Temperature-strain dual function sensor for extracorporeal circulation system monitoring

Abstract

The application discloses a temperature-strain dual-function sensor for extracorporeal circulation system monitoring, and relates to the technical field of flexible electronics and biomedical engineering. The sensor adopts a three-layer stacking structure, and comprises, from top to bottom, a piezoresistive strain response layer based on a silver / graphene / poly(3,4-ethylenedioxythiophene):polystyrene sulfonate composite conductive film, a thermoplastic polyurethane nanofiber heat insulation isolation layer and a temperature sensitive layer based on a graphene / poly(3,4-ethylenedioxythiophene):polystyrene sulfonate composite conductive hydrogel. The temperature-strain dual-function sensor for extracorporeal circulation system monitoring prepared by the application exhibits high sensitivity and fast response characteristics in temperature and strain sensing, and simultaneously exhibits excellent cycle stability and long-term reliability under repeated deformation.

Description

Technical Field

[0001] This invention belongs to the field of flexible electronics and biomedical engineering technology, specifically relating to a flexible dual-function sensor for multi-parameter monitoring in an extracorporeal circulation system, and particularly an integrated sensor that can achieve complete spatial decoupling of temperature and strain signals. Background Technology

[0002] In the treatment of cardiovascular diseases, artificial hearts and extracorporeal circulation systems are key devices. Within these systems, blood flow pressure (or strain) and temperature are crucial parameters reflecting system stability and physiological state. Existing rigid or single-function sensors struggle to achieve simultaneous height detection of curved surfaces and multiple physical signals, and often suffer from temperature-strain signal crosstalk, affecting detection accuracy and real-time performance.

[0003] Therefore, there is an urgent need for a flexible, multifunctional sensor with adjustable structure and non-interfering signals to achieve synchronous decoupled detection of temperature and strain. Summary of the Invention

[0004] To overcome the problems of signal crosstalk, insufficient structural rigidity and multi-parameter detection capability in existing technologies, this invention provides a fully decoupled flexible temperature-strain dual-function sensor with a three-layer partitioned structure, which can achieve independent detection of temperature and strain signals in an extracorporeal circulation system without interference between them.

[0005] To solve the above-mentioned technical problems, the present invention provides the following solution: This invention provides a temperature-strain dual-function sensor for monitoring extracorporeal circulation systems. The temperature-strain dual-function sensor includes a temperature-sensitive layer, a thermal insulation layer, and a strain response layer stacked sequentially from bottom to top. The temperature-sensitive layer is composed of graphene (G) / poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) composite conductive gel. The thermal insulation layer is composed of a thermoplastic polyurethane (TPU) nanofiber membrane; The strain-response layer is composed of a silver paste / G / PEDOT:PSS composite conductive film; Through a three-layer vertical hierarchical integrated structure, spatial independent decoupling and electrical independent output of temperature and strain signals are achieved, effectively avoiding deformation errors and Joule thermal interference caused by temperature changes.

[0006] A method for fabricating a temperature-strain dual-function sensor for monitoring extracorporeal circulation systems includes the following steps: (1) Preparation of G / PEDOT:PSS composite conductive gel temperature-sensitive layer; (2) Preparation of TPU nanofiber thermal insulation layer; (3) Preparation of a silver paste / G / PEDOT:PSS composite conductive thin film strain response layer; (4) The three-layer structure is assembled by layered lamination and flexible bonding, and an independent electrical signal output path is formed.

[0007] As an optimization, the preparation method of the temperature-sensitive layer of the G / PEDOT:PSS composite conductive gel in step (1) is as follows: 0.5 mg / mL graphene dispersion, 1.1~1.3 wt% PEDOT:PSS solution, 10 wt% PVA aqueous solution and BMImBF4 are mixed in a mass ratio of 1.25:5:4:(0.1~0.3), and stirred at 25~30℃ for 20~40 min to obtain a mixed solution; acrylic acid, sodium hydroxide, MBA, APS and deionized water are mixed in a mass ratio of 1:0.2:0.006:0 Mix 0.018:1.5 and stir at 25~30℃ until completely dissolved to obtain a basic gel solution; mix the mixed solution and the basic gel solution at a volume ratio of 3:1 to obtain a composite conductive gel precursor solution; add 0.3 parts of 10wt% gelatin dispersion and 0.015 parts of tetramethylethylenediamine to one part of the composite conductive gel precursor solution, stir at 25~30℃ for 20~40 min, then irradiate under a 200W, 365nm UV lamp for 3 h, vacuum dry and anneal to obtain a three-dimensional porous G / PEDOT:PSS composite conductive gel.

[0008] As an optimization, the annealing treatment is carried out in a DZF type vacuum drying oven at a temperature of 60~80℃ for 1.5~2.5h.

[0009] As an optimization, the concentration of the gelatin dispersion was 10 wt%, purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0010] As an optimization, the preparation method of the TPU nanofiber thermal insulation layer in step (2) is as follows: TPU particles are dissolved in N,N-dimethylformamide at a mass ratio of 10wt% to obtain a TPU solution; the TPU solution is placed in an electrospinning machine and electrospinned under the conditions of voltage 15~20kV, flow rate 0.5~0.7mL / h, and electrode distance 15cm to obtain a TPU nanofiber thermal insulation layer; the thickness of the TPU nanofiber thermal insulation layer is 80~150μm.

[0011] As an optimization, the preparation method of the silver paste / G / PEDOT:PSS composite conductive film strain response layer in step (3) is as follows: Weigh the raw materials according to the following mass parts: 2 parts of non-stretchable silver paste, 1 part of 0.5 mg / mL graphene dispersion, 1 part of 1.1~1.3 wt% PEDOT:PSS solution, and 0.4 parts of 10 wt% PVA aqueous solution. Pattern the non-stretchable silver paste on the surface of the TPU nanofiber thermal insulation layer using screen printing technology to form a preliminary conductive network. After drying, apply the first mechanical pre-stretching. A first mechanically pre-stretched film was prepared by stretching the film with a strain of 5%–15%. A mixture of graphene dispersion, PEDOT:PSS solution, and PVA aqueous solution was sprayed onto the surface of the first mechanically pre-stretched film, covering the silver paste area and drying it. A second small-scale pre-stretching was then performed with a strain of 5%–15% to obtain the second pre-stretched film. Stretchable silver paste was then screen-printed onto the electrode connection areas at both ends of the second pre-stretched film surface, with a wet film thickness controlled at 15–25 μm, equivalent to a unit area mass of approximately 2–4 mg / cm². 2 A strain-responsive silver paste / G / PEDOT:PSS composite conductive thin film was prepared.

[0012] As an optimization, the graphene dispersion concentration was 0.5 mg / mL, purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.; the PEDOT:PSS solution concentration was 1.1~1.3 wt%, purchased from Zhuhai Kaiwei New Materials Technology Co., Ltd.; and the polyvinyl alcohol (PVA) was type 1799 polyvinyl alcohol with a degree of alcoholysis of 98~99% (mol / mol), purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0013] As an optimization, the spraying step adopts uniform layer spraying with a spray gun, the air pressure is 0.2~0.3MPa, and the spraying distance is 15~20cm; the non-stretchable silver paste is purchased from Shanghai McLean Biochemical Technology Co., Ltd.; the stretchable silver paste is LX-30 epoxy conductive adhesive, purchased from Nanjing Chuangyiyou Electronic Technology Co., Ltd.

[0014] As an optimization, the layering and lamination step in step (4) is as follows: the TPU nanofiber membrane is used as the intermediate layer and placed between the temperature-sensitive layer of the G / PEDOT:PSS composite conductive gel and the strain response layer of the silver paste / G / PEDOT:PSS composite conductive film; a uniform pressure of 0.2MPa is applied at 70°C, and after holding the pressure for 10 minutes, it is cooled to 25~30°C under the pressure holding condition, and electrodes are independently led out for the temperature-sensitive layer and the strain response layer to form signal output ports that do not interfere with each other.

[0015] As an optimization, the temperature-strain dual-function sensor for monitoring the extracorporeal circulation system exhibits excellent performance indicators: a Seebeck coefficient of 0.002 V / ℃ for temperature detection and a strain coefficient as high as 3.13 × 10⁻⁶. 5 The cycle stability retention rate exceeds 95%.

[0016] As an optimization, the temperature-strain dual-function sensor for monitoring the extracorporeal circulation system can be integrated into an artificial heart or extracorporeal circulation device to achieve synchronous detection and real-time monitoring of temperature and strain signals; and maintain signal independence and stable output within the range of 0~30% deformation and 0~40℃ temperature.

[0017] Compared with the prior art, the beneficial effects achieved by the present invention are: This invention effectively solves the long-standing technical challenge of crosstalk between temperature and strain signals in flexible integrated sensors through a spatial and electrical decoupling design. Its core lies in employing a unique material and structural co-design to construct a mechanically interconnected yet electrically independent hierarchical architecture: the temperature sensing unit based on the Seebeck effect exhibits good strain insensitivity, while the strain sensing unit based on a crack resistance modulation mechanism possesses high responsivity. The two are isolated by a functional intermediate layer, thus achieving complete decoupling of temperature and strain sensing in both physical space and signal path, ensuring the independence and purity of the signal output.

[0018] Thanks to the aforementioned design, this sensor achieves significant improvements in overall performance. Both its temperature and strain sensing exhibit high sensitivity and rapid response characteristics, while the device demonstrates excellent cyclic stability and long-term reliability under repeated deformation. This high performance enables the sensor to achieve high-precision, real-time synchronous monitoring of temperature and strain parameters in complex dynamic scenarios simulating the human physiological environment. Attached Figure Description

[0019] Figure 1 This is a schematic diagram illustrating the overall structure and working principle of the temperature-strain dual-function sensor of Embodiment 2 of the present invention; Figure 2 This is a process flow diagram of the fabrication of the temperature-strain dual-function sensor in Embodiment 2 of the present invention; Figure 3 The temperature sensing electrical performance curve of the temperature-sensitive layer in step (1) of embodiment 2 of the present invention; Figure 4 The output curves of the temperature-sensitive layer under different temperature differences in step (1) of embodiment 2 of the present invention are shown. Figure 5 The image shows the morphological evolution of the microcrack network on the surface of the strain response layer under different tensile conditions in step (3) of Embodiment 2 of the present invention. Figure 6 This is a sensitivity curve of the relative resistance change of the strain response layer as strain increases in step (3) of embodiment 2 of the present invention; Figure 7 The resistance stability curve of the strain response layer in step (3) of embodiment 2 of the present invention under 10,000 cycles of tensile stress is shown. Figure 8 The graph shows the stability curve of the thermoelectric voltage of the temperature-strain dual-function sensor in Embodiment 2 of the present invention under different strains and the curve showing the effect of temperature on the IV properties of the strain layer. Figure 9 This is a schematic diagram of the integration of the temperature-strain dual-function sensor in an artificial circulatory system and the real-time monitoring results of Embodiment 2 of the present invention; wherein a is a schematic diagram of the integration of the temperature-strain dual-function sensor in the artificial circulatory system; b is a hardware connection and logic control diagram of the monitoring system; and c is a real-time synchronous monitoring curve under different physiological states. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1: A method for fabricating a temperature-strain dual-function sensor for monitoring extracorporeal circulation systems includes the following steps: (1) Mix 0.5 mg / mL graphene dispersion, 1.1~1.3 wt% PEDOT:PSS solution, 10 wt% PVA aqueous solution and BMImBF4 at a mass ratio of 1.25:5:4:0.1 and stir at 25℃ for 20 min to obtain a mixed solution; mix acrylic acid, sodium hydroxide, MBA, APS and deionized water at a mass ratio of 1:0.2:0.006:0.018:1.5 and stir at 25℃ until completely dissolved to prepare... A basic gel solution was obtained; the mixed solution and the basic gel solution were mixed at a volume ratio of 3:1 to obtain a composite conductive gel precursor solution; 0.3 parts of 10wt% gelatin dispersion and 0.015 parts of tetramethylethylenediamine were added to one part of the composite conductive gel precursor solution, stirred at 25℃ for 20 min, and then irradiated under a 200W, 365nm UV lamp for 3 h. After vacuum drying and annealing, a three-dimensional porous G / PEDOT:PSS composite conductive gel temperature sensitive layer was obtained. (2) TPU particles were dissolved in N,N-dimethylformamide at a mass ratio of 10wt% to obtain a TPU solution; the TPU solution was placed in an electrospinning machine and electrospinned under the conditions of 15kV voltage, 0.5mL / h flow rate and 15cm electrode distance to obtain a TPU nanofiber heat insulation layer. (3) Weigh the following raw materials according to the following mass proportions: 2 parts of non-stretchable silver paste, 1 part of 0.5 mg / mL graphene dispersion, 1 part of 1.1~1.3 wt% PEDOT:PSS solution, and 0.4 parts of 10 wt% PVA aqueous solution. Pattern the non-stretchable silver paste on the surface of the TPU nanofiber thermal insulation layer using screen printing technology to form a preliminary conductive network, and dry it. Apply the first mechanical pre-stretch to the film with the silver paste pattern, with a strain of 5%. Mix the graphene dispersion, PEDOT:PSS solution, and PVA aqueous solution and spray it onto the surface of the film after the first mechanical pre-stretch, covering the silver paste area and drying it. Perform a second small-amplitude pre-stretch, with a strain of 5%. Apply the stretchable silver paste to the electrode connection areas at both ends of the surface of the second pre-stretched film using screen printing technology. The wet film thickness is controlled at 15 μm, which is equivalent to a unit area mass of approximately 2 mg / cm². 2 A silver paste / G / PEDOT:PSS composite conductive thin film strain response layer was prepared; (4) Using TPU nanofiber membrane as the intermediate layer, place it between the temperature-sensitive layer of G / PEDOT:PSS composite conductive gel and the strain response layer of silver paste / G / PEDOT:PSS composite conductive film; apply a uniform pressure of 0.2MPa at 70℃, hold the pressure for 10min, and then cool it to 25℃ under pressure holding condition, and lead out electrodes independently for the temperature-sensitive layer and the strain response layer to form signal output ports that do not interfere with each other.

[0022] Example 2: (1) 0.5 mg / mL graphene dispersion, 1.1~1.3 wt% PEDOT:PSS solution, 10 wt% PVA aqueous solution and BMImBF4 were mixed in a mass ratio of 1.25:5:4:0.2 and stirred at 27℃ for 30 min to obtain a mixed solution; acrylic acid, sodium hydroxide, MBA, APS and deionized water were mixed in a mass ratio of 1:0.2:0.006:0.018:1.5 and stirred at 27℃ until completely dissolved to obtain a basic gel solution; the mixed solution and the basic gel solution were mixed in a volume ratio of 3:1 to obtain a composite conductive gel precursor solution; 0.3 parts of 10 wt% gelatin dispersion and 0.015 parts of tetramethylethylenediamine were added to one part of the composite conductive gel precursor solution, stirred at 27℃ for 30 min and then irradiated under a 365 nm UV lamp for 3 h, vacuum dried and annealed to obtain a three-dimensional porous G / PEDOT:PSS composite conductive gel temperature sensitive layer; (2) TPU particles were dissolved in N,N-dimethylformamide at a mass ratio of 10wt% to obtain a TPU solution; the TPU solution was placed in an electrospinning machine and electrospinned under the conditions of voltage 17.5kV, flow rate 0.6mL / h and electrode distance 15cm to obtain a TPU nanofiber heat insulation layer. (3) Weigh the following raw materials according to the following mass proportions: 2 parts of non-stretchable silver paste, 1 part of 0.5 mg / mL graphene dispersion, 1 part of 1.1~1.3 wt% PEDOT:PSS solution, and 0.4 parts of 10 wt% PVA aqueous solution. Pattern the non-stretchable silver paste on the surface of the TPU nanofiber thermal insulation layer using screen printing technology to form a preliminary conductive network, and dry it. Apply the first mechanical pre-stretch to the film with the silver paste pattern with a strain of 10%. Mix the graphene dispersion, PEDOT:PSS solution and PVA aqueous solution and spray it onto the surface of the film after the first mechanical pre-stretch, covering the silver paste area and drying it. Perform a second small pre-stretch with a strain of 10%. Apply the stretchable silver paste to the electrode connection area at both ends of the surface of the second pre-stretched film using screen printing technology. The wet film thickness is controlled at 15 μm, which is equivalent to a unit area mass of approximately 2 mg / cm². 2 A silver paste / G / PEDOT:PSS composite conductive thin film strain response layer was prepared; (4) Using TPU nanofiber thermal insulation layer as the intermediate layer, it is placed between the G / PEDOT:PSS composite conductive gel temperature sensitive layer and the silver paste / G / PEDOT:PSS composite conductive film strain response layer through low temperature lamination process, so that the three layers are composited into one, and electrodes are independently led out for the temperature sensitive layer and the strain response layer to form a signal output port that does not interfere with each other, thus obtaining a temperature-strain dual-function sensor for monitoring the extracorporeal circulation system.

[0023] Example 3: (1) 0.5 mg / mL graphene dispersion, 1.1~1.3 wt% PEDOT:PSS solution, 10 wt% PVA aqueous solution and BMImBF4 were mixed in a mass ratio of 1.25:5:4:0.3 and stirred at 30℃ for 40 min to obtain a mixed solution; acrylic acid, sodium hydroxide, MBA, APS and deionized water were mixed in a mass ratio of 1:0.2:0.006:0.018:1.5 and stirred at 30℃ until completely dissolved to obtain a basic gel solution; the mixed solution and the basic gel solution were mixed in a volume ratio of 3:1 to obtain a composite conductive gel precursor solution; 0.3 parts of 10 wt% gelatin dispersion and 0.015 parts of tetramethylethylenediamine were added to one part of the composite conductive gel precursor solution, stirred at 30℃ for 40 min and then irradiated under a 365 nm UV lamp for 3 h, vacuum dried and annealed to obtain a three-dimensional porous G / PEDOT:PSS composite conductive gel temperature sensitive layer; (2) TPU particles were dissolved in N,N-dimethylformamide at a mass ratio of 10wt% to obtain a TPU solution; the TPU solution was placed in an electrospinning machine and electrospinned under the conditions of 20kV voltage, 0.7mL / h flow rate and 15cm electrode distance to obtain a TPU nanofiber heat insulation layer. (3) Weigh the following raw materials according to the following mass proportions: 2 parts of non-stretchable silver paste, 1 part of 0.5 mg / mL graphene dispersion, 1 part of 1.1~1.3 wt% PEDOT:PSS solution, and 0.4 parts of 10 wt% PVA aqueous solution. Pattern the non-stretchable silver paste on the surface of the TPU nanofiber thermal insulation layer using screen printing technology to form a preliminary conductive network, and dry it. Apply the first mechanical pre-stretch to the film with the silver paste pattern, with a strain of 15%. Mix the graphene dispersion, PEDOT:PSS solution, and PVA aqueous solution and spray it onto the surface of the film after the first mechanical pre-stretch, covering the silver paste area and drying it. Perform a second small-amplitude pre-stretch, with a strain of 15%. Apply the stretchable silver paste to the electrode connection areas at both ends of the surface of the second pre-stretched film using screen printing technology. The wet film thickness is controlled at 15 μm, which is equivalent to a unit area mass of approximately 2 mg / cm². 2 A silver paste / G / PEDOT:PSS composite conductive thin film strain response layer was prepared; (4) Using TPU nanofiber thermal insulation layer as the intermediate layer, it is placed between the G / PEDOT:PSS composite conductive gel temperature sensitive layer and the silver paste / G / PEDOT:PSS composite conductive film strain response layer through low temperature lamination process, so that the three layers are composited into one, and electrodes are independently led out for the temperature sensitive layer and the strain response layer to form a signal output port that does not interfere with each other, thus obtaining a temperature-strain dual-function sensor for monitoring the extracorporeal circulation system.

[0024] Test Example 1: Performance Test of Temperature Sensing Unit like Figure 3 As shown, high-sensitivity temperature measurement is achieved based on the Seebeck effect of G / PEDOT:PSS composite conductive gel, with a Seebeck coefficient of 0.002V / °C, a response time of 8.9 seconds, and a recovery time of 11.8 seconds.

[0025] like Figure 4 As shown, the G / PEDOT:PSS composite conductive gel exhibits stable output within the temperature range of 3.4~18.8°C.

[0026] Test Example 2: Performance Testing of Strain Sensing Unit like Figure 5 As shown in the figure, the strain sequence from 0% to 15% illustrates the crack-induced resistance regulation mechanism: as the degree of stretching increases, microcracks open inside the conductive layer, leading to a significant change in resistance; after unloading, the cracks close and the resistance recovers.

[0027] like Figure 6 As shown, the crack control mechanism of the silver paste / G / PEDOT:PSS composite conductive film achieves crack strength of 3.13 × 10⁻⁶ in both low strain (0–10%) and high strain (10–30%) ranges. 5 and 2.87×10 6 It has an ultra-high strain sensitivity coefficient and a response time of only 1.51 seconds.

[0028] like Figure 7 As shown, the silver paste / G / PEDOT:PSS composite conductive thin film strain response layer retains more than 95% of its performance after 10,000 cycles of loading, demonstrating good durability and fatigue resistance.

[0029] Test Example 3: Performance Test of Decoupling Temperature and Strain Signals like Figure 8 As shown, temperature changes only affect the thermoelectric unit output, and the thermoelectric signal remains stable within the strain range of 0–30%; strain changes only affect the resistance output, and the resistance response remains unaffected within the temperature range of 0.8–18.8°C. This bidirectional decoupling characteristic is achieved through layered structural design and material synergy, fundamentally eliminating the signal crosstalk problem in traditional dual-function sensors.

[0030] Test Example 4: Integration and Real-time Monitoring of Sensors in an Artificial Circulation System like Figure 9 As shown, the sensor was integrated into an in vitro simulated circulatory loop, successfully and synchronously monitoring tubing deformation and temperature changes under different physiological states (resting / exercise). The correlation coefficient between the sensor output signal and the system's standard pressure / temperature sensor data was >0.98, verifying its reliability in dynamic physiological environments.

[0031] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended technical solutions rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the technical solutions are intended to be included within the present invention.

Claims

1. A temperature-strain dual-function sensor for monitoring extracorporeal circulation systems, characterized in that, The temperature-strain dual-function sensor includes a strain response layer, a thermal insulation layer, and a temperature sensitive layer stacked from top to bottom. The strain-response layer is composed of a silver paste / G / PEDOT:PSS composite conductive film; The thermal insulation layer is composed of a thermoplastic polyurethane (TPU) nanofiber membrane; The temperature-sensitive layer is composed of a graphene (G) / poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) composite conductive gel.

2. A method for fabricating a temperature-strain dual-function sensor for monitoring an extracorporeal circulation system as described in claim 1, characterized in that, Includes the following steps: (1) Preparation of G / PEDOT:PSS composite conductive gel temperature-sensitive layer; (2) Preparation of TPU nanofiber thermal insulation layer; (3) Preparation of a silver paste / G / PEDOT:PSS composite conductive thin film strain response layer; (4) The three-layer structure is assembled by layered lamination and flexible bonding, and an independent electrical signal output path is formed.

3. The preparation method according to claim 2, characterized in that, The preparation method of the temperature-sensitive layer of the G / PEDOT:PSS composite conductive gel in step (1) is as follows: 0.5 mg / mL graphene dispersion, 1.1~1.3 wt% PEDOT:PSS solution, 10 wt% polyvinyl alcohol (PVA) aqueous solution and 1-butyl-3-methylimidazolium tetrafluoroborate (BMImBF4) are mixed in a mass ratio of 1.25:5:4:(0.1~0.3) and stirred at 25~30℃ for 20~40 min to obtain a mixed solution; acrylic acid, sodium hydroxide, N,N'-methylenebisacrylamide (MBA), ammonium persulfate (APS) and desaturated sodium hydroxide are added to the mixture. Ionized water was mixed in a mass ratio of 1:0.2:0.006:0.018:1.5 and stirred at 25-30℃ until completely dissolved to obtain a basic gel solution. The mixed solution was mixed with the basic gel solution at a volume ratio of 3:1 to obtain a composite conductive gel precursor solution. 0.3 parts of 10wt% gelatin dispersion and 0.015 parts of tetramethylethylenediamine were added to one part of the composite conductive gel precursor solution. After stirring at 25-30℃ for 20-40 min, the mixture was irradiated under a 200W, 365nm UV lamp for 3 h, vacuum dried, and annealed to obtain a three-dimensional porous G / PEDOT:PSS composite conductive gel.

4. The preparation method according to claim 3, characterized in that, The annealing process is carried out in a DZF type vacuum drying oven at a temperature of 60~80℃ for 1.5~2.5h.

5. The preparation method according to claim 2, characterized in that, The preparation method of the TPU nanofiber thermal insulation layer in step (2) is as follows: TPU particles are dissolved in N,N-dimethylformamide at a mass ratio of 10wt% to obtain a TPU solution; the TPU solution is placed in an electrospinning machine and electrospinned under the conditions of voltage 15~20kV, flow rate 0.5~0.7mL / h, and electrode distance 15cm to obtain a TPU nanofiber thermal insulation layer; the thickness of the TPU nanofiber thermal insulation layer is 80~150μm.

6. The preparation method according to claim 2, characterized in that, The preparation method of the strain-response layer of the silver paste / G / PEDOT:PSS composite conductive film in step (3) is as follows: Weigh the raw materials according to the following mass parts: 2 parts of non-stretchable silver paste, 1 part of 0.5 mg / mL graphene dispersion, 1 part of 1.1~1.3 wt% PEDOT:PSS solution, and 0.4 parts of 10 wt% PVA aqueous solution. Pattern the non-stretchable silver paste on the surface of the TPU nanofiber heat insulation layer by screen printing to form a preliminary conductive network. After drying, apply the first mechanical pre-stretch with a strain of 5%~15% to obtain the first mechanical pre-stretched film. Mix the graphene dispersion, PEDOT:PSS solution and PVA aqueous solution and spray them onto the surface of the first mechanical pre-stretched film to cover the silver paste area and dry. Perform a second small-amplitude pre-stretch with a strain of 5%~15% to obtain the second pre-stretched film. Apply the stretchable silver paste to the electrode connection area at both ends of the surface of the second pre-stretched film by screen printing. The wet film thickness is controlled at 15~25 μm, which is equivalent to a unit area mass of about 2~4 mg / cm². 2 A strain-responsive silver paste / G / PEDOT:PSS composite conductive thin film was prepared.

7. The preparation method according to claim 6, characterized in that, The spraying step involves uniform layering using a spray gun, with an air pressure of 0.2~0.3MPa and a spray distance of 15~20cm; the stretchable silver paste is LX-30 epoxy conductive adhesive.

8. The preparation method according to claim 2, characterized in that, The layering and lamination step (4) is as follows: the TPU nanofiber membrane is used as the intermediate layer and placed between the temperature-sensitive layer of the G / PEDOT:PSS composite conductive gel and the strain response layer of the silver paste / G / PEDOT:PSS composite conductive film; a uniform pressure of 0.2MPa is applied at 70°C, and after holding the pressure for 10 minutes, it is cooled to 25~30°C under the pressure holding condition, and electrodes are independently led out for the temperature-sensitive layer and the strain response layer to form signal output ports that do not interfere with each other.

9. A temperature-strain dual-function sensor for monitoring extracorporeal circulation systems according to claim 1, characterized in that, The temperature detection unit of this sensor generates a thermoelectric voltage based on the Seebeck effect, with a Seebeck coefficient of 0.002 V / ℃; the strain detection unit is based on a crack-induced resistance modulation mechanism, with a strain sensitivity coefficient of 3.3 × 10⁻⁶. 5 The cycle stability retention rate exceeds 95%.

10. A temperature-strain dual-function sensor for monitoring extracorporeal circulation systems according to claim 1, characterized in that, This sensor can be integrated into artificial hearts or extracorporeal circulation devices to achieve synchronous detection and real-time monitoring of temperature and strain signals; it maintains signal independence and stable output within the range of 0~30% deformation and 0~40℃ temperature.

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