Hydrogel-based joint infection bimodal flexible monitoring sensor and preparation method thereof

Abstract

The invention relates to a joint infection bimodal flexible monitoring sensor based on hydrogel and a preparation method thereof. The sensor comprises a flexible film substrate layer, a packaging layer, a PEDOT: PSS-PVA hydrogel pressure module and an NTC thermistor temperature module, and the PEDOT: PSS-PVA hydrogel pressure module and the NTC thermistor temperature module share a negative electrode. The preparation method comprises the following steps: preparing hydrogel ink, carrying out cross-linking bath, forming a hydrogel structure through low-temperature cross-linking 3D printing, preparing a PDMS film, carrying out plasma surface treatment on the hydrogel and the PDMS film, printing a circuit and a temperature sensing element, and finally assembling the sensor. Compared with the prior art, the sensor has the advantages of high sensitivity, wide measurement range and high stability, can accurately and synchronously acquire temperature and pressure signals of a joint part, realizes real-time monitoring and early warning of bone and soft tissue infection, breaks through the limitation of traditional diagnosis, and improves the early diagnosis efficiency and treatment compliance.

Description

Technical Field

[0001] The present invention relates to a convenient monitoring flexible sensor, and in particular to a hydrogel-based dual-modal flexible monitoring sensor for joint infection and a preparation method thereof. Background Art

[0002] Bone and soft tissue infections, and the resulting nonunions and bone defects, are common and intractable diseases in orthopedics. They carry high failure rates, recurrence rates, and disability rates, placing a heavy burden on patients, their families, and society, and represent a global medical challenge that remains unresolved. Timely and accurate detection is crucial for effective intervention and treatment. Currently, the diagnosis of bone and soft tissue infections, particularly periprosthetic joint infections and implant infections following total joint replacement surgery, primarily relies on the detection of inflammatory markers in blood and tissue fluid, as well as bacterial culture techniques. However, these methods have significant drawbacks: insufficient sensitivity and specificity, resulting in inaccurate results; and long diagnostic timelines, which can delay treatment. Furthermore, clinical testing for these markers relies primarily on frequent blood draws, which not only imposes physical pain and infection risks on patients but also only captures data at discrete time points, preventing continuous monitoring. This approach struggles to track the dynamics of infection indicators, delve deeper into disease progression, and precisely guide clinical treatment.

[0003] Wearable sensors, as an emerging technology, have developed rapidly in the monitoring of conventional physiological indicators such as heart rate and blood pressure, but existing technologies have limitations. For example, the sensor mentioned in the CN116380297A document has a novel structure, but it mainly focuses on pressure sensing and lacks the ability to simultaneously monitor key infection-related indicators such as temperature, and is unable to fully capture the physiological changes in the infected area. In addition, although the sensor mentioned in the CN114608716A document can monitor pressure and temperature at the same time, the ion gel material it uses has poor biocompatibility and is difficult to directly apply to the long-term monitoring of human bone and soft tissue infections. Moreover, most of these sensors have complex structures, high costs, or are difficult to adapt to the fitting requirements of complex biological surfaces such as the knee joint, resulting in poor wearing comfort and insufficient signal acquisition accuracy, and cannot meet the requirements of high precision, real-time and long-term stability for infection monitoring in actual clinical applications. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide a hydrogel-based dual-modal flexible monitoring sensor for joint infection and a preparation method thereof, wherein poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS)-polyvinyl alcohol (PVA) hydrogel, polydimethylsiloxane (PDMS) film, printed silver paste and stretchable silver circuit are used, and a pressure-temperature dual-modal flexible sensor for complex joints is designed according to actual clinical application scenarios. It can realize dual-modal high-sensitivity detection of pressure and temperature, monitor bone and soft tissue infections and provide early warning.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A first aspect of the present invention provides a hydrogel-based dual-modal flexible monitoring sensor for joint infection, comprising a sensor layer, a flexible film base layer, and a flexible film encapsulation layer;

[0007] The sensor layer includes a first sensing element and a second sensing element, wherein the first sensing element is a pressure sensing element and the second sensing element is a temperature sensing element;

[0008] The first sensor element and the second sensor element are both provided on the flexible film base layer, the first sensor element and the second sensor element share a negative electrode, the positive electrodes of the first sensor element and the second sensor element are respectively connected to corresponding signal input terminals of an external signal monitoring device, and the flexible film encapsulation layer is used to encapsulate the sensor layer and the flexible film base layer;

[0009] The first sensing element is PEDOT:PSS-PVA hydrogel, the second sensing element is NTC thermistor silver paste, and the flexible film base layer and the flexible film encapsulation layer are both PDMS films;

[0010] The sensor realizes dynamic monitoring of joint infection by synchronously calculating temperature and pressure signals.

[0011] Furthermore, the flexible thin film packaging layer packages the sensor layer and the base layer from above and below to form a sandwich packaging structure.

[0012] Furthermore, the positive electrode and the negative electrode of the first sensing element and the second sensing element are respectively connected to a stretchable silver circuit.

[0013] Furthermore, the PEDOT:PSS-PVA hydrogel is prepared by mixing a PEDOT:PSS solution with a PVA solution, and the solvent is a deionized water-DMSO mixture.

[0014] Furthermore, the PEDOT:PSS-PVA hydrogel is prepared by mixing 7 wt % PEDOT:PSS solution and 7 wt % PVA solution in a mass ratio of 2:3, and the solvent is a deionized water-DMSO mixture.

[0015] A second aspect of the present invention provides a method for preparing the above-mentioned hydrogel-based dual-modal flexible joint infection monitoring sensor, comprising the following steps:

[0016] S1, mixing PEDOT:PSS and PVA solution to form a uniform hydrogel ink;

[0017] S2, using the hydrogel ink as a raw material, printing the hydrogel structure using a direct ink writing 3D printer, and immersing the hydrogel structure in a cross-linking bath for low-temperature cross-linking. After cross-linking, washing and swelling are performed to obtain a PEDOT:PSS-PVA hydrogel;

[0018] S3, mixing PDMS and a cross-linking agent, removing bubbles, pouring into a mold for curing, and cutting into PDMS films of a specified size;

[0019] S4. Plasma surface treatment of PEDOT:PSS-PVA hydrogel and PDMS film to improve the adsorption between the materials;

[0020] S5, laying out an NTC thermistor and a stretchable conductive silver circuit on the PDMS film substrate, wherein the PEDOT:PSS-PVA hydrogel and the negative electrode circuit of the NTC thermistor are fused at the circuit end point;

[0021] S6. The PEDOT:PSS-PVA hydrogel is adhered to the upper layer of the stretchable conductive silver circuit of the PDMS film substrate layer, and then the PDMS film encapsulation layer is covered on the substrate layer and the sensor layer to form a sandwich encapsulation structure.

[0022] Furthermore, in S1, the specific process of mixing the PEDOT:PSS with the PVA solution includes:

[0023] PEDOT:PSS was added to a deionized water-DMSO mixture (85:15 v / v) with a PEDOT to PSS ratio of 1:2.5 w / w and mixed thoroughly to prepare a solution;

[0024] PVA powder was added to deionized water and stirred at 90°C until completely dissolved to prepare a 7% PVA solution;

[0025] The PEDOT:PSS solution and PVA solution were filtered through a disposable filter with a pore size of 0.45 μm using a syringe;

[0026] 7% PEDOT:PSS solution and 7% PVA solution were mixed at a mass ratio of 2:3 and stirred at room temperature until completely dissolved to form a uniform hydrogel ink.

[0027] Further, in S2, the cross-linking bath is prepared by mixing deionized water, anhydrous ethanol and calcium chloride particles;

[0028] The crosslinking bath was stirred for 2 hours and cooled to -5°C before use;

[0029] The low temperature cross-linking specifically includes:

[0030] The printed hydrogel structure was immersed in a cross-linking bath at −5 °C for 12 h;

[0031] After cross-linking, the formed hydrogels were washed several times with deionized water at 5 °C to remove excess reagents and then swelled for 24 h to reach an equivalent state.

[0032] Furthermore, in S3, the mass mixing ratio of the PDMS and the cross-linking agent is 10:1; after stirring, removing bubbles, and pouring into a mold for curing include:

[0033] After uniform stirring at 1000 rpm with a magnetic stirrer for 2 hours, the mixture was placed in a vacuum pressure device for defoaming;

[0034] The degassed PDMS solution was poured into the mold and cured in an oven at 80°C until fully cured.

[0035] Furthermore, in S4, the process of performing plasma surface treatment on the PEDOT:PSS-PVA hydrogel and the PDMS film includes:

[0036] The PEDOT:PSS-PVA hydrogel and PDMS film were placed in a plasma treatment device with a power of 100 W and a treatment time of 8 minutes to enhance the activity of the material surface and improve the adsorption and bonding strength between the PEDOT:PSS-PVA hydrogel and the PDMS film, as well as between the circuit and the PDMS film.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1) The prepared flexible dual-modal sensor material can accurately and synchronously acquire temperature and pressure signals at the knee joint, with excellent sensitivity and linear dynamic range, facilitating real-time monitoring and early warning of bone and soft tissue infections.

[0039] 2) The material of the present invention has excellent flexibility, strong ability to conform to biological surfaces, improved wearing comfort, and can withstand multiple large-scale flexion and extension and shearing of joints, greatly expanding its applicability in complex clinical application environments and facilitating long-term, dynamic monitoring;

[0040] 3) The structure composed of PEDOT:PSS hydrogel and silver electrodes is highly biocompatible and low-irritating, significantly reducing the risk of adverse skin reactions in patients. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a physical picture of the flexible sensor for convenient monitoring of bone and soft tissue infection in the present invention;

[0042] Figure 2 The performance test results of the temperature sensor element in the present invention;

[0043] Figure 3 This is a diagram showing the test results of tactile detection and temperature calculation in the present invention;

[0044] Figure 4 This is a performance test result diagram of the pressure sensing element in the present invention;

[0045] Figure 5 This is a temperature drift compensation characteristic diagram of the present invention;

[0046] Figure 6 This is a graph showing the cyclic stability test results of the pressure sensing element of the present invention;

[0047] Figure 7 This is a schematic flow chart of the preparation method of the hydrogel-based dual-modal flexible monitoring sensor for joint infection in the present invention. DETAILED DESCRIPTION

[0048] Overall, this invention addresses the technical challenges of existing diagnostic methods for bone and soft tissue infections, such as low sensitivity, poor real-time performance, and difficulty adapting to dynamic monitoring of complex areas such as joints. It provides a flexible dual-modal (pressure-temperature) sensor material based on PEDOT:PSS-PVA (poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate-polyvinyl alcohol) hydrogel and its preparation method. This sensor can achieve highly sensitive, real-time, and synchronized pressure and temperature signal detection on complex biological curved surfaces such as the knee joint, significantly improving the efficiency and accuracy of early diagnosis of bone and soft tissue infections and expanding the application scenarios of clinical dynamic monitoring.

[0049] In practice, the flexible sensor for conveniently monitoring bone and soft tissue infections comprises a sandwich structure formed by combining a sensor layer and a flexible film. The sensing elements, including a first sensing element (pressure sensing module) and a second sensing element (temperature sensing module), are disposed on a flexible film base layer and are connected to corresponding stretchable silver circuits. The first and second sensing elements are configured to share a common cathode. A flexible film encapsulation layer is disposed above the sensing elements and circuit.

[0050] In a specific implementation, the first sensing element is a PEDOT:PSS-PVA hydrogel, which can be prepared using conventional PEDOT:PSS (poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate) and PVA (polyvinyl alcohol) materials without special restrictions.

[0051] In a specific implementation, the PEDOT:PSS ratio is 1:2.5 w / w, the solid content is 1.0-1.3 wt %, and a deionized water-DMSO mixture (85:15 v / v) is added and mixed thoroughly.

[0052] In a specific implementation, PVA powder was added to deionized water and stirred at 90°C until completely dissolved;

[0053] In specific implementation, the samples were filtered separately at room temperature using a syringe through a disposable filter with a pore size of 0.45 μm.

[0054] In a specific implementation, a PEDOT:PSS-PVA ink was prepared, and the mass ratio of 7% PEDOT:PSS solution to 7% PVA solution was 2:3, and the solution was stirred at room temperature until it was completely dissolved.

[0055] To prepare the crosslinking bath, deionized water and anhydrous ethanol (70:30 v / v) were mixed, 2 g of calcium chloride granules were added, and stirred until completely dissolved. Before use, all crosslinking baths were stirred for 2 hours and cooled to the reaction temperature.

[0056] In a specific implementation, a low-temperature printing program is set up. The printing program is performed by using a 3D printer;

[0057] In a specific implementation, the structure printed by the hydrogel ink is immersed in a crosslinking bath at -5°C for 12 hours;

[0058] In a specific implementation, after cross-linking is completed, the formed hydrogel is washed several times with deionized water at 5° C. to remove excess reagents, and then swelled for 24 hours to reach an equivalent state to obtain a PEDOT:PSS-PVA hydrogel.

[0059] In a specific implementation, the second sensing element is an NTC thermistor silver paste, which can be prepared using conventional nano-scale thermistor ceramic powder, silver powder and other materials without special restrictions.

[0060] In a specific implementation, the flexible film base layer and the flexible film encapsulation layer are both PDMS films, which can be prepared using conventional PDMS and a cross-linking agent without any special restrictions.

[0061] In a specific implementation, PDMS and a cross-linking agent were mixed in a ratio of 10:1, stirred evenly with a magnetic stirrer (speed 1000 rpm) for 2 hours, and then placed in a vacuum pressure device for degassing.

[0062] In a specific implementation, the PDMS solution is poured into a mold and placed in an oven at 80° C. until completely cured.

[0063] During the specific implementation, the prepared PDMS film was cut into rectangles of 40 mm×15 mm.

[0064] In a specific implementation, the prepared PEDOT:PSS-PVA hydrogel and PDMS film were subjected to plasma surface treatment for 8 minutes (power 100W) to improve adsorption.

[0065] During specific implementation, the plasma processing equipment is a plasma surface treatment machine.

[0066] In a specific implementation, a 3D printer based on direct ink writing is used to print NTC thermistor silver paste and a stretchable conductive silver circuit on a PDMS film substrate layer, wherein the negative electrode circuits of the first sensing element and the second sensing element are fused at the end point.

[0067] In a specific implementation, the prepared PEDOT:PSS-PVA hydrogel is adhered to the upper layer of the stretchable conductive silver circuit on the PDMS film base layer.

[0068] During specific implementation, the prepared PDMS thin film encapsulation layer is used to encapsulate the base layer and the sensor layer.

[0069] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. Component models, material names, connection structures, circuit structures, control methods, algorithms, and other features not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0070] Example 1

[0071] This example first designs and mixes PEDOT:PSS and PVA solutions to form a uniform hydrogel ink, laying the foundation for the sensor's pressure module. Next, the hydrogel ink is printed using low-temperature cross-linking 3D printing technology and treated in a specific low-temperature cross-linking bath to achieve stable hydrogel structure performance. This process meticulously controls the degree of cross-linking and structural morphology of the material, ensuring high sensitivity and stability of the pressure sensor. Simultaneously, the PDMS film is prepared through precise proportioning of PDMS and cross-linking agents, followed by degassing and curing, resulting in a film with excellent flexibility and mechanical properties. This not only provides good flexibility and conformability for the sensor but also helps improve temperature sensing accuracy. To print the circuit and temperature sensing element, direct ink writing 3D printing technology is used to precisely print the NTC thermistor silver paste and stretchable conductive silver circuit onto the PDMS film substrate, achieving precise circuit construction and excellent conductivity, ensuring efficient signal transmission. Finally, the components are integrated and assembled, and plasma surface treatment is used to enhance the bonding between the materials, forming a stable "sandwich" structure, which gives the sensor excellent mechanical properties and stable signal transmission capabilities. This series of preparation steps work together to form an efficient preparation method for the sensor, enabling it to accurately monitor pressure and temperature changes in the joint area, providing strong support for early warning and diagnosis of bone and soft tissue infections.

[0072] See also Figure 7 In this embodiment, a flexible dual-modal (pressure-temperature) sensor material based on PEDOT:PSS-PVA (poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate-polyvinyl alcohol) hydrogel and a preparation method thereof include the following steps:

[0073] Prepare the required materials and assemble the flexible sensor:

[0074] Material preparation: PEDOT:PSS (PH 1000, Ossila); PVA powder (363170, Sigma-Aldrich); deionized water; DMSO (HY-Y0320C, MCE); anhydrous ethanol (Yonghua Chemical); calcium chloride particles (C290953, Aladdin); PDMS and crosslinker (Dow Corning).

[0075] Preparation of PEDOT:PSS-PVA ink: Add PEDOT:PSS to a deionized water-DMSO mixture (85:15 v / v) and mix thoroughly to prepare a 7% PEDOT:PSS solution. Add PVA powder to deionized water and stir at 90°C until completely dissolved to prepare a 7% PVA solution. Filter the PEDOT:PSS solution and PVA solution separately through a 0.45 μm pore size disposable filter using a syringe at room temperature. Mix the 7% PEDOT:PSS solution with the 7% PVA solution in a 2:3 mass ratio and stir at room temperature until completely dissolved to form a uniform hydrogel ink.

[0076] Prepare the crosslinking bath: Mix deionized water and anhydrous ethanol at a ratio of 70:30 (v / v). Add 2g of calcium chloride granules and stir until completely dissolved. Stir the crosslinking bath for 2 hours and cool to -5°C before use.

[0077] Low-temperature cross-linking 3D printing: Using a direct ink writing 3D printer, the hydrogel structure was printed according to the designed pattern. The printed structure was immersed in a -5°C cross-linking bath and cross-linked continuously for 12 hours. After cross-linking, the formed hydrogel was washed several times with deionized water at 5°C to remove excess reagents and then swelled for 24 hours to achieve an equivalent state, resulting in a PEDOT:PSS-PVA hydrogel.

[0078] Prepare the PDMS film: Mix PDMS and crosslinker in a 10:1 mass ratio and stir evenly with a magnetic stirrer (1000 rpm) for 2 hours. Remove bubbles by placing the mixed PDMS solution in a vacuum press. Pour the PDMS solution into a mold and cure in an 80°C oven until fully cured. Cut the prepared PDMS film into 40 mm x 15 mm rectangles.

[0079] Surface treatment: The prepared PEDOT:PSS-PVA hydrogel and PDMS film were subjected to plasma surface treatment for 8 minutes (power 100 W) to improve the adsorption between the materials.

[0080] Printing of circuits and temperature sensing elements: Using a direct ink writing-based 3D printer, NTC thermistor silver paste (as a temperature module) and a stretchable conductive silver circuit are printed on the PDMS film substrate layer. The negative electrode circuits of the first sensing element (pressure module) and the second sensing element (temperature module) are fused at the end point to achieve a shared negative electrode design.

[0081] Flexible sensor assembly: The prepared PEDOT:PSS-PVA hydrogel (as a pressure module) is adhered to the upper layer of the stretchable conductive silver circuit of the PDMS film substrate. The prepared PDMS film encapsulation layer is covered on the substrate layer and the sensor layer to form a "sandwich" sandwich structure. The actual structure is as follows Figure 1 shown.

[0082] The technical principle behind the hydrogel-based flexible dual-modal joint infection monitoring sensor in this embodiment is primarily based on its unique structural design and material properties. The sensor utilizes a "sandwich" structure, consisting of a flexible film substrate, an encapsulation layer, and a sensing element positioned within. The sensing element comprises two modules, one for detecting pressure and the other for detecting temperature.

[0083] The pressure module utilizes PEDOT:PSS-PVA hydrogel, a material with excellent electrical conductivity and mechanical properties. This material responds to external pressure, enabling the sensor to detect pressure signals. The temperature module utilizes NTC thermistor silver paste, a material sensitive to temperature changes that can convert temperature changes into electrical signals, thus enabling temperature monitoring. Furthermore, the cathode circuits of the two modules are fused at the endpoint, achieving a shared cathode design and simplifying the circuit layout.

[0084] In practical applications, when the sensor is attached to the knee joint, it can sense changes in pressure and temperature in the joint in real time. If an abnormal temperature rise or pressure distribution is detected, the system will issue a warning signal, indicating the risk of bone and soft tissue infection. This dual-modal monitoring design can effectively improve the efficiency and accuracy of early diagnosis, providing a reliable tool for dynamic clinical monitoring of bone and soft tissue infections.

[0085] Test Example 1

[0086] Performance test of the prepared sensor:

[0087] like Figure 2 As shown in (left), the temperature sensing module shows excellent linear response (R 2 =0.99), the sensitivity reaches 3.23%℃-1, such as Figure 2 (Right) shows the continuous breathing monitoring data in a 25°C environment. The temperature sensing module in Example 1 can achieve continuous breathing monitoring in a 25°C environment.

[0088] Apply tactile stimulation to the sensor by touching it with an artificial finger, and use a data acquisition system (such as a multi-channel data acquisition instrument) to synchronously collect the tactile signal and temperature signal output by the sensor to observe its response to the tactile event and its ability to synchronously resolve the temperature signal. Figure 3As shown in the demonstration (demonstrating the sensor's dynamic response to tactile stimulation and the synchronous calculation of temperature signals during finger touch / removal events), the sensor can accurately detect tactile events (finger touch / removal) and simultaneously calculate temperature signals, demonstrating the collaborative working ability of the dual-modal function.

[0089] Use a high-precision pressure source (such as a precision pressure pump, micro pressure controller, etc.) to apply a small pressure change, and use a high-precision capacitance measuring instrument (such as a precision capacitance meter, capacitance tester, etc.) to measure the capacitance change of the sensor to determine its minimum pressure resolution value and capacitance baseline. Figure 4 The minimum pressure resolution of the sensor is shown to be 0.12g, and the pressure sensor capacitance baseline is ~8.5nF.

[0090] The sensor is placed in an environment where temperature changes can be precisely controlled (such as a temperature test chamber) and temperature cycles are performed within the range of 30-45°C. Meanwhile, the output signal of the pressure module (such as changes in capacitance value) and the output signal of the temperature sensor are monitored in real time. The temperature drift rate and linearity of the pressure module are evaluated through a data acquisition and analysis system (such as computer-controlled data acquisition and analysis software), and the temperature drift compensation effect of the temperature sensor on the pressure signal is verified. Figure 5 The temperature drift compensation characteristic diagram shows the temperature drift rate (0.31% / °C) and linearity (R 2 =0.998), illustrating the method of signal decoupling through temperature sensor.

[0091] Using a fatigue test device that can apply periodic pressure changes (such as a mechanical fatigue tester, a pressure cycle test system, etc.), apply 2000 strain cycles (1.5kPa / time) to the pressure sensing unit, and use a capacitance measuring instrument (such as a capacitance meter) to monitor the capacitance change after each cycle in real time to evaluate its cyclic stability. Figure 6 As shown, after 2000 strain cycles, the capacitance of the pressure sensing unit decreases but remains stable.

[0092] Finally, the sensor product of Example 1 was used to monitor bone and soft tissue infection:

[0093] Clean the skin on the patient's knee joint. Figure 1 The flexible sensor shown is attached to the knee joint. The sensor transmits pressure and temperature signals to a monitoring device (E4980AL Precision LCR Meter, Keysight) via an integrated stretchable conductive silver circuit.

[0094] Real-time monitoring: The system records and analyzes temperature and pressure changes in the knee joint in real time. If an abnormal temperature rise (e.g., exceeding 38°C) or abnormal pressure distribution is detected, the system will issue an early warning signal, indicating a possible bone or soft tissue infection.

[0095] Clinical verification: Clinical experiments have shown that the sensor has good detection capabilities for temperature increases and pressure changes in the early stages of bone and soft tissue infection, giving early warning signals.

[0096] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A hydrogel-based dual-modal flexible monitoring sensor for joint infection, characterized in that: It includes a sensor layer, a flexible film base layer, and a flexible film encapsulation layer; The sensor layer includes a first sensing element and a second sensing element, wherein the first sensing element is a pressure sensing element and the second sensing element is a temperature sensing element; The first sensor element and the second sensor element are both provided on the flexible film base layer, the first sensor element and the second sensor element share a negative electrode, the positive electrodes of the first sensor element and the second sensor element are respectively connected to corresponding signal input terminals of an external signal monitoring device, and the flexible film encapsulation layer is used to encapsulate the sensor layer and the flexible film base layer; The first sensing element is PEDOT:PSS-PVA hydrogel, the second sensing element is NTC thermistor silver paste, and the flexible film base layer and the flexible film encapsulation layer are both PDMS films; The sensor realizes dynamic monitoring of joint infection by synchronously calculating temperature and pressure signals.

2. The hydrogel-based dual-modal flexible joint infection monitoring sensor according to claim 1, characterized in that: The flexible thin film packaging layer packages the sensor layer and the substrate layer from above and below to form a sandwich packaging structure.

3. The hydrogel-based dual-modal flexible joint infection monitoring sensor according to claim 1, characterized in that: The positive electrode and the negative electrode of the first sensing element and the second sensing element are respectively connected to a stretchable silver circuit.

4. The hydrogel-based dual-modal flexible joint infection monitoring sensor according to claim 1, characterized in that: The PEDOT:PSS-PVA hydrogel is prepared by mixing a PEDOT:PSS solution with a PVA solution, and the solvent is a deionized water-DMSO mixture.

5. The hydrogel-based dual-modal flexible joint infection monitoring sensor according to claim 4, characterized in that: The PEDOT:PSS-PVA hydrogel is prepared by mixing a 7wt% PEDOT:PSS solution and a 7wt% PVA solution in a mass ratio of 2:3, and the solvent is a deionized water-DMSO mixture.

6. A method for preparing a hydrogel-based dual-modal flexible joint infection monitoring sensor according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1, mixing PEDOT:PSS and PVA solution to form a uniform hydrogel ink; S2, using the hydrogel ink as a raw material, printing the hydrogel structure using a direct ink writing 3D printer, and immersing the hydrogel structure in a cross-linking bath for low-temperature cross-linking. After cross-linking, washing and swelling are performed to obtain a PEDOT:PSS-PVA hydrogel; S3, mixing PDMS and a cross-linking agent, removing bubbles, pouring into a mold for curing, and cutting into PDMS films of a specified size; S4. Plasma surface treatment of PEDOT:PSS-PVA hydrogel and PDMS film to improve the adsorption between the materials; S5, laying out an NTC thermistor and a stretchable conductive silver circuit on the PDMS film substrate, wherein the PEDOT:PSS-PVA hydrogel and the negative electrode circuit of the NTC thermistor are fused at the circuit end point; S6. The PEDOT:PSS-PVA hydrogel is adhered to the upper layer of the stretchable conductive silver circuit of the PDMS film substrate layer, and then the PDMS film encapsulation layer is covered on the substrate layer and the sensor layer to form a sandwich encapsulation structure.

7. The method for preparing a hydrogel-based dual-modal flexible joint infection monitoring sensor according to claim 6, characterized in that: In S1, the specific process of mixing the PEDOT:PSS and PVA solution includes: PEDOT:PSS was added to a deionized water-DMSO mixture with a mass ratio of PEDOT to PSS of 1:2.5 and mixed thoroughly to prepare a solution; PVA powder was added to deionized water and stirred at 90°C until completely dissolved to prepare a 7% PVA solution; The PEDOT:PSS solution and PVA solution were filtered through a disposable filter with a pore size of 0.45 μm using a syringe; 7% PEDOT:PSS solution and 7% PVA solution were mixed at a mass ratio of 2:3 and stirred at room temperature until completely dissolved to form a uniform hydrogel ink.

8. The method for preparing a hydrogel-based dual-modal flexible joint infection monitoring sensor according to claim 6, characterized in that: In S2, the crosslinking bath is prepared by mixing deionized water, anhydrous ethanol and calcium chloride particles; The crosslinking bath was stirred for 2 hours and cooled to -5°C before use; The low temperature cross-linking specifically includes: The printed hydrogel structure was immersed in a cross-linking bath at −5 °C for 12 h; After cross-linking, the formed hydrogels were washed several times with deionized water at 5 °C to remove excess reagents and then swelled for 24 h to reach an equivalent state.

9. The method for preparing a hydrogel-based dual-modal flexible joint infection monitoring sensor according to claim 6, characterized in that: In S3, the mass mixing ratio of the PDMS and the cross-linking agent is 10:1; after stirring, removing bubbles, pouring into a mold and curing the mixture include: After uniform stirring at 1000 rpm with a magnetic stirrer for 2 hours, the mixture was placed in a vacuum pressure device for defoaming; The degassed PDMS solution was poured into the mold and cured in an oven at 80°C until fully cured.

10. The method for preparing a hydrogel-based dual-modal flexible joint infection monitoring sensor according to claim 6, characterized in that: In S4, the plasma surface treatment process of the PEDOT:PSS-PVA hydrogel and the PDMS film includes: The PEDOT:PSS-PVA hydrogel and PDMS film were placed in a plasma treatment device with a power of 100 W and a treatment time of 8 minutes to enhance the activity of the material surface and improve the adsorption and bonding strength between the PEDOT:PSS-PVA hydrogel and the PDMS film, as well as between the circuit and the PDMS film.

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