Self-adaptively fixed blood coagulation monitoring flexible pressure sensor and preparation method and application thereof

Abstract

The invention discloses a blood coagulation monitoring flexible pressure sensor capable of being adaptively fixed and a preparation method of the blood coagulation monitoring flexible pressure sensor. A pressure-sensitive layer of the flexible pressure sensor is a nanofiber membrane which is prepared by an electrostatic spinning process and has a hundred-mesh microstructure; the nanofiber membrane is prepared by mixing polylactic acid with shape memory as a substrate material and a multi-walled carbon nanotube as a conductive substance. The flexible pressure sensor is simple in preparation method and has high sensitivity under a small load, the pressure-sensitive layer of the sensor has an initial shape and a temporary shape and is converted between the initial shape and the temporary shape under the driving of external stimulation, and the flexible pressure sensor is mounted and fixed by controlling the deformation process of the sensor. The nanofiber membrane spontaneously deforms and contracts inwards to be attached to the central venous catheter, fixation is achieved, the stability of the flexible pressure sensor can be improved, the flexible pressure sensor is installed at the front end of the central venous catheter in a self-adaptive mode, and the blood flow pressure in a venous blood vessel can be monitored in real time.

Description

Technical Field

[0001] The present invention belongs to the technical field of sensors and relates to a flexible sensor for coagulation monitoring and a preparation method thereof, and in particular to an adaptively fixed flexible pressure sensor for coagulation monitoring and a preparation method and application thereof. Background Art

[0002] Peripherally inserted central catheters (PICCs) provide patients with a long-term treatment channel, ensuring catheter stability and reducing drug stimulation on blood vessels, thereby improving treatment efficacy. However, as a foreign body, PICC carries a risk of complications during indwelling, among which upper limb deep vein thrombosis (DVT) is particularly serious. PICC-related upper limb DVT often has no obvious symptoms, resulting in a high rate of missed diagnosis. Delayed treatment may damage the venous structure and even cause life-threatening pulmonary embolism. Studies have shown that timely detection and treatment of DVT are crucial to patient prognosis. Patients receiving PICC treatment need to be closely monitored for complications, especially upper limb DVT, to ensure timely diagnosis and treatment. Therefore, the development of a small, stable monitoring device that can monitor coagulation in real time is of great significance, which can protect patients' lives and reduce expenses.

[0003] Wearable health monitoring systems are attracting significant public attention due to their enormous potential. Their core component, a flexible pressure sensor, continuously tracks physiological signals such as body movement and heart rate. Its exceptional flexibility and stretchability allow it to accurately reflect a person's health status, providing data support for disease prevention, health management, and telemedicine.

[0004] However, due to the size mismatch between traditional flexible pressure sensors and central venous catheters, and the need to use glue to bond the flexible sensor to the catheter, the diameter of the flexible sensor in the blood vessel will be significantly increased, thereby increasing the probability of thrombosis; long-term use may also cause the glue to fall off, resulting in dangerous situations such as blood vessel blockage.

[0005] Based on this, the present invention proposes a flexible pressure sensor that can be adaptively installed and fixed. The sensor is installed on a central venous catheter and placed into the body together, thereby monitoring the pressure changes around the catheter in real time to determine whether coagulation occurs. Summary of the Invention

[0006] The purpose of the present invention is to address the deficiencies of the existing technology and provide an adaptive fixed coagulation monitoring flexible pressure sensor and a preparation method thereof. The flexible pressure sensor is mainly prepared by a one-step electrospinning process to produce a nanofiber membrane with a hundred-mesh microstructure. The preparation method of the pressure sensor is simple and has high sensitivity under small loads. Since the base material uses polylactic acid with shape memory, the sensor can be more fitly installed at the front end of the central venous catheter, and the blood flow pressure in the venous blood vessels can be monitored in real time.

[0007] The technical solution adopted in the present invention is as follows:

[0008] A method for preparing a flexible pressure sensor for coagulation monitoring that can be adaptively fixed. The pressure-sensitive layer of the flexible pressure sensor is a nanofiber membrane with a fine-mesh microstructure. The pressure-sensitive layer is made by mixing shape memory polylactic acid SMP-PLA and multi-walled carbon nanotubes MWCNTs into a spinning solution, which is then electrospun and received by a receiver with a fine-mesh microstructure during spinning. The flexible pressure sensor can be adaptively fixed to an implantable intravenous catheter for monitoring coagulation conditions after implantation.

[0009] In the above technical solution, further, the flexible pressure sensor is formed of a multi-layer structure, including an electrode layer, a pressure-sensitive layer and a waterproof layer. The pressure-sensitive layer is a hollow cylindrical membrane, and the electrode layer is arranged on the inner side of the hollow cylindrical membrane. The electrode layer is made by screen-printing silver paste on a PI film. The silver paste side is in contact with the hollow cylindrical membrane, and the PI film side is in contact with the implanted intravenous catheter. The shape memory function of the pressure-sensitive layer is used to realize adaptive fixation of the flexible pressure sensor and the implanted intravenous catheter, and the waterproof layer is encapsulated on the outside of the pressure-sensitive layer.

[0010] Furthermore, the method specifically includes the following:

[0011] SMP-PLA and MWCNTs are added to a mixed solvent of dichloromethane and N,N-dimethylformamide, and after thorough mixing and dispersion, a spinning solution is obtained. A steel mesh with a 100-mesh microstructure is fixed on a steel pipe of a desired diameter. The obtained steel pipe is sleeved on a tubular support receiver and electrospinning is performed to obtain an SMP-PLA / MWCNTs composite hollow cylindrical membrane. The composite hollow cylindrical membrane is fixed on an electrode layer, and the electrode layer is attached to the outside of the wall of an implantable intravenous catheter. Adaptive fixation is then achieved through the shape memory process of the pressure-sensitive layer, and finally the membrane is encapsulated with a waterproof layer.

[0012] Furthermore, the volume ratio of dichloromethane to the mixed solution is 70% to 80%, and the volume ratio of N,N-dimethylformamide to the mixed solution is 20% to 30%.

[0013] Furthermore, the concentration of SMP-PLA in the spinning solution is 16-17 wt%.

[0014] Furthermore, the amount of MWCNTs used is 11-15 wt % of SMP-PLA, more preferably 14 wt %.

[0015] Furthermore, the thickness of the SMP-PLA / MWCNTs composite hollow cylinder membrane is 130 to 200 μm.

[0016] Furthermore, the SMP-PLA / MWCNTs composite hollow cylinder membrane is heat-pressed to improve its performance stability. The heat pressing is usually to fix the tubular nanofiber membrane on the hollow cylinder fitting structure prepared with PDMS, and heat-press at 120 °C for 5 - 6 hours.

[0017] A coagulation monitoring flexible pressure sensor with self-adaptive fixation is prepared by the method described in any one of the above.

[0018] An implantable venous catheter for monitoring coagulation, on which there is the above-mentioned coagulation monitoring flexible pressure sensor with self-adaptive fixation. The sensor is adaptively installed and fixed on the venous catheter to monitor the blood flow pressure in the venous blood vessel in real time for monitoring the coagulation situation. The self-adaptive fixation is to increase the tube diameter of the hollow cylinder membrane under the action of heat (T≥Tg) and external force, and then cool down (T<Tg) and remove the external force to fix its temporary shape; nest it on the electrode layer pre-attached to the outside of the implantable venous catheter in vitro, and heat it again (T≥Tg). Due to the nature of the material itself, the hollow cylinder membrane will actively shrink inward to achieve the fixation effect, and finally encapsulate it with a waterproof layer.

[0019] The conductivity range of the conductive fiber membrane (i.e., the composite hollow cylinder membrane) prepared by the present invention is 2.65 - 12.65 μS / cm. The thickness of the conductive fiber membrane is 0.13 - 0.2 mm.

[0020] Combining the conductive fiber membrane with the electrode layer and the waterproof layer can obtain a flexible pressure sensor with excellent signal stability. For example: form an electrode layer by screen-printing silver paste with a certain viscosity on a PI film. The electrode layer contacts the conductive fiber membrane to lead out an electrical signal to form a sensor body, and then wrap the sensor body with a 5-μm PET film on its outside to form a tubular flexible sensor. This sensor can monitor the coagulation situation, has biocompatibility and hydrophobicity, and can ensure long-term stability.

[0021] This flexible sensor primarily utilizes a one-step electrospinning process to create a nanofiber membrane with a fine-mesh microstructure. The nanofiber membrane is made from a base material of shape-memory polylactic acid and a conductive material of multi-walled carbon nanotubes. By adjusting the mass fraction of the multi-walled carbon nanotubes to control the threshold of the resulting conductive composite material, the contact area of ​​the conductive fibers in the nanofiber membrane changes when subjected to different pressures. This change results in a corresponding adjustment in the effective resistance, thereby achieving sensing functionality. The sensor is simple to prepare and exhibits high sensitivity under low loads. Because the base material is shape-memory polylactic acid, the sensor has an initial shape and a temporary shape, transitioning between these two shapes in response to external stimuli. The present invention utilizes the deformation process of the shape-memory nanofiber membrane to control the installation and fixation of the flexible pressure sensor. The nanofiber membrane spontaneously deforms and contracts inwards to adhere to an implanted intravenous catheter, achieving fixation. This improves the stability of the flexible pressure sensor, allowing it to be adaptively mounted at the front end of an implanted intravenous catheter, enabling real-time monitoring of blood pressure within the vein. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the structure of a flexible pressure sensor that is adaptively fixed to the end of an implanted intravenous catheter. DETAILED DESCRIPTION

[0023] The embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without any creative work are within the scope of protection of the present invention.

[0024] Example 1

[0025] (1) Polylactic acid particles (1.586 g) were dissolved in dichloromethane (7.2 ml CH2Cl2) and stirred with electromagnetic stirring for 2 hours. After the particles were completely dissolved, multi-walled carbon nanotube powder (0.196 g) and N,N-dimethylformamide (2.4 ml DMF) were added to the solution and stirred for 1 hour. The solution was then ultrasonicated for 30 minutes to prepare an electrospinning solution. The concentration of multi-walled carbon nanotubes in the SMP-PLA / MWCNTs composite was 11 wt%.

[0026] (2) Fixing a steel mesh with a 100-mesh microstructure on a steel tube with the same diameter as the central venous catheter, and fixing the steel tube on a tubular stent receiver for electrospinning;

[0027] (3) The prepared solution was transferred to a syringe (5 ml) with a 21G needle. Electrospinning was performed for 30 min at a voltage of 20 kV, a discharge rate of 0.1 mm / s, and a needle distance of 10 cm from the collector. Finally, the obtained SMP-PLA / MWCNTs fiber tubular spinning membrane was placed in a 60°C constant temperature oven and dried for 20 h. The pressure-sensitive layer had a thickness of approximately 134 μm and a conductivity of 2.65 μS / cm

[0028] (4) Place the capillary tube in the PDMS solution in advance, take out the capillary tube after solidification to form a hollow mold, and divide it into two halves to form a hot pressing mold; after hot pressing the tubular spinning membrane obtained in (3), the electrode layer is made by screen printing silver paste on the PI film, attached to the central venous catheter, and the tubular spinning membrane is placed on it. After adaptive fixation, the outside of it is wrapped with a 5μm PET film to form a tubular flexible pressure sensor. Its structure is as follows Figure 1 shown.

[0029] Example 2

[0030] (1) Polylactic acid particles (1.586 g) were dissolved in dichloromethane (7.2 ml CH2Cl2) and stirred with electromagnetic stirring for 2 hours. After the particles were completely dissolved, multi-walled carbon nanotube powder (0.216 g) and N,N-dimethylformamide (2.4 ml DMF) were added to the solution and stirred for 1 hour. The solution was then ultrasonicated for 30 minutes to prepare an electrospinning solution. The concentration of multi-walled carbon nanotubes in the SMP-PLA / MWCNTs composite was 12 wt%.

[0031] (2) A steel mesh with a 100-mesh microstructure is fixed on a steel tube with the same diameter as the central venous catheter, and the steel tube with the microstructure is fixed on a tubular stent receiver for electrospinning.

[0032] (3) The prepared solution was transferred to a 5 ml syringe with a 21G needle. Electrospinning was performed for 30 min at a voltage of 20 kV, a discharge rate of 0.1 mm / s, and a needle distance of 10 cm from the collector. Finally, the SMP-PLA / MWCNTs fiber tubular spinning membrane was placed in a 60°C constant temperature oven and dried for 20 h. The pressure-sensitive layer had a thickness of approximately 174 μm and a conductivity of 3.22 μS / cm.

[0033] (4) After hot pressing with a hot pressing mold, the electrode layer was made by screen printing silver paste on the PI film, attached to the central venous catheter, and the tubular spinning membrane was put on it. After adaptive fixation, the sensor was wrapped with a 5 μm PET film to form a closed tubular flexible pressure sensor.

[0034] Example 3

[0035] (1) Polylactic acid particles (1.586 g) were dissolved in dichloromethane (7.2 ml CH2Cl2) and stirred using electromagnetic stirring for 2 hours. After the particles were completely dissolved, multi-walled carbon nanotube powder (0.236 g) and N,N-dimethylformamide (2.4 ml DMF) were added to the solution and stirred for 1 hour. The solution was then ultrasonicated for 30 minutes to prepare an electrospinning solution. The concentration of multi-walled carbon nanotubes in the SMP-PLA / MWCNTs composite was 13 wt%.

[0036] (2) Fixing a steel mesh with a 100-mesh microstructure on a steel tube with the same diameter as the central venous catheter, and fixing the steel tube with the microstructure on a tubular stent receiver for electrospinning.

[0037] (3) The prepared solution was transferred to a 5 ml syringe with a 21G needle. Electrospinning was performed for 30 min at a voltage of 20 kV, a discharge rate of 0.1 mm / s, and a needle distance of 10 cm. Finally, the SMP-PLA / MWCNTs fiber tubular spinning membrane was placed in a 60°C constant temperature oven and dried for 20 h. The pressure-sensitive layer had a thickness of approximately 200 μm and a conductivity of 4.04 μS / cm.

[0038] (4) After hot pressing with a hot pressing mold, the electrode layer was made by screen printing silver paste on the PI film, attached to the central venous catheter, and the tubular spinning membrane was put on it. After adaptive fixation, the sensor was wrapped with a 5 μm PET film to form a closed tubular flexible pressure sensor.

[0039] Example 4

[0040] (1) Polylactic acid particles (1.586 g) were dissolved in dichloromethane (7.2 ml CH2Cl2) and stirred with electromagnetic stirring for 2 hours. After the particles were completely dissolved, multi-walled carbon nanotube powder (0.258 g) and N,N-dimethylformamide (2.4 ml DMF) were added to the solution and stirred for 1 hour. The solution was then ultrasonicated for 30 minutes to prepare an electrospinning solution. The concentration of multi-walled carbon nanotubes in the SMP-PLA / MWCNTs composite was 14 wt%.

[0041] (2) Fixing a steel mesh with a 100-mesh microstructure on a steel tube with the same diameter as the central venous catheter, and fixing the steel tube with the microstructure on a tubular stent receiver for electrospinning.

[0042] (3) The prepared solution was transferred to a 5 ml syringe with a 21G needle. Electrospinning was performed for 30 min at a voltage of 20 kV, a discharge rate of 0.1 mm / s, and a needle distance of 10 cm from the collector. Finally, the SMP-PLA / MWCNTs fiber tubular spinning membrane was placed in a 60°C constant temperature oven and dried for 20 h. The pressure-sensitive layer had a thickness of approximately 173 μm and a conductivity of 6.41 μS / cm.

[0043] (4) After hot pressing with a hot pressing mold, the electrode layer was made by screen printing silver paste on the PI film, attached to the central venous catheter, and the tubular spinning membrane was put on it. After adaptive fixation, the sensor was wrapped with a 5 μm PET film to form a closed tubular flexible pressure sensor.

[0044] Example 5

[0045] (1) Polylactic acid particles (1.586 g) were dissolved in dichloromethane (7.2 ml CH2Cl2) and stirred with electromagnetic stirring for 2 hours. After the particles were completely dissolved, multi-walled carbon nanotube powder (0.279 g) and N,N-dimethylformamide (2.4 ml DMF) were added to the solution and stirred for 1 hour. The solution was then ultrasonicated for 30 minutes to prepare an electrospinning solution. The concentration of multi-walled carbon nanotubes in the SMP-PLA / MWCNTs composite was 15 wt%.

[0046] (2) Fixing a steel mesh with a 100-mesh microstructure on a steel tube with the same diameter as the central venous catheter, and fixing the steel tube with the microstructure on a tubular stent receiver for electrospinning.

[0047] (3) The prepared solution was transferred to a 5 ml syringe with a 21G needle. Electrospinning was performed for 30 min at a voltage of 20 kV, a discharge rate of 0.1 mm / s, and a needle distance of 10 cm from the collector. Finally, the SMP-PLA / MWCNTs fiber tubular spinning membrane was placed in a 60°C constant temperature oven and dried for 20 h. The pressure-sensitive layer had a thickness of approximately 185 μm and a conductivity of 12.65 μS / cm.

[0048] (4) After hot pressing, the electrode layer was made by screen printing silver paste on the PI film, attached to the central venous catheter, and the tubular spinning membrane was put on it. After adaptive fixation, the sensor was wrapped with a 5 μm PET film to form a closed tubular flexible pressure sensor.

[0049] Example 6

[0050] (1) Polylactic acid particles (1.586 g) were dissolved in dichloromethane (7.2 ml CH2Cl2) and stirred with electromagnetic stirring for 2 hours. After the particles were completely dissolved, multi-walled carbon nanotube powder (0.258 g) and N,N-dimethylformamide (2.4 ml DMF) were added to the solution and stirred for 1 hour. The solution was then ultrasonicated for 30 minutes to prepare an electrospinning solution. The concentration of multi-walled carbon nanotubes in the SMP-PLA / MWCNTs composite was 14 wt%.

[0051] (2) Then, the electrospinning parameters are adjusted and the product is received by a drum receiver (without a 100-mesh microstructured steel mesh) for electrospinning.

[0052] (3) The prepared solution was transferred to a 5 ml syringe with a 21G needle. Electrospinning was performed for 30 min at a voltage of 20 kV, a discharge rate of 0.1 mm / s, and a needle distance of 10 cm from the collector. Finally, the SMP-PLA / MWCNTs fiber tubular spinning membrane was placed in a 60°C constant temperature oven and dried for 20 h. The pressure-sensitive layer had a thickness of approximately 192 μm and a conductivity of 6.32 μS / cm.

[0053] (4) After hot pressing with a hot pressing mold, the electrode layer was made by screen printing silver paste on the PI film, attached to the central venous catheter, and the tubular spinning membrane was put on it. After adaptive fixation, the sensor was wrapped with a 5 μm PET film to form a closed tubular flexible pressure sensor.

[0054] Coagulation monitoring

[0055] First, COMSOL was used to simulate the pressure on the central venous catheter wall. A central venous catheter was constructed at the center of the vein model, and then thrombi of different sizes were introduced to perform fluid-structure coupling simulation. When there was no blood clot around the central venous catheter, the maximum blood flow rate in the blood vessel during one heartbeat cycle was 0.36 m / s, and the maximum pressure of blood on the central venous catheter wall was about 400 Pa. When blood clots formed around the central venous catheter (V = 5.22 mm), the blood flow rate was 0.36 m / s, and the maximum pressure of blood on the central venous catheter wall was about 400 Pa. 3 ), the maximum blood velocity within a cardiac cycle drops to 0.32 m / s, while the maximum pressure exerted by the blood on the central venous catheter wall increases to approximately 1 kPa. Simulation results show that as the thrombus grows, the blood flow rate within the vessel slows and the pressure exerted by the blood on the central venous catheter wall increases, reaching a maximum pressure of 1 kPa. This guides the sensor's range design (<1 kPa).

[0056] This flexible pressure sensor is attached to a central venous catheter and implanted within the body. It monitors pressure changes around the catheter in real time to determine the presence of a thrombus within the vessel. An increase in the monitored pressure indicates the onset of blood clot formation within the vessel. To enable the flexible pressure sensor to better detect the pressure of deep vein thrombosis (DVT) formation, this study used an electrospinning process to fabricate a tubular nanofiber membrane with a fine-mesh microstructure. Due to the presence of a fine-mesh steel mesh on the receptor, the nanofibers are selectively distributed in areas without pores, rather than being evenly distributed across the receptor, creating a matrix-like conductive microstructure. The formation of the microstructure increases the effective concentration of carbon nanotubes. Therefore, at the same carbon nanotube content, the conductive paths of the microstructured conductive network are more concentrated than those of a random network, resulting in significantly higher sensitivity. Furthermore, the nanofiber membrane fabricated through electrospinning has a large surface area to volume ratio, resulting in a multi-layered microstructure, further enhancing its sensitivity. Compared to nanofiber membranes without microstructure, the nanofiber membrane with a fine-mesh microstructure can better monitor blood pressure around central venous catheters. In order to deeply explore the performance of SMP-PLA / MWCNTs composite materials, we systematically studied the characteristics of solutions with different ratios, and focused on their effects on the stability of nanospinning membranes. After a series of experiments and summaries, it was found that when the mass ratio of carbon nanotubes to SMP-PLA in the electrospinning solution was less than 14wt%, the prepared nanofiber membrane had poor conductivity and the response to pressure was not obvious enough; when the carbon nanotube content was above 14wt%, the fiber diameters inside the spinning membrane varied significantly, multiple fibers agglomerated, and fibers close to 20 microns in size were formed, and the spinning process was difficult to reproduce; when the carbon nanotube content was 14wt%, the nanospinning membrane showed better structural stability and more sensitive electrical properties. Under different pressure loads, the recovery of the carbon nanotube and SMP-PLA content was very stable at 14wt%, with a sensitivity of up to 204kPa. -1 The formation of a hundred-mesh microstructure can effectively improve the sensitivity of the flexible pressure sensor. The sensitivity of the nanofiber membrane without a hundred-mesh microstructure (Example 6) is only 132.2 kPa. -1 In addition to its high sensitivity, the sensor also boasts an ultra-low detection limit (150 Pa) and a resolution of 100 Pa. It exhibits a stable response platform under increasing pressure, responding to subtle pressure changes within the low-pressure range and detecting the subtle pressures associated with thrombosis. The flexible pressure sensor for coagulation monitoring has a response time of 28 ms, meeting the requirements of real-time medical monitoring, enabling early detection and prompt treatment.

[0057] The sensor of the present invention utilizes polylactic acid with shape memory to achieve the fixation and installation of the flexible pressure sensor through the shape memory property of the material itself. Through DMA testing, it can be understood that the shape fixation rate of the SMP-PLA / MWCNTs film always remains above 97.5%, and the shape recovery rate gradually increases, rising from 66.14% in the first time to 96.37% in the fourth time. The tubular nanofiber membrane with shape memory changes its initial shape under thermal stimulation (T≥Tg) and external force, withdraws the thermal stimulation (T<Tg) and maintains the external force to obtain a temporary shape, and the temporary shape is fixed after withdrawing the external force. The temporary shape of the tubular nanofiber membrane is designed to have an increased tube diameter, and then it is sleeved into the position to be fixed; then under the action of thermal stimulation (T≥Tg), it is restored to the initial shape and actively contracts inward to achieve the fixation effect.

[0058] The present invention illustrates the detailed method of the present invention through the above embodiments, but the present invention is not limited to the above detailed method, that is, it does not mean that the present invention must rely on the above detailed method to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent replacement of each raw material of the products of the present invention, and the selection of specific methods and conditions, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a self-adaptive fixed coagulation monitoring flexible pressure sensor, characterized in that: The pressure-sensitive layer of this flexible pressure sensor is a nanofiber membrane with a fine-mesh microstructure. The pressure-sensitive layer is made by mixing shape memory polylactic acid SMP-PLA and multi-walled carbon nanotubes MWCNTs into a spinning solution, which is then electrospun and received by a receiver with a fine-mesh microstructure during spinning. The flexible pressure sensor can be adaptively fixed to an implanted intravenous catheter for monitoring coagulation conditions after implantation.

2. The method for preparing the adaptively fixable coagulation monitoring flexible pressure sensor according to claim 1, characterized in that: The flexible pressure sensor is formed of a multi-layer structure, including an electrode layer, a pressure-sensitive layer and a waterproof layer. The pressure-sensitive layer is a hollow cylindrical membrane, and the electrode layer is arranged on the inner side of the hollow cylindrical membrane. The electrode layer is made by screen-printing silver paste on a PI film. The silver paste side is in contact with the hollow cylindrical membrane, and the PI film side is in contact with the implanted intravenous catheter. The shape memory function of the pressure-sensitive layer is used to achieve adaptive fixation of the flexible pressure sensor and the implanted intravenous catheter. The waterproof layer is encapsulated on the outside of the pressure-sensitive layer.

3. The method for preparing the adaptively fixable coagulation monitoring flexible pressure sensor according to claim 1, characterized in that: The details include: SMP-PLA and MWCNTs are added to a mixed solvent of dichloromethane and N,N-dimethylformamide, and the mixture is fully mixed and dispersed to obtain a spinning solution. A steel mesh with a 100-mesh microstructure is fixed on a steel pipe of a desired diameter. The obtained steel pipe is placed on a tubular support receiver for electrospinning to obtain an SMP-PLA / MWCNTs composite hollow cylindrical membrane. The composite hollow cylindrical membrane is fixed on an electrode layer, and the electrode layer is attached to the outside of the wall of an implantable intravenous catheter. The membrane is then fixed through the shape memory process of the pressure-sensitive layer and finally encapsulated with a waterproof layer.

4. The method for preparing the adaptively fixable coagulation monitoring flexible pressure sensor according to claim 3, characterized in that: The volume ratio of the dichloromethane to the mixed solution is 70% to 80%, and the volume ratio of the N,N-dimethylformamide to the mixed solution is 20% to 30%.

5. The method for preparing the adaptively fixable coagulation monitoring flexible pressure sensor according to claim 3, characterized in that: The concentration of SMP-PLA in the spinning solution is 16-17 wt %.

6. The method for preparing the adaptively fixable coagulation monitoring flexible pressure sensor according to claim 3, characterized in that: The amount of MWCNTs used is 11-15 wt % of SMP-PLA.

7. The method for preparing the adaptively fixable coagulation monitoring flexible pressure sensor according to claim 3, characterized in that: The amount of MWCNTs used is 14 wt % of SMP-PLA.

8. The method for preparing the adaptively fixable coagulation monitoring flexible pressure sensor according to claim 3, characterized in that: The thickness of the SMP-PLA / MWCNTs composite hollow cylinder membrane is 130 to 200 μm.

9. An adaptively fixed flexible pressure sensor for coagulation monitoring, characterized in that: The method is prepared by the method according to any one of claims 1 to 8.

10. An implantable intravenous catheter capable of monitoring blood coagulation, characterized in that: The implantable intravenous catheter is provided with the adaptively fixable coagulation monitoring flexible pressure sensor as claimed in claim 9, and the sensor is adaptively mounted and fixed on the intravenous catheter.

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