阅读说明：本技术 基于PtNi双金属的两电极集成无酶葡萄糖传感器及制备方法 (PtNi bimetal-based two-electrode integrated enzyme-free glucose sensor and preparation method thereof ) 是由 王玫 周晓斌 刘芳 陈冬冬 于 2021-01-19 设计创作，主要内容包括：本发明提供了一种基于PtNi双金属的两电极集成无酶葡萄糖传感器及制备方法,该传感器在同一个芯片上集成了工作电极和对电极,该无酶葡萄糖传感器的敏感材料采用PtNi双金属材料作为敏感材料,且敏感材料自身也是利用MEMS微加工工艺制备而成,不需要载体及额外的敏感材料负载工艺。与现有技术相较,利用MEMS微加工工艺同时实现了无酶葡萄传感器的敏感材料和电极集成,将极大地促进无酶葡萄糖传感器朝着稳定、小型化、低成本的方向发展,有利于其商业化应用。(The invention provides a PtNi bimetal-based two-electrode integrated enzyme-free glucose sensor and a preparation method thereof, wherein the sensor integrates a working electrode and a counter electrode on the same chip, the sensitive material of the enzyme-free glucose sensor adopts the PtNi bimetal material as the sensitive material, and the sensitive material is prepared by an MEMS micromachining process without a carrier and an additional sensitive material loading process. Compared with the prior art, the MEMS micromachining process is utilized to realize the integration of the sensitive material and the electrode of the enzyme-free glucose sensor, so that the development of the enzyme-free glucose sensor towards the directions of stability, miniaturization and low cost is greatly promoted, and the commercial application of the enzyme-free glucose sensor is facilitated.)

1. The preparation method of the PtNi bimetal-based two-electrode integrated enzyme-free glucose sensor is characterized by comprising the following steps of:

(1) preparing an enzyme-free glucose sensor electrode by using an MEMS (micro electro mechanical System) technology, wherein the enzyme-free glucose sensor electrode comprises a working electrode and a counter electrode; carrying out graphical treatment on the platinum layer obtained by sputtering to obtain a counter electrode; sputtering a platinum layer to form a nickel layer, and carrying out graphical treatment on the obtained nickel layer to prepare the working electrode of the enzyme-free glucose sensor;

(2) and sequentially carrying out thermal annealing treatment and acid solution wet corrosion treatment on the prepared enzyme-free glucose sensor to obtain the sensitive material of the two-electrode integrated enzyme-free glucose sensor.

2. The method according to claim 1, wherein the MEMS technology in step (1) is specifically as follows:

(a) preparing and cleaning: cleaning the silicon wafer before processing by using a standard cleaning process;

(b) thermal oxidation and low pressure chemical vapor deposition: firstly, double-sided dry oxygen oxidation is carried out on a silicon wafer to grow SiO with the thickness of 80-100nm₂A silicon nitride layer is grown by low-pressure chemical vapor deposition, the thickness is 160-200nm and is used as an insulating layer;

(c) electrode sputtering and patterning: firstly, sputtering a titanium layer of 15-20nm and a platinum layer of 80-100nm on a silicon nitride layer; secondly, carrying out graphical processing by adopting a single-sided photoetching and stripping method to form platinum layers required by sensitive materials of counter electrodes and working electrodes of the enzyme-free grape sensor; and sputtering a nickel layer with the thickness of 240-300nm on the platinum layer, and carrying out patterning treatment on the nickel layer by adopting a single-sided photoetching and stripping process to form the nickel layer required by the sensitive material of the working electrode.

3. The method of claim 2, wherein: in the step (a), a silicon wafer which is doped with antimony, oriented in an n-type <100> mode and has a middle resistance of 1-15 omega cm is used as a substrate.

4. The preparation method according to claim 1, wherein the step (2) thermal annealing treatment process is as follows: introducing argon into the tube furnace for 2h, uniformly heating to 400-600 ℃, treating for 1h, and naturally cooling to room temperature.

5. The method for preparing the catalyst according to claim 1, wherein the acid solution wet etching treatment comprises the following steps: and soaking the electrode subjected to annealing treatment in an acid solution.

6. The method of claim 5, wherein: the acid solution is 1M H₂SO₄+0.39M HNO₃The treatment temperature of the aqueous solution is 80 ℃, and the treatment time is 2-3 h.

7. The PtNi bimetallic-based two-electrode integrated enzyme-free glucose sensor prepared by the preparation method of any one of claims 1 to 6, which is characterized in that: the enzyme-free glucose sensor realizes the integration of a working electrode and a counter electrode on the same silicon chip, the sensitive material of the enzyme-free glucose sensor is a PtNi bimetallic material, and the sensitive material and the device of the enzyme-free glucose sensor are prepared by adopting an MEMS micromachining process.

8. The PtNi bimetallic-based two-electrode integrated enzyme-free glucose sensor of claim 7, wherein: the working electrode is composed of PtNi, and glucose can be oxidized on the surface of the electrode; the counter electrode was made of platinum.

9. The PtNi bimetallic-based two-electrode integrated enzyme-free glucose sensor of claim 7, wherein: after annealing treatment at 600 ℃ and acid solution wet etching treatment, the sensitivity of the sensor reaches 1618.15 mu A mM^-1cm^-2The detection limit is 8.76 mu M.

10. The PtNi bimetallic-based two-electrode integrated enzyme-free glucose sensor of claim 7, wherein: the sensor response time was 5.9 s.

Technical Field

The invention relates to the technical field of electrochemical sensors, in particular to a PtNi bimetal-based two-electrode integrated enzyme-free glucose sensor and a preparation method thereof.

Background

Real-time monitoring of blood glucose levels is critical to diabetics, accelerating the development of glucose sensing technology. In recent years, various glucose detection techniques have been reported, such as spectrophotometry, chromatography, and the like. Among them, a glucose sensor manufactured by an electrochemical method has received a wide attention, and the glucose sensor may be classified into an enzyme-based glucose sensor and an enzyme-free glucose sensor according to whether or not an enzyme is used. Enzyme-based glucose sensors are currently the most commonly used electrochemical glucose sensors due to their high sensitivity and selectivity. However, the enzyme-based glucose sensor still faces challenges in practical applications, for example, the enzyme-based glucose sensor needs to go through a complicated enzyme immobilization process, and is expensive, unstable in enzyme performance, and susceptible to environmental factors such as temperature, humidity, and pH. For these reasons, enzyme-free glucose sensors are increasingly attracting attention. Compared with an enzyme-based glucose sensor, the enzyme-free glucose sensor has the advantages of good stability, long service life, easiness in miniaturization and the like, and is very important for integration of the glucose sensor and other intelligent devices and systems, such as an intelligent toothbrush, an intelligent mobile phone and the like.

In recent years, many inorganic nanomaterials, such as metals, metal oxides, carbon nanocomposites, etc., have been used as sensitive materials for enzyme-free glucose sensors. The platinum-containing bimetallic sensitive materials such as Pt-Pd, Pt-Au and Pt-Ag have excellent conductivity and high electrocatalytic activity for glucose oxidation. However, the cost of noble metals is too high, which limits their application. Compared with the noble metals, the transition metal nickel is not only low in cost, but also has excellent catalytic performance on the oxidation of glucose in alkaline solution. However, nickel is easily oxidized and the conductivity of the oxide is low. For these reasons, PtNi bimetallic materials that combine the advantages of Pt and Ni have attracted considerable attention. Wang et al synthesized monodisperse PtNi nanoparticles with a large number of exposed atoms on the surface, and improved the electrocatalytic activity of the PtNi nanoparticles on glucose. Sun et al propose an enzyme-free glucose sensor based on a hollow Pt-Ni alloy nanotube array, which has good sensitivity, stability and repeatability. Li et al reported that PtNi alloy nanoparticles are uniformly dispersed in graphene, and used as a sensitive material of an enzyme-free glucose sensor to construct the enzyme-free glucose sensor with excellent performance. However, most enzyme-free glucose sensors based on PtNi bimetallic materials must have a carrier, and the carrier itself plays an important role in the performance of the enzyme-free glucose sensor.

Micro Electro Mechanical Systems (MEMS) technology can prepare sensitive materials under the condition of no carrier, and further prepare an integrated enzyme-free glucose sensor with small volume and low cost. With the rapid development of the MEMS technology, the MEMS has formed a series of standard and effective micro-processing technologies, and can process a plurality of complex structures, and has the characteristics of flexible design and high reliability. Meanwhile, the device manufactured by adopting the MEMS technology has good stability and repeatability, is easy to realize mass production and is beneficial to reducing the cost. By combining photolithography with the templating method, Wang et al prepared an enzymatic glucose sensor based on nanoporous carbon that was directly formed by MEMS technology. Dai et al also reported an enzymatic glucose sensor with excellent electrochemical performance and reliability, the electrodes of which were fabricated using MEMS technology. Therefore, the MEMS technology will greatly promote the development of the glucose sensor towards the direction of stability, miniaturization and low cost, and is beneficial to the commercial application of the glucose sensor. However, in the current research results, most of the sensors realized by the MEMS technology are enzyme glucose sensors, and the research on enzyme-free glucose sensors is rare, so how to realize a micro enzyme-free glucose sensor by the MEMS technology is a problem in the current research.

Disclosure of Invention

The invention provides a PtNi bimetal-based two-electrode integrated enzyme-free glucose sensor and a preparation method thereof.

The technical scheme for realizing the invention is as follows:

a preparation method of a PtNi bimetal-based two-electrode integrated enzyme-free glucose sensor comprises the following steps:

(1) preparing an enzyme-free glucose sensor electrode by using an MEMS (micro electro mechanical System) technology, wherein the enzyme-free glucose sensor electrode comprises a working electrode and a counter electrode; carrying out graphical treatment on the platinum layer obtained by sputtering to obtain a counter electrode; sputtering a platinum layer to form a nickel layer, and carrying out graphical treatment on the obtained nickel layer to prepare the working electrode of the enzyme-free glucose sensor;

(2) and sequentially carrying out thermal annealing treatment and acid solution wet corrosion treatment on the prepared enzyme-free glucose sensor electrode to obtain the sensitive material of the two-electrode integrated enzyme-free glucose sensor.

The MEMS technology in the step (1) is specifically as follows:

(a) preparing and cleaning: processing an enzyme-free glucose sensor by using an antimony-doped, n-type <100> oriented and medium-resistance (1-15 omega. cm) silicon wafer as a substrate, and cleaning the silicon wafer before processing by using a standard cleaning process;

(b) thermal oxidation and Low Pressure Chemical Vapor Deposition (LPCVD): firstly, double-sided dry oxygen oxidation is carried out on a silicon wafer to grow SiO with the thickness of 80-100nm₂A silicon nitride layer is grown by LPCVD with the thickness of 160-200nm and is used as an insulating layer;

(c) electrode sputtering and patterning: firstly, sputtering a titanium layer of 15-20nm and a platinum layer of 80-100nm on a silicon nitride layer; secondly, carrying out graphical processing by adopting a single-sided photoetching and stripping method to form platinum layers required by sensitive materials of counter electrodes and working electrodes of the enzyme-free grape sensor; and sputtering a nickel layer with the thickness of 240-300nm (the thickness ratio of the platinum nickel layer is 1: 3) on the platinum layer, and carrying out patterning treatment on the nickel layer by adopting a single-sided photoetching and stripping process to form the nickel layer required by the working electrode sensitive material.

The thermal annealing treatment process in the step (2) is as follows: introducing argon into the tube furnace for 2h, uniformly heating to 400-600 ℃, treating for 1h, and naturally cooling to room temperature.

The acid solution wet etching treatment comprises the following steps: and soaking the electrode subjected to annealing treatment in an acid solution.

The acid solution is 1M H₂SO₄+0.39M HNO₃The treatment temperature of the aqueous solution is 80 ℃, and the treatment time is 2-3 h.

The enzyme-free glucose sensor realizes the integration of a working electrode and a counter electrode on the same silicon chip, the sensitive material of the enzyme-free glucose sensor is a PtNi bimetallic material, and the sensitive material and the device of the enzyme-free glucose sensor are prepared by adopting an MEMS micromachining process.

The working electrode is composed of PtNi, glucose can be oxidized on the surface of the electrode, and the size of the working electrode is designed to be 10 x 10 mm²，5*5 mm² and 1*1 mm²The counter electrode was made of platinum and was designed to have a width of 400 μm.

After annealing treatment at 600 ℃ and acid solution wet etching treatment, the sensitivity of the sensor reaches 1618.15 mu A mM^-1cm^-2The detection limit is 8.76 mu M.

The sensor response time was 5.9 s.

The invention has the beneficial effects that: compared with the prior art, the MEMS micromachining process is utilized to realize the integration of the sensitive material and the electrode of the enzyme-free glucose sensor, so that the development of the enzyme-free glucose sensor towards the directions of stability, miniaturization and low cost is greatly promoted, and the commercial application of the enzyme-free glucose sensor is facilitated. The specific surface area of the PtNi bimetallic material prepared by the method is increased, the performance of a sensitive material can be greatly improved, the sensitivity of the sensitive material can be greatly improved, and the response time of the PtNi bimetallic-based two-electrode integrated enzyme-free glucose sensor prepared by the method is 5.9 seconds and has obvious selectivity.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a PtNi bimetallic-based two-electrode integrated enzyme-free glucose sensor.

FIG. 2 is a process flow diagram of a PtNi bimetallic-based two-electrode integrated enzyme-free glucose sensor.

Fig. 3 is a photograph of a device based on a PtNi bimetallic two-electrode integrated enzyme-free glucose sensor.

Fig. 4 SEM image of PtNi bimetallic sensing material.

Fig. 5 performance of a PtNi bimetallic based two-electrode integrated enzyme-free glucose sensor.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive effort based on the embodiments of the present invention, are within the scope of the present invention.

Example 1

The preparation method of the PtNi bimetal-based two-electrode integrated enzyme-free glucose sensor comprises the following steps:

1. preparation of enzyme-free glucose sensor electrode

The electrodes of the enzyme-free glucose sensor mainly comprise a counter electrode and a working electrode, as shown in fig. 1.

The working electrode is composed of PtNi, glucose can be oxidized on the electrode surface, and the size of the working electrode is designed to be 10 x 10 mm²，5*5 mm²And 1 x 1 mm². The counter electrode was made of platinum and the width was designed to be 400 μm. The electrodes of the enzyme-free glucose sensor were processed using MEMS technology, and the schematic is shown in fig. 2.

(a) Preparing and cleaning: processing the enzyme-free glucose sensor by using an antimony-doped, n-type <100> oriented and medium-resistance (1-15 omega. cm) silicon wafer as a substrate, and cleaning the silicon wafer before processing by using a standard cleaning process.

(b) Thermal oxidation and Low Pressure Chemical Vapor Deposition (LPCVD): firstly, double-sided dry oxygen oxidation is carried out on a silicon wafer to grow SiO with the thickness of 80-100nm₂A silicon nitride layer is grown by LPCVD with the thickness of 160-200nm and is used as an insulating layer;

(c) electrode sputtering and patterning: firstly, sputtering a titanium layer of 15-20nm and a platinum layer of 80-100nm on a silicon nitride layer; secondly, carrying out graphical processing by adopting a single-sided photoetching and stripping method to form platinum layers required by sensitive materials of counter electrodes and working electrodes of the enzyme-free grape sensor; and sputtering a nickel layer with the thickness of 240-300nm (the thickness ratio of the platinum nickel layer is 1: 3) on the platinum layer, and carrying out patterning treatment on the nickel layer by adopting a single-sided photoetching and stripping process to form the nickel layer required by the working electrode sensitive material. A photograph of the prepared two-electrode integrated enzyme-free glucose sensor is shown in fig. 3.

(d) Preparing sensitive material PtNi bimetal: the process is as described in 2.

2. Preparation of sensitive material PtNi bimetal

The preparation of the sensitive material PtNi bimetal is divided into two processes: (a) thermal annealing treatment, and (b) acid solution wet etching treatment.

(a) Thermal annealing treatment: the prepared enzyme-free glucose sensor unit was annealed at different annealing temperatures selected from 400 ℃, 500 ℃ and 600 ℃ for 1 hour. The annealing is carried out in a tube furnace under the protection of argon, and the specific operation is as follows: firstly, introducing argon into a tube furnace for 2 hours, and removing air in the tube furnace; secondly, uniformly heating the tube furnace to the annealing temperature according to the speed of 5 ℃/min, and treating for 1 hour at the annealing temperature; and finally, naturally cooling the tube furnace to room temperature, and taking out the slices.

(b) Acid solution wet etching treatment: after the sheet is thermally annealed, the corresponding PtNi bimetallic material is formed, and in order to remove the redundant nickel in the PtNi bimetallic material, the annealed sheet is subjected to the step 1M H₂SO₄+0.39M HNO₃The aqueous solution is soaked for 2 to 3 hours at the temperature of 80 ℃.

The SEM image of the PtNi bimetal material formed after annealing and wet processing is shown in fig. 4. In fig. 4a, 4b and 4c, the PtNi bimetallic material is formed after annealing at 400 ℃, 500 ℃ and 600 ℃ and wet etching, respectively, and it can be seen from the figure that the specific surface area of the PtNi bimetallic material is increased after annealing and wet processing, which is also a factor for improving the performance of the sensitive material.

3. Performance characterization of enzyme-free glucose sensors

(a) The current response characteristics of the enzyme-free glucose sensor were tested using methods recognized in the art and the results are shown in FIG. 5 a; a linear fit curve of current density and glucose concentration is shown in fig. 5 b.

As can be seen, the highest sensitivity was obtained for the enzyme-free glucose sensor after annealing and wet processing at 600 degrees Celsius, which was 1618.15 μ A mM^-1cm^-2The sensitivity of the enzyme-free glucose sensor without annealing treatment and after annealing at 400 deg.C, 500 deg.C and wet treatment was 682.37 μ AmM^-1cm^-2、1200.41 μAmM^-1cm^-2And 1016.76 μ AmM^-1cm^-2Compared with the prior art, the method is obviously improved. From the current response characteristics, it was also calculated that the detection limits (signal-to-noise ratio of 3) of the non-enzymatic glucose sensor after annealing at 400 degrees Celsius, 500 degrees Celsius, and 600 degrees Celsius and after wet processing without annealing treatment were 42.09. mu.M, 17.63. mu.M, 30.33. mu.M, and 8.76. mu.M, respectively.

(b) The response time and selectivity of the enzyme-free glucose sensor was tested using art-recognized methods and the results are shown in FIGS. 5c and 5 d; from the results, the response time of the PtNi bimetallic-based two-electrode integrated enzyme-free glucose sensor prepared by the method is 5.9 seconds, and the selectivity is obvious.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.