Field effect transistor biosensor for calcium ion detection and preparation method thereof
Graphene field effect transistor biosensor prepared through chemical vapor deposition and photolithography technology solves the problem of lack of calcium ion detection methods in the existing technology, realizes low-cost and high-sensitivity calcium ion detection, and fills the field effect tube bios The gap in sensors in the field of calcium ion detection.
Patent Information
- Application Number
- CN202411317740.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-20
- Publication Date
- 2024-12-27
AI Technical Summary
The lack of field effect tube biosensors for calcium ion detection in the prior art cannot meet the growing demand for high sensitivity and integration of smart biosensor chips for portable bedside detection and diagnostic systems.
The graphene layer was prepared by chemical vapor deposition method, and the metal oxide film was reacted with the metal source by physical adsorption of water as an oxidant, and then the HfO2 gate dielectric layer was reacted with the hafnium source, and finally the calcium ions were modified by photolithography. Responsive to substances, a field-effect transistor biosensor was prepared for calcium ion detection.
Low-cost, label-free, fast and highly sensitive calcium ion detection is achieved, providing a high reliability and selective biosensor solution.
Smart Images
Figure CN119208142A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of biosensors, and in particular relates to a field effect transistor biosensor for calcium ion detection and a preparation method thereof. Background Art
[0002] Since Clark and Lyon proposed the idea of biosensors in the 1960s, the development of biosensors has a history of more than 40 years. As an interdisciplinary subject developed between life sciences and information sciences, biosensors have been deeply valued and widely used in fermentation technology, environmental monitoring, food engineering, clinical medicine, military and military medicine. With the further informatization of society, biosensors will be more and more widely used. According to the different signal converters, biosensors can also be classified, such as piezoelectric crystal biosensors, field effect transistor biosensors, etc. Field effect transistor biosensors based on the structure and working principle of metal-oxide-semiconductor (MOS) field effect transistors (MOSFET) are a new type of sensing technology that has flourished in recent years. By measuring the drain current, the biological reactions occurring on the gate ion sensitive membrane can be quantitatively analyzed. These biological reactions include nucleic acid hybridization, protein action, antibody-antigen binding, and enzyme substrate reactions. This sensor has the advantages of high input impedance, low noise, low power consumption, large dynamic range, easy integration, no secondary breakdown problem, and wide safe working area, so it has broad application prospects.
[0003] Ultrasensitive biomolecular sensors are crucial in areas such as gene sequencing, biological threat identification, and early medical diagnosis. Traditional detection methods based on optical and magnetic labels use bulky and expensive equipment, which cannot meet the growing demand for highly sensitive and integrated smart biosensor chips in portable bedside detection and diagnostic systems. Therefore, it is of great significance to develop biosensors with the characteristics of being label-free, rapid, and low-cost. In the field of medical diagnosis, there are no reports on the use of field-effect transistor biosensors for the detection of calcium ions. The present invention is aimed at this problem and proposes a method for device preparation and calcium ion detection, which fills this gap. Summary of the invention
[0004] In view of the deficiencies of the prior art, the purpose of the present invention is to provide a field effect transistor biosensor for calcium ion detection and a preparation method thereof, which solves the problems in the prior art.
[0005] The purpose of the present invention can be achieved through the following technical solutions:
[0006] The method for preparing a field effect transistor biosensor comprises the following steps:
[0007] S1, preparing a graphene layer by chemical vapor deposition method;
[0008] S2, transferring the graphene layer to a silicon wafer substrate of a silicon dioxide substrate, and then using the water physically adsorbed on the surface of the graphene layer as an oxidant to react with a metal source to generate a metal oxide film, which serves as a nucleation layer; then using water as an oxidant to react with a hafnium source to generate a HfO2 gate dielectric layer on the graphene layer; and obtaining a graphene field effect transistor;
[0009] S3, on the graphene field effect transistor, photolithography technology is used to modify the calcium-carrying element of the calcium ion response substance to make a biosensor.
[0010] Furthermore, in S1, the step of preparing the graphene layer specifically includes:
[0011] S11, cleaning the metal substrate with deionized water, then soaking it with ethanol and ultrasonic cleaning it; drying the cleaned metal substrate, and then heating it in a CVD reactor under a hydrogen atmosphere;
[0012] S12, lowering the temperature of the reaction furnace to 800-1090° C., introducing a carbon source precursor, and simultaneously introducing liquid carbon source vapor into the reaction furnace;
[0013] S13, after the reaction is completed, the flow of the carbon source precursor and the liquid carbon source is turned off, and the flow of hydrogen is continued; then the temperature is gradually lowered to room temperature, and the metal substrate is taken out of the reactor; at room temperature, the metal is immersed in an HF solution to remove the metal substrate, and the HF residue is washed with clean water to obtain a graphene layer;
[0014] Furthermore, in S11, the hydrogen flow rate of the CVD reactor is set to 100 sccm, the heating temperature is 1100°C, and maintained for 30 minutes;
[0015] In S12, the liquid carbon source is introduced in the following manner: ethanol is introduced into the reaction furnace in the form of vapor through an evaporator; the ratio of the carbon source precursor to hydrogen is (1-10): (1-10).
[0016] In S13, the HF concentration was 0.1 M and the immersion time was 30 min.
[0017] Furthermore, the carbon source precursor is methane, ethylene or acetylene; the liquid carbon source is ethanol, benzene or toluene; and the metal substrate is copper, nickel or platinum.
[0018] Furthermore, the preparation steps of the graphene field effect transistor include:
[0019] S21, after cleaning and drying the silicon wafer on the silicon dioxide substrate, a gold electrode is deposited by vacuum evaporation; then the graphene layer is transferred to the silicon wafer on the silicon dioxide substrate;
[0020] S22, placing the cleaned silicon wafer into a thermal deposition device, introducing nitrogen as a protective atmosphere; using water as an oxidant, introducing deionized water vapor; then introducing a metal source, maintaining the atmosphere as nitrogen, and after the deposition reaction is completed, closing the aluminum source, continuing to introduce nitrogen to cool to room temperature, and forming a metal oxide film on the graphene layer as a nucleation layer;
[0021] S23, performing treatment on the nucleation layer, keeping the silicon wafer at room temperature, and passing deionized water vapor; spin-coating a hafnium acetic acid solution with a concentration of 0.1M on the graphene layer, and baking after spin coating; and then performing heat treatment to generate a HfO2 film as a gate dielectric layer.
[0022] Furthermore, the metal source is an aluminum source, and the nucleation layer is an aluminum oxide film.
[0023] In S23, the hafnium acetic acid solution is spin-coated by a spin coater, and the spin-coating parameters are: a rotation speed of 3000 rpm, and a spin-coating time of 30 seconds; the heat treatment process is: raising the temperature to 400° C. in a nitrogen atmosphere and maintaining it for 1 hour.
[0024] Furthermore, the biosensor is prepared:
[0025] S31, washing the graphene field effect transistor substrate with deionized water and drying it with nitrogen gas;
[0026] S32, using a spin coater to evenly coat the cleaned graphene field effect transistor substrate with photoresist; then performing soft baking and hard baking; then using a photolithography machine to expose the photoresist, and developing it in a developer; finally, washing it with deionized water, and drying it with nitrogen gas;
[0027] S33, preparing a 0.1 mg / mL calcium solution, using dichloromethane as a solvent, dissolving the calcium, and filtering to remove insoluble matter; then using a spin coater to coat the calcium solution on the graphene surface, followed by drying and thermal curing to obtain a biosensor;
[0028] The soft baking process is: heating at 100° C. for 1 min, and the hard baking process is: heating at 120° C. for 30 min.
[0029] The field effect transistor biosensor is prepared by using the above preparation method.
[0030] Application of the above field effect transistor biosensor in detecting calcium ion concentration.
[0031] A method for preparing a graphene field effect transistor comprises the following steps:
[0032] preparing a graphene layer by chemical vapor deposition;
[0033] The graphene layer is transferred to a silicon wafer base of a silicon dioxide substrate, and then the water physically adsorbed on the surface of the graphene layer is used as an oxidant to react with a metal source to generate a metal oxide film, which serves as a nucleation layer; then water is used as an oxidant to react with a hafnium source to generate a HfO2 gate dielectric layer on the graphene layer; and a graphene field effect transistor is obtained.
[0034] Application of the graphene field effect transistor prepared by the above-mentioned method for preparing the graphene field effect transistor in the preparation of a biosensor.
[0035] Beneficial effects of the present invention:
[0036] 1. The present invention adopts chemical vapor deposition to prepare single-layer graphene, which is low-cost and suitable for large-area preparation.
[0037] 2. The graphene of the present invention has atomic-level thickness and good biocompatibility. It can achieve ultra-low biological detection limits and high selectivity through controllable biochemical functionalization, which is an important application field of field effect transistor biosensors.
[0038] 3. The present invention uses photolithography technology to cover the entire graphene channel, and then assembles calcium ion responsive substances thereon as connectors to connect calcium ions, thereby forming a universal field effect transistor sensor, which provides a guarantee and new choice for high reliability and high sensitivity calcium ion detection. BRIEF DESCRIPTION OF THE DRAWINGS
[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0040] Figure 1 It is a schematic diagram of the preparation principle of the graphene field effect transistor of the present invention;
[0041] Figure 2 is an optical microscope characterization image of the graphene of the present invention;
[0042] Figure 3 is a Raman spectrum of graphene of the present invention;
[0043] Figure 4 This is a physical picture of the prototype device of the graphene field effect transistor obtained by the present invention;
[0044] Figure 5 These are the transfer curves and output curves of a GFET with a channel length of 100 μm;
[0045] Figure 6 This is a schematic diagram of the preparation of a calcium ion detection biosensor;
[0046] Figure 7 It is the output curve and transfer curve of liquid gate GFET. DETAILED DESCRIPTION
[0047] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.
[0048] Example 1
[0049] The method for preparing a field effect transistor biosensor for calcium ion detection comprises the following steps:
[0050] S1, preparing a graphene layer by chemical vapor deposition (CVD);
[0051] The specific steps are:
[0052] S11, the copper foil is cleaned with deionized water, then immersed in ethanol and ultrasonically cleaned for 10 minutes to remove surface impurities; the cleaned copper foil is heated to 150°C in an oven for drying, and then heated to 1100°C in a CVD reactor under a hydrogen atmosphere to remove oxides and other contaminants on the copper surface; wherein the hydrogen flow rate is set to 100 sccm and this state is maintained for 30 minutes.
[0053] S12, lowering the temperature of the reactor to 800°C, maintaining the hydrogen flow rate at 100 sccm; starting to introduce methane, with the flow rate set to 20 sccm, while introducing ethanol vapor into the reactor, with the flow rate of ethanol vapor controlled at 10 sccm; setting the reaction time to 20 min to ensure the growth of graphene; wherein, the introduction method of ethanol is to allow ethanol to enter the reactor in the form of vapor through a preheated evaporator; the ratio of methane to hydrogen is 10:1.
[0054] S13, after the reaction is completed, the flow of methane and ethanol is turned off, and the hydrogen flow is continued for 10 minutes to clean the residual gas in the reactor; then the temperature is gradually lowered to room temperature, and then the copper foil is taken out of the reactor; at room temperature, the copper foil is immersed in a hydrofluoric acid (HF) solution to remove the copper substrate and obtain a graphene layer; wherein the HF concentration is 0.1M and the immersion time is 30 minutes.
[0055] S14, using clean water to rinse to remove HF residues; transferring the graphene layer to the target substrate, and removing bubbles and air interlayers with deionized water.
[0056] Figure 3 This is the Raman spectrum result of the graphene layer. From the Raman results, it can be seen that it basically belongs to a single layer or a double layer of graphene, and the D peak basically does not appear.
[0057] In other embodiments, the carbon source precursor may be gaseous hydrocarbons such as ethylene and acetylene in addition to methane in this embodiment; the carbon source may be liquid carbon sources such as benzene and toluene in addition to ethanol in this embodiment; the reaction substrate may be metal substrates such as nickel and platinum in addition to copper.
[0058] S2, preparing a graphene field effect transistor (GFET) using the graphene layer;
[0059] like Figure 1 As shown, the specific steps are:
[0060] S21, washing the silicon wafer on the silicon dioxide substrate with deionized water, drying it with nitrogen, and then depositing a gold electrode by vacuum evaporation; then transferring the graphene layer prepared in S1 to the silicon wafer on the silicon dioxide substrate;
[0061] S22, putting the cleaned silicon wafer into a thermal deposition device, introducing nitrogen as a protective atmosphere at 300°C, with a flow rate set to 50sccm; using water as an oxidant, introducing deionized water vapor with a flow rate of 5sccm for 10 minutes; then introducing an aluminum source (aluminum target material), maintaining the atmosphere as nitrogen, with a flow rate set to 30sccm, and a deposition time of 30 minutes. After the reaction is completed, the aluminum source is turned off, and nitrogen is continued to be introduced for 10 minutes to cool to room temperature, so as to form a uniform, high-quality nucleation layer on the graphene layer; the nucleation layer is a uniform aluminum oxide film with a thickness of 4nm;
[0062] S23, processing is performed on the nucleation layer, the silicon wafer is kept at room temperature, and deionized water vapor is introduced with a flow rate of 5 sccm for 10 minutes to increase the surface activity; a hafnium acetic acid (Hf(OAc)4) solution is prepared to a concentration of 0.1M, and a spin coater is used to spin coat the graphene layer at a rotation speed of 3000 rpm for 30 seconds; after spin coating, baking is performed at 100°C for 10 minutes to remove the solvent and promote uniform growth of the film; then heat treatment is performed, the temperature is increased to 400°C in a nitrogen atmosphere, and maintained for 1 hour to promote the reaction of the hafnium source with water to generate an HfO2 film as a gate dielectric layer with a thickness of 10nm.
[0063] The actual picture of the graphene field effect transistor (GFET) prototype device is as follows Figure 4 shown.
[0064] Figure 5 The transfer curve and output curve of the GFET with a channel length of 100μm. It can be seen from the figure that the transfer curve and the output curve are both typical field effect tube response curves, indicating that the graphene field effect transistor has been successfully prepared.
[0065] like Figure 7 As shown, the left figure is the output curve, and the ordinate and abscissa are the source-drain current and voltage respectively. Different curves represent different gate voltages. Under different gate voltages, the current of the GFET device will be different, which is a manifestation of the field effect; the right figure is the transfer curve, and the ordinate and abscissa are the source-drain current and gate voltage respectively, and the source-drain voltage is fixed; this curve also shows the characteristics of the field effect, and the source-drain current will change with the change of the gate voltage. As can be seen from the figure, the field effect signal of the liquid-gate GFET was preliminarily measured, that is, the signal of the PBS solution containing calcium ions.
[0066] S3, fabrication of biosensors using graphene field-effect transistors;
[0067] like Figure 6 As shown, the specific steps are:
[0068] S31, washing the graphene field effect transistor substrate with deionized water to remove surface contaminants, and drying with nitrogen gas;
[0069] S32, on the cleaned graphene field effect transistor substrate, use a spin coater to evenly coat photoresist S1813; spin coating parameters: rotation speed 3000rpm, spin coating time 30 seconds, to form a photoresist layer about 1μm thick; then heat at 100℃ for 1min, and heat at 120℃ for 30min; then use a photolithography machine to expose the photoresist, the light source wavelength is 365nm, the exposure time is 20 seconds, and a standard mask is used to expose the desired pattern; and develop in developer MF-319, the development time is 1 minute, and the unexposed photoresist is removed; finally, it is washed with deionized water and blown dry with nitrogen to remove the residual photoresist after development.
[0070] S33, Calcium ion response molecular modification:
[0071] A 0.1 mg / mL calcium solution was prepared, and dichloromethane was used as a solvent. After the calcium was dissolved, the insoluble matter was filtered out; the calcium solution was then coated on the graphene surface using a spin coater, and the spin coating parameters were: rotation speed 1000 rpm, spin coating time 30 seconds; then dried at 60°C for 30 minutes, and finally placed in an oven for thermal curing at 80°C for 1 hour.
[0072] Embodiment 2-9
[0073] The difference between Example 2-9 and Example 1 is only that:
[0074] In S12, the volume ratio of methane to hydrogen and the reaction temperature are shown in Table 1.
[0075] Table 1 Experimental parameters for preparing graphene layer by chemical vapor deposition
[0076]
[0077] Furthermore, the characterization results of the graphene prepared in Examples 1-9 under a scanning electron microscope (SEM) are as follows: Figure 2 As shown in 1-9.
[0078] It is worth mentioning that the principle of using graphene-based field effect transistors (GFETs) for biosensor is to modify the surface of graphene to adsorb the molecules to be detected, and detect the content of biological molecules by measuring the changes in GFET channel current and the displacement of Dirac points caused by the adsorbed molecules.
[0079] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.
[0080] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.
Claims
1. A method for preparing a field effect transistor biosensor, characterized in that: The following steps are involved: S1, preparing a graphene layer by chemical vapor deposition method; S2, transferring the graphene layer to a silicon wafer substrate of a silicon dioxide substrate, and then using the water physically adsorbed on the surface of the graphene layer as an oxidant to react with a metal source to generate a metal oxide film, which serves as a nucleation layer; then using water as an oxidant to react with a hafnium source to generate a HfO2 gate dielectric layer on the graphene layer; and obtaining a graphene field effect transistor; S3, on the graphene field effect transistor, photolithography technology is used to modify the calcium-carrying element of the calcium ion response substance to make a biosensor.
2. The method for preparing a field effect transistor biosensor according to claim 1, characterized in that: In S1, the step of preparing the graphene layer specifically includes: S11, cleaning the metal substrate with deionized water, then soaking it with ethanol and ultrasonic cleaning it; drying the cleaned metal substrate, and then heating it in a CVD reactor under a hydrogen atmosphere; S12, lowering the temperature of the reaction furnace to 800-1090° C., introducing a carbon source precursor, and simultaneously introducing liquid carbon source vapor into the reaction furnace; S13, after the reaction is completed, the flow of the carbon source precursor and the liquid carbon source is turned off, and the hydrogen flow is continued; then the temperature is gradually lowered to room temperature, and then the metal substrate is taken out of the reactor; at room temperature, the metal is immersed in an HF solution to remove the metal substrate, and the HF residue is rinsed with clean water to obtain a graphene layer.
3. The method for preparing a field effect transistor biosensor according to claim 2, characterized in that: In S11, the hydrogen flow rate of the CVD reactor is set to 100 sccm, the heating temperature is 1100°C, and it is maintained for 30 minutes; In S12, the liquid carbon source is introduced in the following manner: ethanol is introduced into the reaction furnace in the form of vapor through an evaporator; the ratio of the carbon source precursor to hydrogen is (1-10): (1-10). In S13, the HF concentration was 0.1 M and the immersion time was 30 min.
4. The method for preparing a field effect transistor biosensor according to claim 2, characterized in that: The carbon source precursor is methane, ethylene or acetylene; the liquid carbon source is ethanol, benzene or toluene; and the metal substrate is copper, nickel or platinum.
5. The method for preparing a field effect transistor biosensor according to claim 1, characterized in that: The preparation steps of graphene field effect transistor include: S21, after cleaning and drying the silicon wafer on the silicon dioxide substrate, a gold electrode is deposited by vacuum evaporation; then the graphene layer is transferred to the silicon wafer on the silicon dioxide substrate; S22, placing the cleaned silicon wafer into a thermal deposition device, introducing nitrogen as a protective atmosphere; using water as an oxidant, introducing deionized water vapor; then introducing a metal source, maintaining the atmosphere as nitrogen, and after the deposition reaction is completed, closing the aluminum source, continuing to introduce nitrogen to cool to room temperature, and forming a metal oxide film on the graphene layer as a nucleation layer; S23, performing treatment on the nucleation layer, keeping the silicon wafer at room temperature, and passing deionized water vapor; spin coating a hafnium acetic acid solution with a concentration of 0.1M on the graphene layer, and baking after spin coating; and then performing heat treatment to generate a HfO2 film as a gate dielectric layer; The metal source is an aluminum source, and the nucleation layer is an aluminum oxide film.
6. The method for preparing a field effect transistor biosensor according to claim 1, characterized in that: The steps of making the biosensor include: S31, washing the graphene field effect transistor substrate with deionized water and drying it with nitrogen gas; S32, using a spin coater to evenly coat the cleaned graphene field effect transistor substrate with photoresist; then performing soft baking and hard baking; then using a photolithography machine to expose the photoresist, and developing it in a developer; finally, washing it with deionized water, and drying it with nitrogen gas; S33, preparing a 0.1 mg / mL calcium solution, using dichloromethane as a solvent, dissolving the calcium, and filtering to remove insoluble matter; then using a spin coater to coat the calcium solution on the graphene surface, followed by drying and thermal curing to obtain a biosensor; The soft baking process is: heating at 100° C. for 1 min, and the hard baking process is: heating at 120° C. for 30 min.
7. A field effect transistor biosensor, characterized in that The preparation method is described in any one of claims 1 to 6.
8. Use of the field effect transistor biosensor according to claim 7 in detecting calcium ion concentration.
9. A method for preparing a graphene field effect transistor, characterized in that: The following steps are involved: preparing a graphene layer by chemical vapor deposition; The graphene layer is transferred to a silicon wafer base of a silicon dioxide substrate, and then the water physically adsorbed on the surface of the graphene layer is used as an oxidant to react with a metal source to generate a metal oxide film, which serves as a nucleation layer; then water is used as an oxidant to react with a hafnium source to generate a HfO2 gate dielectric layer on the graphene layer; and a graphene field effect transistor is obtained.
10. Use of a graphene field effect transistor prepared by the method for preparing a graphene field effect transistor according to claim 9 in preparing a biosensor.