CN211158037U - Miniature pressure sensor - Google Patents

Abstract

The utility model discloses a miniature pressure sensor. The sensor comprises a pressure sensor body fixedly connected to the outer wall of a guide pipe, wherein the pressure sensor body with a coaxial annular structure is formed on the outer wall of the guide pipe, when the outer electrode layer is deformed due to the fact that the outer electrode layer feels external pressure, the outer electrode layer is inwards attached to a dielectric layer and an inner electrode layer to form an electrode/dielectric/electrode capacitor structure, the butt joint area of the outer electrode layer and the inner electrode layer changes along with the change of the external pressure, the capacity of formed capacitance changes, the numerical value of the external pressure is presumed to be known through the specific change of electric quantity obtained by a capacitance detection device, and the purpose of detecting the change of the external pressure applied to the head of the guide pipe in real. The pressure sensor main body has mechanical flexibility, can be bent randomly along with the catheter, and adapts to the application scene of bending blood vessels in an interventional body.

Description

A miniature pressure sensor

technical field

The utility model relates to the technical field of micro pressure sensors, in particular to a micro pressure sensor which can be fixed on a millimeter-level catheter or guide wire.

Background technique

The existing pressure sensor, such as the published article, "Piezoresistive Medical Catheter End Micro Pressure Sensor", discloses the pressure sensor is a piezoresistive sensor, which is a silicon chip to measure the pressure, but the upper part of the catheter is a silicon chip. Without covering the entire catheter, the entire sensor has a measurement blind spot. The sensor is greatly affected by temperature, and the measurement accuracy is not high.

Utility model content

In view of the problems existing in the prior art, the purpose of the present invention is to provide a micro pressure sensor which is fixed on a millimeter-scale catheter or guide wire and can be bent with it.

In order to solve the above-mentioned problems, the utility model adopts the following technical scheme:

A miniature pressure sensor is characterized in that it comprises a ring-shaped pressure sensor body fixedly connected to the outer wall of a millimeter-scale catheter, the pressure sensor body is a capacitive pressure sensor, and includes inner electrodes with electronic conductivity distributed sequentially from the inside to the outside. layer, dielectric layer with ion conductivity, non-conductive spacer layer, external electrode layer with electronic conductivity, encapsulation layer, the stretching range of the above-mentioned inner electrode layer, dielectric layer, spacer layer and outer electrode layer, encapsulation layer are not less than the stretching range of the catheter, and the inner electrode layer and the outer electrode layer are respectively connected with conductive leads.

The conductive lead is made of a biocompatible material or the outer surface is wrapped with a biocompatible material, the conductive lead is adhered to the catheter, and is connected to an external capacitance detection device.

The spacer layer can be a complete air layer or an incomplete air layer with intermittently distributed supporting structures, and the supporting structures are made of non-conductive materials.

The outer surface of the encapsulation layer is sprayed with a biocompatible thermal isolation film with a stretching amplitude consistent with that of the catheter.

The encapsulation layer is made of biocompatible materials.

The inner electrode layer and the outer electrode layer are made of materials with both mechanical flexibility and good electron conductivity, preferably but not limited to the following materials, such as metal coating or graphene film or carbon nanotube film or silver nanowire film. The dielectric layer is made of materials with both mechanical flexibility and good ionic conductivity, preferably but not limited to the following materials, such as ion gel polymer.

The diameter of the catheter is 0.5-3 mm, and the overall diameter of the catheter head after the micro pressure sensor is fixed is thickened by 0.01-2 mm.

A preparation method of the above-mentioned miniature pressure sensor, the steps of the method are:

S1. After stirring the graphene ink evenly, invert the beaker, insert a PFA plastic plug at one end of the pipe (1), block the pipe, and then vertically immerse one end of the pipe (1) with the PFA plastic plug. In the graphene ink, it is pulled out vertically after being dipped, and is formed into a film by natural air drying for 10-14 hours to form an inner electrode layer (21), and then a conductive lead is connected somewhere in the inner electrode layer (21);

S2. The catheter (1) covered with the inner electrode layer (21) is vertically immersed in the ion gel stock solution, dipped in the ion gel and then pulled out vertically, and after being naturally air-dried for 3-4 hours, the coated ion gel stock solution Most of the water in the volatilization forms a gel dielectric layer (22);

S3. Under the exposure conditions, take a sufficient amount of photoresist in a beaker, place the catheter (1) with the dielectric layer (22) vertically in the photoresist, dip the photoresist and then pull it out vertically, and let it stand After 10-15 minutes, drying in the effective temperature range of the ion gel to cure the photoresist film;

S4. Under the condition of exposure, the catheter (1) coated with the photoresist film is placed vertically in the graphene conductive ink, and then pulled out vertically, and the film is formed by natural air-drying for 10-14 hours to form the outer electrode layer. (twenty four);

S5. Place the catheter (1) with the outer electrode layer (24) in a sufficient amount of degumming solution to wash off the photoresist film to form a spacer layer (23) with air, and the gap between the outer electrode layer and the dielectric layer is formed. They are connected together by residual trace photoresist, a conductive lead is connected somewhere on the external electrode layer (24), and a packaging layer (25) is attached to form a miniature pressure sensor.

Further, the preparation process of the ion gel stock solution is as follows: mixing polyvinyl alcohol, water and phosphoric acid in proportion, gradually heating to 80-100 ° C under stirring conditions, until the mixed solution becomes clear and transparent, and then naturally cooling to room temperature , to obtain an ion gel stock solution; the mass ratio of the polyvinyl alcohol, water and phosphoric acid is 0.8-1.2:8-10:0.8-1.2.

Further, a thermal isolation film (3) is fixedly connected to the outer surface of the encapsulation layer, and the thermal isolation film (3) is formed by a spraying method and has a thickness of 0.001-0.500 mm; The material with mechanical flexibility and biocompatibility is parylene or polytetrafluoroethylene. The main body of the pressure sensor will generate a small amount of heat during use. Human blood vessels cause damage to the blood vessels, and at the same time, the thermal isolation membrane has good flexibility and is not easy to affect the use of the catheter and the main body of the pressure sensor.

Further, the thickness of the conductive lead is 0.01-1.00mm.

Further, the photoresist described in S3 is selected from a material that is soluble in the degumming phase, preferably but not limited to the following materials, such as positive photoresist resin, and the positive photoresist resin is a phenolic resin called novolak resin. Formaldehyde, provides photoresist adhesion, chemical resistance.

Compared with the prior art, the beneficial effects of the present utility model are:

The essential feature of the utility model is: the utility model adopts the electrode layer in the form of film coating, which is directly fixed on the electrode layer with the help of the flexibility of the catheter or the guide wire itself to form a coaxial ring, and realizes the realization of the millimeter-scale tube or It is flexibly attached to the cylinder, which can be bent with the bending of the catheter without peeling off. It forms a capacitive micro pressure sensor. Compared with the resistive pressure sensor, it is less affected by temperature and has higher sensitivity. It can have a large capacitance value change; and it is fixed on the head of the catheter in a ring shape, which can collect signals on the entire sensor contact surface, with almost no measurement blind area, and the production cost is relatively low and economical.

The remarkable progress of the present utility model is:

(1) In the present invention, a pressure sensor body with a coaxial annular structure is formed on the outer wall of the catheter. When the outer electrode layer is deformed by the external pressure, the outer electrode layer is attached to the inner electrode layer and the dielectric layer is attached to the inner electrode layer to form an electrode/dielectric / The capacitor structure of the electrode, and the butting area of the outer electrode layer and the inner electrode layer changes with the change of the external pressure, resulting in the change of the capacity of the formed capacitor. Through the external capacitance detection device, the specific change of the electric quantity is obtained, and the external pressure is deduced. The pressure sensor body is small in size and thin in thickness, and its structural material has mechanical flexibility, so that its appearance and shape can fit the symmetrical cylinder of the catheter under different bending states. The shape can be arbitrarily bent with the catheter to adapt to the application scenario of intervening curved blood vessels in the human body.

(2) In the utility model, the inner electrode layer and the outer electrode layer are made of film materials with both mechanical flexibility and good electronic conductivity, and are directly attached to the catheter. The thickness is very thin, and the flexibility is good. The flexibility of the catheter can follow the bending , to achieve device flexibility requirements. The dielectric layer is made of materials with both mechanical flexibility and good ionic conductivity, preferably but not limited to the following materials, such as ion gel polymer, the formed dielectric layer is interconnected or entangled by polymer molecular chains to form a spatial network structure, The voids of the structure are filled with anions and cations as dispersion medium, and the network structure provides high tensile strength for the ion gel, and also provides channels for the movement of ions, ensuring its toughness and ion conductivity.

(3) The outer surface of the pressure sensor body is fixedly connected with a thermal isolation film, and the thermal isolation film is made of materials with both mechanical flexibility and biocompatibility, preferably but not limited to the following materials, such as parylene, polytetrafluoroethylene, The thermal isolation film is formed by spraying, with a thickness of 0.001-0.500mm. The main body of the pressure sensor will generate a small amount of heat during use. The thermal isolation film has the function of isolating the temperature, so that the generated heat is not easy to act on the human blood vessels and cause damage to the blood vessels. At the same time, the thermal isolation film has good flexibility and is not easy to affect the use of the catheter and the pressure sensor body.

Description of drawings

Fig. 1 is the structural representation when the utility model is used;

Fig. 2 is the sectional view of the utility model;

3 is a schematic structural diagram of the main body of the pressure sensor of the present invention;

FIG. 4 is a flow chart of the preparation of the main body of the pressure sensor of the present invention.

Description of the labels in the figure:

1 catheter, 2 pressure sensor body, 21 inner electrode layer, 22 dielectric layer, 23 spacer layer, 24 outer electrode layer, 25 encapsulation layer, 3 thermal isolation film.

Detailed ways

The following will be combined with the accompanying drawings in the embodiments of the present utility model; the technical solutions in the embodiments of the present utility model will be described clearly and completely; obviously; the described embodiments are only a part of the embodiments of the present utility model; rather than all the implementations For example, based on the embodiments of the present invention; all other embodiments obtained by persons of ordinary skill in the art without creative work; all belong to the protection scope of the present invention.

In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "top/bottom", etc. is based on the drawings shown in the drawings. The orientation or positional relationship is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limit.

In the description of the present invention, it should be noted that, unless otherwise expressly specified and limited, the terms "installation", "provided with", "sleeve/connection", "connection", etc., should be understood in a broad sense, such as "Connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be two elements Internal connectivity. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific situations.

Example 1:

1 and 2, a miniature pressure sensor is fixedly connected to the annular pressure sensor body 2 on the outer wall of the head of the catheter 1. The pressure sensor body is a capacitive pressure sensor. Please refer to the structure diagram of the pressure sensor body. 3. The main body of the pressure sensor of the utility model can also be fixedly attached to the outer wall of the head of the guide wire.

The pressure sensor body 2 includes an inner electrode layer 21 , a dielectric layer 22 , a spacer layer 23 , an outer electrode layer 24 and an encapsulation layer 25 that are sequentially distributed from the inside to the outside. It is attached to the outer surface of the inner electrode layer 21 , the spacer layer 23 is located between the dielectric layer 22 and the outer electrode layer 24 , the encapsulation layer 25 is closely attached to the outer surface of the outer electrode layer 24 , and the pressure sensor body 2 also includes a connection between the inner electrode layers respectively. 21 and the conductive leads of the outer electrode layer 24, the conductive leads are respectively drawn out from somewhere in the inner electrode layer and the outer electrode layer, the conductive leads are made of biocompatible materials or the outer surface is wrapped with biocompatible materials, and the conductive leads are adhered to the catheter. Together, connect with an external capacitance detection device. The spacer layer 23 can be completely used as the spacer layer, and the spacer layer can also be used as the spacer layer with discontinuous distribution of supporting structures with incomplete air layers, and the material of the support structure is a non-conductive material.

Both the inner electrode layer 21 and the outer electrode layer 24 are made of materials with both mechanical flexibility and good electronic conductivity, the stretching range is consistent with the stretching range of the catheter, the conductivity is good, and the conductivity is high, preferably but not limited to the following materials: Such as metal coating or graphene film or carbon nanotube film or silver nanowire film; the dielectric layer 22 is made of materials with both mechanical flexibility and good ion conductivity, and the stretching range is consistent with the stretching range of the catheter. It has good mobility, similar to electrical conductivity, and has a strong ability to transfer ions, preferably but not limited to the following materials, such as ionogel polymers. The materials of the inner electrode layer 21 and the outer electrode layer 24 may be the same or different.

The utility model forms a pressure sensor body with a coaxial annular structure on the outer wall of the catheter. When the outer electrode layer is deformed by the external pressure, the outer electrode layer is inwardly attached to the dielectric layer and the inner electrode layer to form an electrode/dielectric/electrode connection. Capacitor structure, and the interface area between the outer electrode layer and the inner electrode layer changes with the change of the external pressure, which leads to the change of the capacity of the formed capacitor. The specific change of the electric quantity is obtained through the capacitance detection device, and the value of the external pressure is deduced to realize real-time. The purpose of detecting the change of external pressure on the catheter, and the main body of the pressure sensor is small in size and thin in thickness, and its structural material has mechanical flexibility, so that its appearance and shape can fit the symmetrical cylindrical shape of the catheter under different bending states, and can be arbitrarily matched with the catheter. Bending, the present invention can be applied to, but not limited to, detecting real-time blood pressure in the catheter head region during interventional operations.

The diameter of the catheter in the utility model is about 0.5-3mm, the overall diameter of the catheter head after the micro pressure sensor is fixed is thickened by 0.01-2mm, and the front and rear length of the micro pressure sensor can be controlled manually according to the length of the dipping during manufacture. , the length of the dip in this embodiment is 3cm.

Referring to Figure 4, the preparation method of the micro pressure sensor is:

S1. After stirring the graphene ink evenly, invert the beaker, insert a PFA plastic (soluble polytetrafluoroethylene) plug into the mouth of one end of the conduit 1, block the mouth, and then place the conduit 1 with the PFA plastic plug. One end is immersed in the graphene ink vertically, and after dipping, it is pulled out vertically, and the film is formed by natural air drying for 10-14 hours to form the inner electrode layer 21, and then a conductive lead is connected somewhere on the inner electrode layer 21. The thickness of the conductive lead is 0.01-1.00mm;

The single-layer thickness of graphene is only 0.335nm, which is also the strongest material, and its breaking strength is 200 times higher than that of the best steel; at the same time, it has good elasticity, and the stretching range is not less than that of the catheter. , the stretching amplitude affects the ability to follow the deformation of the catheter, which can reach 20% of its own size.

S2. Vertically immerse the catheter 1 covered with the inner electrode layer 21 in the ion gel stock solution, dip it in the ion gel stock solution, and then pull it out vertically. Part of the water volatilizes to form the dielectric layer 22 in a gel state.

S3. Under the exposure conditions, take a sufficient amount of photoresist in a beaker, place the catheter 1 with the dielectric layer 22 vertically in the photoresist, dip the photoresist and pull it out vertically, and let it stand for 10-15 minutes Then, dry the photoresist film for 2-4 minutes at 80-90°C (not higher than the failure temperature of the ion gel, and no capacitance can be formed after failure) to cure the photoresist film; at this drying temperature, the ion gel can be guaranteed. No failure, that is, the dielectric layer does not fail;

S4. Under the exposure condition, the catheter 1 coated with the photoresist film is placed vertically in the graphene conductive ink. The graphene conductive ink is produced by Deyang Encarbon Technology Co., Ltd., and it is pulled out vertically after dipping, and it is dried by natural air. 10-14 hours of film formation to form the outer electrode layer 24;

S5. Place the catheter 1 with the outer electrode layer 24 in a sufficient amount of degumming solution to wash off the entire photoresist film to form a spacer layer 23 with air, connect a conductive lead somewhere on the outer electrode layer 24, and then Paste the encapsulation layer 25 to complete the preparation of the pressure sensor body 2;

S5, spray the thermal isolation film 3 on the outside of the encapsulation layer, remove the PFA plastic plug, and form a miniature pressure sensor.

In step S3, the photoresist is selected from a material that is compatible with the degumming phase, preferably but not limited to the following materials, such as positive photoresist resin, which is a kind of phenolic formaldehyde called novolac resin, which has good properties. Adhesion and chemical resistance.

The utility model can also use other film materials when preparing the inner electrode layer or the outer electrode layer. When a metal coating material is selected as the electrode layer material, the method of electroplating is used to attach to the catheter or the photoresist, and the carbon nanotube film is selected as the electrode. The method of wrapping is adopted when the layer material is used; when the silver nanowire film is used as the electrode layer material, the same process as the graphene film is used to obtain it. The catheter or guide wire is made of polymer material, preferably but not limited to the following materials, such as amino silicone oil siloxane, polyvinylpyrrolidone, and polyurethane.

The sensitivity of the pressure sensor body 2 is inversely proportional to the thickness of the spacer layer 23, which is 0.3 mm in this example. In the case of meeting the measurement requirements, the thickness of the spacer layer 23 should take the minimum value. Therefore, the thickness of the formed photoresist film should be minimized, and the amount of photoresist to be dipped should be strictly controlled. The amount to be taken is based on its own surface adhesion, that is, the viscosity of the photoresist itself. Different types of photoresists can be used. Different types of photoresists have different surface adhesion and viscosity. Or after dipping in the photoresist, artificially shake it vertically up and down to get rid of the excess photoresist to control the adhesion amount of the photoresist.

The preparation method of the ion gel stock solution in step S2 is as follows: mixing polyvinyl alcohol, water and phosphoric acid in a ratio of 1:9:1, gradually heating to 80-100°C under stirring conditions, until the mixed solution becomes clear and transparent, then Naturally cooled to room temperature to obtain an ion gel stock solution.

The formed dielectric layer 22 is interconnected or intertwined by polymer molecular chains to form a spatial network structure, the structural voids are filled with anions and cations as a dispersion medium, and the network structure provides high tensile strength for the ion gel, and at the same time It also provides a channel for the movement of ions.

The formed outer electrode layer 24 is a surface-coupling driving electrode that senses changes in environmental pressure; the formed inner electrode layer 21 is a bottom-coupling sensing electrode, which forms a counter-coupling electrode with the outer electrode layer 24 to collect electrical signals. When the pressure is deformed, the capacitance between the inner electrode layer 21 and the outer electrode layer 24 changes.

Please refer to FIG. 2, a thermal isolation film 3 is fixedly connected to the outer surface of the pressure sensor body 2. The thermal isolation film 3 is made of a material with both mechanical flexibility and biocompatibility. Not limited to the following materials, such as parylene and polytetrafluoroethylene, the thermal isolation film 3 is formed by spraying, and the thickness is 0.001-0.500mm. The pressure sensor body 2 will generate a small amount of heat during use. The thermal isolation film 3 has The function of isolating temperature makes it difficult for the generated heat to act on the blood vessels of the human body and avoid damage to the blood vessels. Meanwhile, the thermal isolation membrane 3 has good flexibility and is not easy to affect the use of the catheter 1 and the pressure sensor body 2 .

The annular miniature pressure sensor provided by the utility model has high response accuracy, wide measurement area and no measurement blind area, can be used as a general device for interventional surgery treatment, promotes the development of intelligent drug automatic bolus injection equipment, and is used for improving cardiovascular and cerebrovascular diseases. The intelligence level and reliability of the gastrointestinal minimally invasive surgical robot have broad application prospects.

The above is only a preferred embodiment of the present invention; but the protection scope of the present invention is not limited to this; any person skilled in the art is within the technical scope disclosed by the present invention; according to the present invention The technical solutions and their improvement ideas are equivalently replaced or changed; all should be covered within the protection scope of the present invention.

The points not mentioned in the present invention are applicable to the prior art.

Claims (5)

1. a miniature pressure sensor, it is characterized in that, comprise the annular pressure sensor main body that is fixedly connected on the outer wall of the millimeter-level conduit, described pressure sensor main body is capacitive pressure sensor, comprises and has electron conductivity distributed in turn from inside to outside. Internal electrode layer, dielectric layer with ion conductivity, non-conductive spacer layer, external electrode layer with electronic conductivity, encapsulation layer, the above-mentioned inner electrode layer, dielectric layer, spacer layer and outer electrode layer, encapsulation layer. The extension range is not less than the extension range of the catheter, and the inner electrode layer and the outer electrode layer are respectively connected with conductive leads. 2 . The miniature pressure sensor according to claim 1 , wherein the outer surface of the encapsulation layer is sprayed with a biocompatible thermal isolation film with a stretching amplitude consistent with that of the catheter. 3 . 3 . The micro pressure sensor according to claim 2 , wherein the thickness of the thermal isolation film ( 3 ) is 0.001-0.500 mm. 4 . 4. The miniature pressure sensor according to claim 1, wherein the inner electrode layer (21) and the outer electrode layer (24) are metal coating, graphene film, carbon nanotube film or silver nanowire film; the The dielectric layer (22) is an ionogel polymer. 5 . The micro pressure sensor according to claim 1 , wherein the diameter of the catheter is 0.5-3 mm, the overall diameter of the catheter after fixing the micro pressure sensor is thickened by 0.01-2 mm, and the thickness of the conductive lead is 0.01 mm. 6 . -1.00mm.

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