes is 50 to 100 nm.

[0029] The semiconductor layer is made of a semiconductor material with good stability, low turn-on voltage, high switching ratio and high transconductance, such as poly(2,5-di(2-ethylhexyl)-1,4-phenylene) dibenzothiophene (gDPP-g2T), poly(2,5-di(2-ethylhexyl)-1,4-phenylene)-2,3,4-thiophene (gDPP-ttt), poly(3-hexylthiophene) (P3HT), poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS). The semiconductor material of the present invention is preferably poly(2,5-di(2-ethylhexyl)-1,4-phenylene)-2,3-thiophene (gDPP-ttt).

[0030] The gate is an Au thin film with good conductivity, and the modified nucleic acid can be adsorbed on the gate surface through thiol groups to achieve fixation and modification.

[0031] The encapsulation layer 4 is made of a material with good adhesion, stable properties, and little effect of the solution required for development on the semiconductor. The encapsulation layer is at least one of Az2035 photoresist, Su-8 photoresist, and 1,4-di(trifluoromethyl)phenyl-2,5-difluorophenylene, preferably Az2035 photoresist.

[0032] The DNA modification layer 1 is a paired nucleic acid sequence designed based on the nucleic acid to be identified, and the 5' end thereof is modified with a thiol group, and fixed by the adsorption of the thiol group and gold.

[0033] A method for preparing a nucleic acid sensor device comprises the following steps: Step 1: Clean the silicon wafer substrate with detergent, deionized water, acetone, and isopropyl alcohol, and then dry it to prepare a base; Step 2: Spin-coating Az2035 photoresist on the substrate, then annealing, drying, exposing under a photolithography machine, and then drying again, using MIF300 to develop, patterning the photoresist, thereby preparing a patterned photoresist layer; Step 3: Fully evaporate Cr and Au layers on the patterned photoresist layer; evaporate Cr and Au layers on the gate at the same time; Step 4: Soak the entire evaporated silicon wafer substrate in acetone to strip the photoresist and prepare the drain electrode; Step 5: Spin-coat a semiconductor layer on the drain electrode. The semiconductor layer is prepared by mixing gDPP-TTT, cellouse, and dtfDA dissolved in chloroform and then cross-linking with ultraviolet light. After cross-linking, chloroform is used for development and then nitrogen is used for drying to achieve the preparation of the semiconductor layer. Step 6: Au is fully evaporated on the dried semiconductor layer, and then photoresist is fully spin-coated, pre-baked, and photoresist patterning is achieved by exposure and development using a photolithography machine, and then baked again after exposure, and developed using MIF300; then the fully evaporated Au on the top is etched using a diluted gold etching solution to achieve patterning of the top electrode, and the surface photoresist is washed off with acetone to achieve the preparation of the source electrode; Step 7: Spin-coat the photoresist AZ2035 on the source electrode again, pre-bake at 110° for 60 seconds, use a photolithography machine to expose, bake again at 110° for 60 seconds, use MIF300 to develop to achieve patterning, and prepare the encapsulation layer; Step 8: Add thiol-modified ssDNA onto the gate to achieve gate modification. The ssDNA is in liquid form dissolved in TE buffer to achieve a DNA modification layer.

[0034] Example 1 (as a control group for Example 2) The structure of the sensor device from bottom to top is: Si / Cr (3 nm) / Au (80 nm) / gDPP-TTT (30 nm) / Au (80 nm) / PBS / Au (80 nm) / Cr (3 nm); The preparation method steps are as follows: Step 1: ultrasonically clean the silicon wafer substrate using detergent, acetone, deionized water and isopropanol solution in sequence.

[0035] Step 2: Spin-coat Az2035 photoresist on the dried silicon wafer substrate, then perform annealing at 110 degrees for 60 seconds, dry it, and expose it to 80mj / cm2 in a photolithography machine. 2 Then, the photoresist was patterned by baking at 110 degrees for 60 seconds and developing with MIF300 for 60 seconds. A patterned photoresist layer was prepared.

[0036] Step 3: Cr (3 nm) and Au (80 nm) layers are fully evaporated on the patterned photoresist layer. At the same time, the gate is also evaporated with a Cr / Au layer of the same thickness.

[0037] Step 4: Soak the entire evaporated silicon wafer in acetone for 15 minutes to strip the photoresist and prepare the drain.

[0038] Step 5: Spin-coat a semiconductor layer on the drain electrode. The semiconductor layer of the present invention is made of 20 mg / ml gDPP-TTT dissolved in chloroform, cellouse, and dtfDA mixed in a certain proportion. The semiconductor layer is spun at a speed of 3000 r / min, and then cross-linked with ultraviolet light. After cross-linking, chloroform is used for development for about 2 seconds, and then nitrogen is used for drying to prepare the semiconductor layer.

[0039] Step 6: Fully evaporate Au on the semiconductor layer with a thickness of about 80nm, then fully spin-coat photoresist, pre-bake at 110 degrees for 60s, use a photolithography machine to expose and develop to achieve patterning, and then bake at 110 degrees for 60s after exposure, and use MIF300 to develop. Then use a 1:4 diluted gold etching solution to etch the top gold for about 45s to achieve patterning of the source, and use acetone to wash off the photoresist on the top gold surface. The source is prepared.

[0040] Step 7: Spin-coat the photoresist AZ2035 again on the device, pre-bake at 110 degrees for 60 seconds, use a photolithography machine to expose, bake at 110 degrees for 60 seconds, and use MIF300 to develop to achieve patterning. This realizes the preparation of the encapsulation layer. Step 8: Add TE buffer (solute of ssDNA) on the gate to achieve gate modification.

[0041] The device 1 prepared in Example 1 is Device 1. Figure 2 A comparison chart of the source-drain current of Example 1 when the target DNA is added for modification in steady state is shown.

[0042] Example 2

[0043] The structure of the sensor device from bottom to top is: Si / Cr (3 nm) / Au (80 nm) / gDPP-TTT (30 nm) / Au (80 nm) / PBS / ssDNA / Au (80 nm) / Cr (3 nm); The preparation method steps are as follows: Step 1: ultrasonically clean the silicon wafer substrate using detergent, acetone, deionized water and isopropanol solution in sequence.

[0044] Step 2: Spin-coat Az2035 photoresist on the dried silicon wafer substrate, then perform annealing at 110 degrees for 60 seconds, dry it, and expose it to 80mj / cm2 in a photolithography machine. 2 Then, the photoresist was patterned by baking at 110 degrees for 60 seconds and developing with MIF300 for 60 seconds. A patterned photoresist layer was prepared.

[0045] Step 3: Cr (3 nm) and Au (80 nm) layers are fully evaporated on the patterned photoresist layer. At the same time, the gate is also evaporated with a Cr / Au layer of the same thickness.

[0046] Step 4: Soak the entire evaporated silicon wafer in acetone for 15 minutes to strip the photoresist and prepare the drain.

[0047] Step 5: Spin-coat a semiconductor layer on the drain electrode. The semiconductor layer of the present invention is made of 20 mg / ml gDPP-TTT dissolved in chloroform, cellouse, and dtfDA mixed in a certain proportion. The semiconductor layer is spun at a speed of 3000 r / min, and then cross-linked with ultraviolet light. After cross-linking, chloroform is used for development for about 2 seconds, and then nitrogen is used for drying to prepare the semiconductor layer.

[0048] Step 6: Fully evaporate Au on the semiconductor layer with a thickness of about 80nm, then fully spin-coat photoresist, pre-bake at 110 degrees for 60s, use a photolithography machine to expose and develop to achieve patterning, and then bake at 110 degrees for 60s after exposure, and use MIF300 to develop. Then use a 1:4 diluted gold etching solution to etch the top gold for about 45s to achieve patterning of the source, and use acetone to wash off the photoresist on the top gold surface. The source is prepared.

[0049] Step 7: Spin-coat the photoresist AZ2035 again on the device, pre-bake at 110 degrees for 60 seconds, use a photolithography machine to expose, bake at 110 degrees for 60 seconds, and use MIF300 to develop to achieve patterning. This realizes the preparation of the encapsulation layer. Step 8: Add thiol-modified ssDNA (1 μM) on the gate and incubate for 1 hour, then rinse with deionized water 5 to 6 times to achieve gate modification.

[0050] The device 2 prepared in Example 2 is Device 2.

[0051] Example 3 (as a control group for Example 4) The structure of the sensor device from bottom to top is: Si / Cr (3 nm) / Au (80 nm) / gDPP-TTT (30 nm) / Au (80 nm) / PBS / dsDNA / Au (80 nm) / Cr (3 nm); The preparation method steps are as follows: Step 1: ultrasonically clean the silicon wafer substrate using detergent, acetone, deionized water and isopropanol solution in sequence.

[0052] Step 2: Spin-coat Az2035 photoresist on the dried silicon wafer substrate, then perform annealing at 110 degrees for 60 seconds, dry it, and expose it to 80mj / cm2 in a photolithography machine. 2 Then, the photoresist was patterned by baking at 110 degrees for 60 seconds and developing with MIF300 for 60 seconds. A patterned photoresist layer was prepared.

[0053] Step 3: Cr (3 nm) and Au (80 nm) layers are fully evaporated on the patterned photoresist layer. At the same time, the gate is also evaporated with a Cr / Au layer of the same thickness.

[0054] Step 4: Soak the entire evaporated silicon wafer in acetone for 15 minutes to strip the photoresist and prepare the drain.

[0055] Step 5: Spin-coat a semiconductor layer on the drain electrode. The semiconductor layer of the present invention is made of 20 mg / ml gDPP-TTT dissolved in chloroform, cellouse, and dtfDA mixed in a certain proportion. The semiconductor layer is spun at a speed of 3000 r / min, and then cross-linked with ultraviolet light. After cross-linking, chloroform is used for development for about 2 seconds, and then nitrogen is used for drying to prepare the semiconductor layer.

[0056] Step 6: Fully evaporate Au on the semiconductor layer with a thickness of about 80nm, then fully spin-coat photoresist, pre-bake at 110 degrees for 60s, use a photolithography machine to expose and develop to achieve patterning, and then bake at 110 degrees for 60s after exposure, and use MIF300 to develop. Then use a 1:4 diluted gold etching solution to etch the top gold for about 45s to achieve patterning of the source, and use acetone to wash off the photoresist on the top gold surface. The source is prepared.

[0057] Step 7: Spin-coat the photoresist AZ2035 again on the device, pre-bake at 110 degrees for 60 seconds, use a photolithography machine to expose, bake at 110 degrees for 60 seconds, and use MIF300 to develop to achieve patterning. This realizes the preparation of the encapsulation layer. Step 8: Add thiol-modified ssDNA (1 μM) to the gate and incubate for 1 hour, rinse with deionized water 5 to 6 times, and then add a solution containing the target detection DNA (1 μM) for pairing to achieve gate modification.

[0058] The device 3 prepared in Example 3 is Device 3.

[0059] Example 4 The structure of the sensor device from bottom to top is: Si / Cr (3 nm) / Au (80 nm) / gDPP-TTT (30 nm) / Au (80 nm) / PBS / ssDNA / Au (80 nm) / Cr (3 nm); The preparation method steps are as follows: Step 1: ultrasonically clean the silicon wafer substrate using detergent, acetone, deionized water and isopropanol solution in sequence.

[0060] Step 2: Spin-coat Az2035 photoresist on the dried silicon wafer substrate, then perform annealing at 110 degrees for 60 seconds, dry it, and expose it to 80mj / cm2 in a photolithography machine. 2 Then, the photoresist was patterned by baking at 110 degrees for 60 seconds and developing with MIF300 for 60 seconds. A patterned photoresist layer was prepared.

[0061] Step 3: Cr (3 nm) and Au (80 nm) layers are fully evaporated on the patterned photoresist layer. At the same time, the gate is also evaporated with a Cr / Au layer of the same thickness.

[0062] Step 4: Soak the entire evaporated silicon wafer in acetone for 15 minutes to strip the photoresist and prepare the drain.

[0063] Step 5: Spin-coat a semiconductor layer on the drain electrode. The semiconductor layer of the present invention is made of 20 mg / ml gDPP-TTT dissolved in chloroform, cellouse, and dtfDA mixed in a certain proportion. The semiconductor layer is spun at a speed of 3000 r / min, and then cross-linked with ultraviolet light. After cross-linking, chloroform is used for development for about 2 seconds, and then nitrogen is used for drying to prepare the semiconductor layer.

[0064] Step 6: Fully evaporate Au on the semiconductor layer with a thickness of about 80nm, then fully spin-coat photoresist, pre-bake at 110 degrees for 60s, use a photolithography machine to expose and develop to achieve patterning, and then bake at 110 degrees for 60s after exposure, and use MIF300 to develop. Then use a 1:4 diluted gold etching solution to etch the top gold for about 45s to achieve patterning of the source, and use acetone to wash off the photoresist on the top gold surface. The source is prepared.

[0065] Step 7: Spin-coat the photoresist AZ2035 again on the device, pre-bake at 110 degrees for 60 seconds, use a photolithography machine to expose, bake at 110 degrees for 60 seconds, and use MIF300 to develop to achieve patterning. This realizes the preparation of the encapsulation layer. Step 8: Add thiol-modified ssDNA (10 μM) on the gate and incubate for 1 hour, rinse with PBS 5 to 6 times, and then add TE buffer to achieve gate modification.

[0066] The device prepared in Example 4 is Device 4. Figure 3 A comparison diagram of the turn-on voltage and the on-state current of Example 1 (the control group of Example 2), Example 2 (the experimental group), Example 3 (the experimental group) and Example 4 (the control group of Example 3) is shown.

[0067] The preparation process of the present invention is relatively simple, and the detection time is relatively short for a biosensor device for a specific nucleic acid fragment. The device has good reusability, and the device is modularized, and the modification of the target test nucleic acid can be achieved through simple processing and modification. The significant advantage of the sensor device is the simplicity and efficiency of its preparation process, thereby reducing the production cost and improving the consistency of the device. Due to the high selectivity of the electrochemical transistor to modify the specific nucleic acid fragment, the sensitivity of the sensor is significantly enhanced. By modifying the gate with nucleic acid fragments, the sensor can accurately identify the target nucleic acid, thereby providing a high-precision detection result. In addition, the design of the sensor makes data reading easier, and the operator can quickly obtain and interpret the test results, further improving the convenience of use. Therefore, the present invention not only has significant advantages in improving the detection accuracy, but also makes the detection process more intuitive and easy to operate, and has a wide range of application prospects. The gate area is adjustable, and different gate areas correspond to different recognition accuracies. It can simultaneously realize a device with high precision but a large area and a device with multiple simultaneous measurements but relatively low accuracy, and this device has relatively good flexibility.

[0068] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A nucleic acid sensing device, characterized in that: It includes: a substrate, a drain electrode, a semiconductor layer, a source electrode, a DNA modification layer, and a gate electrode, which are arranged in sequence from bottom to top. The encapsulation layer is used to encapsulate the substrate, the drain electrode, the semiconductor layer, the source electrode, the DNA modification layer, and the gate electrode to expose the working part of the semiconductor layer.

2. The nucleic acid sensing device according to claim 1, characterized in that: The drain and the source are both metal films, and the metal films are divided into two-layer structures, wherein the first film layer close to the substrate is chromium or ITO or a metal oxide film, and the second film layer above the first film layer is gold.

3. The nucleic acid sensing device according to claim 1, characterized in that: The thickness of the source and drain electrodes is 50 to 100 nm.

4. The nucleic acid sensing device according to claim 1, characterized in that: The semiconductor layer is made of at least one of gDPP-g2T, gDPP-ttt, P3HT, and PEDOT:PSS.

5. The nucleic acid sensing device according to claim 1, characterized in that: The gate is Au thin film.

6. The nucleic acid sensing device according to claim 1, characterized in that: The encapsulation layer is at least one of Az2035 photoresist, Su-8 photoresist, and 1,4-di(trifluoromethyl)phenyl-2,5-difluorophenylene.

7. The nucleic acid sensing device according to claim 1, characterized in that: The DNA modification layer 1 is a paired nucleic acid sequence designed based on the nucleic acid to be identified, and the 5' end thereof is modified with a thiol group.

8. The method for preparing a nucleic acid sensor device according to any one of claims 1 to 7, characterized in that: The following steps are involved: Step 1: Clean the silicon wafer substrate with detergent, deionized water, acetone, and isopropyl alcohol, and then dry it to prepare a base; Step 2: Spin-coating Az2035 photoresist on the substrate, then annealing, drying, exposing under a photolithography machine, and then drying again, using MIF300 to develop, patterning the photoresist, thereby preparing a patterned photoresist layer; Step 3: Fully evaporating Cr and Au layers on the patterned photoresist layer; The gate is simultaneously evaporated with Cr and Au layers; Step 4: Soak the entire evaporated silicon wafer substrate in acetone to strip the photoresist and prepare the drain electrode; Step 5: Spin-coat a semiconductor layer on the drain electrode, then cross-link with ultraviolet light, develop with chloroform after cross-linking, and then blow dry with nitrogen to prepare the semiconductor layer; Step 6: Au is fully evaporated on the dried semiconductor layer, and then photoresist is fully spin-coated, pre-baked, and photoresist patterning is achieved by exposure and development using a photolithography machine, and then baked again after exposure, and developed using MIF300; then the fully evaporated Au on the top is etched using a diluted gold etching solution to achieve patterning of the top electrode, and the surface photoresist is washed off with acetone to achieve the preparation of the source electrode; Step 7: Spin-coat the photoresist AZ2035 on the source electrode again, pre-bake at 110° for 60 seconds, use a photolithography machine to expose, bake again at 110° for 60 seconds, use MIF300 to develop to achieve patterning, and prepare the encapsulation layer; Step 8: Add thiol-modified ssDNA onto the gate to achieve gate modification. The ssDNA is in liquid form dissolved in TE buffer to achieve a DNA modification layer.

9. The method for preparing a nucleic acid sensor device according to claim 8, characterized in that: In step 5, the semiconductor layer is prepared by mixing gDPP-TTT, cellouse, and dtfDA dissolved in chloroform and by dynamic spinning.

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