A self-climbing, self-adhesive flexible electrode patch for neuromonitoring

Abstract

The application discloses a self-climbing and self-adhesive flexible electrode patch for nerve monitoring, comprising: a flexible base film with an open sandwich; a memory alloy strip trained to have a phase change characteristic of bending from a straight line to a circle within a specific temperature range, which is inserted into the open sandwich of the flexible base film; a temperature-controlled hydrogel film having a temperature control characteristic, which is attached to the upper surface of the flexible base film; and an electrode array comprising electrode pieces and their corresponding electrode leads wrapped by the temperature-controlled hydrogel film, wherein one side of the electrode pieces is exposed outside the temperature-controlled hydrogel film for direct contact with the human body nerve, the electrode leads extend outward in the temperature-controlled hydrogel, and the extension part has an electrode adapter interface. The electrode patch can automatically wrap the nerve by heating, is easy to operate, can adapt to nerves of different sizes, can perform high-quality electrical stimulation monitoring, and can change the interface adhesion by heating and cooling, facilitating taking and placing.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of biomedicine, and particularly relates to a self-climbing and self-adhesive flexible electrode patch for nerve monitoring. BACKGROUND

[0002] Neural electrode technology plays an important role in the field of neuroscience and neurology, especially in neural regulation and neural signal monitoring. Neural electrodes can capture brain electrical signals in real time, providing important information about the state of the nervous system, helping doctors make immediate decisions during surgery. In thyroid surgery, the application of intraoperative monitoring electrodes mainly focuses on the protection of the recurrent laryngeal nerve. The recurrent laryngeal nerve is responsible for the muscle movement and sound production of the larynx, and is crucial to the success of the operation and postoperative recovery. If the recurrent laryngeal nerve is damaged during surgery, it may cause serious complications such as hoarseness and difficulty swallowing. Therefore, accurate monitoring of the status of the recurrent laryngeal nerve has become an important link to ensure the safety of the operation.

[0003] To check the status of the recurrent laryngeal nerve during surgery, the most commonly used and effective method is the nerve electrical stimulation-electromyography monitoring method. The process induces muscle vibration in the vocal cords by applying electrical stimulation to the vagus nerve, and uses the tracheal catheter as a sensor to obtain signals, and observes the amplitude, duration and conduction velocity of the electromyographic signals to determine whether the nerve is damaged. Among them, the monitoring electrode / probe that outputs the electrical stimulation signal to the nerve is the core of the whole system.

[0004] Traditional intraoperative neural monitoring electrodes are roughly divided into two types. One is an intermittent electrical stimulation monitoring probe, which has accurate stimulation sites and high feedback accuracy. However, it needs to be held by hand to apply electrical stimulation at certain intervals, increasing the additional operation during surgery and reducing the efficiency of the operation. At the same time, it cannot judge the state of the nerve in real time, so there is a probability that the abnormality will not be monitored until the nerve is damaged. The other is a continuous electrical stimulation cuff electrode. Compared with the first probe, this electrode can be fixed on the nerve to monitor the nerve state in real time, and theoretically can reduce the damage rate to 0. However, this electrode still has some clinical application bottlenecks: (1) Difficulty in operating the electrode buckle: Intraoperative instruments need to be operated in a small space, and the electrode buckle needs to be manually opened to accurately clamp the nerve. Even experienced doctors need nearly half an hour, and the structure is very inconvenient in actual operation and use. (2) Poor electrode adaptability: The elastic modulus of the current electrode is quite different from that of the nerve, and it cannot adapt to the size and shape of the nerve, further increasing the difficulty of operation. (3) Unstable electrode attachment: The electrode-nerve interface has no adhesion, so the electrode cannot be tightly fixed on the nerve, causing mutual movement and introducing motion artifacts and other interference signals, resulting in poor signal quality of electrical stimulation. The existing intraoperative neural monitoring electrodes do not comprehensively consider these problems.

[0005] Therefore, it is an urgent problem to design an intraoperative nerve monitoring electrode which can be simply operated, adapt to different sizes of nerves, and has a stable electrode-nerve interface. SUMMARY

[0006] In view of the above, the purpose of the present application is to provide a self-climbing and self-adhesive flexible electrode patch for nerve monitoring, which can automatically wrap around the nerve by heating, is easy to operate, can adapt to nerves of different sizes, can perform high-quality electrical stimulation monitoring, and can change the interface adhesion by heating and cooling, facilitating taking and placing.

[0007] To achieve the above-mentioned purpose of the application, the present application provides the following technical solutions:

[0008] A self-climbing and self-adhesive flexible electrode patch for nerve monitoring, characterized in that it comprises a flexible base film, a memory alloy strip, a temperature-controlled hydrogel film, and an electrode array.

[0009] The flexible base film is an insulating flexible polymer with biocompatibility, and has an open sandwich.

[0010] The memory alloy strip has a phase change characteristic of bending from a straight line to a circle within a specific temperature range, and is inserted into the open sandwich of the flexible base film.

[0011] The temperature-controlled hydrogel film has a temperature control characteristic of changing adhesion based on temperature changes, and is attached to the upper surface of the flexible base film.

[0012] The electrode array includes an electrode patch wrapped by the temperature-controlled hydrogel film and its corresponding electrode lead wire, wherein one side of the electrode patch is exposed outside the temperature-controlled hydrogel film for direct contact with the human nerve, and the electrode lead wire extends outward in the temperature-controlled hydrogel film, and the extension has an electrode adapter interface.

[0013] The temperature-controlled self-adhesive flexible electrode patch is placed around the nerve in a normal temperature environment during surgery, and in a temperature environment with elevated temperature by light or contact with human physiological tissue, the memory alloy strip drives the entire electrode patch to self-wrap around the nerve based on the phase change characteristic, and the temperature-controlled hydrogel film increases adhesion based on the temperature control characteristic to make the electrode disc tightly fit the nerve, and after the fitting is completed, the memory alloy strip removes the electrode patch through the open sandwich; after the surgery is completed, the electrode patch automatically detaches from the nerve by reducing the adhesion through temperature reduction, achieving the functions of convenient operation and continuous monitoring of intraoperative nerve function.

[0014] Preferably, the memory alloy strip has a phase change characteristic of bending from a straight line to a circle within a specific temperature range, including: the phase change temperature is 30℃-40℃, and the bending radius of the memory alloy strip is 0.5mm-10mm.

[0015] Further, the memory alloy strip is a nickel-titanium alloy strip, and the heat treatment process is to train the alloy strip on a mold in a specific constant temperature state at 100-450℃ for 2-5 hours to obtain phase transition characteristics.

[0016] Preferably, the temperature-controlled hydrogel film has a temperature-controlled adhesion property of changing adhesion based on temperature change, including that the viscosity of the temperature-controlled hydrogel film surface is less than 3N / m at 25℃, the viscosity is greater than 90N / m at 37℃, and the adhesion range is 1-100N / m in the interval of 20-40℃.

[0017] Further, the temperature-controlled hydrogel film includes an acrylic acid, ammonium persulfate, N,N'-methylene bisacrylamide, acrylamide, and a solution containing carbon nanofiber, and the mass ratio of the acrylic acid, ammonium persulfate, N,N'-methylene bisacrylamide, acrylamide, and the carbon nanofiber dispersion solution is 51-357:25:2:357:3600, wherein the carbon nanofiber dispersion solution includes deionized water and a carbon nanofiber dispersion solution with a corresponding mass ratio of 1:8-8:1, so that the temperature-controlled hydrogel film has a temperature-controlled adhesion property.

[0018] Preferably, the flexible substrate film includes acetate fibers that are strongly bonded with the temperature-controlled hydrogel film, and further includes at least one of rubber, polyimide, polyester fiber, polydimethylsiloxane, polyurethane, polyethylene terephthalate, and polylactic acid as an encapsulation layer to form a composite structure with a thickness of 1μm-5mm. The flexible substrate film of such a structure is tightly connected to the temperature-controlled hydrogel film through molecular chain entanglement.

[0019] Preferably, the flexible substrate film has an opening sandwiched between a pair of adjacent long edges and short edges of the flexible substrate film, facilitating the placement of the memory alloy strip in an initial state and the removal of the memory alloy strip in a bent state.

[0020] Preferably, the temperature-controlled self-adhesive flexible electrode patch has an overall strip shape, and the overall length including the memory alloy strip is 2cm-20cm, the length of the entire electrode patch bendable area of the temperature-controlled hydrogel film is 1cm-5cm, the width is 5mm-30mm, and the thickness is 0.5mm-20mm. The memory alloy strip has an overall strip shape, a width of 5mm-30mm, and a thickness of 0.05mm-0.2mm.

[0021] Preferably, the electrode patches in the electrode array have a thickness of 1μm-500μm, and the spacing between the electrode patches is 1mm-10mm. When the electrode patches are circular, the radius of each electrode patch is 1mm-10mm, and each electrode patch has both collection and stimulation functions.

[0022] Preferably, the material of the electrode array is copper, gold, silver, silver chloride or conductive carbon black, and the number of electrode array is 2-128.

[0023] Compared with the prior art, the present application has at least the following beneficial effects:

[0024] (1) The traditional continuous monitoring electrode is in the form of a buckle, which is difficult to hold. The temperature-controlled self-adhesive flexible electrode patch designed in the present application utilizes the stable physiological parameter of body temperature and the temperature-controlled bendable phase change characteristics of the trained memory alloy strip, so that the electrode patch can automatically curl onto the nerve, avoiding the inconvenience of operation in a small space, and greatly improving the efficiency of the operation.

[0025] (2) The traditional continuous monitoring electrode is fixed in shape and cannot adapt to different nerve sizes. The electrode and the substrate are prepared from low-modulus flexible materials, and the minimum bending radius of the memory alloy strip is set, so that the electrode can adapt to the size and shape of the nerve after bending, and the adaptability is better.

[0026] (3) The traditional continuous monitoring electrode does not have close contact with the tissue interface, and the signal quality is not good. The temperature-controlled hydrogel film changes the adhesion based on temperature change, so that the electrode can be closely attached to the nerve when heated, and the electrode can be easily removed after the operation is completed by cooling, ensuring high-quality signal acquisition. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0028] Figure 1 is a schematic diagram of the overall structure of the temperature-controlled self-adhesive flexible electrode patch provided by the embodiment;

[0029] Figure 2 is a structure diagram of the extensible part of the temperature-controlled self-adhesive flexible electrode patch provided by the embodiment;

[0030] Figure 3 is a schematic diagram of the adhesion function of the temperature-controlled hydrogel film, wherein (a) is a diagram of the adhesion function of the temperature-controlled hydrogel film at 25℃, and (b) is a diagram of the change of the adhesion function of the temperature-controlled hydrogel film of the electrode patch in the environment of 37℃ and in the case of encountering water;

[0031] Figure 4 is a state of the memory alloy strip provided by the embodiment, wherein (a) is a bending schematic diagram of the trained memory alloy strip, and (b) is an application schematic diagram of the memory alloy strip removed from the open sandwich.

[0032] Figure 5 is a temperature-controlled self-adhesive flexible electrode patch of an embodiment is a physical diagram;

[0033] Figure 6 is an application display diagram of a temperature-controlled self-adhesive flexible electrode patch provided by the embodiment wound on a 5mm diameter cylinder;

[0034] Figure 7 is an action potential of a guinea pig recorded by a temperature-controlled self-adhesive flexible electrode patch provided by the embodiment under a specific voltage. DETAILED DESCRIPTION

[0035] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the protection scope of the present application.

[0036] As shown in Figure 1 and Figure 2 , the self-climbing self-adhesive flexible electrode patch for neural monitoring provided by the embodiment includes an electrode array 1, a temperature-controlled hydrogel film 2, a memory alloy strip 3, and a flexible substrate film 4. The overall length of the electrode patch including the length of the memory alloy strip is 100mm, the corresponding head bendable area of the temperature-controlled hydrogel film has a length of 20mm, a width of 10mm, and a thickness of 0.8mm.

[0037] The electrode array 1 is flexible and includes electrode pieces and their corresponding electrode leads wrapped by the temperature-controlled hydrogel film 2, wherein one side of the electrode pieces is exposed outside the temperature-controlled hydrogel film 2 for direct contact with the human body nerves, and the electrode leads extend outwardly in the temperature-controlled hydrogel film 2, and the extension part has an electrode adapter interface 5. Specifically, the electrode array 1 includes 2 electrode pieces with a thickness of 0.1mm, and the electrode pieces are round pieces with a radius of 4mm, which refers to the radius of the outermost circle, and the distance between the electrode pieces is 2mm.

[0038] The electrode piece substrate material is polyimide, and the electrode piece head material in contact with the human body is copper (Cu), conductive carbon material, gold (Au), silver, or silver chloride. The electrode leads corresponding to each electrode piece wrapped in the temperature-controlled hydrogel film 2 are arranged in a serpentine shape, the serpentine line extends to the tail of the electrode bendable part, the rear end of the extension lead is gathered to the electrode adapter interface, and is connected to the adapter board through the electrode adapter interface. Specifically, the tail of the extendable flexible electrode array 1 is connected to the external circuit using a zero insertion force (ZIF) FPC connector, and the related interface with shielding is connected to the signal acquisition part after adapter.

[0039] The thickness of the temperature-controlled hydrogel film 2 is 0.5 mm, which is composed of acrylic acid (AA), acrylamide (AAm), ammonium persulfate (APS), N, N'-methylene bisacrylamide (MBAA), and carbon nanofiber (CNFs) material, and the proportions are as follows: 5 g of CNFs dispersion liquid (1.768 wt%), 4 g of deionized water, 0.4457 g of AA, 0.8913 g of AAm, 0.005 g of MBAA, and 0.0625 g of APS. The CNF / P(AA-co-AAm) hydrogel is synthesized by adjusting the mixture, as shown in Figure 3 Fig. (a) in the middle, the viscosity of the hydrogel surface is 3 N / m at 25°C, and the viscosity is 90 N / m at 37°C. The adhesion range in the interval of 20°C-40°C is 1-100 N / m. The electrode patch can be rolled on the surface of the phase change area, and the rest of the flexible electrode array 1 is the temperature-controlled hydrogel film 2, which accounts for 74.88% of the total area of the adhesion part.

[0040] As shown in Figure 3 Fig. (b) in the middle, the adhesion of the temperature-controlled hydrogel film 2 decreases sharply after being exposed to water, and this property is applied to the surface of the patch after the operation to add cold water to the patch to facilitate peeling.

[0041] The material of the memory alloy strip 3 is nickel-titanium alloy, which is in the form of a long sheet with a width of 10 mm, a length of 20 mm, and a thickness of 0.2 mm. The proportion of nickel and titanium is 50.2:49.8. The memory alloy strip is wound and clamped on a 1 mm diameter mold at standard atmospheric pressure, as shown in Figure 6 Fig. (a) in the middle, and a heat treatment process is carried out at 350°C for 120 minutes to train the memory alloy strip to be rolled into a circular shape. The phase change temperature is in the range of 30°C-40°C, and the bending radius is 2.5 mm, as shown in Figure 4 Fig. (b) in the middle. The memory alloy strip 3 is inserted into the open sandwich of the flexible base film 2, as shown in Figure 5 Fig. (a) in the middle.

[0042] The material of the flexible base film 4 is polyimide and acetate fiber, with a thickness of 0.2 mm. The acetate fiber is located above the polyimide, and the flexible base film 4 is tightly connected to the temperature-controlled hydrogel film 2 through the entanglement of molecular chains, forming an integrated electrode patch. The flexible base film 4 also has an open sandwich, as shown in Figure 5 Fig. (b) in the middle, which is located on the adjacent pair of long edges and short edges of the flexible base film, facilitating the placement of the memory alloy strip in the initial state and the removal of the bent state.

[0043] The temperature-controlled self-adhesive flexible electrode patch contacts the nerve with the transformable bending part of the temporarily planar flexible electrode patch after the nerve is separated. Under the continuous temperature rise driven by the body temperature, the memory alloy strip 3 part reaches the phase transition temperature, starts to adapt to the nerve diameter and automatically curls. After the curling is completed, the temperature-controlled hydrogel film 2 part reaches the phase transition temperature, the electrode-nerve interface adhesion increases, the electrode patch is in close contact with the nerve, and the memory alloy strip 3 is translated along the axis of the nerve from the opening of the temperature-controlled hydrogel film 2, as shown in Figure 4 (b). As shown in Figure 7 The electrical stimulation signal of the back-end system is input to the electrode patch through the electrode connection interface 5 to stimulate the nerve, and the collected data is transmitted out through the electrode connection interface 5 for analysis. After the operation is completed, the nerve area is cooled by using cold water, the adhesion of the temperature-controlled hydrogel film 2 decreases, the electrode patch is separated from the nerve, and the electrode patch is removed.

[0044] The above specific embodiments have described the technical solutions and beneficial effects of the present application in detail. It should be understood that the above description is only the most preferred embodiment of the present application and is not intended to limit the present application. Any modification, supplement and equivalent replacement within the principle range of the present application should be included in the protection scope of the present application.

Claims

1. A self-climbing, self-adhesive flexible electrode patch for neural monitoring, characterized in that, The electrode patch is used for intraoperative nerve monitoring and includes a flexible substrate film, a shape memory alloy strip, a temperature-controlled hydrogel film, and an electrode array. The flexible substrate film is an insulating flexible polymer with biocompatibility and has an open interlayer. The shape memory alloy strip is trained to exhibit phase transition characteristics, bending from a straight line to a circle within a specific temperature range, and is inserted into the open interlayer of a flexible substrate film. The temperature-controlled hydrogel film has temperature-controlled properties that change adhesion based on temperature changes, including: the viscosity of the temperature-controlled hydrogel film surface temperature is less than 3N / m at 25℃, the viscosity is >90N / m at 37℃, and the adhesion range is 1 to 100N / m in the range of 20℃ to 40℃. The temperature-controlled hydrogel film is attached to the upper surface of the flexible substrate film. The electrode array includes electrode sheets wrapped in a temperature-controlled hydrogel film and their corresponding electrode wires, wherein one side of the electrode sheet is exposed outside the temperature-controlled hydrogel film for direct contact with human nerves, and the electrode wires extend outward in the temperature-controlled hydrogel film, and the extension portion has an electrode adapter interface. During surgery, a self-climbing, self-adhesive flexible electrode patch is placed around the nerve at room temperature. In an elevated temperature environment, the shape memory alloy strip, based on its phase change properties, causes the entire electrode patch to self-wrap around the nerve, allowing the electrode to bend and adapt to the size and shape of the nerve. The temperature-controlled hydrogel film, based on its temperature-controlled properties, increases adhesion, ensuring the electrode disc adheres tightly to the nerve. After adhesion is complete, the shape memory alloy strip removes the electrode patch through an opening in the interlayer. After surgery, by lowering the temperature to reduce adhesion, the electrode patch automatically detaches from the nerve.

2. The self-climbing, self-adhesive flexible electrode patch for neural monitoring according to claim 1, characterized in that, The memory alloy strip is trained to exhibit phase transition characteristics, bending from a straight line to a circle within a specific temperature range, including: a phase transition temperature of 30℃ to 40℃ and a bending radius of 0.5mm to 10mm.

3. The self-climbing, self-adhesive flexible electrode patch for neural monitoring according to claim 2, characterized in that, The shape memory alloy strip is a nickel-titanium alloy strip. The heat treatment process involves binding the alloy strip onto a mold and training it for 2 to 5 hours under a specific constant temperature condition of 100℃ to 450℃ to obtain phase transformation characteristics.

4. The self-climbing, self-adhesive flexible electrode patch for neural monitoring according to claim 1, characterized in that, The temperature-controlled hydrogel film comprises acrylic acid, ammonium persulfate, N,N'-methylenebisacrylamide, acrylamide, and a solution containing carbon nanofibers. The mass ratio of acrylic acid, ammonium persulfate, N,N'-methylenebisacrylamide, acrylamide, and the carbon nanofiber dispersion is 51-357:25:2:357:3600. The carbon nanofiber dispersion comprises deionized water and carbon nanofiber dispersion in a mass ratio of 1:8–8:1, which gives the temperature-controlled hydrogel film temperature-controlled adhesion properties.

5. The self-climbing, self-adhesive flexible electrode patch for neural monitoring according to claim 1, characterized in that, The flexible substrate film includes cellulose acetate that is strongly bonded to the temperature-controlled hydrogel film, and also includes at least one of rubber, polyimide, polyester fiber, polydimethylsiloxane, polyurethane, polyethylene terephthalate and polylactic acid as an encapsulation layer to form a composite structure with a thickness of 1μm to 5mm.

6. The self-climbing, self-adhesive flexible electrode patch for neural monitoring according to claim 1, characterized in that, The openings of the open interlayer of the flexible substrate film are located on a pair of adjacent long and short sides of the flexible substrate film, which facilitates the initial placement and removal of the shape memory alloy strip in a bent state.

7. The self-climbing, self-adhesive flexible electrode patch for neural monitoring according to claim 1, characterized in that, The flexible area of ​​the entire electrode patch corresponding to the temperature-controlled hydrogel film has a length of 1cm to 5cm, a width of 5mm to 30mm, and a thickness of 0.5mm to 20mm.

8. The self-climbing, self-adhesive flexible electrode patch for neural monitoring according to claim 1, characterized in that, The electrode plates in the electrode array have a thickness of 1μm to 500μm, and the spacing between the electrode plates is 1mm to 10mm. When the electrode plates are circular, the radius of each electrode plate is 1mm to 10mm.

9. The self-climbing, self-adhesive flexible electrode patch for neural monitoring according to claim 1, characterized in that, The electrode array is made of copper, gold, silver, silver chloride, or conductive carbon black, and the number of electrode plates in the array is 2-128.

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