Implementation method of ionic gel flexible oxygen sensor and packaging monitoring system

Abstract

The invention discloses an implementation method of an ionic gel flexible oxygen sensor and a packaging monitoring system. The method comprises the following steps: mixing a PVDF-HFP polymer and EMIMTFSI ionic liquid according to a preset weight ratio, and dissolving the obtained mixture in acetone to obtain an ionic gel precursor solution; coating the metal interdigital electrode with an ionic gel precursor solution with a preset volume, and after acetone is volatilized, obtaining the ionic gel flexible oxygen sensor; the metal interdigital electrode is arranged on the flexible substrate. According to the embodiment of the invention, the ionic gel flexible oxygen sensor is prepared from the ionic gel precursor solution prepared from the PVDF-HFP polymer and the EMIMTFSI ionic liquid, the ionic gel flexible oxygen sensor can be used in food packaging, meanwhile, the problems of volatilization and leakage of aqueous electrolyte are relieved, the detection precision of the oxygen sensor is improved, and the application scene of the oxygen sensor is expanded. The method can be widely applied to the technical field of gas concentration measurement.

Description

Technical Field

[0001] The invention relates to the technical field of gas concentration measurement, in particular to an implementation method of an ion gel flexible oxygen sensor and a packaging monitoring system. Background Art

[0002] At present, food safety issues are increasingly attracting the attention of food agencies and people. Among them, food is very easy to deteriorate during production, storage, transportation and sales, and most food deterioration is caused by oxygen. The presence of oxygen not only allows a large number of aerobic microorganisms that pose a threat to health to grow, but also causes oxidative chemical reactions, thereby reducing the quality, nutrition and flavor of food. The current common solution is to use modified atmosphere packaging, in which the package is sealed in an inert gas atmosphere. In this case, the oxygen content in the package can be maintained at an extremely low concentration, greatly extending the storage period of the food. However, during transportation or handling, the integrity of the food packaging may be destroyed. Therefore, real-time monitoring of the oxygen concentration inside the package can accurately evaluate the sealing of the food packaging, thereby ensuring food safety.

[0003] In the related art, oxygen content in the package is monitored by an oxygen sensor. Specifically, metal oxide oxygen sensors, optical oxygen sensors, etc. have rigid shells or high energy consumption, lack portability and flexibility, and are difficult to be installed on packaging containers of various shapes for long-term measurement, and cannot meet the application requirements of real-time monitoring of oxygen content in changing scenarios. In this regard, in addition to superior performance in sensitivity, selectivity, and detection limit, electrochemical gas sensors also have the advantages of low cost and suitability for miniaturization. However, traditional electrochemical gas sensors face problems such as electrolyte volatilization and leakage, which affect the measurement accuracy of oxygen sensors. Summary of the invention

[0004] The purpose of the present invention is to solve one of the technical problems existing in the prior art to at least a certain extent.

[0005] To this end, the object of the present invention is to provide a method for realizing a high-precision ion gel flexible oxygen sensor and a packaging monitoring system.

[0006] In order to achieve the above technical objectives, one aspect of an embodiment of the present invention provides a method for realizing an ion gel flexible oxygen sensor, comprising the following steps: mixing a PVDF-HFP polymer and an EMIMTFSI ionic liquid according to a preset weight ratio, dissolving the obtained mixture in acetone to obtain an ion gel precursor solution; applying a preset volume of the ion gel precursor solution on a metal interdigital electrode, and after the acetone evaporates, obtaining the ion gel flexible oxygen sensor; the metal interdigital electrode is placed on a flexible substrate. The embodiment of the present application prepares an ion gel flexible oxygen sensor using an ion gel precursor solution prepared from a PVDF-HFP polymer and an EMIMTFSI ionic liquid, which can be used in food packaging. At the same time, it alleviates the problem of volatilization and leakage of aqueous electrolytes, which is beneficial to improving the detection accuracy of oxygen sensors and expanding the application scenarios of oxygen sensors.

[0007] In some embodiments, the method for realizing the ion gel flexible oxygen sensor of the embodiment of the present invention comprises mixing the PVDF-HFP polymer and the EMIMTFSI ionic liquid according to a preset weight ratio, dissolving the obtained mixture in acetone, and obtaining an ion gel precursor solution, comprising:

[0008] The PVDF-HFP polymer and the EMIMTFSI ionic liquid are mixed in a weight ratio of 2:3, and the volume of acetone required is determined according to the weight of the mixture and the preset ratio;

[0009] The mixture is dissolved in the acetone and stirred for a first period of time to obtain an ion gel precursor solution.

[0010] In some embodiments, in one embodiment of the present invention, the ion gel flexible oxygen sensor measures oxygen content by the following steps:

[0011] Applying a potential to the metal interdigital electrodes by a transient double potential method, and obtaining a first current after a second time period;

[0012] Based on the first current, the oxygen content is determined.

[0013] In some embodiments, in one embodiment of the present invention, applying a potential on the metal interdigital electrode by a transient dual potential method and obtaining a first current after a second time period includes:

[0014] An oxidation potential is applied to the metal interdigital electrodes by a transient dual potential method, and a reduction potential is applied to the metal interdigital electrodes to obtain a first current after a second time period.

[0015] On the other hand, an embodiment of the present invention provides a packaging monitoring system, comprising: an ion gel flexible oxygen sensor prepared by the above-mentioned method for realizing the ion gel flexible oxygen sensor;

[0016] The control module is connected to the ion gel flexible oxygen sensor via a driving module, and the ion gel flexible oxygen sensor is connected to the control module via a signal acquisition module;

[0017] The control module is used to send a driving signal of the ion gel flexible oxygen sensor, receive a measurement signal returned by the ion gel flexible oxygen sensor, and determine the oxygen content according to the measurement signal;

[0018] The ion gel flexible oxygen sensor is placed inside the package and is used to measure the measurement signal inside the package.

[0019] In some embodiments, in the packaging monitoring system provided by the embodiments of the present application, the driving module includes an inverting proportional amplifier and an analog gating unit;

[0020] The control module is connected to the first input port of the analog gating unit through the inverting proportional amplifier, the control module is connected to the second input port of the analog gating unit, and the output port of the analog gating unit is connected to the ion gel flexible oxygen sensor;

[0021] The control module is used to output voltage pulses to the inverting proportional amplifier and the analog gating unit;

[0022] The analog gating unit is used to select the voltage pulse after passing through the inverting proportional amplifier, or to select the voltage pulse.

[0023] In some embodiments, in the packaging monitoring system provided by the embodiments of the present application, the inverting proportional amplifier includes an inverting proportional amplifier chip, and the analog gating unit includes a switch chip;

[0024] The control module is used to output a voltage pulse to the inverting input terminal of the inverting proportional amplifier chip and the first signal input terminal of the switch chip. The inverting input terminal of the inverting proportional amplifier chip is connected to the output terminal of the inverting proportional amplifier chip through a first resistor, and the non-inverting input terminal of the inverting proportional amplifier chip is grounded through a second resistor; the output terminal of the inverting proportional amplifier chip is connected to the second signal input terminal of the switch chip, and the control module is used to output a selection voltage pulse to the third signal input terminal of the switch chip.

[0025] In some embodiments, in the packaging monitoring system provided by the embodiments of the present application, the signal acquisition module includes a transimpedance amplifier and an adder;

[0026] The ion gel flexible oxygen sensor is connected to the adder through the transimpedance amplifier, and the adder is connected to the control module.

[0027] In some embodiments, the packaging monitoring system provided by the embodiments of the present application further includes a host computer;

[0028] The host computer is wirelessly connected to the control module;

[0029] The host computer is used to receive the oxygen content and send a reminder signal according to the relationship between the oxygen content and a preset content.

[0030] On the other hand, an embodiment of the present invention provides a smart package, including the above-mentioned package monitoring system.

[0031] The embodiments of the present application include at least the following beneficial effects: the method provided in the embodiments of the present invention includes: mixing PVDF-HFP polymer and EMIMTFSI ionic liquid according to a preset weight ratio, dissolving the obtained mixture in acetone to obtain an ion gel precursor solution; applying a preset volume of the ion gel precursor solution on a metal interdigital electrode, and after the acetone evaporates, obtaining the ion gel flexible oxygen sensor; the metal interdigital electrode is placed on a flexible substrate. The embodiments of the present application prepare an ion gel flexible oxygen sensor using an ion gel precursor solution prepared from PVDF-HFP polymer and EMIMTFSI ionic liquid, which can be used in food packaging. At the same time, it alleviates the problem of volatilization and leakage of aqueous electrolytes, which is beneficial to improving the detection accuracy of oxygen sensors and expanding the application scenarios of oxygen sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the embodiments of the present invention or the drawings of related technical solutions in the prior art are introduced below. It should be understood that the drawings introduced below are only for the convenience of clearly describing some embodiments of the technical solutions of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0033] Figure 1 A schematic flow chart of an embodiment of a method for implementing an ion gel flexible oxygen sensor provided by the present invention;

[0034] FIG. 2( a ) is a schematic structural diagram of an embodiment of an ion gel flexible oxygen sensor provided by the present invention;

[0035] FIG2( b ) is a schematic diagram of the test results of the cyclic voltammetry test of the ion gel flexible oxygen sensor provided by the present invention;

[0036] FIG3( a ) is a schematic diagram showing the test results of the current response of the sensor provided by the present invention in a high concentration oxygen environment;

[0037] FIG3( b ) is a schematic diagram of the test results of the current response of the sensor provided by the present invention in a low concentration oxygen environment;

[0038] FIG3( c ) is a schematic diagram showing the response fitting of the sensor provided by the present invention in a high concentration oxygen environment;

[0039] FIG3( d ) is a schematic diagram showing the response fitting of the sensor provided by the present invention in a low concentration oxygen environment;

[0040] FIG3( e ) is a schematic diagram showing the result of the low response value of the sensor provided by the present invention to the interfering gas;

[0041] FIG4( a ) is a schematic diagram showing a comparison of weight changes of a sensor provided by the present invention and a sensor of the related art at room temperature;

[0042] FIG4( b ) is a schematic diagram of the test results of the differential scanning calorimetry test of the sensor provided by the present invention;

[0043] FIG5( a ) is a schematic diagram showing a performance comparison of the sensor provided by the present invention under different driving modes;

[0044] FIG5( b ) is a schematic diagram showing a comparison of electrode deposition of the sensor provided by the present invention under different driving modes;

[0045] FIG5( c ) is a schematic diagram showing the oxygen response fitting comparison of the sensor provided by the present invention under different driving modes;

[0046] FIG5( d ) is a schematic diagram showing a comparison of current stabilization time of the sensor provided by the present invention under different driving modes;

[0047] FIG6( a ) is a schematic diagram showing a physical display of an embodiment of a packaging monitoring system provided by the present invention;

[0048] FIG6( b ) is a schematic diagram of the connection relationship of an embodiment of the packaging monitoring system provided by the present invention;

[0049] FIG. 7( a ) is a schematic diagram of an application scenario of an embodiment of a packaging monitoring system provided by the present invention;

[0050] FIG. 7( b ) is a schematic diagram showing an interface of an embodiment of a packaging monitoring system provided by the present invention;

[0051] Figure 8 A circuit schematic diagram of an embodiment of a control module provided by the present invention;

[0052] FIG9( a) is a circuit diagram of an embodiment of a power module provided by the present invention;

[0053] FIG9( b ) is a circuit diagram of another embodiment of a voltage module provided by the present invention;

[0054] FIG10( a ) is a circuit diagram of an embodiment of an inverting proportional amplifier provided by the present invention;

[0055] FIG10( b ) is a circuit diagram of an embodiment of an analog gating unit provided by the present invention;

[0056] FIG11( a ) is a circuit diagram of an embodiment of a transimpedance amplifier provided by the present invention;

[0057] FIG11( b) is a circuit diagram of an embodiment of an adder provided by the present invention;

[0058] Fig.12 A circuit schematic diagram of an embodiment of the Bluetooth module provided by the present invention. DETAILED DESCRIPTION

[0059] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and are not to be construed as limitations of the present invention. For the step numbers in the following embodiments, they are only provided for the convenience of explanation, and the order between the steps is not limited in any way, and the execution order of each step in the embodiment can be adaptively adjusted according to the understanding of those skilled in the art.

[0060] First, the concepts involved in this application are explained:

[0061] Constant potential method: A constant potential is applied to the sensor, causing the target molecule to undergo an electrochemical reaction at the interface between the electrode and the electrolyte, while recording the Faraday current proportional to the concentration of the target molecule.

[0062] At present, food safety issues are receiving more and more attention from food agencies and people. Among them, food is very easy to deteriorate during production, storage, transportation and sales. Especially for perishable products such as fruits, meat, wine and foods that are sensitive to air and / or moisture. Most food deterioration is caused by oxygen. The presence of oxygen not only allows a large number of aerobic microorganisms that pose a threat to health to grow, but also causes oxidative chemical reactions, thereby reducing the quality, nutrition and flavor of food. The current common solution is to use modified atmosphere packaging, in which the packaging is sealed in an inert gas (usually nitrogen, argon or carbon dioxide) atmosphere. In this case, the oxygen content in the package can be maintained at an extremely low concentration, greatly extending the storage period of the food. However, during transportation or handling, the integrity of the food packaging may be destroyed. Therefore, real-time monitoring of the oxygen concentration inside the package can accurately evaluate the sealing of the food packaging, thereby ensuring food safety. However, most common oxygen sensors such as metal oxide oxygen sensors and optical oxygen sensors have rigid shells or high energy consumption, lack portability and flexibility, and are difficult to be installed on packaging containers of various shapes for long-term measurement, and cannot meet the application requirements of real-time monitoring of oxygen content in changing scenarios. Compared with MOS gas sensors (MOS gas sensors are gas sensors made of metal-oxide-semiconductor materials) and optical sensors, electrochemical gas sensors have advantages such as low cost and suitability for miniaturization in addition to superior performance in terms of sensitivity, selectivity and detection limit. However, traditional electrochemical gas sensors face problems such as electrolyte volatilization and leakage. As a new type of flexible electronic material, ion gel has good stretchability. The ionic liquid swollen inside has almost no vapor pressure, is non-volatile, and has good chemical stability and thermal stability. It is expected to replace traditional aqueous electrolytes and is very suitable as the sensitive layer of flexible wearable oxygen sensors. Flexible gas sensors based on ion gel, as a new generation of wearable gas sensor devices, have broad research and application prospects in the future.

[0063] In addition to the leakage and volatilization of the electrolyte, electrode corrosion is also a major challenge facing electrochemical gas sensors. Driven by a constant electrode potential, the anode metal of the sensor continues to oxidize and dissolve, resulting in severe electrode corrosion and drastic changes in morphology. The sensor performance deteriorates during long-term testing, greatly limiting its application in long-term real-time wireless monitoring scenarios. Proposing effective solutions in terms of sensing mechanism, electrode materials or device design is the key to building a highly stable wearable oxygen sensor. In addition, most of the current gas sensors use dedicated measuring instruments for signal acquisition and lack portability.

[0064] In summary, the more mature gas sensors currently include metal oxide semiconductor sensors, optical sensors, and electrochemical sensors. Metal oxide gas (MOS) sensors have the advantages of high sensitivity, fast response, low detection limit, and a wide variety of detectable gases. However, MOS gas sensors often need to be heated to a higher temperature to accelerate gas absorption and catalytic reactions, which consumes a lot of power. Optical gas sensors have high sensitivity, good stability, and fast response speed, but they are often large in size and lack portability. Compared with MOS gas sensors and optical sensors, electrochemical gas sensors have superior performance in terms of sensitivity, selectivity, and detection limit, as well as low cost and suitability for miniaturization. However, traditional electrochemical gas sensors face problems such as electrolyte volatilization and leakage.

[0065] As a polymer electrolyte material, organic hydrogels have solved the problems of traditional electrochemical sensor electrolytes being unshaped and easy to leak to a certain extent. At present, some research teams have conducted in-depth research on the gas-sensing mechanism of conductive hydrogel-based gas sensors, and achieved a wide response range and fast response recovery of oxygen sensors. However, the large amount of water swollen inside the hydrogel-based electrochemical sensor device faces the problems of high-temperature volatilization and low-temperature freezing, which greatly limits its application scenarios. Ionic liquids have almost no vapor pressure, are non-volatile, and have good chemical and thermal stability, and are expected to replace traditional aqueous electrolytes. Domestic and foreign scholars have carried out a lot of research work on the application of ionic liquid electrolytes in electrochemical gas sensing. Although ionic liquids effectively solve the problem of electrolyte volatilization, as liquid electrolytes, they still have problems such as packaging difficulties and leakage. In addition, electrochemical sensors often have a long establishment time due to the interference of double-layer current, and must wait for the double-layer charging current to drop to a certain value before starting to measure. The traditional constant potential test method makes it difficult to avoid anode corrosion of electrochemical sensors, which greatly affects the service life of the sensor. In response to the above challenges, domestic and foreign research teams have not yet proposed mature solutions.

[0066] Considering the shortcomings of traditional aqueous electrolytes and hydrogel electrolytes in electrochemical sensors, this application proposes an electrochemical sensor with a solid polymer swollen with an ionic liquid - an ion gel as an electrolyte, which not only has many advantages of solid-state electrochemical sensors, but also solves the problems of volatilization and leakage of traditional aqueous electrolytes. It makes it possible to prepare a safe, reliable, and intrinsically flexible wearable oxygen sensor. As for the problems of double-layer current interference and electrode corrosion, this application proposes to use a transient dual-potential driven oxygen sensor to achieve dynamic electrode repair. At the same time, this method is to collect the response current at a fixed time after applying the reduction potential, which can alleviate the interference of the charging current of the charging layer to a certain extent and greatly shorten the sensor establishment time. In order to apply the sensor to the scene of real-time wireless monitoring, the wireless monitoring circuit supporting the sensor is crucial. To this end, the sensor drive circuit, signal acquisition circuit and wireless transmission circuit based on the transient dual-potential test method were successfully designed and applied to the sealing monitoring of food.

[0067] The implementation method and system of the ion gel flexible oxygen sensor proposed in the embodiment of the present invention are described in detail below with reference to the accompanying drawings. First, the implementation method of the ion gel flexible oxygen sensor proposed in the embodiment of the present invention will be described with reference to the accompanying drawings.

[0068] In an embodiment of the present invention, a method for implementing an ion gel flexible oxygen sensor is provided. The method for implementing the ion gel flexible oxygen sensor in the embodiment of the present invention can be applied to a terminal, a server, or software running in a terminal or a server. The terminal can be a tablet computer, a laptop computer, a desktop computer, etc., but is not limited thereto. The server can be an independent physical server, or a server cluster or a distributed system composed of multiple physical servers, or a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communications, middleware services, domain name services, security services, CDN, and big data and artificial intelligence platforms. The method for implementing the ion gel flexible oxygen sensor in the embodiment of the present invention mainly includes the following steps:

[0069] S100: mixing the PVDF-HFP polymer and the EMIMTFSI ionic liquid according to a preset weight ratio, and dissolving the obtained mixture in acetone to obtain an ion gel precursor solution;

[0070] S200: applying a preset volume of the ion gel precursor solution on the metal interdigital electrode, and after the acetone is volatilized, obtaining the ion gel flexible oxygen sensor; the metal interdigital electrode is placed on a flexible substrate.

[0071] In some possible implementations, the metal interdigitated electrodes in the embodiments of the present application may be silver interdigitated electrodes, gold interdigitated electrodes, or platinum interdigitated electrodes. The present application does not limit the type of metal. Similarly, the flexible substrate in the embodiments of the present application may be a flexible substrate of a polymer material, specifically, including polyimide (PI), polyethylene (PE) and polystyrene (PS). After the propylene in the embodiments of the present application volatilizes, the ion gel spontaneously physically polymerizes, and finally an ion gel-based flexible oxygen sensor is obtained.

[0072] The present invention consists of an ion gel-based oxygen sensor and a wireless sensor circuit (i.e., a packaging monitoring system). The ion gel-based oxygen sensor is polymerized by dripping a precursor solution on a polyimide silver interdigital electrode. The silver interdigital electrode acts as the cathode and anode of the electrochemical oxygen sensor, and the PVDF-HFP / EMIMTFSI ion gel is used as a flexible solid electrolyte material. Figure 1 The preparation flow chart of ion gel-based oxygen sensor. First, 0.64g of PVDF-HFP polymer and 0.96g of EMIMTFSI ionic liquid were dissolved in 14mL of acetone. Magnetic stirring was performed for 5h (i.e., the first duration) until PVDF-HFP was completely dissolved to obtain an ion gel precursor solution. Subsequently, 0.1mL (i.e., the preset volume) of the precursor solution was drop-coated on the flexible silver interdigital electrode using a pipette. After the acetone evaporated, the ion gel spontaneously physically polymerized to finally obtain an ion gel-based flexible oxygen sensor. Figure 2(a) is a device schematic diagram of an ion gel-based flexible oxygen sensor, and Figure 2(b) is a cyclic voltammetry test curve of the oxygen sensor. It can be seen from the curve that the anode peak potential is about 0.4V and the cathode peak potential is about -0.9V. During the cathode scan, O2 is reduced to superoxide anions; during the anode scan, superoxide anions are oxidized to O2. The whole process is a single-electron redox of oxygen. In order to make the redox reactions both in the diffusion rate-limited state, the oxidation potential of the sensor was set to 0.5 V and the reduction potential was set to -1 V.

[0073] In addition, the sensor also has good gas selectivity. It shows low response values ​​for typical concentrations of interfering gases such as hydrogen sulfide, acetone, ethanol, isopropanol, carbon dioxide, nitric oxide, ammonia, etc. (refer to Figure 3 (e)). Figure 3 is the performance characterization of the ion gel-based flexible oxygen sensor. Figure 3 (a) The current response of the sensor in a high concentration oxygen environment of 20-60%; Figure 3 (b) The current response of the sensor in a low concentration oxygen environment of 500-100ppm; Figure 3 (cd) The response fitting curves of the sensor in high and low concentration oxygen environments respectively; Figure 3 (e) The low response value of the sensor to typical concentrations of interfering gases such as hydrogen sulfide, acetone, ethanol, isopropanol, carbon dioxide, nitric oxide, ammonia, etc. and high selectivity for oxygen. From Figure 3 (ad), it can be seen that the sensor has good linear response whether in the high concentration oxygen range of 20-60% or the low concentration range of 100-500ppm.

[0074] Due to the internal swelling of non-volatile ionic liquids, ion gels exhibit good environmental tolerance. In order to characterize the environmental stability of ion gels, the original PAM hydrogel, PAM-carrageenan organic hydrogel and PVDF-HFP ion gel were placed in a constant temperature and humidity environment. It can be seen that although the strategy of alcohol soaking can delay the water loss process of the hydrogel, long-term water loss still exists. In contrast, the quality of PVDF-HFP ion gel remains unchanged for a long time, proving the superior moisturizing properties of PVDF-HFP ion gel (Figure 4 (a)). Differential scanning calorimetry tests found that the freezing point of the ion gel was as low as -44°C, which indicates that the ion gel can maintain a stable form even in extremely low temperature environments (Figure 4 (b)).

[0075] Optionally, in one embodiment of the present invention, the PVDF-HFP polymer and the EMIMTFSI ionic liquid are mixed according to a preset weight ratio, and the obtained mixture is dissolved in acetone to obtain an ion gel precursor solution, comprising:

[0076] The PVDF-HFP polymer and the EMIMTFSI ionic liquid are mixed in a weight ratio of 2:3, and the volume of acetone required is determined according to the weight of the mixture and the preset ratio;

[0077] The mixture is dissolved in the acetone and stirred for a first period of time to obtain an ion gel precursor solution.

[0078] In some possible embodiments, the preset ratio can be adjusted according to actual needs, and the present application is not specifically limited. In a specific embodiment, 14 mL of acetone is used to dissolve every 1.6 g of the mixture. Of course, the first duration can also be adjusted according to actual needs. In some embodiments, the first duration can be 5 hours, and those skilled in the art can lengthen or shorten the time according to actual needs.

[0079] Optionally, in one embodiment of the present invention, the ion gel flexible oxygen sensor measures oxygen content by the following steps:

[0080] Applying a potential to the metal interdigital electrodes by a transient double potential method, and obtaining a first current after a second time period;

[0081] Based on the first current, the oxygen content is determined.

[0082] In some possible implementations, the second duration may be 1 second, and may be adjusted as required.

[0083] Optionally, in one embodiment of the present invention, applying a potential on the metal interdigital electrode by a transient dual potential method and obtaining a first current after a second time period comprises:

[0084] An oxidation potential is applied to the metal interdigital electrodes by a transient dual potential method, and a reduction potential is applied to the metal interdigital electrodes to obtain a first current after a second time period.

[0085] It can be understood that compared with the traditional constant potential test method, the transient double potential test method can effectively alleviate the corrosion of the sensor electrode, while accelerating the stabilization speed of the double-layer charging current and shortening its establishment time. Scanning electron microscopy was used to observe the morphological changes of the electrode after long-term testing by the traditional constant potential method (CPA) and the transient double potential method DPA (DPA). Figure 5 shows the performance comparison of the sensor when tested by the traditional constant potential method (CPA) and the transient double potential method (DPA). Figure 5 (ab) shows the EDS silver element distribution diagram and the weight proportion of the silver element at the cathode and anode of the sensor after a long-term test in air for 24 hours using different test methods; Figure 5 (c) shows the oxygen response fitting curve of the sensor when using different test methods; Figure 5 (d) shows the current stabilization time (establishment time) of the sensor when using different test methods. From the element mapping diagram on the left, it can be seen that after a long-term test by the CPA method, the silver element at the anode has dropped significantly, while after a long-term test by the DPA method, the silver element at the anode has not dropped significantly (Figure 5 (ab)). In addition, by comparing the two test methods, it is found that DPA has a higher response sensitivity than CPA (Figure 5(c)). Moreover, it only takes 14.4s for DPA to reduce the current change rate to one thousandth, while CPA takes 714s, which proves that DPA has a stronger ability to resist the interference of double-layer charging current and has a shorter settling time (Figure 5(d)).

[0086] The following is a detailed description of the implementation method of the ion gel flexible oxygen sensor provided by the present application with specific embodiments: Specific embodiment 1:

[0088] Figure 1 The following is a flow chart for the preparation of ion gel-based flexible oxygen sensors. First, 0.64 g of PVDF-HFP polymer and 0.96 g of EMIMTFSI ionic liquid were dissolved in 14 ml of acetone. Then, a magnetic stirrer was used to stir continuously for 5 hours until PVDF-HFP was completely dissolved to form an ion gel precursor solution. Then, 0.1 ml of the precursor solution was accurately measured using a pipette and dropped onto the surface of the flexible silver interdigital electrode. After the acetone was completely evaporated, the ion gel would undergo spontaneous physical polymerization, and finally a flexible oxygen sensor based on ion gel was obtained. Specific embodiment 2:

[0090] Gas-sensitive test: A transient bipotential voltage pulse is applied to both ends of the electrode of the flexible oxygen sensor. The reaction current signal is collected by an electrochemical workstation. The target gas pure oxygen is mixed with pure N2 through a digital mass flow controller to obtain oxygen with different concentrations. The mixed test gas with different oxygen concentrations is injected into the test chamber, and the current signal of the module is recorded at the same time, and then the laboratory is purged with N2 to restore the signal. When performing the gas selectivity test of the sensor, the interfering gas (hydrogen sulfide, acetone, ethanol, isopropanol, carbon dioxide, nitric oxide, ammonia) is mixed with pure N2 through a digital mass flow controller, and then the mixed test gas is injected into the test chamber, and the current signal of the module is recorded at the same time, and then the laboratory is purged with N2 to restore the signal.

[0091] The test method of transient bipotential current method is as follows: oxidation potential and reduction potential are applied to the working electrode (i.e., the metal interdigitated electrode in the embodiment of the present application) in sequence, and the current at the end of the reduction stage is used as the response current. In this test method, each application of reduction (oxidation) potential can be regarded as a constant potential step. Since the current is collected at t=1s each time, the double layer charging current will decay to the same value after each application of the reduction potential for 1s. Therefore, when using transient bipotential current method, there is no need to worry about the baseline drift of the response current caused by the decay of the charging current. Using transient current as the oxygen response current not only has a higher sensitivity, but also the O2 formed during the O2 reduction process - It can be consumed in the oxidation process, thus extending the service life of the electrode system.

[0092] In summary, the method provided in the embodiment of the present application includes: mixing PVDF-HFP polymer and EMIMTFSI ionic liquid according to a preset weight ratio, dissolving the obtained mixture in acetone to obtain an ion gel precursor solution; applying a preset volume of the ion gel precursor solution on a metal interdigital electrode, and after the acetone evaporates, the ion gel flexible oxygen sensor is obtained; the metal interdigital electrode is placed on a flexible substrate. The embodiment of the present application prepares an ion gel flexible oxygen sensor using an ion gel precursor solution prepared from PVDF-HFP polymer and EMIMTFSI ionic liquid, which can be used in food packaging. At the same time, it alleviates the problem of volatilization and leakage of aqueous electrolytes, which is beneficial to improving the detection accuracy of oxygen sensors and expanding the application scenarios of oxygen sensors.

[0093] Secondly, an embodiment of the present invention provides a packaging monitoring system, comprising: an ion gel flexible oxygen sensor prepared by the above-mentioned implementation method of the ion gel flexible oxygen sensor;

[0094] The control module is connected to the ion gel flexible oxygen sensor via a driving module, and the ion gel flexible oxygen sensor is connected to the control module via a signal acquisition module;

[0095] The control module is used to send a driving signal of the ion gel flexible oxygen sensor, receive a measurement signal returned by the ion gel flexible oxygen sensor, and determine the oxygen content according to the measurement signal;

[0096] The ion gel flexible oxygen sensor is placed inside the package and is used to measure the measurement signal inside the package.

[0097] The measurement signal in the embodiment of the present application is a signal characterizing the oxygen content measured by the oxygen sensor. Of course, the oxygen sensor in the embodiment of the present application can also be placed in other areas / occasions for measuring oxygen content, and the present application does not specifically limit the use location of the oxygen sensor.

[0098] In some embodiments, in the packaging monitoring system provided by the embodiments of the present application, the driving module includes an inverting proportional amplifier and an analog gating unit;

[0099] The control module is connected to the first input port of the analog gating unit through the inverting proportional amplifier, the control module is connected to the second input port of the analog gating unit, and the output port of the analog gating unit is connected to the ion gel flexible oxygen sensor;

[0100] The control module is used to output voltage pulses to the inverting proportional amplifier and the analog gating unit;

[0101] The analog gating unit is used to select the voltage pulse after passing through the inverting proportional amplifier, or to select the voltage pulse.

[0102] In some embodiments, in the packaging monitoring system provided by the embodiments of the present application, the inverting proportional amplifier includes an inverting proportional amplifier chip, and the analog gating unit includes a switch chip;

[0103] The control module is used to output a voltage pulse to the inverting input terminal of the inverting proportional amplifier chip and the first signal input terminal of the switch chip. The inverting input terminal of the inverting proportional amplifier chip is connected to the output terminal of the inverting proportional amplifier chip through a first resistor, and the non-inverting input terminal of the inverting proportional amplifier chip is grounded through a second resistor; the output terminal of the inverting proportional amplifier chip is connected to the second signal input terminal of the switch chip, and the control module is used to output a selection voltage pulse to the third signal input terminal of the switch chip.

[0104] In some embodiments, in the packaging monitoring system provided by the embodiments of the present application, the signal acquisition module includes a transimpedance amplifier and an adder;

[0105] The ion gel flexible oxygen sensor is connected to the adder through the transimpedance amplifier, and the adder is connected to the control module.

[0106] In some embodiments, the packaging monitoring system provided by the embodiments of the present application further includes a host computer;

[0107] The host computer is wirelessly connected to the control module;

[0108] The host computer is used to receive the oxygen content and send a reminder signal according to the relationship between the oxygen content and a preset content.

[0109] The host computer in the embodiment of the present application receives oxygen content data, and compares the value represented by the oxygen content data with the value represented by the preset content to determine whether to issue a reminder signal.

[0110] The present application combines an ion gel-based flexible oxygen sensor with a wireless sensing circuit to achieve wireless real-time monitoring of ambient oxygen concentration.

[0111] The present invention combines a flexible oxygen sensor with a wireless gas alarm circuit to construct an integrated wearable oxygen sensing system. Figure 6(a) is a physical diagram of the wireless oxygen sensing system. Figure 6(b) is a system block diagram of the wireless oxygen sensing system. The smart packaging bag constructed based on the wireless oxygen sensing system can easily evaluate the sealing of food storage (Figure 7(a)). The flexible oxygen sensor is installed on the inner wall of the packaging bag to measure the oxygen concentration in the package in real time. The responsive sensor drive and signal acquisition circuit board are installed on the outer wall of the food packaging bag. When nitrogen is gradually filled into the packaging bag, the oxygen in the packaging bag is discharged, the oxygen concentration decreases, and the current value displayed on the mobile phone terminal decreases. When the food packaging bag is damaged, a large amount of oxygen flows in, causing the oxygen concentration to rise sharply, and the sensor current value monitored on the mobile phone terminal increases, thereby issuing an alarm. Specifically, Figure 7 is a flexible wireless oxygen sensing smart packaging for food storage sealing evaluation, Figure 7(a) is a schematic diagram of a wireless oxygen sensing system for food packaging sealing evaluation; Figure 7(b) transmits the sealing data to the mobile phone terminal through a low-power Bluetooth module.

[0112] In some embodiments, Figure 6 is a schematic diagram and system block diagram of an integrated wireless oxygen monitoring system. The wireless alarm circuit is controlled by a STM32F103RCT6 microprocessor and uses a 12-bit digital-to-analog converter (DAC) to output a voltage pulse with a pulse width of 1s and a voltage of 0.5V and 1V respectively. Figure 8 It is the schematic diagram of the minimum system circuit of STM32F103RCT6. Figure 9 is the schematic diagram of the power module of the entire wireless detection system. Figure 9 (a) provides a 5V voltage for the module in the embodiment of the present application, and Figure 9 (b) provides a 3.3V voltage for the module in the embodiment of the present application. Those skilled in the art can design a voltage circuit according to the voltage value actually required, and the present application does not specifically limit the power module. Figure 10 is a dual-potential drive circuit (i.e., drive module) of the sensor. Among them, Figure 10 (a) is a circuit schematic diagram of the inverting proportional amplifier provided by the present invention, and Figure 10 (b) is a circuit schematic diagram of the analog gating unit provided by the present invention. First, the voltage pulse output by the DAC of the main control chip (i.e., control module) is amplified and inverted by the inverting ratio, and then the original voltage pulse signal and the inverted voltage pulse signal are gated by the analog switch. At the same time, the MCU outputs a voltage pulse with alternating high and low voltages as the selection signal of the analog switch, and the pulse width is 1s. After passing through the analog switch, a sensor drive signal with alternating positive and negative voltages is obtained. Figure 11 is a schematic diagram of the response signal acquisition circuit (i.e., signal acquisition module). Figure 11(a) is a circuit diagram of the transimpedance amplifier provided by the present invention; Figure 11(b) is a circuit diagram of the adder provided by the present invention. The response signal acquisition process is as follows: the response current of the sensor is converted into a voltage signal through a transimpedance amplifier. The voltage signal is adjusted to a suitable voltage range by an adder, and then read by a microcontroller unit (MCU) through a 12-bit analog-to-digital converter (ADC). The recorded data is FIR filtered inside the single-chip microcomputer to filter out the noise signal, and then converted back into the corresponding current data. Finally, the processed data is sent to the Bluetooth low-energy (BLE) chip through a universal asynchronous receiver and transmitter. The BLE module transmits the data wirelessly to the mobile terminal through a specific protocol for further processing (see Fig.12 ).

[0113] In some embodiments, the sensor module of the integrated wireless oxygen monitoring system is placed on the inner wall of the plastic package, and the package bag is sealed with a sealing machine to maintain a closed environment. The circuit part of the wireless oxygen monitoring system is placed outside the package bag (Figure 6(a)). Nitrogen is then filled in through the one-way air valve on the package bag. As can be seen from Figure 6(b), as the nitrogen concentration increases and the oxygen concentration decreases, the current value displayed by the program decreases rapidly. When the food packaging bag is damaged, the oxygen concentration in the packaging bag rises rapidly, and the current value displayed on the mobile phone program rises sharply, and the program reminds the user that the food packaging is damaged. The combination of flexible oxygen sensor and wireless alarm circuit provides strong technical support for the sealing evaluation of smart food packaging.

[0114] Understandably, a common solution is to use discrete rigid oxygen sensors to monitor oxygen concentrations. However, rigid sensors often lack mechanical flexibility and cannot conform to packaging bags, making them difficult to integrate and install on various packaging containers. Current flexible gas sensors still face problems such as electrode corrosion and electrolyte volatilization and freezing, which greatly limits their application in long-term real-time wireless monitoring. In addition, most current gas sensors rely on measuring instruments for signal acquisition, and the collected data is often processed locally, making it impossible to achieve real-time data transmission and remote monitoring.

[0115] In this regard, the present application proposes a new type of flexible oxygen sensor based on ion gel. The high environmental stability of ion gel makes it flexible while avoiding problems such as electrolyte leakage or high temperature volatilization and low temperature freezing. In addition, the use of transient dual potential test method has greatly solved the challenges of electrode corrosion and long establishment time of traditional electrochemical sensors. The intrinsic flexibility of ion gel-based oxygen sensors enables the sensor to fit the surface of the packaging bag very well. Good electrode corrosion resistance and resistance to double-layer charging current interference make long-term real-time wireless oxygen monitoring possible.

[0116] In this application, the flexible oxygen sensor is installed in the smart packaging bag and combined with the wireless oxygen monitoring circuit to successfully achieve accurate evaluation of the sealing of food packaging. The oxygen concentration data in the packaging bag is transmitted to the terminal via low-power Bluetooth technology. Based on the received data, merchants or users can accurately evaluate the sealing degree of food packaging and ensure food safety.

[0117] Compared with existing oxygen sensors, the oxygen sensor in the present invention has good flexibility and can be installed on any curved surface, which greatly expands the application scenarios of the sensor. The use of ion gel gas-sensitive materials and transient dual potential test methods greatly prolongs the service life of the sensor. Most importantly, under the synergistic effect of hardware circuits, the wireless oxygen monitoring system can successfully achieve accurate evaluation of the sealing of food packaging and ensure food safety.

[0118] On the other hand, an embodiment of the present invention provides a smart package, including the above-mentioned package monitoring system.

[0119] Similarly, the contents of the above method embodiments are all applicable to the present smart packaging embodiment. The functions specifically implemented by the present smart packaging embodiment are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0120] An embodiment of the present invention further provides a computer-readable storage medium, in which a program executable by a processor is stored. When the program executable by the processor is executed by the processor, it is used to execute the above-mentioned method for implementing the ion gel flexible oxygen sensor.

[0121] Similarly, the contents of the above method embodiments are all applicable to the present storage medium embodiments. The functions specifically implemented by the present storage medium embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0122] In some selectable embodiments, the function / operation mentioned in the block diagram may not occur in the order mentioned in the operation diagram. For example, depending on the function / operation involved, the two boxes shown in succession can actually be executed substantially simultaneously or the boxes can sometimes be executed in reverse order. In addition, the embodiment presented and described in the flow chart of the present invention is provided by way of example, for the purpose of providing a more comprehensive understanding of technology. The disclosed method is not limited to the operation and logic flow presented herein. Selectable embodiments are expected, wherein the order of various operations is changed and the sub-operation of a part for which is described as a larger operation is performed independently.

[0123] In addition, although the present invention is described in the context of functional modules, it should be understood that, unless otherwise specified, one or more of the functions and / or features can be integrated into a single physical device and / or software module, or one or more functions and / or features can be implemented in a separate physical device or software module. It is also understood that a detailed discussion of the actual implementation of each module is unnecessary for understanding the present invention. More specifically, in view of the properties, functions and internal relationships of the various functional modules in the device disclosed herein, the actual implementation of the module will be understood within the conventional skills of the engineer. Therefore, those skilled in the art can implement the present invention set forth in the claims without excessive experimentation using ordinary techniques. It is also understood that the specific concepts disclosed are merely illustrative and are not intended to limit the scope of the present invention, which is determined by the full scope of the appended claims and their equivalents.

[0124] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several programs to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program codes.

[0125] The logic and / or steps represented in the flowchart or otherwise described herein, for example, may be considered as an ordered list of executable programs for implementing the logical functions, and may be embodied in any computer-readable medium for use by a program execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch and execute a program from a program execution system, device or apparatus), or in conjunction with such program execution systems, devices or apparatuses. For purposes of this specification, a "computer-readable medium" may be any device that can contain, store, communicate, propagate or transmit a program for use by a program execution system, device or apparatus, or in conjunction with such program execution systems, devices or apparatuses.

[0126] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a computer memory.

[0127] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable program execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0128] In the above description of this specification, the description with reference to the terms "one embodiment / example", "another embodiment / example" or "certain embodiments / examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0129] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

[0130] The above is a specific description of the preferred implementation of the present invention, but the present invention is not limited to the embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of the present invention.

Claims

1. A method for realizing an ion gel flexible oxygen sensor, characterized in that: The following steps are involved: Mixing PVDF-HFP polymer and EMIMTFSI ionic liquid according to a preset weight ratio, dissolving the obtained mixture in acetone to obtain an ion gel precursor solution; The ion gel precursor solution of a preset volume is coated on the metal interdigital electrode, and after the acetone is volatilized, the ion gel flexible oxygen sensor is obtained; the metal interdigital electrode is placed on a flexible substrate.

2. The method for realizing the ion gel flexible oxygen sensor according to claim 1, characterized in that: The PVDF-HFP polymer and the EMIMTFSI ionic liquid are mixed according to a preset weight ratio, and the obtained mixture is dissolved in acetone to obtain an ion gel precursor solution, comprising: The PVDF-HFP polymer and the EMIMTFSI ionic liquid are mixed in a weight ratio of 2:3, and the volume of acetone required is determined according to the weight of the mixture and the preset ratio; The mixture is dissolved in the acetone and stirred for a first period of time to obtain an ion gel precursor solution.

3. The method for realizing the ion gel flexible oxygen sensor according to claim 2, characterized in that: The ion gel flexible oxygen sensor measures oxygen content through the following steps: Applying a potential to the metal interdigital electrodes by a transient double potential method, and obtaining a first current after a second time period; Based on the first current, the oxygen content is determined.

4. The method for realizing the ion gel flexible oxygen sensor according to claim 3, characterized in that: The step of applying a potential to the metal interdigital electrode by a transient dual potential method and obtaining a first current after a second time period includes: An oxidation potential is applied to the metal interdigital electrodes by a transient dual potential method, and a reduction potential is applied to the metal interdigital electrodes to obtain a first current after a second time period.

5. A packaging monitoring system, characterized in that: include: An ion gel flexible oxygen sensor prepared by the method for realizing an ion gel flexible oxygen sensor according to any one of claims 1 to 4; The control module is connected to the ion gel flexible oxygen sensor via a driving module, and the ion gel flexible oxygen sensor is connected to the control module via a signal acquisition module; The control module is used to send a driving signal of the ion gel flexible oxygen sensor, receive a measurement signal returned by the ion gel flexible oxygen sensor, and determine the oxygen content according to the measurement signal; The ion gel flexible oxygen sensor is placed inside the package and is used to measure the measurement signal inside the package.

6. The packaging monitoring system according to claim 5, characterized in that: The driving module includes an inverting proportional amplifier and an analog gating unit; The control module is connected to the first input port of the analog gating unit through the inverting proportional amplifier, the control module is connected to the second input port of the analog gating unit, and the output port of the analog gating unit is connected to the ion gel flexible oxygen sensor; The control module is used to output voltage pulses to the inverting proportional amplifier and the analog gating unit; The analog gating unit is used to select the voltage pulse after passing through the inverting proportional amplifier, or to select the voltage pulse.

7. The packaging monitoring system according to claim 6, characterized in that: The inverting proportional amplifier includes an inverting proportional amplifier chip, and the analog gating unit includes a switch chip; The control module is used to output a voltage pulse to the inverting input terminal of the inverting proportional amplifier chip and the first signal input terminal of the switch chip. The inverting input terminal of the inverting proportional amplifier chip is connected to the output terminal of the inverting proportional amplifier chip through a first resistor, and the non-inverting input terminal of the inverting proportional amplifier chip is grounded through a second resistor; the output terminal of the inverting proportional amplifier chip is connected to the second signal input terminal of the switch chip, and the control module is used to output a selection voltage pulse to the third signal input terminal of the switch chip.

8. The packaging monitoring system according to claim 5, characterized in that: The signal acquisition module includes a transimpedance amplifier and an adder; The ion gel flexible oxygen sensor is connected to the adder through the transimpedance amplifier, and the adder is connected to the control module.

9. The packaging monitoring system according to claim 5, characterized in that: The system also includes a host computer; The host computer is wirelessly connected to the control module; The host computer is used to receive the oxygen content and send a reminder signal according to the relationship between the oxygen content and a preset content.

10. A smart package, characterized in that: Comprising a packaging monitoring system as claimed in any one of claims 5 to 9.

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