CN111257396A - A miniature electrochemical system and detection method based on near field communication technology - Google Patents

Abstract

The invention discloses a miniature electrochemical system and a detection method based on NFC technology. The system includes a first substrate, an NFC antenna processed on the first substrate and connected in sequence, an NFC chip and its peripheral circuit, a single-chip microcomputer chip and its peripheral circuit, an electrochemical potentiostat circuit, an electrode connection pad, and a heavy metal detection electrode array. . The invention integrates a miniature electrochemical system on the wireless passive flexible NFC tag, and realizes the miniaturization, flexibility and integration of the electrochemical detection device. It has a wide range of application prospects in the fields of food safety and environmental monitoring. The method of the invention can be used for quantitative detection of trace amounts of heavy metal ions such as lead and cadmium.

Description

A miniature electrochemical system and detection method based on near field communication technology

technical field

Embodiments of the present invention relate to an electrochemical detection technology, and in particular, to a miniature electrochemical system and a detection method based on a near field communication (NFC) technology.

Background technique

Heavy metals such as lead, cadmium, mercury, and copper can pose a very serious threat to life and health, such as cancer, cardiovascular disease, brain damage, and kidney disease. Some of our commonly used containers, such as ceramic, enamel, or glazed glass containers, will slowly migrate heavy metals such as lead and cadmium into the food during the long-term storage of food or beverages, which indirectly harms our health. Therefore, it is particularly urgent to build a miniaturized, label-type heavy metal detection system that can be placed in a container to monitor the content of heavy metals in food or beverages.

At present, in the field of research, the technical means of heavy metal detection have been very mature. Traditional detection methods mainly use large-scale instruments to analyze heavy metals in target samples, such as X-ray fluorescence spectroscopy, atomic absorption spectroscopy (AAS), inductively coupled plasma mass spectrometry (ICP-MS), etc., but these large-scale instruments are expensive and time-consuming to detect. It is labor-intensive, requires professional operation and complex pre-processing, and is not suitable for our detection anytime and anywhere in our daily life.

SUMMARY OF THE INVENTION

In view of this, the embodiments of the present invention provide a miniature electrochemical system and a detection method based on near field communication (NFC) technology, which solves the problem that the detection system in the related art is not integrated enough, miniaturized enough, flexible enough, and expensive instruments , detection of time-consuming and labor-intensive problems.

The purpose of the embodiment of the present invention is achieved through the following technical solutions:

An embodiment of the present invention provides a miniature electrochemical system based on near-field communication technology, which is characterized in that it includes a first substrate, an NFC antenna processed on the first substrate and connected in sequence, an NFC chip and its peripheral circuits, a single-chip microcomputer chip, and an NFC antenna. Its peripheral circuit, electrochemical potentiostat circuit, electrode connection pad, heavy metal detection electrode array.

Further, the mobile terminal with NFC function wirelessly supplies power to the NFC chip and its peripheral circuits, the single-chip microcomputer chip and its peripheral circuits, and the electrochemical potentiostat circuit through electromagnetic induction with the NFC antenna; Under the control of the single chip microcomputer and its peripheral circuits, the corresponding potential excitation is applied to the heavy metal detection electrode array through the electrode connection pads. The heavy metal ions in the solution are first reduced and deposited on the electrode array, and then oxidized, and the generated response current is connected through the electrodes. The pad is transmitted to the electrochemical potentiostat circuit, and after signal processing, it is transmitted to the single-chip microcomputer chip and its peripheral circuits for analog-to-digital conversion, and the converted data is transmitted to the NFC chip and its peripheral circuits; the mobile terminal with NFC function The electromagnetic induction between the antennas can obtain the concentration information of heavy metal ion detection in real time.

Further, the heavy metal detection electrode array includes a second substrate, a working electrode, a common reference electrode, and a common counter electrode processed on the second substrate.

Further, the working electrodes include lead ion working electrodes and cadmium ion working electrodes.

Further, the carbon substrate of the lead ion working electrode is decorated with a layer of gold nanoparticles and covered with a layer of Nafion film.

Further, the carbon substrate of the cadmium ion working electrode is decorated with a layer of bismuth nanoparticles and covered with a layer of Nafion film.

Further, the material of the common reference electrode is a silver-silver chloride substrate.

Further, the material of the common counter electrode is a carbon substrate.

Further, the preparation method of the gold nanoparticle layer is as follows:

Dissolve 0.1wt% chloroauric acid in 0.5M sodium sulfate solution, add an appropriate amount of mixture dropwise to the carbon substrate of the lead ion working electrode, and scan 5 times by cyclic voltammetry, with a scanning voltage of -1.4V-1V , the scanning rate is 0.1V/s, and the gold nanoparticle layer is obtained after scanning.

Further, the preparation method of the bismuth nanoparticle layer is as follows:

Dissolve Bi(NO ₃ ) ₃ in 1M HCl solution, add an appropriate amount of the mixture dropwise to the carbon substrate of the cadmium ion working electrode, and use the potentiostatic method to scan for 120 s with a scan voltage of -0.5V. particle layer.

Another object of the present invention is to provide a method for detecting target heavy metal ions based on a micro-electrochemical system based on near-field communication technology, comprising the following steps:

(1) Use the electronic patch to detect standard sample solutions of heavy metal ions with different concentrations

The mobile terminal with NFC function is close to the NFC antenna, and the NFC chip and its peripheral circuit, the single-chip chip and its peripheral circuit, and the electrochemical potentiostat circuit are wirelessly powered; The target heavy metal ion standard sample solution; the electrochemical potentiostat circuit, under the control of the single chip microcomputer and its peripheral circuit, applies the potential excitation of anodic stripping square wave pulse voltammetry (SWASV) to the heavy metal detection electrode array through the electrode connection pad, and the solution The heavy metal ions in the working electrode are first reduced and deposited on the working electrode, and then oxidized. The generated response current is transmitted to the electrochemical potentiostat circuit through the electrode connection pad. After signal processing, it is transmitted to the single-chip microcomputer chip and its peripheral circuits for analog and digital After conversion, the converted data is transmitted to the NFC chip and its peripheral circuits; the mobile terminal with NFC function continuously receives the current signal measured by the micro electrochemical system through electromagnetic induction with the NFC antenna, and calculates the current signal at each concentration. Peak current, after measuring each concentration, it is necessary to apply constant potential to the working electrode for electrode cleaning, rinse the surface of the heavy metal detection electrode array and dry;

(2) Establish a standard curve between the concentration of the heavy metal ion standard sample solution and the peak current of the square wave pulse voltammetry curve:

For each heavy metal ion, use at least three heavy metal detection electrode arrays respectively, repeat the measurement process in step (1), obtain the peak current of each heavy metal detection electrode array under different heavy metal ion concentrations, and then obtain each heavy metal ion The relationship curve between the concentration of the standard sample solution and the peak current, the relationship curve is used to calculate the target heavy metal concentration in the real sample through the measured peak current value of the square wave pulse voltammetry curve;

(3) Detection of target heavy metal ion concentration in real samples:

The heavy metal detection electrode array to be tested is connected to the electrochemical potentiostat circuit through the electrode connection pad; The chemical potentiostat circuit is powered wirelessly; the real sample solution to be tested is dripped on the surface of the heavy metal detection electrode array, and the electrochemical potentiostat circuit is controlled by the single chip microcomputer and its peripheral circuits, and applies anodes to the heavy metal detection electrode array through the electrode connection pads The potential excitation of stripping square wave pulse voltammetry (SWASV), the target heavy metal ions in the solution are first reduced and deposited on the working electrode, and then oxidized, and the generated response current is transmitted to the electrochemical potentiostat circuit through the electrode connection pad , after signal processing, it is sent to the single-chip microcomputer chip and its peripheral circuits for analog-to-digital conversion, and the converted data is transmitted to the NFC chip and its peripheral circuits; the mobile terminal with NFC function continues to receive microelectronics through electromagnetic induction with the NFC antenna. The current signal measured by the electrochemical system, and the peak current is calculated. Using the relationship curve between the concentration of the heavy metal ion standard sample solution and the peak current in step (2), the concentration of the target heavy metal ion is calculated and displayed; after each heavy metal ion is measured, a constant potential needs to be applied to the corresponding working electrode for cleaning.

Compared with the existing electrochemical heavy metal ion detection system, the present invention has the following beneficial effects: the embodiment of the present invention can realize a complete heavy metal detection function by using a mobile terminal with NFC function, and does not need to rely on any external instrument. The system is constructed based on the near field communication NFC technology. It does not need battery power, nor does it need to transmit data with a mobile terminal through a wired connection, but realize wireless data transmission and wireless power supply through an NFC antenna. This design greatly improves the miniaturization, integration and flexibility of the system. Based on this design, we integrated a potentiostat system for electrochemical sensing analysis on an ultra-thin flexible NFC tag for quantitative detection of trace heavy metal ions. After the system is well packaged, it can be attached to the inner wall of various containers, such as mineral water barrels, wine jars, and vegetable jars, to achieve long-term heavy metal ion detection. The system can be widely used in food safety, water pollution monitoring and other fields in the future, and has broad application prospects.

Description of drawings

The accompanying drawings described herein are used to provide further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the attached image:

1 is an overall structural block diagram of a micro-electrochemical system based on near field communication (NFC) technology in an embodiment of the present invention;

2 is an external view of an electrode array used for heavy metal ion detection in an embodiment of the present invention;

3 is a detailed view of an electrode array layered for heavy metal ion detection in an embodiment of the present invention;

4 is a block diagram of the overall workflow of the system in the embodiment of the present invention;

5 is a schematic diagram of the potential excitation of the anode stripping square wave pulse voltammetry (SWASV) in the embodiment of the present invention;

Fig. 6 is the detection mechanism diagram of the target heavy metal on the electrode surface in the embodiment of the present invention;

7 is an APP interface diagram of a mobile terminal in an embodiment of the present invention;

Fig. 8 is the system test result in the embodiment of the present invention and the electrochemical workstation test result comparison diagram;

Fig. 9 is the square wave pulse voltammetry diagram of the lead ions of different concentrations that the embodiment of the present invention tests obtains;

Fig. 10 is the lead ion concentration-peak current standard curve that the embodiment of the present invention test obtains;

Fig. 11 is the square wave pulse voltammetry curves of different concentrations of cadmium ions obtained by testing in the embodiment of the present invention;

Fig. 12 is the cadmium ion concentration-peak current standard curve obtained by testing in the embodiment of the present invention;

FIG. 13 is a diagram of a practical application scenario of the micro-electrochemical system in the embodiment of the present invention.

In the figure: the first substrate 1, the NFC antenna 2, the NFC chip and its peripheral circuit 3, the single-chip microcomputer chip and its peripheral circuit 4, the electrochemical potentiostat circuit 5, the electrode connection pad 6, the heavy metal detection electrode array 7, the second Substrate 71, lead ion working electrode 72, cadmium ion working electrode 73, common reference electrode 74, common counter electrode 75, carbon substrate 721 on lead ion working electrode, gold nanoparticles 722, Nafion film 723 on lead ion working electrode , a carbon base 731 on the cadmium ion working electrode, bismuth nanoparticles 732, a Nafion film 733 on the cadmium ion working electrode, a silver-silver chloride substrate 741 on the common reference electrode, and a carbon substrate 751 on the common counter electrode.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the specific embodiments of the embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments in the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative work fall within the protection scope of the embodiments of the present invention.

As shown in FIG. 1, the present invention provides a miniature electrochemical system based on near field communication technology, which includes a first substrate 1, an NFC antenna 2 processed on the first substrate 1 and connected in sequence, an NFC chip and its peripheral circuits 3. SCM chip and its peripheral circuit 4, electrochemical potentiostat circuit 5, electrode connection pad 6, heavy metal detection electrode array 7.

The mobile terminal with NFC function wirelessly supplies power to the NFC chip and its peripheral circuit 3, the single-chip chip and its peripheral circuit 4, and the electrochemical potentiostat circuit 5 through electromagnetic induction with the NFC antenna 2; the electrochemical potentiostat circuit 5 Under the control of the single chip microcomputer and its peripheral circuit 4, the corresponding potential excitation is applied to the heavy metal detection electrode array 7 through the electrode connection pad 6, and the heavy metal ions in the solution are first reduced and deposited on the electrode array 7, and then oxidized to produce The response current is transmitted to the electrochemical potentiostat circuit 5 through the electrode connection pad 6, and after signal processing, it is transmitted to the single-chip microcomputer chip and its peripheral circuit 4 for analog-to-digital conversion, and the converted data is transmitted to the NFC chip and its peripheral circuit 3. ; The mobile terminal with NFC function obtains the concentration information of heavy metal ion detection in real time through electromagnetic induction with the NFC antenna 2 .

In a possible implementation, as shown in FIG. 2 , the heavy metal detection electrode array 7 includes a second substrate 71 , a working electrode, a common reference electrode 74 , and a common counter electrode 75 processed on the second substrate 71 .

In a possible implementation manner, the working electrodes include lead ion working electrodes 72 and cadmium ion working electrodes 73 and the like.

The two working electrodes, the common reference electrode, and the common counter electrode are all modified with multiple layers, as shown in FIG. 3 .

In a possible implementation manner, the carbon substrate 721 of the lead ion working electrode 72 is decorated with a layer of gold nanoparticles 722 and covered with a layer of Nafion film 723 .

Further, the manufacturing method of the gold nanoparticle layer 722 is as follows:

Dissolve 0.1wt% chloroauric acid in 0.5M sodium sulfate solution, add an appropriate amount of mixture dropwise to the carbon substrate of the lead ion working electrode, and scan 5 times by cyclic voltammetry, with a scanning voltage of -1.4V-1V , the scanning rate is 0.1V/s, and the gold nanoparticle layer is obtained after scanning.

In a possible implementation manner, the carbon substrate 731 of the cadmium ion working electrode 73 is decorated with a layer of bismuth nanoparticles 732 and covered with a layer of Nafion film 733 .

Further, the manufacturing method of the bismuth nanoparticle layer 732 is as follows:

Dissolve Bi(NO ₃ ) ₃ in 1M HCl solution, add an appropriate amount of the mixture dropwise to the carbon substrate of the cadmium ion working electrode, and use the potentiostatic method to scan for 120 s with a scan voltage of -0.5V. particle layer.

In a possible implementation manner, the material of the common reference electrode 74 is a silver-silver chloride substrate 741 .

In a possible implementation manner, the material of the common counter electrode 75 is a carbon substrate 751 .

Another object of the present invention is to provide a method for heavy metal detection using the above-mentioned micro-electrochemical system based on Near Field Communication (NFC) technology, comprising the following steps:

(1) Use the electronic patch to detect standard sample solutions of heavy metal ions with different concentrations

Figure 4 shows a block diagram of the workflow of the miniature electrochemical system. The mobile terminal with NFC function is close to the NFC antenna 2, and the NFC chip and its peripheral circuit 3, the single-chip chip and its peripheral circuit 4, and the electrochemical potentiostat circuit 5 are wirelessly powered; on the surface of the heavy metal detection electrode array 7, dropwise and prepare Good standard sample solutions of target heavy metal ions with different concentrations; electrochemical potentiostat circuit 5, under the control of single chip microcomputer and its peripheral circuit 4, applies anode stripping square wave pulse voltammetry to heavy metal detection electrode array 7 through electrode connection pad 6 The potential excitation of the method (SWASV), the heavy metal ions in the solution are first reduced and deposited on the working electrode, and then oxidized, and the generated response current is transmitted to the electrochemical potentiostat circuit 5 through the electrode connection pad 6, and after signal processing. It is transmitted to the single-chip microcomputer chip and its peripheral circuit 4 for analog-to-digital conversion, and the converted data is transmitted to the NFC chip and its peripheral circuit 3; the mobile terminal with NFC function continues to receive micro-electrochemical signals through electromagnetic induction with the NFC antenna 2. The current signal measured by the system, and the peak current at each concentration is calculated. After each concentration is measured, a constant potential needs to be applied to the working electrode for electrode cleaning, and the surface of the heavy metal detection electrode array 7 is washed and dried;

(2) Establish a standard curve between the concentration of the heavy metal ion standard sample solution and the peak current of the square wave pulse voltammetry curve:

For each heavy metal ion, use at least three heavy metal detection electrode arrays 7 respectively, repeat the measurement process in step (1), obtain the peak current of each heavy metal detection electrode array 7 under different heavy metal ion concentrations, and then obtain each The relationship curve between the concentration of the heavy metal ion standard sample solution and the peak current, the relationship curve is used to calculate the target heavy metal concentration in the real sample through the measured peak current value of the square wave pulse voltammetry curve;

(3) Detection of target heavy metal ion concentration in real samples:

The heavy metal detection electrode array 7 to be tested is connected with the electrochemical potentiostat circuit 5 through the electrode connection pad 6; Its peripheral circuit 4 and electrochemical potentiostat circuit 5 are wirelessly powered; the real sample solution to be tested is dropped on the surface of the heavy metal detection electrode array 7, and the electrochemical potentiostat circuit 5 is controlled by the single-chip microcomputer and its peripheral circuit 4. The connection pad 6 applies the potential excitation of anodic stripping square wave pulse voltammetry (SWASV) to the heavy metal detection electrode array 7, and the target heavy metal ions in the solution are first reduced and deposited on the working electrode, and then oxidized, and the generated response current passes through The electrode connection pad 6 is transmitted to the electrochemical potentiostat circuit 5, and after signal processing, it is transmitted to the single-chip microcomputer chip and its peripheral circuit 4 for analog-to-digital conversion, and the converted data is transmitted to the NFC chip and its peripheral circuit 3; with NFC function The mobile terminal continuously receives the current signal measured by the micro electrochemical system through electromagnetic induction with the NFC antenna 2, and calculates the peak current. Using the relationship curve between the concentration of the heavy metal ion standard sample solution and the peak current in step (2), the concentration of the target heavy metal ion is calculated and displayed; after each heavy metal ion is measured, a constant potential needs to be applied to the corresponding working electrode for cleaning.

The electrochemical heavy metal ion detection system of the present invention includes modules such as sensing electrodes, electrochemical sensing circuits, data transmission, energy collection, etc. The complete heavy metal detection function can be realized by using a mobile terminal with NFC function, and does not need to rely on any external instruments. The system is constructed based on the near field communication NFC technology. It does not need battery power, nor does it need to transmit data with a mobile terminal through a wired connection, but realize wireless data transmission and wireless power supply through an NFC antenna. This design greatly improves the miniaturization, integration and flexibility of the system. Based on this design, we integrated a potentiostat system for electrochemical sensing analysis on an ultra-thin flexible NFC tag, which can realize several classical electrochemical sensing methods in electrochemical sensing, such as anodic dissolution method. Wave pulse voltammetry can be used for quantitative detection of trace amounts of heavy metal ions such as lead and cadmium. After the system is well packaged, it can be attached to the inner wall of various containers, such as mineral water barrels, wine jars, and vegetable jars, to achieve long-term heavy metal ion detection. The system can be widely used in food safety, water pollution monitoring and other fields in the future, and has broad application prospects.

The present invention will be described in further detail below by means of examples.

Example:

1. Design of miniature electrochemical system based on near field communication (NFC) technology:

As shown in Figure 1, the substrate of the flexible circuit board adopts flexible polyimide (PI) as the first substrate 1, the resonance frequency of the NFC antenna is 13.56MHz, the NFC chip adopts NT3H2111 of NXP, and the experiment has NFC The functional mobile terminal is Samsung Galaxy S5. The wireless power supply and two-way data transmission of the system are realized through electromagnetic induction between the smartphone and the NFC antenna. The single chip and its peripheral circuit 4 adopt MSP430FR2632 of Texas Instruments and 16-bit AD conversion chip ADS1115 of Texas Instruments. Electrochemical potentiostat circuit 5 uses 4 operational amplifiers AD8605, a sixteen-bit DA converter DAC8562, and a multiplexing chip SN74LVC1G3157 for selecting different working electrodes.

The workflow diagram of the whole micro-electrochemical system is shown in Figure 4. The energy transmission starts from the NFC module of the smartphone, and is transmitted to the NFC antenna 2 of the detection device through the mutual inductance of the antenna. The NFC chip and its peripheral circuit 3 connected to the NFC antenna obtain energy from the NFC antenna 2, and pass the energy through the internal power management. The circuit continues to transmit to the back-end circuit (about 2.72V), and the back-end single-chip microcomputer and its peripheral circuit 4 work under the energy provided by the NFC chip and its peripheral circuit 3 . Under the control of the smart phone, the single-chip microcomputer and its peripheral circuit 4, the electrochemical potentiostat circuit 5 applies the potential excitation of the anodic stripping square wave pulse voltammetry to the heavy metal detection electrode array 7 (as shown in FIG. 5). The heavy metal ions are first reduced and deposited on the surface of the corresponding working electrode, and then oxidized and dissolved (as shown in Figure 6). The generated current signal is captured by the electrochemical potentiostat circuit 5, and the current signal is converted into The voltage signal is then converted into a digital signal and transmitted to the internal storage space of the NFC chip. The smartphone application software reads the internal storage data of the NFC chip by calling the application programming interface (Abbreviation for Application Programming Interface, hereinafter referred to as API) related to the internal NFC driver. And display the results in the mobile phone interface (Figure 7).

The micro-electrochemical system was compared with the standard electrochemical workstation. The electrode used in the comparison was a standard electrochemical three-electrode system, and the target solution was the redox of 20mM potassium ferricyanide/potassium ferrocyanide containing 0.1MKCl solution. right. Three groups of different parameters were selected for comparison: step, 4mV or 10mV; pulse, 40mV or 80mV; frequency, 40Hz; voltage range: -0.4to 0.8V relative to the standard Ag/AgCl reference electrode. As can be seen from Figure 8, in the three cases, the errors of the two are 0.48%, 0.39%, and 2.33%, respectively, achieving high consistency.

2. Design and construction and modification of electrode arrays:

As shown in FIG. 2 , the heavy metal detection electrode array 7 adopts flexible polyethylene terephthalate (PET) as the second substrate 71 , on which four electrodes are printed, including a lead ion working electrode 72 and a cadmium ion working electrode 73. Common reference electrode 74, common counter electrode 75, etc. The four electrodes all adopt a layered design (as shown in Figure 3). Among them, the lead ion working electrode 72 and the cadmium ion working electrode 73 are ellipses with a size of 4 mm × 2.5 mm, and the substrates are all printed with carbon ink; The substrate of the counter electrode 75 is also printed with carbon ink; and the conductive part of the electrode array and the substrate of the common reference electrode 74 are printed with silver-silver chloride ink, and the electrode array with the printed ink needs to be in an environment of 80 ° C. Dry for 15 minutes and store at room temperature for later use.

The preparation method of the gold nanoparticle layer 722 on the lead ion working electrode 72 is as follows: Dissolve 0.1 wt % chloroauric acid in a 0.5 M sodium sulfate solution, take an appropriate amount of the mixture and drop it on the carbon substrate of the lead ion working electrode , using cyclic voltammetry to scan 5 times, the scanning voltage is -1.4V-1V, and the scanning rate is 0.1V/s.

The preparation method of the bismuth nanoparticle layer 732 on the cadmium ion working electrode 73 is as follows: Dissolve Bi(NO ₃ ) ₃ in a 1M HCl solution, take an appropriate amount of the mixture and drop it on the carbon substrate of the cadmium ion working electrode, and use a constant The potential method was scanned for 120 s, and the scanning voltage was -0.5V. After the scanning, the bismuth nanoparticle layer was obtained.

Both the gold nanoparticle layer 722 and the bismuth nanoparticle layer 732 are covered with a layer of Nafion film. The manufacturing method is as follows: take 3 μl of 5wt% Nafion solution and apply it to two working electrodes respectively to cover the nanoparticle layer.

3. Electrode sensitivity and linearity test:

In all experiments, the target heavy metal ions were dissolved in 0.01 M acetate buffer solution at pH 4.6 containing 50 mM NaCl. In the lead ion test, the gradient distribution of lead ions is 0ppb, 50ppb, 100ppb, 150ppb, 200ppb, 250ppb, and 300ppb, the working electrode is the lead ion working electrode 72 modified with gold nanoparticles, and the test method is anodic dissolution method. Wave Pulse Voltammetry (SWASV), consisting of three stages. In the first stage, lead ions were deposited for 120s at a voltage of -0.7V; in the second stage, electrochemical scanning of square wave stripping voltammetry was performed at a voltage range of -0.7V to 0.1V, with a scanning step of 4mV and an amplitude of 4mV. (pulse) was 40mV, and the frequency was 40Hz; in the third stage, the electrode cleaning process was performed at a voltage of 0.1V for 120s. In the test of cadmium ions, the gradient distribution of cadmium ions is 0ppb, 100ppb, 150ppb, 200ppb, 250ppb, and 300ppb, the working electrode is the cadmium ion working electrode 73 modified by bismuth nanoparticles, and the test method is anodic stripping square wave pulse Voltammetry (SWASV), including three stages. In the first stage, cadmium ions were deposited for 120 s at a voltage of -1.5V; in the second stage, electrochemical scanning of square wave stripping voltammetry was performed at a voltage range of -1.2V to -0.5V, with a scanning step of 4mV and an amplitude of 4mV. The value (pulse) was 40 mV, and the frequency was 40 Hz; in the third stage, the electrode cleaning process was performed for 180 s at a voltage of -0.5 V.

Figure 9 shows the square wave pulse voltammogram of the lead ion test with different concentrations using the micro electrochemical system. It can be seen that the peak current of lead ions mostly appears at about -0.22V. Figure 10 shows the lead ion concentration-peak current standard curve. It can be seen from the figure that the sensitivity of lead ion detection is 0.1531 μA/ppb, and the R ² is 0.997, showing good linearity. Figure 10 shows the square-wave pulse voltammogram of using the micro electrochemical system to test different concentrations of cadmium ions. It can be seen that the peak of cadmium ions appears at about -0.96V. Figure 12 shows the cadmium ion concentration-peak current standard curve. It can be seen from the figure that the sensitivity of cadmium ion detection is 0.18338 μA/ppb, and the R ² is 0.976, which also shows good detection linearity.

4. Actual application scenario test.

FIG. 13 shows the actual application scene diagram of the micro electrochemical system in the present invention. In practical applications, this miniaturized, integrated and flexible label system can be attached to the inner walls of various containers, such as wine jars, vegetable jars, etc., for a long time after proper packaging. When we need to know the content of heavy metals in the food or drink in the container, we only need to open the APP of the smartphone, power the system wirelessly through the shell of the container, and detect whether the lead and cadmium ions in the container exceed the standard. Since the label does not require batteries, there is no need to consider the safety issues of battery replacement or battery leakage. This kind of label will have broad application prospects in the fields of food safety and environmental pollution.

It should be noted that the heavy metal ions in the present invention are not limited to the cadmium ions and lead ions in the above embodiments, but also various other heavy metal ions such as copper, mercury, and zinc. Through the above examples, those skilled in the art can undoubtedly determine how other heavy metal ions, such as copper, mercury, zinc, etc., are detected. For the preparation of other heavy metal ion working electrodes, reference may also be made to the preparation methods of cadmium ion and lead ion working electrodes in this specification.

The above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications can be made. It should be regarded as the protection scope of the present invention.

Claims (9)

1. A miniature electrochemical system based on near-field communication technology, characterized in that it comprises a first substrate (1) and an NFC antenna (2), an NFC chip and the NFC antenna (2) that are processed on the first substrate (1) and are connected in turn. A peripheral circuit (3), a single-chip microcomputer chip and its peripheral circuit (4), an electrochemical potentiostat circuit (5), an electrode connection pad (6), and a heavy metal detection electrode array (7). 2. A kind of miniature electrochemical system based on near field communication technology according to claim 1, it is characterized in that, the mobile terminal with NFC function passes the electromagnetic induction between the NFC antenna (2), to the NFC chip and the NFC antenna (2). The peripheral circuit (3), the single-chip microcomputer chip and its peripheral circuit (4), and the electrochemical potentiostat circuit (5) are wirelessly powered; the electrochemical potentiostat circuit (5) is controlled by the single-chip microcomputer and its peripheral circuit (4), The corresponding potential excitation is applied to the heavy metal detection electrode array (7) through the electrode connection pad (6), the heavy metal ions in the solution are first reduced and deposited on the electrode array (7), and then oxidized, and the generated response current is connected through the electrode The pad (6) is transmitted to the electrochemical potentiostat circuit (5), and after signal processing, it is transmitted to the single-chip microcomputer chip and its peripheral circuit (4) for analog-to-digital conversion, and the converted data is transmitted to the NFC chip and its peripheral circuit ( 3); the mobile terminal with NFC function acquires the concentration information of heavy metal ion detection in real time through electromagnetic induction with the NFC antenna (2). 3. A micro-electrochemical system based on near field communication technology according to claim 1, wherein the heavy metal detection electrode array (7) comprises a second substrate (71) and a second substrate (71) processed on the second substrate (71). ) on the working electrode, the common reference electrode (74), and the common counter electrode (75). 4. A micro-electrochemical system based on near field communication technology according to claim 3, wherein the working electrodes comprise lead ion working electrodes (72) and cadmium ion working electrodes (73). 5 . The micro-electrochemical system based on near-field communication technology according to claim 4 , wherein the carbon substrate ( 721 ) of the lead ion working electrode ( 72 ) is decorated with a layer of gold nanoparticles ( 722 ). 6 . ), covered with a layer of Nafion film (723). 6 . The micro-electrochemical system based on near-field communication technology according to claim 4 , wherein the carbon substrate ( 731 ) of the cadmium ion working electrode ( 73 ) is decorated with a layer of bismuth nanoparticles ( 732 ). 7 . ), covered with a layer of Nafion film (733). 7 . The micro-electrochemical system based on near field communication technology according to claim 4 , wherein the material of the common reference electrode ( 74 ) is a silver-silver chloride substrate ( 741 ). 8 . 8 . The micro-electrochemical system based on near field communication technology according to claim 4 , wherein the material of the common counter electrode ( 75 ) is a carbon substrate ( 751 ). 9 . 9. The method for detecting target heavy metal ions based on a micro-electrochemical system based on near-field communication technology according to any one of claims 1-8, wherein the method comprises the following steps: (1) Use the electronic patch to detect standard sample solutions of heavy metal ions with different concentrations The mobile terminal with the NFC function is brought close to the NFC antenna (2), and the NFC chip and its peripheral circuit (3), the single-chip microcomputer chip and its peripheral circuit (4), and the electrochemical potentiostat circuit (5) are wirelessly powered; The prepared standard sample solutions of target heavy metal ions with different concentrations are sequentially dropped on the surface of the electrode array (7); 6) Apply the potential excitation of anodic stripping square wave pulse voltammetry (SWASV) to the heavy metal detection electrode array (7), the heavy metal ions in the solution are first reduced and deposited on the working electrode, and then oxidized, and the generated response current passes through the electrode The connection pad (6) is transmitted to the electrochemical potentiostat circuit (5), and after signal processing, it is transmitted to the single-chip microcomputer chip and its peripheral circuit (4) for analog-to-digital conversion, and the converted data is transmitted to the NFC chip and its peripheral circuit. (3); The mobile terminal with NFC function continuously receives the current signal measured by the micro electrochemical system through electromagnetic induction with the NFC antenna (2), and calculates the peak current at each concentration, and after measuring each concentration It is necessary to apply a constant potential to the working electrode for electrode cleaning, rinse the surface of the heavy metal detection electrode array (7) and dry it; (2) Establish a standard curve between the concentration of the heavy metal ion standard sample solution and the peak current of the square wave pulse voltammetry curve: For each heavy metal ion, at least three heavy metal detection electrode arrays (7) are respectively replaced, and the measurement process in step (1) is repeated to obtain the peak current of each heavy metal detection electrode array (7) under different heavy metal ion concentrations , and then obtain the relationship curve between the concentration of each heavy metal ion standard sample solution and the peak current, and the relationship curve is used to calculate the target heavy metal concentration in the real sample through the measured peak current value of the square wave pulse voltammetry curve; (3) Detection of target heavy metal ion concentration in real samples: The heavy metal detection electrode array (7) to be tested is connected to the electrochemical potentiostat circuit (5) through the electrode connection pad (6); the mobile terminal with NFC function is brought close to the NFC antenna (2), and the NFC chip and the The peripheral circuit (3), the single-chip microcomputer chip and its peripheral circuit (4), the electrochemical potentiostat circuit (5) are wirelessly powered; the real sample solution to be tested is dropped on the surface of the heavy metal detection electrode array (7), and the electrochemical potentiostatic The instrument circuit (5), under the control of the single chip microcomputer and its peripheral circuit (4), applies the potential excitation of anodic stripping square wave pulse voltammetry (SWASV) to the heavy metal detection electrode array (7) through the electrode connecting pad (6), The target heavy metal ions in the solution are first reduced and deposited on the working electrode, and then oxidized. The generated response current is transmitted to the electrochemical potentiostat circuit (5) through the electrode connection pad (6), and is transmitted to the single-chip microcomputer after signal processing. The chip and its peripheral circuit (4) perform analog-to-digital conversion, and the converted data is transmitted to the NFC chip and its peripheral circuit (3). The current signal measured by the miniature electrochemical system, and the peak current is calculated. Using the relationship curve between the concentration of the heavy metal ion standard sample solution and the peak current in step (2), the concentration of the target heavy metal ion is calculated and displayed; after each heavy metal ion is measured, a constant potential needs to be applied to the corresponding working electrode for cleaning.

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