Photoelectric immunoassay device based on field effect transistor structure and manufacturing method thereof

Abstract

The present invention discloses a photoelectric immune detection device based on a field effect transistor structure and a manufacturing method thereof. The device utilizes an indirect immunofluorescence assay method to convert optical signals into electrical signals to detect antigens. The device consists of a field effect transistor, a silicon optical waveguide ring resonator, and a liquid reservoir. The three parts are all prepared on a silicon substrate on the same insulating layer. A silicon film is etched on the insulating layer to form a silicon optical waveguide ring resonator. One end of the straight waveguide of the silicon optical waveguide ring resonator is connected to the liquid reservoir as an optical input port, and the other end is connected to the channel of the field effect transistor as an optical output port. The surface of the liquid reservoir is modified for dripping a sample to be detected and fixing the antigen in the sample. The present invention can well combine immunoassay with integrated circuit manufacturing process, reducing detection cost and operation difficulty.

Description

Technical Field

[0001] The present invention belongs to the field of biosensors and relates to a detection device based on field effect transistors that converts light signals into electrical signals for immune sensing and a manufacturing method thereof. Background Art

[0002] Immunosensor is a type of biosensor developed based on the specific recognition function of antigens and antibodies. It has the advantages of high analytical sensitivity, strong specificity, ease of use and low cost. It is used in a wide range of fields such as clinical medicine, biological monitoring, environmental monitoring and treatment.

[0003] Antibodies (immunoglobulins) can bind to fluorescent dyes without losing their immunological activity. There are two different methods for detecting antibodies using fluorescent antibody staining. Direct immunofluorescence uses antibodies directly labeled with fluorescent dyes, while indirect immunofluorescence uses a secondary antibody labeled with fluorescein. After the antibody binds to the corresponding antigen, the fluorescently labeled secondary antibody interacts with the bound antibody, thereby inferring the presence of the antigen or antibody. Indirect immunofluorescence is more specific.

[0004] Traditional fluorescence immunoassay equipment has certain limitations. It often needs to be equipped with a spectrometer to detect fluorescence, which increases the cost of the detection equipment to a certain extent and also increases the size of the equipment. Summary of the Invention

[0005] The purpose of the present invention is to address the deficiencies of existing immunoassay devices and to provide a photoelectric immunoassay device based on a field effect transistor structure and a manufacturing method thereof.

[0006] The purpose of the present invention is achieved through the following technical principles: when the ultraviolet light beam is irradiated on the object to be tested after indirect immunofluorescence treatment, the fluorescent pigment absorbs the light and emits another light beam with a longer wavelength. For example, the most commonly used fluorescent dye, fluorescein isothiocyanate (FITC), has an excitation wavelength of about 488nm and an emission wavelength of 520nm. The emitted light beam can be transmitted through a silicon optical waveguide. The ring optical resonator uses a waveguide to guide the light field to form a closed loop. When the light field passes through the ring waveguide, if the propagation length is an integer multiple of the wavelength, the light field will form positive feedback, which will strongly excite the resonant mode in the resonant cavity. The resonance condition formula is mλ=2πRn eff , where m is the resonance order, λ is the wavelength, R is the radius of the ring waveguide, and n effis the effective refractive index of the waveguide. Therefore, it is possible to modulate the amplitude of light, amplify light of a specific wavelength, suppress light of other wavelengths, and act as a filter. Taking fluorescein as isothiocyanate as an example, a 488nm wavelength light is applied to the analyte treated with fluorescein. When a specific antigen is present in the analyte, the isothiocyanate fluorochrome emits a 520nm wavelength light beam, which is transmitted to the field-effect transistor through the silicon optical waveguide, changing the electrical properties of the field-effect transistor, while the excitation light (488nm) is suppressed by the ring optical resonator.

[0007] Using a field effect transistor (MOSFET) structure as an immune detection device, by detecting the output current of the MOSFET device, it is determined whether there is light shining on the MOSFET device, thereby determining whether there is a specific antigen in the sample to be tested. This is one of the feasible solutions to improve traditional immune sensing devices and has a series of advantages. First, the MOSFET-based photoelectric immune detection device utilizes the photoelectric effect of semiconductors. When light shines on the semiconductor surface, if the photon energy is greater than the band gap width E of the semiconductor material, the photon will be reflected by the light. g , electrons are excited to transition into the conduction band, leaving behind a hole in the valence band. Illumination reduces the MOSFET threshold voltage, and the electrical properties of MOSFETs, such as output characteristics and transfer characteristics, are easily measured, significantly reducing operational complexity. Secondly, because the threshold voltage of the MOSFET structure changes in real time with the environment, it responds quickly, enabling real-time monitoring of cells. Furthermore, photoelectric immunoassay devices based on MOSFET structures can be manufactured using wafer processing and easily integrated with peripheral electrical components to form a system-on-chip, facilitating miniaturization of sensing systems. In summary, immunoassay devices based on MOSFET structures have promising application prospects. Furthermore, compared to photoelectric immunoassay devices that directly apply light emitted by fluorescein to the channel of a field-effect transistor without passing through a ring optical resonator, this device incorporates a ring optical resonator between the liquid reservoir and the field-effect transistor. By adjusting the radius of the ring waveguide, the wavelength of the light beam that can be transmitted through the optical waveguide to the field-effect transistor can be precisely adjusted, while suppressing light from other wavelengths, effectively preventing interference from the excitation light source and ambient light on the immunoassay.

[0008] The object of the present invention is achieved through the following technical solutions:

[0009] According to a first aspect of the present specification, a photoelectric immunoassay device based on a field effect transistor structure is provided. The device comprises a field effect transistor, a silicon optical waveguide ring resonator, and a liquid reservoir. The three parts are all fabricated on a silicon substrate on an insulating layer.

[0010] The field effect transistor is composed of a silicon film on an insulating layer, a gate dielectric, a metal gate layer and a source / drain electrode, wherein the source and drain electrodes are symmetrically arranged on both sides of the gate electrode, and the gate electrode, the source electrode and the drain electrode all lead to contact electrodes;

[0011] The silicon film on the insulating layer is etched to form a silicon optical waveguide ring resonator, which consists of a straight waveguide and a ring waveguide. One end of the straight waveguide is connected to the liquid reservoir as an optical input port, and the other end is connected to the channel of the field effect transistor as an optical output port. The straight waveguide is perpendicular to the channel length direction of the field effect transistor, and the ring waveguide is adjacent to the straight waveguide.

[0012] The surface of the silicon film on the insulating layer is covered with a transparent insulating layer as the upper cladding of the waveguide, and the buried oxide layer of the silicon substrate on the insulating layer serves as the lower cladding of the waveguide; a liquid reservoir area is provided on the transparent insulating layer, and except for the liquid reservoir area and the lead-out electrodes, the rest of the device surface is covered with an opaque insulating layer; the surface of the liquid reservoir is modified for dripping the sample to be tested and fixing the antigen in the sample.

[0013] Furthermore, the gate dielectric material of the field effect transistor is selected from silicon oxide, aluminum oxide, and hafnium oxide, with a thickness of 10 to 30 nm; the metal gate layer material is selected from tungsten and gold, with a thickness of 30 to 50 nm.

[0014] Furthermore, the source and drain of the field effect transistor are ion-implanted silicon or NiSi metal source and drain; the contact electrode is nickel or gold and needs to be led out to the surface of the device.

[0015] Furthermore, the silicon optical waveguide ring resonator and the channel of the field effect transistor share a silicon film on the insulating layer; the material of the waveguide upper cladding is a silicon dioxide polymer organic material, and the thickness of the waveguide upper cladding should be no less than the thickness of the waveguide; the material of the opaque insulating layer is a black insulating series PET or a light-shielding epoxy resin.

[0016] Furthermore, the straight waveguide of the silicon optical waveguide ring resonator is a long strip structure, the optical output port is connected to the channel of the field effect transistor through a trapezoidal structure, the ring waveguide is a circular ring structure, and both the straight waveguide and the ring waveguide are formed by ICP etching silicon.

[0017] According to a second aspect of this specification, a method for manufacturing a photoelectric immunoassay device based on a field effect transistor structure is provided, comprising the following steps:

[0018] (1) depositing a gate dielectric on the silicon film on the insulating layer, depositing a metal gate layer on the gate dielectric, and forming a gate structure of a field effect transistor by photolithography and etching;

[0019] (2) preparing source / drain electrodes on the silicon film on the insulating layer on both sides of the gate structure to form a field effect transistor structure;

[0020] (3) performing photolithography on the surface of the silicon substrate on the insulating layer in the region adjacent to the gate of the field effect transistor, and etching the silicon film on the insulating layer to form a silicon optical waveguide ring resonator;

[0021] (4) depositing a light-transmitting insulating layer on the surface of the device formed in step (3) as a waveguide upper cladding;

[0022] (5) depositing a light-proof insulating layer on the surface of the device formed in step (4) to isolate it from interference from external light;

[0023] (6) performing photolithography on the reservoir region and the gate, source, and drain regions of the field effect transistor, and etching the opaque insulating layer; subsequently, performing photolithography on the gate, source, and drain regions of the field effect transistor, and etching the light-transmitting insulating layer;

[0024] (7) Photolithography of the gate, source, and drain electrodes of the field-effect transistor, and deposition of contact electrodes;

[0025] (8) The surface of the liquid reservoir is modified so that it can be used to fix the antigen in the sample to be detected, thereby completing the preparation of the immunoassay device.

[0026] Furthermore, in the step (3), photolithography is performed on the surface of the silicon substrate on the insulating layer in an area adjacent to the gate of the field effect transistor, and the shape is a combination of a rectangle, a circular ring and a trapezoid. The rectangular area is a straight waveguide, the trapezoid is connected to the narrow side of the rectangle, and is used to connect the straight waveguide and the channel of the field effect transistor. The circular ring is a ring waveguide, which is adjacent to the long side of the rectangle.

[0027] Furthermore, in step (8), the insulating layer at the liquid reservoir is surface-modified so that the antigen can be fixed on the surface of the liquid reservoir by the fixing solution.

[0028] According to the third aspect of this specification, a detection method for a photoelectric immunoassay device based on a field effect transistor structure is provided, the method comprising: when the photoelectric immunoassay device is working, applying light of a certain wavelength to the surface to perform an electrical test on the field effect transistor; then, adding a primary antibody of a certain dilution concentration to the liquid reservoir in the immune sensing area, incubating for a period of time at a constant temperature and then washing; then adding a fluorescent-labeled secondary antibody of a certain dilution concentration, incubating for a period of time at a constant temperature and then washing; keeping the illumination conditions unchanged, performing an electrical test on the field effect transistor under the same experimental conditions; and judging whether a specific antigen is present in the sample to be detected by comparing the electrical performance of the field effect transistor when the primary antibody / secondary antibody is added or not under the same experimental conditions.

[0029] The beneficial effects of the present invention are as follows: the photoelectric immunoassay device based on the field-effect transistor structure provided by the present invention has the advantages of not requiring the additional use of a spectrometer, low cost, miniaturization, fast response speed, and strong specificity, and has broad application prospects in the biomedical field. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 (a) is a schematic diagram of growing a gate dielectric on a semiconductor substrate on an insulating layer, and (b) is a schematic diagram of growing a metal gate layer on the gate dielectric;

[0031] Figure 2 (a) is a schematic diagram of etching the gate pattern of a field-effect transistor, and (b) is a schematic diagram of preparing the source / drain region;

[0032] Figure 3 Schematic diagram of etching a silicon optical waveguide ring resonator;

[0033] Figure 4 Schematic diagram of depositing two insulating layers, one transparent and one opaque, on the device surface;

[0034] Figure 5 Schematic diagram of etching the reservoir in the sample drop area and etching at the gate / source / drain of the field effect transistor;

[0035] Figure 6 Schematic diagram of photolithography of field effect transistor gate, source, drain electrodes and deposition of contact electrodes;

[0036] Figure 7 Schematic diagram of fixing the antigen in the sample to be tested on the surface of the reservoir;

[0037] Figure 8 This is a schematic diagram of the state of the detection device when adding samples for detection under light;

[0038] Figure 9 Schematic diagram of the principle of applying light to the detection device and the sample to be detected containing specific antigens;

[0039] Figure 10 A schematic diagram of the transfer characteristic curve of the presence or absence of specific antigens in the sample to be tested;

[0040] In the figure, there is a supporting substrate 1, a buried oxide layer 2, a silicon film on an insulating layer 3, a gate dielectric 4, a metal gate layer 5, a source / drain 6, a light-transmitting insulating layer 7, an opaque insulating layer 8, a contact electrode 9, an antigen 10, a primary antibody 11, and a fluorescent-labeled secondary antibody 12. DETAILED DESCRIPTION

[0041] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] Example 1

[0043] This embodiment provides a photoelectric immunoassay device based on a field-effect transistor structure. The device consists of three parts: a field-effect transistor, a silicon optical waveguide ring resonator, and a liquid reservoir. All three parts are fabricated on a silicon substrate on a common insulating layer.

[0044] The field effect transistor is composed of a silicon film 3 on an insulating layer, a gate dielectric 4, a metal gate layer 5 and a source / drain 6. The source and drain are symmetrically arranged on both sides of the gate. The gate, source and drain are all connected to a metal lead contact electrode 9.

[0045] The silicon film 3 on the insulating layer is etched to form a silicon optical waveguide ring resonator, which consists of a straight waveguide and a ring waveguide. One end of the straight waveguide is connected to the liquid reservoir as an optical input port, and the other end is connected to the channel of the field effect transistor as an optical output port. The straight waveguide is perpendicular to the channel length direction of the field effect transistor, and the ring waveguide is adjacent to the straight waveguide.

[0046] The surface of the silicon film 3 on the insulating layer is covered with a transparent insulating layer 7 as the upper cladding of the waveguide, and the buried oxide layer 2 of the silicon substrate on the insulating layer serves as the lower cladding of the waveguide; a liquid reservoir area is provided on the transparent insulating layer 7, and except for the liquid reservoir area and the lead-out electrodes, the rest of the device surface is covered with an opaque insulating layer 8; the surface of the liquid reservoir is modified for dripping the sample to be tested and fixing the antigen 10 in the sample.

[0047] The silicon-on-insulator substrate generally includes a supporting substrate 1, a buried oxide layer 2 and a silicon film 3 on the insulating layer. This embodiment has no special requirements on the doping concentration of the silicon film 3 on the insulating layer. The buried oxide layer 2 is generally SiO2.

[0048] Furthermore, the gate dielectric 4 of the field effect transistor includes but is not limited to silicon oxide, aluminum oxide, or hafnium oxide, and has a thickness of 10 to 30 nm. The metal gate layer 5 includes but is not limited to W or Au, and has a thickness of 30 to 50 nm.

[0049] The source and drain are ion-implanted silicon or NiSi metal. The contact electrodes are made of metal materials, including but not limited to Ni and Au. There is no specific thickness requirement, but they need to be extended to the device surface.

[0050] Furthermore, the silicon optical waveguide ring resonator and the channel of the field-effect transistor share the silicon film 3 on the insulating layer. The thickness of the waveguide upper cladding layer should be no less than the waveguide thickness (i.e., the thickness of the silicon film 3 on the insulating layer) to ensure complete coverage of the waveguide. The material of the waveguide upper cladding layer includes, but is not limited to, SiO2 polymer organics (such as PMMA, SU-8, etc.). SU-8 is typically used as the upper cladding layer. Its bulk refractive index is approximately 1.6, which can form a high refractive index difference with Si (bulk refractive index of approximately 3) and can therefore be used as a cladding material. The material of the opaque insulating layer that finally covers the surface of the device includes, but is not limited to, optical black insulating series PET, light-shielding epoxy resin, etc.

[0051] Furthermore, the straight waveguide of the silicon optical waveguide ring resonator is a long strip structure, the optical output port is connected to the channel of the field effect transistor through a trapezoidal structure, and the ring waveguide is a circular ring structure. Both the straight waveguide and the ring waveguide are formed by ICP etching silicon.

[0052] Example 2

[0053] This embodiment provides a method for manufacturing a photoelectric immunoassay device based on a field effect transistor structure as in Example 1, the method comprising the following steps:

[0054] (1) Figure 1 As shown in (a), a gate dielectric 4 is deposited on the silicon film 3 on the insulating layer by atomic layer deposition. The gate dielectric 4 is made of hafnium oxide with a thickness of 15 nm.

[0055] (2) Figure 1 As shown in (b), a metal gate layer 5 is deposited on the gate dielectric 4 by evaporation or sputtering. The material of the metal gate layer 5 is tungsten and has a thickness of 40 nm.

[0056] (3) Figure 2 As shown in (a), the metal gate layer 5 and gate dielectric 4 outside the gate region are removed through an etching process until the surface of the silicon film 3 on the insulating layer is reached, thereby forming a gate structure of the field effect transistor. Tungsten is etched using hydrogen peroxide, and hafnium oxide is etched using ICP dry etching.

[0057] (4) Figure 2 As shown in (b), source / drain electrodes 6 are prepared on the silicon film 3 on the insulating layer, and the source and drain electrodes are formed by ion implantation, specifically:

[0058] For pMOSFET, B is implanted with a dose of 1E15 cm -2 , energy is 10keV, angle is 0°; for nMOSFET, P is implanted, and the dose is 1E15cm -2 , energy is 18keV, angle is 0°; after ion implantation, annealing activation treatment is required at 600℃ for 3min in nitrogen atmosphere;

[0059] (5) Figure 3 As shown, photolithography is performed on the surface of the silicon substrate on the insulating layer adjacent to the gate of the field effect transistor, and the silicon film 3 on the insulating layer is etched to form a silicon optical waveguide ring resonator. The etching method is ICP. The size of the silicon optical waveguide ring resonator depends on the specific application. Figure 3 is a top view of the device;

[0060] (6) Figure 4 As shown, a light-transmitting insulating layer 7 is deposited on the surface of the device formed in step (5) as the upper cladding of the waveguide;

[0061] Specifically, the method for depositing the light-transmitting insulating layer is as follows: when a polymer is used as the upper cladding layer, a uniform coating process is used. Taking SU-8 (refractive index of approximately 1.6) as the upper cladding layer as an example, its film forming parameters are shown in Table 1 below, and the final film thickness is approximately 1.8 μm; when SiO2 is used as the cladding material, a PECVD system is used for deposition.

[0062]

[0063] (7) Figure 4 As shown, a light-proof insulating layer 8 is deposited on the surface of the device formed in step (6) to isolate the interference of external light. The deposition method is to drip potting glue, etc.

[0064] (8) Figure 5 As shown, photolithography is performed on the reservoir region and the gate, source, and drain regions of the field effect transistor, and the opaque insulating layer 8 is etched using a wet etching method; subsequently, photolithography is performed on the gate, source, and drain regions of the field effect transistor, and the transparent insulating layer 7 is etched using a wet etching method and BOE as the etching solution;

[0065] (9) Figure 6 As shown in (a) and (b), the gate, source, and drain electrodes of the field effect transistor are photolithographically formed, and the contact electrode 9 is deposited by evaporation or sputtering, and the material is Au;

[0066] (10) Figure 7 As shown, the antigen 10 in the sample to be detected is fixed on the surface of the liquid reservoir. The antigen can be fixed by a fixative and then washed with PBS buffer.

[0067] Example 3

[0068] This embodiment describes in detail the working principle of the above-mentioned photoelectric immune detection device based on the field effect transistor structure.

[0069] like Figure 8As shown, when the photoelectric immunoassay device is operating, light of a certain wavelength is applied to the surface, and electrical testing of the field-effect transistor is performed to obtain output characteristic curves and transfer characteristic curves. Next, a primary antibody 11 of a certain dilution is added to the reservoir of the immunosensor area. After incubation at a constant temperature for a period of time, the sample is washed three to four times with PBS buffer. A fluorescently labeled secondary antibody 12 of a certain dilution is then added. After incubation at a constant temperature for a period of time, the sample is washed three to four times with PBS buffer. Maintaining the same illumination conditions, electrical testing of the field-effect transistor is performed under the same experimental conditions.

[0070] like Figure 9 As shown, taking the fluorescent dye fluorescein isothiocyanate (FITC) as an example, the resonant wavelength of the silicon optical waveguide ring resonator is 520nm. When 488nm wavelength light is applied to the device surface, and when the sample to be tested does not contain a specific antigen, the resulting field-effect transistor electrical performance remains the same as when no primary / secondary antibody is added. However, when the sample contains a specific antigen, the antigen binds to the primary antibody, and the complex can further bind to the fluorescently labeled secondary antibody, emitting light with a wavelength of 520nm. This light can be transmitted through the silicon optical waveguide ring resonator to the field-effect transistor channel, while light in other bands is suppressed. Therefore, by comparing the electrical performance of the field-effect transistor with and without the addition of primary / secondary antibodies under the same experimental conditions, the presence of a specific antigen in the sample to be tested can be determined.

[0071] like Figure 10 As shown, when there is a specific antigen in the sample to be detected, the transfer characteristic curve of the field effect transistor shifts, thereby determining whether the sample contains the specific antigen.

[0072] The above description is merely a preferred embodiment of one or more embodiments of this specification and is not intended to limit one or more embodiments of this specification. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of this specification shall be included in the scope of protection of one or more embodiments of this specification.

Claims

1. A photoelectric immune detection device based on a field effect transistor structure, characterized in that: The detection device consists of three parts: a field-effect transistor, a silicon optical waveguide ring resonator, and a liquid reservoir. All three parts are fabricated on the same silicon substrate on an insulating layer. The field effect transistor is composed of a silicon film on an insulating layer, a gate dielectric, a metal gate layer and a source / drain electrode, wherein the source and drain electrodes are symmetrically arranged on both sides of the gate electrode, and the gate electrode, the source electrode and the drain electrode all lead to contact electrodes; The silicon film on the insulating layer is etched to form a silicon optical waveguide ring resonator, which consists of a straight waveguide and a ring waveguide. One end of the straight waveguide is connected to the liquid reservoir as an optical input port, and the other end is connected to the channel of the field effect transistor as an optical output port. The straight waveguide is perpendicular to the channel length direction of the field effect transistor, and the ring waveguide is adjacent to the straight waveguide. The surface of the silicon film on the insulating layer is covered with a transparent insulating layer as the upper cladding of the waveguide, and the buried oxide layer of the silicon substrate on the insulating layer serves as the lower cladding of the waveguide; a liquid reservoir area is provided on the transparent insulating layer, and except for the liquid reservoir area and the lead-out electrodes, the rest of the device surface is covered with an opaque insulating layer; the surface of the liquid reservoir is modified for dripping the sample to be tested and fixing the antigen in the sample.

2. The photoelectric immunoassay device based on a field effect transistor structure according to claim 1, characterized in that: The gate dielectric material of the field effect transistor is selected from silicon oxide, aluminum oxide, and hafnium oxide, and has a thickness of 10 to 30 nm; the metal gate layer material is selected from tungsten and gold, and has a thickness of 30 to 50 nm.

3. The photoelectric immunoassay device based on a field effect transistor structure according to claim 1, characterized in that: The source and drain of the field effect transistor are ion-implanted silicon or NiSi metal source and drain; the contact electrode is nickel or gold and needs to be led out to the surface of the device.

4. The photoelectric immunoassay device based on a field effect transistor structure according to claim 1, characterized in that: The silicon optical waveguide ring resonator and the channel of the field effect transistor share a silicon film on the insulating layer; the material of the waveguide upper cladding is a silicon dioxide polymer organic material, and the thickness of the waveguide upper cladding should be no less than the thickness of the waveguide; the material of the opaque insulating layer is a black insulating series PET or a light-shielding epoxy resin.

5. The photoelectric immunoassay device based on a field effect transistor structure according to claim 1, characterized in that: The straight waveguide of the silicon optical waveguide ring resonator is a long strip structure, the light output port is connected to the channel of the field effect transistor through a trapezoidal structure, and the ring waveguide is a circular ring structure. Both the straight waveguide and the ring waveguide are formed by ICP etching silicon.

6. A method for manufacturing a photoelectric immunoassay device based on a field effect transistor structure, characterized in that: The following steps are involved: (1) depositing a gate dielectric on the silicon film on the insulating layer, depositing a metal gate layer on the gate dielectric, and forming a gate structure of a field effect transistor by photolithography and etching; (2) preparing source / drain electrodes on the silicon film on the insulating layer on both sides of the gate structure to form a field effect transistor structure; (3) performing photolithography on the surface of the silicon substrate on the insulating layer in the region adjacent to the gate of the field effect transistor, and etching the silicon film on the insulating layer to form a silicon optical waveguide ring resonator; (4) depositing a light-transmitting insulating layer on the surface of the device formed in step (3) as a waveguide upper cladding; (5) depositing a light-proof insulating layer on the surface of the device formed in step (4) to isolate it from interference from external light; (6) performing photolithography on the reservoir region and the gate, source, and drain regions of the field effect transistor, and etching the opaque insulating layer; subsequently, performing photolithography on the gate, source, and drain regions of the field effect transistor, and etching the light-transmitting insulating layer; (7) Photolithography of the gate, source, and drain electrodes of the field-effect transistor, and deposition of contact electrodes; (8) The surface of the liquid reservoir is modified so that it can be used to fix the antigen in the sample to be detected, thereby completing the preparation of the immunoassay device.

7. The manufacturing method according to claim 6, characterized in that In the step (3), photolithography is performed on the surface of the silicon substrate on the insulating layer in an area adjacent to the gate of the field effect transistor. The shape is a combination of a rectangle, a ring and a trapezoid. The rectangular area is a straight waveguide. The trapezoid is connected to the narrow side of the rectangle and is used to connect the straight waveguide and the channel of the field effect transistor. The ring is a ring waveguide and is adjacent to the long side of the rectangle.

8. The manufacturing method according to claim 6, characterized in that In the step (8), the insulating layer at the liquid reservoir is surface modified so that the antigen can be fixed on the surface of the liquid reservoir by the fixing solution.

9. A detection method for the photoelectric immunoassay device based on a field effect transistor structure according to any one of claims 1 to 5, the method comprising: When the photoelectric immunoassay device is operating, light of a certain wavelength is applied to the surface to perform electrical testing on the field-effect transistor. Next, a primary antibody of a certain dilution concentration is added to the reservoir of the immunosensor area, incubated at a constant temperature for a period of time, and then washed. Then, a fluorescent-labeled secondary antibody of a certain dilution concentration is added, incubated at a constant temperature for a period of time, and then washed. The field-effect transistor is electrically tested under the same experimental conditions, maintaining the same illumination conditions. By comparing the electrical performance of the field-effect transistor when the primary antibody / secondary antibody is added under the same experimental conditions, it can be determined whether a specific antigen is present in the sample to be tested.

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