CN115452922A - Dopamine concentration detector, preparation method thereof and method for detecting dopamine concentration - Google Patents

Abstract

The invention discloses a dopamine concentration detector, 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 The film is arranged on the silicon substrate, and the two-dimensional plane direction of the graphene nanocrystal is perpendicular to the silicon substrate; the first electrode is connected to the silicon substrate; the second electrode, The second electrode is connected to the carbon film embedded with graphene nanocrystals. The dopamine concentration detector provided by the present invention is simple in structure, has good stability and durability, has a single selectivity for the detection of dopamine, can realize the detection of dopamine concentration by using a single droplet, has fast response speed, and 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

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

technical field

The invention relates to the technical field of dopamine detection, in particular to a dopamine concentration detector, a preparation method thereof, and a method for detecting dopamine concentration.

Background technique

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

Therefore, the prior art still needs to be improved and developed.

Contents of the invention

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. Expensive and mixed chemicals can also interfere with detection results.

Technical scheme of the present invention is as follows:

A first aspect of the present invention provides a dopamine concentration detector, wherein the dopamine concentration detector includes:

Silicon substrate;

A carbon film embedded with graphene nanocrystals, 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, the first electrode is connected to the silicon substrate;

A second electrode, the second electrode is connected to the carbon film embedded with graphene nanocrystals.

Optionally, the silicon substrate is selected from one of an intrinsic silicon substrate, a p-type silicon substrate, and an n-type silicon substrate.

Optionally, the carbon film embedded with graphene nanocrystals has a thickness of 50-200 nm.

Optionally, the first electrode is a wire, and the second electrode is a wire.

The second aspect of the present invention provides a method for preparing the dopamine concentration detector as described above in the present invention, which includes 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, 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 with the carbon film embedded with graphene nanocrystals to obtain the dopamine concentration detector.

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:

Place the silicon substrate in the vacuum chamber of the nanometer surface processing system irradiated by electron cyclotron resonance, and perform vacuum pumping. When the air pressure in the vacuum chamber is lower than 1.0×10 ^-4 Pa, turn on the circulating water cooling system and pass in argon , control the air pressure of the vacuum chamber at 1 to 8×10 ^-2 Pa, turn on the magnetic coil and the microwave power supply, so that argon plasma is generated in the vacuum chamber;

Setting the substrate bias voltage to -50--100V to attract argon ions in the argon plasma, and cleaning the silicon substrate with argon ions for 3-5 minutes;

Set the target bias voltage to -500~-800V, and clean the target for 3~5 minutes;

The bias voltage of the substrate is set to +5-+80V, the carbon film is deposited by electron irradiation, and the deposition time is 10-60min, and the carbon film embedded with graphene nanocrystals is deposited on the silicon substrate.

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

Provide the dopamine solution to be tested;

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 attached to the platform with an inclination angle, and the dopamine concentration detector is embedded with The carbon film of the graphene nanocrystal is arranged away from the platform direction with an inclination angle; the first electrode and the second electrode in the dopamine concentration detector are connected to a current amplifier;

The dopamine solution to be tested is dropped on the surface of the carbon film embedded with graphene nanocrystals in the form of a single dopamine solution droplet, and the triboelectric current signal is obtained by collecting the current amplifier, and the dopamine is obtained through the triboelectric current signal. The concentration of dopamine in the solution.

Optionally, the volume of the single dopamine solution droplet is 40-60 μL, and the drop height is 10-40 mm.

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

Optionally, under the condition of laser irradiation with a wavelength of 785nm, the dopamine solution is dropped on the surface of the carbon film embedded with graphene nanocrystals in the dopamine concentration detector in the form of a single dopamine solution droplet, and an electric current The triboelectric photoelectric coupling current signal is collected by the amplifier, and the concentration of dopamine in the dopamine solution is obtained through the triboelectric photoelectric coupling current signal.

Beneficial effects: the dopamine concentration detector provided by the present invention is simple in structure, has good stability and durability, has a single selectivity for the detection of dopamine, can realize the detection of dopamine concentration by using a single droplet, and has a fast response speed and can detect The cost is low, 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 of drawings

Figure 1 is an optical photo of the carbon film embedded with graphene nanocrystals prepared in Example 1 of the present invention.

Fig. 2 is the Raman spectrum curve of the carbon film embedded with graphene nanocrystals prepared in Example 1 of the present invention.

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

Fig. 4a is a schematic structural diagram of a dopamine concentration detector in an embodiment of the present invention.

Fig. 4b is a schematic diagram of triboelectric current signal detection in an embodiment of the present invention.

FIG. 4c is a schematic diagram of photocurrent signal detection in Embodiment 2 of the present invention.

Fig. 4d is a schematic diagram of triboelectric photoelectric coupling current signal detection in an embodiment of the present invention.

FIG. 5 is a graph showing the output result of the triboelectric current signal when the deionized water droplet falls on the surface of the detector in Example 1 of the present invention.

FIG. 6 is a graph showing the output results of tribocurrent signals when deionized water droplets fall on the surface of a pure p-type silicon substrate in Example 1 of the present invention.

Fig. 7 is a graph showing the output result of the photocurrent signal when the laser with a wavelength of 785nm irradiates the detector in Example 2 of the present invention.

Fig. 8 is a graph showing the photocurrent signal output result of the pure p-type substrate irradiated by a laser with a wavelength of 785nm in Embodiment 2 of the present invention.

FIG. 9 is a diagram showing the output results of current signals of deionized water droplets falling on the surface of the detector before and after laser irradiation with a wavelength of 785 nm in Example 3 of the present invention.

Fig. 10 is the current signal output result graph of the 0.1-400 μM dopamine solution measured by the 785nm laser irradiation detector in Example 4 of the present invention and the current signal output result of the 0.1-400 μM dopamine solution measured by the 785nm laser irradiation detector in Example 5. Current signal output result graph.

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

Fig. 12 is the current signal output result diagram of the 400 μM dopamine solution measured by the 785nm laser irradiation detector in Example 4 of the present invention and the current signal output result diagram of the 400 μM dopamine solution measured by the 785nm laser irradiation detector in Example 5 .

Fig. 13 is a graph showing the output results of current signals under the condition of alternate irradiation with and without laser in Example 6 of the invention.

Fig. 14 is a graph showing the stability test results of the detector under continuous 8000 drops of dopamine solution under the condition of laser irradiation with a wavelength of 785nm in Embodiment 7 of the present invention.

Fig. 15 is a diagram of the durability test results of the detector in three months under the condition of laser irradiation with a wavelength of 785nm in Example 7 of the present invention.

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

Fig. 17 is a graph showing the effect of droplet size on current signal in Example 9 of the present invention, wherein (a) is a current-time graph, and (b) is a current-droplet volume graph.

Fig. 18 is a graph showing the effect of drop height on current signal in Example 10 of the present invention, wherein (a) is a current-time graph, and (b) is a current-drop height graph.

Fig. 19 is a graph showing the influence of the platform inclination angle on the current signal in Example 11 of the present invention, wherein (a) is a current-time diagram, and (b) is a current-platform inclination diagram.

Fig. 20 is a schematic diagram of the energy band structure of the heterojunction in the embodiment of the present invention.

detailed description

The present invention provides a dopamine concentration detector, a preparation method thereof, and a method for detecting dopamine concentration. In order to make the purpose, technical solution and effect of the present invention clearer and clearer, the present invention will be further described in detail below. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field of the invention. The terminology used herein in the description of the present invention is only for the purpose of describing specific embodiments, and is not intended to limit the present invention.

An embodiment of the present invention provides a dopamine concentration detector, wherein, as shown in FIG. 4a, the dopamine concentration detector includes:

Silicon substrate 1;

A carbon film 2 embedded with a graphene nanocrystal 3, the carbon film 2 embedded with a graphene nanocrystal 3 is arranged on the silicon substrate 1, and the two-dimensional plane direction of the graphene nanocrystal 3 is perpendicular to the The silicon substrate 1;

a first electrode 5, the first electrode 5 is connected to the silicon substrate 1;

The second electrode 4 is connected to the carbon film 2 embedded with the graphene nanocrystal 3 .

The dopamine concentration detector provided by the embodiments of 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 by using a single droplet, and has fast response speed and low detection cost. Low, even if the dopamine solution is mixed with chemical substances, it will not interfere with the detection effect, and the detection concentration can be as low as 0.1 μM.

It should be noted that in this embodiment, the connection may be direct connection or indirect connection. For example, the first electrode may be directly connected to the silicon substrate, or may be connected to the silicon substrate through a conductive medium. The electrode is connected to the carbon film embedded with graphene nanocrystals in the same way.

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 p-type silicon substrates.

In one embodiment, the carbon film embedded with graphene nanocrystals has a thickness of 50-200 nm, such as 50, 60, 80, 100, 120, 140, 160, 180 or 200 nm.

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 can also be other metal electrodes, such as gold electrodes, copper electrodes, etc. . Specifically, copper foil can be used to connect one end of the first electrode (wire) to the silicon substrate, 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 the second electrode. One end of an electrode (wire connection) is connected; the second electrode (wire) can be bonded on the carbon film embedded with graphene nanocrystals with copper foil, that is, one end of the second electrode (wire) is arranged on the carbon film embedded with graphene nanocrystals. On the carbon film, the copper foil is covered on the end where the second electrode (wire) is connected to the carbon film embedded with graphene nanocrystals.

The embodiment of the present invention also provides a method for preparing the dopamine concentration detector as described above in the embodiment of the present invention, which includes the steps of:

S11. Providing a silicon substrate, a first electrode, and a second electrode;

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

S13. Connecting the first electrode to the silicon substrate;

S14. Connecting the second electrode to the carbon film embedded with graphene nanocrystals to obtain the dopamine concentration detector.

The preparation method provided by the embodiment of the present invention is simple and efficient, and the prepared dopamine concentration detector has a simple structure, good stability and durability, has a single selectivity for the detection of dopamine, and can realize the detection of dopamine concentration by using a single droplet. Detection (no need for a large amount of dopamine solution), fast response, low detection cost, even if the dopamine solution is mixed with chemical substances, it will not interfere with the detection effect, and the detection concentration can be as low as 0.1 μM.

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

Place the silicon substrate in the vacuum chamber of the nanometer surface processing system irradiated by electron cyclotron resonance, and perform vacuum pumping. When the air pressure in the vacuum chamber is lower than 1.0×10 ^-4 Pa, turn on the circulating water cooling system and pass in argon , control the air pressure of the vacuum chamber at 1 to 8×10 ^-2 Pa, turn on the magnetic coil and the microwave power supply, so that argon plasma is generated in the vacuum chamber;

Set the substrate bias voltage to -50 ~ -100V (for example, it can be -50, -60, -70, -80, -90 or -100V, etc.) to attract argon ions in the argon plasma, and to the silicon The substrate is cleaned with argon ions for 3 to 5 minutes;

Set the target bias to -500 ~ -800V (for example, it can be -500, -600, -700 or -800V), and clean the target for 3 ~ 5 minutes;

Set the substrate bias voltage to +5 ~ +80V (for example, it can be +5, +10, +20, +30, +40, +50, +60, +70 or +80V, etc.), and use electron irradiation to conduct carbon Film deposition, the deposition time is 10-60 minutes (for example, 10, 20, 30, 40, 50 or 60 minutes), and a carbon film embedded with graphene nanocrystals is deposited on the silicon substrate. Within this voltage range, the performance of the prepared carbon film embedded with graphene nanocrystals is good, and the two-dimensional plane direction of graphene nanocrystals is perpendicular to the silicon substrate. As a result, the performance of the carbon film changes, and then under the condition of laser irradiation with a wavelength of 785nm, the output intensity of the photocurrent signal decreases (see below).

The embodiment of the present invention also provides a method for detecting the concentration of dopamine, wherein, as shown in Figure 4b, the method for detecting the concentration of dopamine includes the steps of:

S21, providing a dopamine solution to be tested;

S22. Place the dopamine concentration detector as described above in the embodiment of the present invention on a platform with an inclination angle, the silicon substrate 1 in the dopamine concentration detector is attached to the platform with an inclination angle, and the dopamine concentration detection The carbon film 2 embedded with the graphene nanocrystal 3 in the device is set away from the platform direction with an inclination angle; the first electrode 2 and the second electrode 4 in the dopamine concentration detector are connected to a current amplifier 6;

S23. Drop the dopamine solution to be tested on the surface of the carbon film 5 embedded with the graphene nanocrystal 3 in the form of a single dopamine solution droplet, and collect the triboelectric current signal through the current amplifier 6, and pass the triboelectric current The signal yields the concentration of dopamine in the dopamine solution.

In this embodiment, the reason why the detector can detect the concentration of dopamine is: when the dopamine solution droplet drops on the surface of the carbon film embedded with graphene nanocrystals, the dopamine solution droplet is due to the container wall where the dopamine solution drops. (such as the wall of a silicone tube) and the air are charged by friction, based on the "self-catalyzed" chemical reaction mechanism of dopamine and the carbon film (that is, the adsorption layer of catechol formed by the droplet of the dopamine solution dripping on the carbon film can be used as The electrocatalyst of solution phase redox component promotes the chemical reaction between dopamine and graphene nanocrystalline carbon film), and the edge state of graphene nanocrystalline structure provides more active sites, which is helpful for the interaction between dopamine solution droplets and graphene nanocrystalline carbon film. Hydrogen bonds are formed between the edge states of the crystal structure, and the electrostatic repulsion between dopamine and the oxygen functional groups on the surface of the carbon film is negligible in neutral solution. Therefore, the edge state of the graphene nanocrystal structure serves as the hydrogen bond position and promotes the transfer of electrons from the dopamine droplet to the carbon film. The different concentrations of dopamine make the electron transfer amount different and the current intensity obtained is different.

The detection method provided by the embodiment of the present invention is simple, can realize the detection of dopamine concentration by using a single droplet, has 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, and the detection concentration can be as low as 0.1 μM.

In one embodiment, the volume of the single dopamine solution droplet is 40-60 μL, and the drop height is 10-40 mm. The point that falls on the surface of the carbon film embedded with graphene nanocrystals, the straight-line distance between the two points is the height of the drop.

In one embodiment, the inclination angle of the platform is 10-40°, such as 10°, 20°, 30° or 40°. The volume of the dopamine solution droplet, the drop height and the inclination angle of the platform all affect the tribocurrent signal.

In one embodiment, as shown in Figure 4d, under the condition of laser irradiation with a wavelength of 785nm (according to the selection specificity of the carbon film to the laser wavelength, there is no effect when using other wavelengths to measure), the dopamine solution is mixed with a single dopamine The form of solution droplet drops on the surface of the carbon film 2 embedded with graphene nanocrystal 3 in the dopamine concentration detector, and the triboelectric photoelectric coupling current signal is obtained through the collection of the current amplifier 6, and the triboelectric photoelectric coupling current signal is passed through the triboelectric photoelectric coupling current signal. The signal obtains the concentration of dopamine in the dopamine solution, and under the condition of laser irradiation, more sensitive self-driven detection can be realized.

Compared with the condition of no 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 shown in that the current signal output corresponding to dopamine in the same concentration range has Significantly enhanced effect, under this condition can generate triboelectric photoelectric coupling current signal. Specifically, the reason for the generation of photocurrent is: when red light with a wavelength of 785nm is irradiated on the surface of the carbon film embedded with graphene nanocrystals, photoexcited current carrying occurs at the interface between the carbon film embedded with graphene nanocrystals and the silicon substrate. son. The edge part of the graphene nanocrystal (graphene nanosheet) will capture the photo-generated electron as the capture center of the photoexcited electron, and improve the Fermi energy level of the carbon film embedded with the graphene nanocrystal (as shown in Figure 20, qV _f In order to increase the chemical potential barrier), at the same time reduce the recombination of photogenerated electrons and holes on the carbon film embedded with graphene nanocrystals, which can effectively improve the lifetime of charge carriers, which will significantly increase the lifetime of graphene nanocrystals The surface charge density at the interface between the carbon film and the silicon substrate, thereby generating a photocurrent signal output. The energy band structure of the heterojunction at this time is shown in FIG. 20 . However, when the substrate bias voltage increases above +80V, the performance of the carbon film may change due to the increase of the cavity temperature, and the output intensity of the photocurrent signal of the detector begins to decrease until there is no photoresponse.

Further, the reason why the laser irradiation enhances the detection effect is: when the dopamine solution droplet falls on the surface of the carbon film embedded with graphene nanocrystals, the dopamine solution droplet is due to the container wall (such as a silicone tube) where the dopamine solution drops. wall) and air triboelectrification, based on the "autocatalytic" chemical reaction mechanism of dopamine and carbon film (that is, the adsorption layer of catechol formed by dopamine solution droplets falling on the carbon film can be used as a solution-phase redox component The electrocatalyst promotes the chemical reaction between dopamine and graphene nanocrystalline carbon film), and the edge state of graphene nanocrystalline structure provides more active sites, which contributes to the interaction between dopamine solution droplets and graphene nanocrystalline structure edge states. Hydrogen bonds are formed, and in neutral solution, the electrostatic repulsion between dopamine and the oxygen functional groups on the surface of the carbon film is negligible. The edge states of the graphene nanocrystalline structure thus serve as hydrogen bonding sites and facilitate electron transfer from the dopamine droplet to the carbon film. At the same time, under the friction between the dopamine solution droplet and the surface of the carbon film 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 the the other electrode, thereby generating a higher output external current signal.

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

The following will be described in detail through specific examples.

Example 1

Turn on the substrate system of the electron cyclotron resonance irradiation nanometer surface processing system, clamp the p-type silicon substrate (25mm×25mm×0.525mm) wiped with acetone on the substrate holder, and blow it with the ear cleaning ball after the clamping is completed. Remove the dust on the surface; then close the substrate system, send the p-type silicon substrate into the vacuum chamber, tighten the substrate connection screws, and wait for automatic vacuuming. When the pressure in the vacuum chamber reaches 8×10 ^-5 pa, turn on the circulating water The cooling system is fed with argon gas, the pressure of the vacuum chamber is controlled at 8×10 ^{- 2} Pa, the middle and right magnetic coils, the microwave power supply and the left magnetic coil are turned on in turn, so that argon plasma is generated in the vacuum chamber; next, the substrate Adjust the bias voltage to -50V to attract argon ions in the argon plasma, clean the substrate with argon ions for 3 minutes, and then turn off the substrate power; adjust the bias voltage of the target to -500V, and clean the target for 3 minutes; finally, adjust The substrate bias output is +50V, select the electron irradiation method, 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 sequence and turn off the power supply. After cooling for 1.5 h, the chamber temperature was close to the outdoor temperature, and the p-type silicon substrate was taken out, and a carbon film embedded with graphene nanocrystals was prepared on the p-type silicon substrate, and its optical photo is shown in Figure 1. The Raman spectrum curve is shown in Figure 2, and its TEM image is shown in Figure 3, and the graphene nanocrystal structure can be seen in the carbon film.

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

The dopamine concentration detector is placed on a platform with an inclination angle of 30°, the carbon film embedded with graphene nanocrystals faces upward, and the wires in the detector are connected to the current amplifier (as shown in Figure 4a).

As shown in Figure 4b, the deionized water in the beaker was driven by the peristaltic pump and dropped on the surface of the carbon film embedded with graphene nanocrystals through the silicone tube and then slid down smoothly (the drop volume was 60 μL, and the drop height was 30 mm). , so that the measured triboelectric current signal of the deionized water droplet is 33.81nA (as shown in FIG. 5 ).

Under the same conditions, drop deionized water directly on the surface of a pure p-type silicon substrate as a comparison, and the measured triboelectric current signal of the dropped deionized water droplet is 23.18nA (as shown in Figure 6). The triboelectric current signal increased by about 38% when the ionic water droplets landed on the surface of the carbon film embedded with graphene nanocrystals compared with those dropped on the surface of the p-type silicon substrate.

Example 2

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

As shown in Figure 4c, the surface of the carbon film embedded with graphene nanocrystals is irradiated with a laser with a wavelength of 785nm, and the photocurrent signal generated by the carbon film embedded with graphene nanocrystals is measured to be 15.45nA (as shown in Figure 7) , indicating that the graphene nanocrystalline carbon film has good photoelectric properties.

However, when a laser with a wavelength of 785nm 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 (as shown in Figure 8), indicating that the pure p-type silicon substrate does not have photoelectric properties. .

Example 3

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

The dopamine concentration detector is placed on a platform with an inclination angle of 30°, the carbon film embedded with graphene nanocrystals faces upward, and the wires in the detector are connected to the current amplifier.

Driven by a peristaltic pump, the deionized water in the beaker was dropped on 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), thereby measuring the deionized water. The triboelectric current signal of water droplets falling is 34.73nA;

As shown in Figure 4d, a laser with a wavelength of 785 nm is used to irradiate the surface of the carbon film embedded with graphene nanocrystals, and the deionized water in the beaker is driven by a peristaltic pump to drop on the carbon film embedded with graphene nanocrystals through a silicone tube. The surface of the membrane then slides down smoothly (the droplet volume is 60 μL, and the drop height is 30mm), so that the measured triboelectric photoelectric coupling current signal of the deionized water droplet is 92.81nA, which is 2.7 times of the triboelectric current signal without laser irradiation. (as shown in Figure 9).

Example 4

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

The dopamine concentration detector is placed on a platform with an inclination angle of 30°, the carbon film embedded with graphene nanocrystals faces upward, and the wires in the detector are connected to the current amplifier.

Different masses of dopamine hydrochloride powder were weighed and dissolved in 250 mL of deionized water 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.

Dopamine solutions of different concentrations were dripped on 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), thereby generating tribocurrent signals. It was found 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, and the results are shown in Figure 10, where the tribocurrent signal results of the dopamine solution with a concentration of 400 μM are shown in Figure 11 and 12 shown.

Example 5

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

The dopamine concentration detector is placed on a platform with an inclination angle of 30°, the carbon film embedded with graphene nanocrystals faces upward, and the wires in the detector are connected to the current amplifier.

Different masses of dopamine hydrochloride powder were weighed and dissolved in 250 mL of deionized water respectively. Dopamine solutions with concentrations of 0.1 μM, 1 μM, 10 μM, 50 μM, 100 μM, 200 μM, 300 μM and 400 μM were obtained in sequence.

A laser with a wavelength of 785 nm was used to irradiate the surface of the carbon film embedded with graphene nanocrystals, and dopamine solutions of different concentrations were dropped on the surface of the carbon film embedded with graphene nanocrystals through a silicone tube driven by a peristaltic pump (droplet volume, The drop height is the same as in embodiment 1), thereby generating a triboelectric photoelectric coupling current signal. The experiment found that when the concentration of dopamine increased from 0.1 μM to 400 μM, the triboelectric photoelectric coupling current signal increased from 19.62 nA to 704.52 nA, and the results are shown in Figure 10, where the triboelectric photoelectric coupling current The signal result is shown in Figure 12. It is proved that a more sensitive detection of dopamine concentration can be achieved under the condition of one droplet falling.

Example 6

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

The dopamine concentration detector is placed on a platform with an inclination angle of 30°, the carbon film embedded with graphene nanocrystals faces upward, and the wires in the detector are connected to the current amplifier.

Weigh 0.019 g of dopamine hydrochloride powder, and dissolve it in 250 mL of deionized water to obtain a dopamine solution with a concentration of 400 μM.

The dopamine solution droplet was driven by the peristaltic pump and dropped on the surface of the carbon film embedded with graphene nanocrystals through the silica gel tube (the volume of the droplet and the height of the droplet were the same as in Example 1). On the surface of carbon film with graphene nanocrystals, the current signal is collected. The results show that there is good reversibility between the triboelectric current signal and the triboelectric photoelectric coupling current signal (as shown in Figure 13).

Example 7

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

The dopamine concentration detector is placed on a platform with an inclination angle of 30°, the carbon film embedded with graphene nanocrystals faces upward, and the wires in the detector are connected to the current amplifier.

Weigh 0.019 g of dopamine hydrochloride powder, and dissolve it in 250 mL of deionized water to obtain a dopamine solution with a concentration of 400 μM.

A laser with a wavelength of 785nm is used to irradiate the surface of the carbon film embedded with graphene nanocrystals, and the dopamine solution drops on the surface of the carbon film embedded with graphene nanocrystals through a silicone tube driven by a peristaltic pump (droplet volume, drop Highly with embodiment 1), when continuous 8000 drops of dopamine droplets with a concentration of 400 μM are driven by a peristaltic pump and drop on the surface of a carbon film embedded with graphene nanocrystals through a silicone tube, the triboelectric photoelectric coupling current produced by it The signals are all stable at about 704nA (as shown in Figure 14); in addition, in the three-month durability test, the triboelectric photoelectric coupling current signal is also relatively stable, indicating that the dopamine concentration detector has good stability (as shown in Figure 14). 15).

Example 8

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

The dopamine concentration detector is placed on a platform with an inclination angle of 30°, the carbon film embedded with graphene nanocrystals faces upward, and the wires in the detector are connected to the current amplifier.

Weigh a certain mass of dopamine hydrochloride (Dopamine, DA), ascorbic acid (Ascorbic acid, AA) and urea (Uricacid, UA) powders, and dissolve them in 250 mL of deionized water to obtain dopamine hydrochloride solutions with concentrations of 400 μM, Ascorbic acid solution, urea solution, mixed solution of dopamine hydrochloride and ascorbic acid, mixed solution of dopamine hydrochloride and urea, mixed solution of the three.

A laser with a wavelength of 785nm was used to irradiate the surface of the carbon film embedded with graphene nanocrystals, and different solutions were dripped on 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. Example 1). The results show that: compared with ascorbic acid and urea, dopamine will interact with the carbon film embedded with graphene nanocrystals, thereby increasing the current signal output of the detector; while in the mixed solution of two substances and three substances, the The detector still has excellent single selectivity for the detection of dopamine (as shown in FIG. 16 ), that is, the presence of other substances in the dopamine solution will not affect the detection result.

Example 9 explores the influence of droplet size on the current signal

The preparation method of the dopamine concentration detector is the same as in Example 1, except that the substrate bias voltage is +20V when carbon film deposition is performed.

The dopamine concentration detector is placed on a platform with an inclination angle of 30°, the carbon film embedded with graphene nanocrystals faces upward, and the wires in the detector are connected to the current amplifier.

Driven by the peristaltic pump, the deionized water in the beaker was dropped on the surface of the carbon film embedded with graphene nanocrystals through the silicone tube and then slid down smoothly (the droplet volumes were 40 μL, 50 μL, 60 μL, and the drop height was 30 mm). As a result, the triboelectric current signal measured by the deionized water droplet increased from 18.75nA to 33.26nA (as shown in (a) and (b) in Figure 17), indicating that the output of the triboelectric current signal is affected by the size of the droplet .

Example 10 explores the influence of drop height on current signal

The preparation method of the dopamine concentration detector is the same as in Example 1, except that the substrate bias voltage is +20V when carbon film deposition is performed.

The dopamine concentration detector is placed on a platform with an inclination angle of 30°, the carbon film embedded with graphene nanocrystals faces upward, and the wires in the detector are connected to the current amplifier.

Driven by the peristaltic pump, the deionized water in the beaker was dropped on the surface of the carbon film embedded with graphene nanocrystals through the silicone tube and then slid down smoothly (the drop volume was 60 μL, and the drop heights were 10mm, 20mm, 30mm, 40mm, respectively. ), so that the measured triboelectric current signal under the deionized water droplet increased from 23.62nA to 33.75nA (as shown in (a) and (b) in Figure 18), an increase of 42.8%.

Example 11 explores the influence of the platform inclination angle on the current signal

The preparation method of the dopamine concentration detector is the same as in Example 1, except that the substrate bias voltage is +20V when carbon film deposition is performed.

Place the dopamine concentration detectors on platforms with inclination angles of 10°, 20°, 30°, and 40° respectively, with the carbon film embedded with graphene nanocrystals facing upwards, and the wires in the detectors are connected to the current amplifier.

Driven by the peristaltic pump, the deionized water in the beaker was dropped on the surface of the carbon film embedded with graphene nanocrystals through the silicone tube and then slid down smoothly (the drop volume was 60 μL, and the drop height was 30 mm). When the platform inclination angle was At 10° and 20°, the droplet will stay on the surface of the film, and it can be considered that there is no tribocurrent signal at this time; while when the platform inclination angle is 30° and 40°, the droplet can slide smoothly from the surface of the film, and the friction at this time The maximum values of the current signals are respectively 32.75nA and 33.14nA (as shown in (a) and (b) in Figure 19), and the difference is small.

Therefore, the detector in the present invention can realize the self-driven detection of dopamine concentration, and the detection range is 0.1-400 μM; it can complete the efficient detection of dopamine concentration under the condition that the droplet size is 60 μL; under the condition of laser irradiation, this The invented detector is more sensitive to the detection of dopamine concentration, and the current signal shows good stability in the continuous 8000 drops of dopamine solution droplet and three-month durability test; it has a single choice for the detection of dopamine in the mixed solution sex.

In summary, the present invention provides a dopamine concentration detector, a preparation method thereof, and a dopamine concentration detection method. The dopamine concentration detector provided by the present invention is simple in structure, has good stability and durability, and has a single choice for the detection of dopamine. It can realize the detection of dopamine concentration by using a single droplet, with fast response speed and 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.

It should be understood that the application of the present invention is not limited to the above examples, and those skilled in the art can make improvements or transformations according to the above descriptions, and all these improvements and transformations should belong to the protection scope of the appended claims of the present invention.

Claims (10)

1. a dopamine concentration detector, is characterized in that, described dopamine concentration detector comprises: Silicon substrate; A carbon film embedded with graphene nanocrystals, 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, the first electrode is connected to the silicon substrate; A second electrode, the second electrode is connected to the carbon film embedded with graphene nanocrystals. 2. The dopamine concentration detector according to claim 1, wherein the silicon substrate is selected from one of an intrinsic silicon substrate, a p-type silicon substrate, and an n-type silicon substrate. 3. The dopamine concentration detector according to claim 1, characterized in that, the carbon film embedded with graphene nanocrystals has a thickness of 50-200 nm. 4. The dopamine concentration detector according to claim 1, wherein the first electrode is a wire, and the second electrode is a wire. 5. a preparation method of the dopamine concentration detector as described in any one of claim 1-4, is characterized in that, comprises the steps: 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, 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 with the carbon film embedded with graphene nanocrystals to obtain the dopamine concentration detector. 6. the preparation method of dopamine concentration detector according to claim 5 is characterized in that, the described step of adopting the electron cyclotron resonance electron irradiation method to deposit the carbon film embedded with graphene nanocrystals on the silicon substrate is specific include: Place the silicon substrate in the vacuum chamber of the nanometer surface processing system irradiated by electron cyclotron resonance, and perform vacuum pumping. When the air pressure in the vacuum chamber is lower than 1.0×10 ^-4 Pa, turn on the circulating water cooling system and pass in argon , control the air pressure of the vacuum chamber at 1 to 8×10 ^-2 Pa, turn on the magnetic coil and the microwave power supply, so that argon plasma is generated in the vacuum chamber; Setting the substrate bias voltage to -50--100V to attract argon ions in the argon plasma, and cleaning the silicon substrate with argon ions for 3-5 minutes; Set the target bias voltage to -500~-800V, and clean the target for 3~5 minutes; The bias voltage of the substrate is set to +5-+80V, the carbon film is deposited by electron irradiation, and the deposition time is 10-60min, and the carbon film embedded with graphene nanocrystals is deposited on the silicon substrate. 7. A method for detecting dopamine concentration, characterized in that, the method for detecting dopamine concentration comprises steps: Provide the dopamine solution to be tested; The dopamine concentration detector described in any one of claims 1-4 is placed on a platform with an inclination angle, the silicon substrate in the dopamine concentration detector is attached to the platform with an inclination angle, and the dopamine concentration detector The carbon film embedded with graphene nanocrystals in the device is set away from the platform direction with an inclination angle; the first electrode and the second electrode in the dopamine concentration detector are connected to a current amplifier; The dopamine solution to be tested is dropped on the surface of the carbon film embedded with graphene nanocrystals in the form of a single dopamine solution droplet, and a triboelectric current signal is obtained through a current amplifier, and the dopamine is obtained through the tribocurrent signal. The concentration of dopamine in the solution. 8. The method for detecting the concentration of dopamine solution according to claim 7, characterized in that the volume of the single dopamine solution droplet is 40-60 μL, and the drop height is 10-40 mm. 9. The method for detecting the concentration of dopamine solution according to claim 7, characterized in that, the inclination angle of the platform is 10-40°. 10. The method for detecting the concentration of dopamine solution according to claim 7, characterized in that, under the condition of laser irradiation with a wavelength of 785nm, the dopamine solution is dropped on the dopamine concentration detection zone in the form of a single dopamine solution droplet. The surface of the carbon film embedded with graphene nanocrystals in the device is collected by a current amplifier to obtain a triboelectric photoelectric coupling current signal, and the concentration of dopamine in the dopamine solution is obtained through the triboelectric photoelectric coupling current signal.

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