A thin film type flexible eddy current flaw detector sensor and a development method thereof

Abstract

This invention relates to a thin-film flexible eddy current flaw detection sensor and its manufacturing method, belonging to the field of measurement technology. The thin-film flexible eddy current flaw detection sensor includes a bottom encapsulation layer, a sensitive layer, an isolation layer, an excitation layer, and a top encapsulation layer. The bottom encapsulation layer, isolation layer, and top encapsulation layer are all composed of an intrinsically flexible thin film of insulating polymer material. The sensitive layer is composed of an intrinsically flexible coil spiraled from a composite conductive polymer material. The excitation layer is composed of a coil spiraled from quick-drying conductive ink. Lead wires from the sensitive layer and excitation layer are embedded in the isolation layer and top encapsulation layer, respectively. The thin-film flexible eddy current flaw detection sensor manufactured using the method proposed in this invention can significantly reduce the use of metal materials, effectively improve the flexibility of the flaw detection sensor, and is suitable for applications such as non-destructive testing of complex curved metal surfaces.

Description

Technical Field

[0001] This invention belongs to the field of measurement technology, and specifically relates to the development of flexible eddy current flaw detection sensors. Background Technology

[0002] Eddy current testing technology, as an important component of non-destructive testing technology, plays a key role in structural health monitoring. Sensors developed based on eddy current testing technology are widely used in rail transportation, aerospace, nuclear power, energy and mining, and other fields. However, with the development of technology, many applications involve metal materials with complex curved surface characteristics. Traditional eddy current testing sensors are made of metal components, and the sensing probes are rigid but lack flexibility, making it difficult to adapt to the detection of complex curved surfaces. Therefore, there is an urgent need for flexible testing sensors. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of existing technologies and propose a thin-film flexible eddy current flaw detection sensor and its manufacturing method. The thin-film flexible eddy current flaw detection sensor includes a bottom encapsulation layer, a sensitive layer, an isolation layer, an excitation layer, and a top encapsulation layer. The bottom encapsulation layer, isolation layer, and top encapsulation layer are all composed of an intrinsically flexible thin film of insulating polymer material. The sensitive layer is composed of an intrinsically flexible coil spiraled from a composite conductive polymer material. The excitation layer is composed of a coil spiraled from quick-drying conductive ink. Lead wires from the sensitive layer and excitation layer are embedded in the isolation layer and top encapsulation layer, respectively.

[0004] The method for developing a thin-film flexible eddy current flaw detection sensor includes the following steps: Polydimethylsiloxane, tetraethyl orthosilicate, and dibutyltin dibutylsilicate are mixed in a certain proportion. After the mixture is vulcanized, an intrinsically flexible insulating polymer material thin film is formed. Two long strips of insulating film with a certain width are cut from the edge of the intrinsically flexible insulating polymer material thin film for later use. The remaining intrinsically flexible insulating polymer material thin film is used as the bottom encapsulation layer of the thin-film flexible eddy current flaw detection sensor. Carbon nanotubes, polydimethylsiloxane, and n-hexane are mixed in a certain proportion. Mechanical stirring and ultrasonic vibration are used to fully disperse the carbon nanotubes in the mixed solution of polydimethylsiloxane and n-hexane. The organic solvent n-hexane is allowed to evaporate... After the initial processing, a composite conductive polymer material consisting of carbon nanotubes filled with polydimethylsiloxane is formed. A rigid mold with helical grooves is placed on the bottom encapsulation layer, with equal spacing between the helical grooves. The composite conductive polymer material is poured into the grooves. After the composite conductive polymer material vulcanizes, a helical intrinsic flexible coil is formed. The rigid mold with helical grooves is removed, and the helical intrinsic flexible coil is used as the sensitive layer of a thin-film flexible eddy current flaw detection sensor. The remaining composite conductive polymer material is spin-coated onto the surface of a long strip of insulating film to prepare a sensitive layer lead wire. The sensitive layer lead wire is connected from the center of the intrinsic flexible coil of the sensitive layer. An insulating strip is placed between the sensitive layer's lead wire and the intrinsically flexible coil to form insulation. A mixture of polydimethylsiloxane, tetraethyl orthosilicate, and dibutyltin dibutylsilicate in a certain proportion is applied to the sensitive layer and lead wire. The insulating intrinsically flexible film formed after the mixture is vulcanized serves as the isolation layer for the thin-film flexible eddy current sensor. Another rigid mold with helical slots is placed on the isolation layer. The helical slots of the rigid mold are evenly spaced. Quick-drying conductive ink is poured into the slots. After the conductive ink solidifies, a helical coil is formed. The rigid mold is removed, and the helical coil serves as the excitation layer for the thin-film flexible eddy current sensor. The remaining conductive... Ink is spin-coated onto the surface of another elongated insulating film to form an excitation layer lead wire. The excitation layer lead wire is connected from the center of the solenoid coil of the excitation layer, so that the elongated insulating film is placed between the excitation layer lead wire and the solenoid coil to form insulation. A mixture of polydimethylsiloxane, tetraethyl orthosilicate, and dibutyltin dibutylsilicate in a certain proportion is covered on the excitation layer and the lead wire. The insulating intrinsic flexible film formed after the mixture is vulcanized is used as the top encapsulation layer of the thin-film flexible eddy current flaw detection sensor. The bottom encapsulation layer, the isolation layer, and the top encapsulation layer are cut to the required size around the solenoid coil of the sensitive layer and the excitation layer, thereby completing the fabrication of the thin-film flexible eddy current flaw detection sensor.

[0005] The features and beneficial effects of this invention are as follows:

[0006] The proposed method utilizes an intrinsically flexible thin film of insulating polymer material as the bottom encapsulation layer, isolation layer, and top encapsulation layer; an intrinsically flexible coil spiraled from composite conductive polymer material as the sensing layer; and a coil spiraled from quick-drying conductive ink as the excitation layer. This significantly reduces the use of metal materials, thus effectively improving the flexibility of the flaw detection sensor. Experimental verification has shown that the intrinsically flexible coil spiraled from composite conductive polymer material can detect eddy current magnetic field distortion signals caused by cracks on metal surfaces. Therefore, the thin-film flexible eddy current flaw detection sensor prepared using the proposed method is suitable for applications such as non-destructive testing of complex curved metal surfaces. Attached Figure Description

[0007] Figure 1 This is a top view of the excitation layer and the solenoidized coil of the sensing layer in a thin-film flexible eddy current flaw detection sensor.

[0008] Figure 2 This is a cross-sectional view of a thin-film flexible eddy current flaw detection sensor.

[0009] Figures 1-2 In the diagram, 'a' represents the bottom encapsulation layer, 'b' represents the sensitive layer with a composite conductive polymer material spiral-shaped flexible coil, 'c' represents the isolation layer, 'd' represents the excitation layer with a quick-drying conductive ink spiral-shaped coil, 'e' represents the top encapsulation layer, 'f' represents the sensitive layer lead wire, and 'g' represents the excitation layer lead wire. Detailed Implementation

[0010] The present invention will be further described in detail below with reference to embodiments and figures, but the embodiments of the present invention are not limited thereto. This application aims to provide a thin-film flexible eddy current flaw detection sensor and its fabrication method. Figure 1 The image shown is a top view of the excitation layer and the solenoidized coil of the sensing layer in a thin-film flexible eddy current flaw detection sensor. The main steps include:

[0011] Polydimethylsiloxane, tetraethyl orthosilicate, and dibutyltin dibutylsilicate are mixed in a certain proportion. The mixture is homogenized under the combined action of ultrasonic vibration and mechanical stirring. The mixture is then spin-coated onto an insulating rigid smooth plate. Another insulating rigid smooth plate is then placed on top of the plate with the spin-coated mixture. The distance between the two plates is controlled by a lifting platform. The mixture of polydimethylsiloxane, tetraethyl orthosilicate, and dibutyltin dibutylsilicate is extruded to the desired thickness. After the mixture vulcanizes, an intrinsically flexible insulating polymer film is formed. The upper insulating rigid smooth plate is removed, and two strips are cut along the edge of the intrinsically flexible insulating polymer film. A long strip of insulating film with a certain width is reserved. The remaining intrinsically flexible film of the insulating polymer material is used as the bottom encapsulation layer a of the thin-film flexible eddy current flaw detection sensor. Carbon nanotubes, polydimethylsiloxane, and n-hexane are mixed in a certain proportion. The carbon nanotubes are fully dispersed in the mixed solution of polydimethylsiloxane and n-hexane by mechanical stirring and ultrasonic vibration. After the organic solvent n-hexane has evaporated, a composite conductive polymer material filled with carbon nanotubes and polydimethylsiloxane is formed. A rigid mold with spiral grooves is placed on the bottom encapsulation layer a. The spacing between the spiral grooves of the rigid mold is equal. The composite conductive polymer material is poured into the grooves. After vulcanization, a spiral-shaped intrinsically flexible coil is formed. The rigid mold with the spiral groove is removed, and the spiral-shaped intrinsically flexible coil is used as the sensitive layer b of the thin-film flexible eddy current flaw detection sensor. The remaining composite conductive polymer material is spin-coated onto the surface of the long strip insulating film to prepare a sensitive layer lead wire f. The sensitive layer lead wire f is connected from the center of the intrinsically flexible coil of the sensitive layer b, so that the long strip insulating film is placed between the sensitive layer lead wire f and the intrinsically flexible coil to form insulation. A mixture of polydimethylsiloxane, tetraethyl orthosilicate, and dibutyltin dibutylsilicate in a certain proportion is covered on the sensitive layer b and the lead wire f, and an insulating rigid film is placed on top of it. A smooth plate is used, and the distance between the insulating rigid smooth plate and the sensitive layer b is controlled by a lifting platform. The mixture is extruded to the required thickness. After the mixture is vulcanized, an intrinsically flexible film of insulating polymer material is formed. The insulating rigid smooth plate on the upper surface is removed, and the intrinsically flexible film of insulating polymer material is used as the isolation layer c of the film-type flexible eddy current flaw detection sensor. Another rigid mold with spiral through-slots is placed on the isolation layer c. The spacing between the spiral through-slots of the rigid mold is equal. Quick-drying conductive ink is poured into the through-slots. After the conductive ink solidifies, a spiral coil is formed. The rigid mold is removed, and the spiral coil is used as the excitation layer d of the film-type flexible eddy current flaw detection sensor.The remaining conductive ink is spin-coated onto the surface of the other elongated insulating film to form an excitation layer lead wire g. The excitation layer lead wire g is connected from the center of the helical coil of the excitation layer d, so that the elongated insulating film is positioned between the excitation layer lead wire g and the helical coil to form insulation. A mixture of polydimethylsiloxane, tetraethyl orthosilicate, and dibutyltin dibutylsilicate in a certain proportion is applied to the excitation layer d and the lead wire g. An insulating rigid smooth plate is then placed on top of this mixture. The rigid smooth plate is controlled by a lifting platform. The distance between the excitation layers d is determined by extruding the mixture to the required thickness. After the mixture is vulcanized, an intrinsically flexible insulating polymer material film is formed. The insulating rigid smooth plate on the upper surface is removed, and the intrinsically flexible insulating polymer material film is used as the top encapsulation layer e of the thin-film flexible eddy current flaw detection sensor. The bottom encapsulation layer a, the isolation layer c, and the top encapsulation layer e are cut to the required size around the spiral coil of the sensitive layer b and the excitation layer d, thereby completing the fabrication of the thin-film flexible eddy current flaw detection sensor. The cross-sectional view of the thin-film flexible eddy current flaw detection sensor is shown below. Figure 2 As shown.

[0012] Example

[0013] Polydimethylsiloxane, tetraethyl orthosilicate, and dibutyltin dibutylsilicate are mixed in a mass ratio of 1:0.12:0.24. The mixture is homogenized under the combined action of ultrasonic vibration and mechanical stirring. The mixture is then spin-coated onto an insulating rigid smooth plate. Another insulating rigid smooth plate is then placed on top of the plate with the spin-coated mixture. The distance between the two plates is controlled by a lifting platform. The mixture of polydimethylsiloxane, tetraethyl orthosilicate, and dibutyltin dibutylsilicate is extruded to a thickness of 0.1 mm. After the mixture vulcanizes, an intrinsically flexible insulating polymer film is formed. The upper insulating rigid smooth plate is removed, and the edges of the intrinsically flexible insulating polymer film are trimmed. Two long strips of insulating film, each 30 mm long and 2 mm wide, are prepared for later use. The remaining intrinsically flexible film of the insulating polymer material is used as the bottom encapsulation layer of the thin-film flexible eddy current flaw detection sensor. Carbon nanotubes, polydimethylsiloxane, and n-hexane are mixed in a mass ratio of 1:20:100. The carbon nanotubes are fully dispersed in the mixed solution of polydimethylsiloxane and n-hexane using mechanical stirring and ultrasonic vibration. After the organic solvent n-hexane has evaporated, a composite conductive polymer material filled with carbon nanotubes and polydimethylsiloxane is formed. A rigid mold with spiral grooves is placed on the bottom encapsulation layer. The spiral grooves of the rigid mold are evenly spaced, with a groove width of 1 mm and a groove depth of 0.4 mm. The material is poured into the grooves. A composite conductive polymer material is used to form a spiral-shaped intrinsically flexible coil with a thickness of 0.4 mm after vulcanization. The rigid mold with spiral grooves is removed, and the spiral-shaped intrinsically flexible coil is used as the sensitive layer of a thin-film flexible eddy current flaw detection sensor. The remaining composite conductive polymer material is spin-coated onto the surface of a long strip of insulating film to prepare a sensitive layer lead wire with a width of 1 mm. The sensitive layer lead wire is connected from the center of the intrinsically flexible coil of the sensitive layer, so that the long strip of insulating film is placed between the sensitive layer lead wire and the intrinsically flexible coil to form insulation. Polydimethylsiloxane, tetraethyl orthosilicate, and dibutyl dimethylsiloxane are mixed in a mass ratio of 1:0.12:0.24. A tin mixture is applied to the sensitive layer and the lead wires, and then covered with an insulating rigid smooth plate. The distance between the insulating rigid smooth plate and the sensitive layer is controlled by a lifting platform. The mixture is extruded to a thickness of 0.2 mm. After the mixture is vulcanized, it forms an intrinsically flexible film of insulating polymer material. The insulating rigid smooth plate on the upper surface is removed, and the intrinsically flexible film of insulating polymer material is used as the isolation layer of the film-type flexible eddy current flaw detection sensor. Another rigid mold with spiral through-slots is placed on the isolation layer. The spiral through-slots of the rigid mold are evenly spaced, with a width of 1 mm and a depth of 0.1 mm. Quick-drying conductive silver paste is poured into the through-slots. After the conductive silver paste solidifies, it forms a spiral with a thickness of 0 mm.A 1mm coil is used. The rigid mold is removed, and the spiral coil is used as the excitation layer of a thin-film flexible eddy current flaw detector sensor. The remaining conductive ink is spin-coated onto the surface of another long strip of insulating film to form a 1mm wide excitation layer lead wire. This lead wire is connected from the center of the spiral coil of the excitation layer, with the long strip of insulating film positioned between the lead wire and the spiral coil to form insulation. A mixture of polydimethylsiloxane, tetraethyl orthosilicate, and dibutyltin dibutylsilicate, mixed in a 1:0.12:0.24 mass ratio, is applied to the lead wire, and an insulating sheet is then placed on top of it. A rigid, smooth plate is used. The distance between the rigid, smooth plate and the excitation layer is controlled by a lifting platform. The mixture is extruded to a thickness of 0.2 mm. After vulcanization, an intrinsically flexible insulating polymer material film is formed. The rigid, smooth plate on the upper surface is removed. This intrinsically flexible insulating polymer material film serves as the top encapsulation layer of the thin-film flexible eddy current flaw detection sensor. A bottom encapsulation layer, an isolation layer, and a top encapsulation layer are cut to square films with sides of 60 mm around the spiral coils of the sensitive and excitation layers, thus completing the fabrication of the thin-film flexible eddy current flaw detection sensor. The total thickness of the thin-film flexible eddy current flaw detection sensor is 1 mm.

[0014] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for developing a thin-film flexible eddy current flaw detection sensor, characterized in that, The research and development method includes the following steps: Polydimethylsiloxane, tetraethyl orthosilicate, and dibutyltin dibutylsilicate are mixed in a certain proportion. After the mixture is vulcanized, an intrinsically flexible insulating polymer material film is formed. Two long strips of insulating film with a certain width are cut from the edge of the intrinsically flexible insulating polymer material film for later use. The remaining intrinsically flexible insulating polymer material film is used as the bottom encapsulation layer of the thin-film flexible eddy current flaw detection sensor. Carbon nanotubes, polydimethylsiloxane, and n-hexane are mixed in a certain proportion. Mechanical stirring and ultrasonic vibration are used to fully disperse the carbon nanotubes in the mixed solution of polydimethylsiloxane and n-hexane. After the organic solvent n-hexane evaporates completely, carbon nanotubes are formed. A composite conductive polymer material, polydimethylsiloxane, is filled into a tube. A rigid mold with helical grooves is placed on a bottom encapsulation layer. The helical grooves of the rigid mold are evenly spaced. The composite conductive polymer material is poured into the grooves. After the composite conductive polymer material is vulcanized, a helical intrinsic flexible coil is formed. The rigid mold with helical grooves is removed. The helical intrinsic flexible coil is used as the sensitive layer of a thin-film flexible eddy current flaw detection sensor. The remaining composite conductive polymer material is spin-coated onto the surface of a long strip of insulating film to prepare a sensitive layer lead wire. The sensitive layer lead wire is connected from the center of the intrinsic flexible coil of the sensitive layer, making the long strip of insulating film... An insulating film is placed between the sensitive layer's lead wires and the intrinsically flexible coil to form insulation. A mixture of polydimethylsiloxane, tetraethyl orthosilicate, and dibutyltin dibutylsilicate in a certain proportion is applied to the sensitive layer and lead wires. The insulating intrinsically flexible film formed after the mixture is vulcanized serves as the isolation layer for the thin-film flexible eddy current sensor. Another rigid mold with helical slots is placed on the isolation layer. The helical slots of the rigid mold are evenly spaced. Quick-drying conductive ink is poured into the slots. After the conductive ink solidifies, a helical coil is formed. The rigid mold is removed, and the helical coil serves as the excitation layer for the thin-film flexible eddy current sensor. The remaining conductive ink is then... An excitation layer lead wire is prepared by coating the surface of another long strip of insulating film. The excitation layer lead wire is connected to the center of the spiral coil of the excitation layer, so that the long strip of insulating film is placed between the excitation layer lead wire and the spiral coil to form insulation. A mixture of polydimethylsiloxane, tetraethyl orthosilicate and dibutyltin dibutylsilicate in a certain proportion is covered on the excitation layer and the lead wire. The insulating intrinsic flexible film formed after the mixture is vulcanized serves as the top encapsulation layer of the thin-film flexible eddy current flaw detection sensor. The bottom encapsulation layer, the isolation layer and the top encapsulation layer are cut to the required size around the spiral coil of the sensitive layer and the excitation layer, thereby completing the fabrication of the thin-film flexible eddy current flaw detection sensor.

2. A thin-film flexible eddy current flaw detection sensor prepared by the method described in claim 1, characterized in that, The thin-film flexible eddy current flaw detection sensor includes a bottom encapsulation layer, a sensitive layer, an isolation layer, an excitation layer, and a top encapsulation layer. The bottom encapsulation layer, the isolation layer, and the top encapsulation layer are all made of an intrinsically flexible thin film of insulating polymer material. The sensitive layer is made of an intrinsically flexible coil spiraled from a composite conductive polymer material. The excitation layer is made of a coil spiraled from quick-drying conductive ink. The isolation layer and the top encapsulation layer are respectively embedded with lead wires from the sensitive layer and the excitation layer.

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