Dopamine concentration detector and preparation method thereof, and method for detecting dopamine concentration

Abstract

The present invention discloses a dopamine concentration detector and a preparation method thereof, and a method for detecting dopamine concentration. The dopamine concentration detector comprises: a silicon substrate; a carbon film embedded with graphene nanocrystals, the carbon film embedded with graphene nanocrystals being arranged on the silicon substrate, the two-dimensional plane direction of the graphene nanocrystals being perpendicular to the silicon substrate; a first electrode, the first electrode being connected to the silicon substrate; and a second electrode, the second electrode being connected to the carbon film embedded with graphene nanocrystals. The dopamine concentration detector provided by the present invention has a simple structure, good stability and durability, has a single selectivity for the detection of dopamine, can realize the detection of dopamine concentration using a single droplet, has a fast response speed, and has a low detection cost. Even if the dopamine solution is mixed with other chemical substances, it will not interfere with the detection effect, and the detection concentration can be as low as 0.1 μM.

Description

Technical Field

[0001] The present invention relates to the technical field of dopamine detection, and in particular to a dopamine concentration detector and a preparation method thereof, and a method for detecting dopamine concentration. Background Art

[0002] Dopamine (DA) is secreted by the brain and is a neurotransmitter that plays a critical role in the kidneys and nervous system of the human body. Currently, most methods for dopamine detection on the market have the problem of long sample preparation time or high cost before detection. In addition, in the chemical detection of dopamine, the mixed chemical substances will also interfere with the detection effect.

[0003] Therefore, the prior art still needs to be improved and developed. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a dopamine concentration detector and a preparation method thereof, and a method for detecting dopamine concentration, aiming to solve the problems that most of the existing methods for detecting dopamine concentration have a long sample preparation time before detection, high cost, and mixed chemical substances that also interfere with the detection effect.

[0005] The technical solution of the present invention is as follows:

[0006] A first aspect of the present invention provides a dopamine concentration detector, wherein the dopamine concentration detector comprises:

[0007] Silicon substrate;

[0008] A carbon film embedded with graphene nanocrystals, wherein the carbon film embedded with graphene nanocrystals is arranged on the silicon substrate, and the two-dimensional plane direction of the graphene nanocrystals is perpendicular to the silicon substrate;

[0009] a first electrode connected to the silicon substrate;

[0010] A second electrode is connected to the carbon film embedded with graphene nanocrystals.

[0011] Optionally, the silicon substrate is selected from an intrinsic silicon substrate, a p-type silicon substrate, and an n-type silicon substrate.

[0012] Optionally, the carbon film embedded with graphene nanocrystals has a thickness of 50 to 200 nm.

[0013] Optionally, the first electrode is a wire, and the second electrode is a wire.

[0014] A second aspect of the present invention provides a method for preparing the dopamine concentration detector as described above, comprising the steps of:

[0015] Providing a silicon substrate, a first electrode, and a second electrode;

[0016] Depositing a carbon film embedded with graphene nanocrystals on the silicon substrate by electron cyclotron resonance electron irradiation method, wherein the two-dimensional plane direction of the graphene nanocrystals is perpendicular to the silicon substrate;

[0017] connecting the first electrode to the silicon substrate;

[0018] The second electrode is connected to the carbon film embedded with graphene nanocrystals to obtain the dopamine concentration detector.

[0019] Optionally, the step of depositing a carbon film embedded with graphene nanocrystals on the silicon substrate by electron cyclotron resonance electron irradiation method specifically includes:

[0020] The silicon substrate was placed in the vacuum chamber of the electron cyclotron resonance irradiation nano-surface processing system and evacuated. When the pressure of the vacuum chamber was lower than 1.0×10 -4 Pa, open the circulating water cooling system, introduce argon gas, and control the pressure of the vacuum chamber to 1-8×10 -2 Pa, turn on the magnetic coil and microwave power supply to generate argon plasma in the vacuum chamber;

[0021] The substrate bias voltage is set to -50 to -100 V to attract argon ions in the argon plasma, and the silicon substrate is cleaned with argon ions for 3 to 5 minutes;

[0022] Set the target bias voltage to -500 to -800 V and clean the target for 3 to 5 minutes;

[0023] The substrate bias voltage is set to +5 to +80 V, and the carbon film is deposited by electron irradiation for 10 to 60 minutes, so as to obtain a carbon film embedded with graphene nanocrystals on the silicon substrate.

[0024] A third aspect of the present invention provides a method for detecting dopamine concentration, wherein the method for detecting dopamine concentration comprises the steps of:

[0025] providing a dopamine solution to be tested;

[0026] The dopamine concentration detector of the present invention as described above is placed on a platform with an inclination angle, the silicon substrate in the dopamine concentration detector is arranged in contact with the platform with an inclination angle, and the carbon film embedded with graphene nanocrystals in the dopamine concentration detector is arranged away from the platform with an inclination angle; the first electrode and the second electrode in the dopamine concentration detector are connected to a current amplifier;

[0027] The dopamine solution to be tested is dropped onto the surface of the carbon film embedded with graphene nanocrystals in the form of a single dopamine solution droplet, a friction current signal is acquired by a current amplifier, and the concentration of dopamine in the dopamine solution is obtained by the friction current signal.

[0028] Optionally, the volume of a single dopamine solution droplet is 40 to 60 μL, and the drop height is 10 to 40 mm.

[0029] Optionally, the inclination angle of the platform is 10-40°.

[0030] Optionally, under laser irradiation with a wavelength of 785 nm, the dopamine solution is dropped in the form of a single dopamine solution droplet onto the surface of the carbon film embedded with graphene nanocrystals in the dopamine concentration detector, and a triboelectric photoelectric coupled current signal is collected by a current amplifier, and the concentration of dopamine in the dopamine solution is obtained by the triboelectric photoelectric coupled current signal.

[0031] Beneficial effects: The dopamine concentration detector provided by the present invention has a simple structure, good stability and durability, and has single selectivity for the detection of dopamine. It can realize the detection of dopamine concentration using a single droplet, has a fast response speed, and has a low detection cost. Even if the dopamine solution is mixed with other chemical substances, it will not interfere with the detection effect. The lowest detection concentration can reach 0.1μM. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is an optical photograph of the carbon film embedded with graphene nanocrystals prepared in Example 1 of the present invention.

[0033] Figure 2 This is a Raman spectrum curve of the carbon film embedded with graphene nanocrystals prepared in Example 1 of the present invention.

[0034] Figure 3 This is a TEM image of the carbon film embedded with graphene nanocrystals prepared in Example 1 of the present invention.

[0035] Figure 4a Schematic diagram of the structure of a dopamine concentration detector in an embodiment of the present invention.

[0036] Figure 4b Schematic diagram of friction current signal detection in an embodiment of the present invention.

[0037] Figure 4c This is a schematic diagram of photocurrent signal detection in Example 2 of the present invention.

[0038] Figure 4d Schematic diagram of triboelectric photoelectric coupling current signal detection in an embodiment of the present invention.

[0039] Figure 5 This is a diagram showing the output result of the friction current signal when a deionized water droplet falls on the detector surface in Example 1 of the present invention.

[0040] Figure 6 This is a diagram showing the output result of the friction current signal when a deionized water droplet falls on the surface of a pure p-type silicon substrate in Example 1 of the present invention.

[0041] Figure 7 This is a graph showing the photocurrent signal output result of the detector irradiated by a laser with a wavelength of 785 nm in Example 2 of the present invention.

[0042] Figure 8 This is a graph showing the photocurrent signal output result when a laser with a wavelength of 785 nm irradiates a pure p-type substrate in Embodiment 2 of the present invention.

[0043] Fig. 9 This is a graph showing the current signal output results of a deionized water droplet falling on the detector surface before and after laser irradiation with a wavelength of 785 nm in Example 3 of the present invention.

[0044] Fig.10 This is a graph showing the current signal output result of a 0.1-400 μM dopamine solution measured without using a 785 nm laser irradiation detector in Example 4 of the present invention and a graph showing the current signal output result of a 0.1-400 μM dopamine solution measured with a 785 nm laser irradiation detector in Example 5.

[0045] Fig.11 This is a graph showing the current signal output result of a 400 μM dopamine solution measured in Example 4 of the present invention without using a laser with a wavelength of 785 nm to irradiate the detector.

[0046] Fig.12 This is a graph showing the current signal output result of a 400 μM dopamine solution measured in Example 4 of the present invention without using a laser irradiation detector with a wavelength of 785 nm, and a graph showing the current signal output result of a 400 μM dopamine solution measured in Example 5 with a laser irradiation detector with a wavelength of 785 nm.

[0047] Fig.13 This is a graph showing the current signal output results under the conditions of alternating laser irradiation and non-laser irradiation in Invention Example 6.

[0048] Fig.14 This is a graph showing the stability test results of the detector under the condition of laser irradiation with a wavelength of 785 nm in Embodiment 7 of the present invention when 8000 drops of dopamine solution are continuously dropped.

[0049] Fig.15 A graph showing the results of a three-month durability test of the detector under 785 nm laser irradiation conditions in Example 7 of the present invention.

[0050] Fig.16 This is a diagram showing the single selective detection result of dopamine by the detector in an interference environment under the condition of laser irradiation with a wavelength of 785 nm in Example 8 of the present invention.

[0051] Fig.17 Result diagrams showing the effect of droplet size on current signal in Example 9 of the present invention, where (a) is a current-time diagram and (b) is a current-droplet volume diagram.

[0052] Fig.18 Result diagram of the effect of drop height on current signal in Example 10 of the present invention, where (a) is a current-time diagram and (b) is a current-drop height diagram.

[0053] Fig.19 Result diagram of the influence of the platform inclination angle on the current signal in Example 11 of the present invention, where (a) is a current-time diagram and (b) is a current-platform inclination angle diagram.

[0054] Fig. 20 Schematic diagram of the heterojunction energy band structure in an embodiment of the present invention. DETAILED DESCRIPTION

[0055] The present invention provides a dopamine concentration detector and a preparation method thereof, and a method for detecting dopamine concentration. To make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0056] Unless otherwise defined, all technical terms and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0057] An embodiment of the present invention provides a dopamine concentration detector, wherein, as Figure 4a As shown, the dopamine concentration detector comprises:

[0058] Silicon substrate 1;

[0059] A carbon film 2 embedded with graphene nanocrystals 3, wherein the carbon film 2 embedded with graphene nanocrystals 3 is arranged on the silicon substrate 1, and the two-dimensional plane direction of the graphene nanocrystals 3 is perpendicular to the silicon substrate 1;

[0060] A first electrode 5, wherein the first electrode 5 is connected to the silicon substrate 1;

[0061] The second electrode 4 is connected to the carbon film 2 embedded with the graphene nanocrystals 3 .

[0062] The dopamine concentration detector provided by the embodiment of the present invention has a simple structure, good stability and durability, and single selectivity for the detection of dopamine. It can realize the detection of dopamine concentration using a single droplet, has a fast response speed, and low detection cost. Even if the dopamine solution is mixed with chemical substances, it will not interfere with the detection effect. The lowest detection concentration can reach 0.1μM.

[0063] It should be noted that, in this embodiment, the connection can be a direct connection or an indirect connection. For example, the first electrode can be directly connected to the silicon substrate or connected to the silicon substrate through a conductive medium. The connection method between the second electrode and the carbon film embedded with graphene nanocrystals is similar.

[0064] In one embodiment, the silicon substrate is selected from one of an intrinsic silicon substrate, a p-type silicon substrate, and an n-type silicon substrate, but is not limited thereto. In a further embodiment, the silicon substrate is selected from a p-type silicon substrate.

[0065] In one embodiment, the thickness of the carbon film embedded with graphene nanocrystals is 50 to 200 nm, for example, 50, 60, 80, 100, 120, 140, 160, 180 or 200 nm.

[0066] In one embodiment, the first electrode is a wire, and the second electrode is a wire, but not limited thereto, the first electrode and the second electrode may also be other metal electrodes, such as gold electrodes, copper electrodes, etc. Specifically, one end of the first electrode (wire) may be connected to the silicon substrate by using copper foil, one end of the copper foil is arranged on the side of the silicon substrate away from the carbon film embedded with graphene nanocrystals, and the other end is connected to one end of the first electrode (wire connection); the second electrode (wire) may be bonded to the carbon film embedded with graphene nanocrystals by using copper foil, that is, one end of the second electrode (wire) is arranged on the carbon film embedded with graphene nanocrystals, and the copper foil covers the end of the second electrode (wire) connected to the carbon film embedded with graphene nanocrystals.

[0067] The present invention also provides a method for preparing the dopamine concentration detector according to the present invention, which comprises the following steps:

[0068] S11, providing a silicon substrate, a first electrode, and a second electrode;

[0069] S12, depositing a carbon film embedded with graphene nanocrystals on the silicon substrate by electron cyclotron resonance electron irradiation method, wherein the two-dimensional plane direction of the graphene nanocrystals is perpendicular to the silicon substrate;

[0070] S13, connecting the first electrode to the silicon substrate;

[0071] S14, connecting the second electrode to the carbon film embedded with graphene nanocrystals to obtain the dopamine concentration detector.

[0072] The preparation method provided by the embodiment of the present invention is simple and efficient. The prepared dopamine concentration detector has a simple structure, good stability and durability, and single selectivity for the detection of dopamine. It can realize the detection of dopamine concentration using a single droplet (without requiring a large amount of dopamine solution). It has a fast response speed and low detection cost. Even if the dopamine solution is mixed with chemical substances, it will not interfere with the detection effect. The lowest detection concentration can reach 0.1 μM.

[0073] In step S12, in one embodiment, the step of depositing a carbon film embedded with graphene nanocrystals on the silicon substrate by using electron cyclotron resonance electron irradiation method specifically includes:

[0074] The silicon substrate was placed in the vacuum chamber of the electron cyclotron resonance irradiation nano-surface processing system and evacuated. When the pressure of the vacuum chamber was lower than 1.0×10 -4 Pa, open the circulating water cooling system, introduce argon gas, and control the pressure of the vacuum chamber to 1-8×10 -2 Pa, turn on the magnetic coil and microwave power supply to generate argon plasma in the vacuum chamber;

[0075] The substrate bias voltage is set to -50 to -100 V (for example, -50, -60, -70, -80, -90 or -100 V) to attract argon ions in the argon plasma, and the silicon substrate is cleaned with argon ions for 3 to 5 minutes;

[0076] Set the target bias voltage to -500 to -800 V (e.g., -500, -600, -700, or -800 V), and clean the target for 3 to 5 minutes;

[0077] The substrate bias voltage is set to +5 to +80V (for example, it can be +5, +10, +20, +30, +40, +50, +60, +70 or +80V, etc.), and the carbon film is deposited by electron irradiation for a deposition time of 10 to 60min (for example, it can be 10, 20, 30, 40, 50 or 60min), and a carbon film embedded with graphene nanocrystals is deposited on the silicon substrate. Within this voltage range, the prepared carbon film embedded with graphene nanocrystals has good performance, and the two-dimensional plane direction of the graphene nanocrystals is perpendicular to the silicon substrate. Beyond this voltage range, the performance of the carbon film may change due to the increase in the cavity temperature, and then under the condition of laser irradiation with a wavelength of 785nm, the output intensity of the photocurrent signal decreases (see below).

[0078] The present invention also provides a method for detecting dopamine concentration, wherein: Figure 4b As shown, the method for detecting dopamine concentration comprises the steps of:

[0079] S21, providing a dopamine solution to be tested;

[0080] S22, placing the dopamine concentration detector as described above in the embodiment of the present invention on a platform with an inclination angle, wherein the silicon substrate 1 in the dopamine concentration detector is arranged in contact with the platform with an inclination angle, and the carbon film 2 embedded with graphene nanocrystals 3 in the dopamine concentration detector is arranged away from the platform with an inclination angle; the first electrode 2 and the second electrode 4 in the dopamine concentration detector are connected to the current amplifier 6;

[0081] S23, dropping the dopamine solution to be tested in the form of a single dopamine solution droplet on the surface of the carbon film 5 embedded with graphene nanocrystals 3, collecting a friction current signal through a current amplifier 6, and obtaining the concentration of dopamine in the dopamine solution through the friction current signal.

[0082] In this embodiment, the detector can detect the concentration of dopamine because: when a dopamine solution droplet falls on the surface of the carbon film embedded with graphene nanocrystals, the dopamine solution droplet is charged due to friction with the container wall (such as the wall of the silicone tube) and the air where the dopamine solution is dripping. Based on the "self-catalytic" chemical reaction mechanism of dopamine and carbon film (i.e., the adsorption layer of catechol formed by the dopamine solution droplet falling on the carbon film can be used as an electrocatalyst of the solution phase redox component to promote the chemical reaction of dopamine and graphene nanocrystal carbon film), the edge state of the graphene nanocrystal structure provides more active sites, which helps to form hydrogen bonds between the dopamine solution droplet and the edge state of the graphene nanocrystal structure, and in a neutral solution, the electrostatic repulsion between dopamine and the oxygen functional groups on the surface of the carbon film can be ignored. Therefore, the edge state of the graphene nanocrystal structure serves as a hydrogen bond position and promotes the transfer of electrons from the dopamine droplet to the carbon film. Different dopamine concentrations result in different electron transfer amounts, and different current intensities are obtained.

[0083] The detection method provided by the embodiment of the present invention is simple and can realize the detection of dopamine concentration using a single droplet. It has a fast response speed and low detection cost. Even if the dopamine solution is mixed with chemical substances, it will not interfere with the detection effect. The lowest detection concentration can reach 0.1 μM.

[0084] In one embodiment, the volume of the single dopamine solution droplet is 40 to 60 μL, and the drop height is 10 to 40 mm. It can be understood that the straight-line distance between the initial position of the droplet and the position where the droplet drops onto the surface of the carbon film embedded with graphene nanocrystals under the action of gravity is the drop height.

[0085] In one embodiment, the inclination angle of the platform is 10-40°, for example, 10°, 20°, 30° or 40°, etc. The volume of the dopamine solution droplet, the drop height and the inclination angle of the platform all affect the friction current signal.

[0086] In one embodiment, Figure 4d As shown, under the condition of laser irradiation with a wavelength of 785nm (due to the carbon film's selectivity for the laser wavelength, there is no effect when measuring with other wavelengths), the dopamine solution is dropped in the form of a single dopamine solution droplet on the surface of the carbon film 2 embedded with graphene nanocrystals 3 in the dopamine concentration detector, and a triboelectric photoelectric coupling current signal is collected by the current amplifier 6. The concentration of dopamine in the dopamine solution is obtained by the triboelectric photoelectric coupling current signal, and under laser irradiation conditions, more sensitive self-driven detection can be achieved.

[0087] Compared with the condition without laser irradiation, the dopamine concentration detector has a more sensitive detection effect on dopamine in the same concentration range under the condition of laser irradiation with a wavelength of 785nm, which is specifically manifested in that the current signal output corresponding to dopamine in the same concentration range has a significant enhancement effect, and a triboelectric photoelectric coupling current signal can be generated under this condition. Specifically, the reason for the generation of photocurrent is that when red light with a wavelength of 785nm is irradiated on the surface of the carbon film embedded with graphene nanocrystals, photoexcited carriers appear at the interface between the carbon film embedded with graphene nanocrystals and the silicon substrate. The edge portion of the graphene nanocrystals (graphene nanosheets) will capture photogenerated electrons as the capture center of photoexcited electrons, thereby increasing the Fermi level of the carbon film embedded with graphene nanocrystals (such as Fig. 20 As shown, qV f The chemical barrier for the increase of the photogenerated electrons and the holes on the carbon film embedded with graphene nanocrystals are reduced, thereby effectively improving the charge carrier lifetime. This will significantly increase the surface charge density at the interface between the carbon film embedded with graphene nanocrystals and the silicon substrate, thereby generating a photocurrent signal output. The heterojunction band structure at this time is as follows Fig. 20 However, when the substrate bias increases to above +80 V, the increase in cavity temperature may cause the performance of the carbon film to change, and the output intensity of the detector's photocurrent signal begins to decrease until there is no light response.

[0088] Furthermore, the reason why laser irradiation enhances the detection effect is that when a dopamine solution droplet falls on the surface of a carbon film embedded with graphene nanocrystals, the dopamine solution droplet is charged due to friction with the container wall (such as the wall of a silicone tube) and the air where the dopamine solution is dripping. Based on the "self-catalytic" chemical reaction mechanism of dopamine and carbon film (i.e., the adsorption layer of catechol formed by the dopamine solution droplet falling on the carbon film can serve as an electrocatalyst of the solution phase redox component to promote the chemical reaction between dopamine and the graphene nanocrystal carbon film), the edge states of the graphene nanocrystal structure provide more active sites, which are conducive to the formation of hydrogen bonds between the dopamine solution droplet and the edge states of the graphene nanocrystal structure, and in a neutral solution, the electrostatic repulsion between dopamine and the oxygen functional groups on the surface of the carbon film can be ignored. Therefore, the edge states of the graphene nanocrystal structure serve as hydrogen bonding sites and promote the transfer of electrons from the dopamine droplet to the carbon film. At the same time, under the friction between the dopamine solution droplets and the carbon film surface and the laser irradiation, the interface between the carbon film and the silicon substrate will excite carriers. In order to balance the charges of the two electrodes, the carriers will be transferred from one electrode to another through the wire, thereby generating a higher output external current signal.

[0089] Specifically, by pre-preparing a dopamine solution of known concentration and performing the above test, the current intensity corresponding to different dopamine concentrations is obtained, that is, the relationship between the current intensity and the concentration of the dopamine solution is obtained. When the concentration of the dopamine solution to be tested (unknown concentration) is tested, the concentration of the dopamine solution to be tested is obtained by using the measured current intensity and the relationship between the current intensity and the dopamine concentration obtained above.

[0090] The following describes it in detail through specific embodiments.

[0091] Example 1

[0092] The substrate system of the electron cyclotron resonance irradiation nano-surface processing system was turned on, and the p-type silicon substrate (25 mm × 25 mm × 0.525 mm) cleaned with acetone was clamped on the substrate holder. After clamping, the dust on the surface was blown away with an ear bulb. Then the substrate system was closed, the p-type silicon substrate was sent into the vacuum chamber, the substrate connection screws were tightened, and the automatic vacuum was waited. When the vacuum chamber pressure reached 8×10 -5 After pa, the circulating water cooling system was turned on, argon gas was introduced, and the vacuum chamber pressure was controlled at 8×10 - 2Pa, turn on the middle and right magnetic coils, microwave power supply and left magnetic coil in turn to generate argon plasma in the vacuum chamber; next, adjust the substrate bias to -50V to attract argon ions in the argon plasma, and clean the substrate with argon ions for 3 minutes, then turn off the substrate power; adjust the target bias to -500V, and clean the target for 3 minutes; finally, adjust the substrate bias output to +50V, select the electron irradiation mode, open the baffle, and deposit the carbon film for 25 minutes. After the deposition is completed, close the baffle, adjust the microwave output, magnetic coil current and target voltage to zero in turn, and turn off the power. After cooling for 1.5 hours, the chamber temperature is close to the outdoor temperature, take out the p-type silicon substrate, and prepare a carbon film embedded with graphene nanocrystals on the p-type silicon substrate. The optical photograph is shown in Figure 2. Figure 1 Its Raman spectrum curve is shown as Figure 2 As shown in the TEM image Figure 3 As shown, graphene nanocrystalline structure can be seen in the carbon film.

[0093] The p-type silicon substrate and the carbon film embedded with graphene nanocrystals are connected with wires respectively to obtain a dopamine concentration detector.

[0094] The dopamine concentration detector was placed on a platform with an inclination angle of 30°, with the carbon film embedded with graphene nanocrystals facing upwards. The wires in the detector were connected to a current amplifier (such as Figure 4a shown).

[0095] like Figure 4b As shown in FIG. 1 , the deionized water in the beaker is driven by a peristaltic pump and dripped onto the surface of the carbon film embedded with graphene nanocrystals through a silicone tube and then slid smoothly (the drop volume is 60 μL and the drop height is 30 mm), thereby measuring the friction current signal of the deionized water droplet falling to be 33.81 nA (as shown in FIG. 1 ). Figure 5 shown).

[0096] Under the same conditions, deionized water was directly dropped on the surface of a pure p-type silicon substrate for comparison. The friction current signal of the deionized water droplet was 23.18 nA (e.g. Figure 6 As shown in Figure 2, when a deionized water droplet is dropped on the surface of a carbon film embedded with graphene nanocrystals, the friction current signal is increased by about 38% compared to when the deionized water droplet is dropped on the surface of a p-type silicon substrate.

[0097] Example 2

[0098] The preparation method of the dopamine concentration detector is the same as that in Example 1.

[0099] like Figure 4c As shown, the surface of the carbon film embedded with graphene nanocrystals was irradiated with a laser having a wavelength of 785 nm, and the photocurrent signal generated by the carbon film embedded with graphene nanocrystals was measured to be 15.45 nA (as shown in FIG. Figure 7As shown), it shows that graphene nanocrystalline carbon film has good photoelectric properties.

[0100] When a laser with a wavelength of 785 nm is irradiated on the surface of a pure p-type silicon substrate, the photocurrent signal generated by the p-type silicon substrate is measured to be 0 (e.g. Figure 8 As shown), it shows that pure p-type silicon substrate has no optoelectronic properties.

[0101] Example 3

[0102] The preparation method of the dopamine concentration detector is the same as that in Example 1.

[0103] The dopamine concentration detector was placed on a platform with an inclination angle of 30°, with the carbon film embedded with graphene nanocrystals facing upward, and the wires in the detector were connected to the current amplifier.

[0104] The deionized water in the beaker was driven by a peristaltic pump and dripped onto the surface of the carbon film embedded with graphene nanocrystals through a silicone tube and then slid down smoothly (the drop volume was 60 μL and the drop height was 30 mm), and the friction current signal of the deionized water droplet was measured to be 34.73 nA.

[0105] like Figure 4d As shown in FIG. 1 , a laser with a wavelength of 785 nm was used to irradiate the surface of a carbon film embedded with graphene nanocrystals. The deionized water in a beaker was dripped onto the surface of a carbon film embedded with graphene nanocrystals through a silicone tube driven by a peristaltic pump and then slid smoothly (the drop volume was 60 μL and the drop height was 30 mm). The triboelectric photoelectric coupling current signal of the deionized water droplet was measured to be 92.81 nA, which is 2.7 times the triboelectric current signal without laser irradiation (as shown in FIG. 1 ). Fig. 9 shown).

[0106] Example 4

[0107] The preparation method of the dopamine concentration detector is the same as that in Example 1.

[0108] The dopamine concentration detector was placed on a platform with an inclination angle of 30°, with the carbon film embedded with graphene nanocrystals facing upward, and the wires in the detector were connected to the current amplifier.

[0109] Different masses of dopamine hydrochloride powder were weighed and dissolved in 250 mL of deionized water, respectively, to obtain dopamine solutions with concentrations of 0.1 μM, 1 μM, 10 μM, 50 μM, 100 μM, 200 μM, 300 μM and 400 μM, respectively.

[0110] Dopamine solutions of different concentrations were respectively dripped onto the surface of the carbon film embedded with graphene nanocrystals through a silicone tube under the drive of a peristaltic pump (the drop volume and drop height were the same as in Example 1), thereby generating a triboelectric current signal. The results showed that when the dopamine concentration increased from 0.1 μM to 400 μM, the triboelectric current signal increased from 10.45 nA to 223.37 nA. The results are as follows: Fig.10 As shown in Figure 2, the triboelectric current signal of a dopamine solution with a concentration of 400 μM is shown in Figure 2. Fig.11 and 12 shown.

[0111] Example 5

[0112] The preparation method of the dopamine concentration detector is the same as that in Example 1.

[0113] The dopamine concentration detector was placed on a platform with an inclination angle of 30°, with the carbon film embedded with graphene nanocrystals facing upward, and the wires in the detector were connected to the current amplifier.

[0114] Different masses of dopamine hydrochloride powder were weighed and dissolved in 250 mL of deionized water, respectively, to obtain dopamine solutions with concentrations of 0.1 μM, 1 μM, 10 μM, 50 μM, 100 μM, 200 μM, 300 μM and 400 μM, respectively.

[0115] The surface of the carbon film embedded with graphene nanocrystals was irradiated with a laser of 785 nm wavelength, and dopamine solutions of different concentrations were respectively dripped onto the surface of the carbon film embedded with graphene nanocrystals through a silicone tube driven by a peristaltic pump (the droplet volume and droplet height were the same as in Example 1), thereby generating a triboelectric photoelectric coupling current signal. The experiment found that when the dopamine concentration increased from 0.1 μM to 400 μM, the triboelectric photoelectric coupling current signal increased from 19.62 nA to 704.52 nA. The results are shown in FIG. Fig.10 As shown in Figure 2, the triboelectric photoelectric coupled current signal of a dopamine solution with a concentration of 400 μM is shown in Figure 2. Fig.12 It is shown that a more sensitive detection of dopamine concentration can be achieved under the condition of a drop of liquid falling.

[0116] Example 6

[0117] The preparation method of the dopamine concentration detector is the same as that in Example 1.

[0118] The dopamine concentration detector was placed on a platform with an inclination angle of 30°, with the carbon film embedded with graphene nanocrystals facing upward, and the wires in the detector were connected to the current amplifier.

[0119] 0.019 g of dopamine hydrochloride powder was weighed and dissolved in 250 mL of deionized water to obtain a dopamine solution with a concentration of 400 μM.

[0120] The dopamine solution droplets were driven by a peristaltic pump and dropped onto the surface of the carbon film embedded with graphene nanocrystals through a silicone tube (the droplet volume and drop height were the same as in Example 1). At the same time, a laser with a wavelength of 785 nm was used to intermittently irradiate the surface of the carbon film embedded with graphene nanocrystals to collect its current signal. The results showed that there was good reversibility between the friction current signal and the friction electric photoelectric coupling current signal (such as Fig.13 shown).

[0121] Example 7

[0122] The preparation method of the dopamine concentration detector is the same as that in Example 1.

[0123] The dopamine concentration detector was placed on a platform with an inclination angle of 30°, with the carbon film embedded with graphene nanocrystals facing upward, and the wires in the detector were connected to the current amplifier.

[0124] 0.019 g of dopamine hydrochloride powder was weighed and dissolved in 250 mL of deionized water to obtain a dopamine solution with a concentration of 400 μM.

[0125] The surface of the carbon film embedded with graphene nanocrystals was irradiated with a laser having a wavelength of 785 nm. The dopamine solution droplets were driven by a peristaltic pump through a silicone tube and dripped onto the surface of the carbon film embedded with graphene nanocrystals (the droplet volume and droplet height were the same as those in Example 1). When 8000 consecutive drops of 400 μM dopamine droplets were driven by a peristaltic pump through a silicone tube and dripped onto the surface of the carbon film embedded with graphene nanocrystals, the triboelectric photoelectric coupling current signal generated was stable at about 704 nA (e.g. Fig.14 In addition, in the durability test for three consecutive months, the triboelectric photoelectric coupling current signal was also relatively stable, indicating that the dopamine concentration detector has good stability (as shown in Figure 2). Fig.15 shown).

[0126] Example 8

[0127] The preparation method of the dopamine concentration detector is the same as that in Example 1.

[0128] The dopamine concentration detector was placed on a platform with an inclination angle of 30°, with the carbon film embedded with graphene nanocrystals facing upward, and the wires in the detector were connected to the current amplifier.

[0129] A certain mass of dopamine hydrochloride (DA), ascorbic acid (AA) and urea (UA) powders were weighed respectively and dissolved in 250 mL of deionized water to obtain 400 μM dopamine hydrochloride solution, ascorbic acid solution, urea solution, a mixed solution of dopamine hydrochloride and ascorbic acid, a mixed solution of dopamine hydrochloride and urea, and a mixed solution of the three.

[0130] The surface of the carbon film embedded with graphene nanocrystals was irradiated with a laser having a wavelength of 785 nm, and different solutions were dripped onto the surface of the carbon film embedded with graphene nanocrystals through a silicone tube driven by a peristaltic pump (the droplet volume and drop height were the same as in Example 1). The results showed that, compared with ascorbic acid and urea, dopamine would react with the carbon film embedded with graphene nanocrystals, thereby increasing the current signal output of the detector; and in the mixed solution of two substances and three substances, the detector still had excellent single selectivity for the detection of dopamine (such as Fig.16 ), that is, the presence of other substances in the dopamine solution will not affect the test results.

[0131] Example 9: Investigating the effect of droplet size on current signal

[0132] The preparation method of the dopamine concentration detector is the same as that of Example 1, except that the substrate bias voltage is +20V during the carbon film deposition.

[0133] The dopamine concentration detector was placed on a platform with an inclination angle of 30°, with the carbon film embedded with graphene nanocrystals facing upward, and the wires in the detector were connected to the current amplifier.

[0134] The deionized water in the beaker was driven by a peristaltic pump and dripped onto the surface of the carbon film embedded with graphene nanocrystals through a silicone tube and then slid down smoothly (the droplet volumes were 40 μL, 50 μL, and 60 μL, respectively, and the drop height was 30 mm). The friction current signal of the deionized water droplet increased from 18.75 nA to 33.26 nA (e.g. Fig.17 (a) and (b) in the figure), indicating that the friction current signal output is affected by the droplet size.

[0135] Example 10: Influence of drop height on current signal

[0136] The preparation method of the dopamine concentration detector is the same as that of Example 1, except that the substrate bias voltage is +20V during the carbon film deposition.

[0137] The dopamine concentration detector was placed on a platform with an inclination angle of 30°, with the carbon film embedded with graphene nanocrystals facing upward, and the wires in the detector were connected to the current amplifier.

[0138] The deionized water in the beaker was driven by a peristaltic pump and dripped onto the surface of the carbon film embedded with graphene nanocrystals through a silicone tube and then slid down smoothly (the drop volume was 60 μL, and the drop heights were 10 mm, 20 mm, 30 mm, and 40 mm, respectively). The friction current signal of the deionized water droplet increased from 23.62 nA to 33.75 nA (as shown in Figure 2). Fig.18 (a) and (b)), an improvement of 42.8%.

[0139] Example 11: Influence of platform inclination on current signal

[0140] The preparation method of the dopamine concentration detector is the same as that of Example 1, except that the substrate bias voltage is +20V during the carbon film deposition.

[0141] The dopamine concentration detector was placed on platforms with inclination angles of 10°, 20°, 30°, and 40°, with the carbon film embedded with graphene nanocrystals facing upward, and the wires in the detector were connected to the current amplifier.

[0142] The deionized water in the beaker was dripped onto the surface of the carbon film embedded with graphene nanocrystals through a silicone tube driven by a peristaltic pump and then slid down smoothly (the droplet volume was 60 μL and the droplet height was 30 mm). When the platform inclination angle was 10° and 20°, the droplet would stay on the film surface, and it can be considered that there was no friction current signal at this time; when the platform inclination angle was 30° and 40°, the droplet could slide down smoothly from the film surface, and the maximum friction current signal at this time was 32.75 nA and 33.14 nA, respectively (as shown in Figure 2). Fig.19 (a) and (b) in the figure), the difference is small.

[0143] Therefore, the detector in the present invention can realize self-driven detection of dopamine concentration with a detection range of 0.1-400 μM; it can complete efficient detection of dopamine concentration under the condition of a droplet size of 60 μL; under laser irradiation conditions, the detector of the present invention is more sensitive to the detection of dopamine concentration, and the current signal shows good stability in the continuous dripping of 8000 drops of dopamine solution and three months of durability test; the detection of dopamine in a mixed solution has single selectivity.

[0144] In summary, the present invention provides a dopamine concentration detector and a preparation method thereof, and a dopamine concentration detection method. The dopamine concentration detector provided by the present invention has a simple structure, good stability and durability, and has a single selectivity for the detection of dopamine. It can realize the detection of dopamine concentration using a single droplet, has a fast response speed, and a low detection cost. Even if the dopamine solution is mixed with other chemical substances, it will not interfere with the detection effect, and the lowest detection concentration can reach 0.1 μM.

[0145] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for detecting dopamine concentration, characterized in that: The method for detecting dopamine concentration comprises the steps of: providing a dopamine solution to be tested; A dopamine concentration detector is placed on a platform with an inclination angle, wherein the silicon substrate in the dopamine concentration detector is arranged in contact with the platform with an inclination angle, and the carbon film embedded with graphene nanocrystals in the dopamine concentration detector is arranged away from the platform with an inclination angle; the first electrode and the second electrode in the dopamine concentration detector are connected to a current amplifier; Dropping the dopamine solution to be tested in the form of a single dopamine solution droplet on the surface of the carbon film embedded with graphene nanocrystals, collecting a friction current signal through a current amplifier, and obtaining the concentration of dopamine in the dopamine solution through the friction current signal; The dopamine concentration detector comprises: Silicon substrate; A carbon film embedded with graphene nanocrystals, wherein the carbon film embedded with graphene nanocrystals is arranged on the silicon substrate, and the two-dimensional plane direction of the graphene nanocrystals is perpendicular to the silicon substrate; a first electrode connected to the silicon substrate; A second electrode is connected to the carbon film embedded with graphene nanocrystals.

2. The method for detecting dopamine concentration according to claim 1, characterized in that: The volume of a single dopamine solution droplet is 40-60 μL, and the drop height is 10-40 mm.

3. The method for detecting dopamine concentration according to claim 1, characterized in that: The inclination angle of the platform is 10-40°.

4. The method for detecting dopamine concentration according to claim 1, characterized in that: Under the condition of laser irradiation with a wavelength of 785nm, the dopamine solution is dropped in the form of a single dopamine solution droplet on the surface of the carbon film embedded with graphene nanocrystals in the dopamine concentration detector, and a triboelectric photoelectric coupling current signal is obtained by collecting it through a current amplifier. The concentration of dopamine in the dopamine solution is obtained through the triboelectric photoelectric coupling current signal.

5. The method for detecting dopamine concentration according to claim 1, characterized in that: The silicon substrate is selected from an intrinsic silicon substrate, a p-type silicon substrate, and an n-type silicon substrate.

6. The method for detecting dopamine concentration according to claim 1, characterized in that: The thickness of the carbon film embedded with graphene nanocrystals is 50-200 nm.

7. The method for detecting dopamine concentration according to claim 1, characterized in that: The first electrode is a wire, and the second electrode is a wire.

8. The method for detecting dopamine concentration according to claim 1, characterized in that: The preparation method of the dopamine concentration detector comprises the steps of: Providing a silicon substrate, a first electrode, and a second electrode; Depositing a carbon film embedded with graphene nanocrystals on the silicon substrate by electron cyclotron resonance electron irradiation method, wherein the two-dimensional plane direction of the graphene nanocrystals is perpendicular to the silicon substrate; connecting the first electrode to the silicon substrate; The second electrode is connected to the carbon film embedded with graphene nanocrystals to obtain the dopamine concentration detector.

9. The method for detecting dopamine concentration according to claim 8, characterized in that: The step of depositing a carbon film embedded with graphene nanocrystals on the silicon substrate by using an electron cyclotron resonance electron irradiation method specifically includes: The silicon substrate was placed in the vacuum chamber of the electron cyclotron resonance irradiation nano-surface processing system and evacuated. When the pressure of the vacuum chamber was lower than 1.0×10 -4 Pa, open the circulating water cooling system, introduce argon gas, and control the pressure of the vacuum chamber to 1-8×10 -2 Pa, turn on the magnetic coil and microwave power supply to generate argon plasma in the vacuum chamber; The substrate bias voltage is set to -50 to -100 V to attract argon ions in the argon plasma, and the silicon substrate is cleaned with argon ions for 3 to 5 minutes; Set the target bias voltage to -500 to -800 V and clean the target for 3 to 5 minutes; The substrate bias voltage is set to +5 to +80 V, and the carbon film is deposited by electron irradiation for 10 to 60 minutes, so as to obtain a carbon film embedded with graphene nanocrystals on the silicon substrate.

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