WO2023282386A1

WO2023282386A1 - Strain measuring sensor and manufacturing method therefor

Info

Publication number: WO2023282386A1
Application number: PCT/KR2021/012819
Authority: WO
Inventors: 김회준; 류채현
Original assignee: 재단법인대구경북과학기술원
Priority date: 2021-07-05
Filing date: 2021-09-17
Publication date: 2023-01-12
Also published as: KR20230006966A

Abstract

A strain measuring sensor according to the present invention may comprise: a substrate layer formed of a flexible material; and a conductive thin-film layer provided on a surface of the substrate layer and having at least any one pattern with irregular straight lines or irregular curves.

Description

Strain measurement sensor and its manufacturing method

The present invention relates to a strain measuring sensor using cracks and a method for manufacturing the same, and more particularly, to a strain measuring sensor capable of forming a conductive thin film layer having straight or curved cracks on a substrate layer by a simple method such as electroplating, and It relates to a manufacturing method thereof.

In general, a strain measurement sensor is a device that detects minute signals (eg, tension, force, bending, pressure, friction, etc.) and transmits them as data such as electrical signals, and is one of the parts essential in modern industry.

Among strain measurement sensors, capacitive sensors, piezoelectric sensors, and strain gauges are widely known as sensors that measure pressure or tensile force. Recently, resistance changes due to cracks caused by tension on the surface of a conductive thin film Research on crack-based strain sensors that measure strain by measuring is being actively conducted.

On the other hand, FIG. 1 is a conventional strain measuring sensor 1, in which a metal thin film layer 20 as a sensing layer is deposited on a flexible substrate 10, and a sensing range is provided between the substrate 10 and the metal thin film layer 20. It includes an intermediate layer 30 made of a conductive material having a smaller modulus of elasticity than metal to increase the thickness. Accordingly, after forming a crack 20a in the metal thin film layer 20 by applying pre-strain in the direction to be measured, when tension is applied by measuring the change in resistance between both ends of the strain measuring sensor 1 strain can be measured.

However, when the intermediate layer 30 is provided between the substrate 10 and the metal thin film layer 20 in this way, precise and expensive equipment such as a sputtering device is required to deposit the intermediate layer 30, and it takes a lot of time. However, there is a limitation that the size of the result is determined by the manufacturing equipment.

In addition, the strain measuring sensor has better sensitivity and a wider sensing range as the distribution area of the crack 20a formed in the metal thin film layer 20 increases. In the case of the conventional strain measuring sensor 1, the crack 20a moves in one direction. Since it is formed in the form of a continuous straight line, it is difficult to increase the distribution area of the crack 20a.

An object of the present invention is to provide a strain measuring sensor capable of forming a conductive thin film layer having straight or curved cracks on a substrate layer by a simple method such as electroplating, and a manufacturing method thereof.

Strain measurement sensor according to the present invention for achieving the above object is a substrate layer formed of a flexible material; and a conductive thin film layer provided on one side of the base layer and formed with cracks having at least one pattern of irregular straight lines or irregular curves.

In addition, the conductive thin film layer includes a plurality of island portions formed by growing metal nanoparticles on a conductive wire coated on one surface of the base layer, and the crack is formed between the island portions by a space between the conductive wires. It can be.

In addition, the conductive wire may include at least one of CNT, silver nano wire, graphene, or graphite.

In addition, when an external force is applied to the substrate layer, the area of the crack widens or narrows to change the contact area between the island portions, and the electrical change of the island portion according to the change in the contact area is measured to obtain The external force applied to it can be measured.

In addition, the conductive thin film layer may be deposited and formed on the substrate layer using an electrochemical deposition process including at least one of electrodeposition, electroplating, electrophorethic deposition, and electroless plating.

A method of manufacturing a strain measuring sensor according to the present invention for achieving the above object includes providing a conductive wire on one surface of a substrate; coating one surface of the substrate with a liquid polymer material to form a substrate layer with the conductive wire interposed therebetween; Separating the base layer on which the conductive wire is fixed on one side of the substrate from the substrate; growing metal nanoparticles on the conductive wire through an electrochemical deposition process actively using the conductive wire after immersing the substrate layer in a solution containing metal ions; and forming a conductive thin film layer having at least one pattern of cracks among irregular straight lines and irregular curves on the base layer by using the growth of the metal nanoparticles.

In addition, the forming of the base layer may include spin-coating the liquid polymer material on the substrate provided with the conductive wire, and curing the polymer material to form a base layer having a portion of the conductive wire fixed to one surface. Acquisition process may be included.

In addition, the step of separating the base layer from the substrate may include cutting the base layer into a desired size and shape after separating the base layer from the substrate.

In addition, in the step of growing the metal nanoparticles on the conductive wire, the density and size of the metal nanoparticles may be controlled by controlling at least one of the electrochemical deposition process time and the size of the electric field.

In addition, the distribution of the cracks may be controlled according to the amount of the conductive wire provided on the substrate.

In addition, the electrochemical deposition process may include at least one of an electrodeposition method, an electroplating method, an electrophorethic deposition method, and an electroless plating method.

In addition, the polymer material is one selected from PDMS (Polydimethylsiloxane), PI (Polyimide), PET (Polyehtylene-terephthalate), PES (Polyether sulfone), PEN (Polyethylene naphthalate), PMMA (PolymethymethAcrylate), PC (Polycarbonate), and Ecoflex. can include

According to the present invention, since the conductive thin film layer having cracks can be formed on the base layer by a simple method such as electroplating, the manufacturing time can be shortened compared to the manufacturing process of the conductive thin film layer using a conventional sputtering device, Since expensive equipment is not required, manufacturing costs can be reduced.

In addition, as the conductive thin film layer deposited on the substrate layer has cracks having at least one pattern of straight lines or curves, the sensitivity and sensing range of the strain measuring sensor are improved without providing an intermediate layer between the substrate layer and the conductive thin film layer. can make it

In addition, since the conductive thin film layer is prepared by growing metal nanoparticles on the conductive wire by using the conductive wire as an electrode during electroplating, when controlling the time of electroplating and the size of the applied electric field, the size and Density can be controlled. That is, since the sensing range increases as the size of the metal nanoparticles decreases, a strain measuring sensor having a wide sensing range can be manufactured when the time and the size of the electric field are appropriately controlled during electroplating.

In addition, since the external force applied to the strain measuring sensor can be measured by measuring the electrical change of the conductive thin film layer, it can be applied to a wearable device to measure a biosignal or movement.

1 is a perspective view showing the configuration of a strain measuring sensor according to the prior art.

2 is a perspective view showing the configuration of a strain measuring sensor according to an embodiment of the present invention.

FIG. 3 is a view showing a state in which an external force is applied in the X-axis direction to the strain measuring sensor of FIG. 2 .

FIG. 4 is a view showing a state in which an external force is applied in the Y-axis direction to the strain measuring sensor of FIG. 2 .

5 is a flowchart of a method of manufacturing a strain measuring sensor according to an embodiment of the present invention.

FIG. 6 is a diagram schematically illustrating a process for implementing the manufacturing method of the strain measuring sensor shown in FIG. 5 .

FIG. 7 is a view showing an electroplating apparatus for forming a conductive thin film layer on a substrate layer in FIG. 5 .

8(a) is a SEM image of a strain measuring sensor manufactured by a conventional manufacturing method, and FIG. 8(b) is a SEM image of a strain measuring sensor manufactured by the manufacturing method of FIG. 4 .

9 is a diagram showing an example in which the strain measuring sensor according to the present invention is applied to wearable devices.

10 is a diagram showing an example in which the strain measuring sensor according to the present invention is applied to a sound recognition device.

Hereinafter, a strain measuring sensor and a manufacturing method thereof according to a preferred embodiment will be described in detail with reference to the accompanying drawings. Here, the same reference numerals are used for the same components, and repeated descriptions and detailed descriptions of known functions and configurations that may unnecessarily obscure the subject matter of the invention are omitted. Embodiments of the invention are provided to more completely explain the present invention to those skilled in the art. Accordingly, the shapes and sizes of elements in the drawings may be exaggerated for clarity.

2 is a perspective view showing the configuration of a strain measuring sensor according to an embodiment of the present invention, FIG. 3 is a view showing a state in which an external force is applied in the X-axis direction to the strain measuring sensor of FIG. 2, and FIG. It is a diagram showing a state in which an external force is applied in the Y-axis direction to the strain measuring sensor of Fig. 2.

Referring to FIGS. 2 to 4 , the strain measuring sensor 100 converts and detects minute mechanical changes (strain) into electrical signals, and may include a substrate layer 110 and a conductive thin film layer 120.

The substrate layer 110 forms the base of the strain measuring sensor 100 and may be formed in a plate shape made of a flexible material. The base layer 110 may be formed by processing a polymer material such as PDMS, which will be described in detail later.

The conductive thin film layer 120 may be provided on one surface of the substrate layer 110 and cracks 120a having at least one pattern of irregular straight lines or irregular curves may be formed. Hereinafter, in this embodiment, only cracks 120a having an irregular curved pattern are formed on one surface of the substrate layer 110 for convenience of description.

In this way, as the crack 120a having an irregular curved pattern is formed in the conductive thin film layer 120 of the strain measuring sensor 100, compared to the conventional strain measuring sensor 1 in which the straight crack 20a is formed, Cracks 120a having a wide distribution may be formed. That is, in the case of the conventional strain measuring sensor 1, as shown in FIG. 1, the crack 20a is formed in only one direction, but in the case of the strain measuring sensor 100 according to the present invention, as shown in FIG. Since the cracks 120a are formed not only in one direction but also in a direction perpendicular thereto, cracks 120a having a wider distribution can be provided. Due to the increase in the distribution area of the cracks 120a, the sensitivity and sensing range of the strain measuring sensor 100 may be improved without an intermediate layer.

In addition, since the crack 120a is formed in both one direction and a direction perpendicular thereto, it is possible to measure an external force applied in both directions (biaxial). That is, conventionally, since cracks are formed in only one direction, only external force applied in a single direction could be measured, but in the case of the present invention, as shown in FIGS. 3 and 4, applied in the X-axis direction and the Y-axis direction External forces can be measured. Therefore, there is an advantage in that tension applied in various directions can be measured using only one strain measuring sensor 100 .

Meanwhile, resistance change in the conductive thin film layer 120 may be determined according to the state of the crack 120a. That is, when a tensile force is applied to the strain measuring sensor 100 as shown in FIG. 3, the crack 120a widens and increases in area, thereby reducing the conductivity of the conductive thin film layer 120, which causes the conductive thin film layer 120 to will increase the resistance of Conversely, when the tensile force applied to the strain measuring sensor 100 is released and restored to its original state, the area of the crack 120a is reduced to increase the conductivity of the conductive thin film layer 120, which reduces the resistance of the conductive thin film layer 120 be able to do Therefore, when the electrical change of the conductive thin film layer 120 is measured using this change in resistance, the external force applied to the base layer 110 can be measured.

The conductive thin film layer 120 may include an island portion 121 and a crack 120a.

The island portion 121 may be formed by growing metal nanoparticles 21 on the conductive wire 22 coated on one surface of the base layer 110 . Here, the conductive wire 22 may include at least one of CNT, silver nano wire, graphene, or graphite, and the metal nanoparticle 21 may be any material capable of electroplating. Metal, for example, may be provided with gold (Au).

The crack 120a may be formed between the island portions 121 and may be formed due to the space 22a between the skein-shaped conductive wires 22 . For example, when electroplating is performed after immersing the substrate layer 110 having CNTs on one surface in a solution containing gold (Au) ions, gold nanoparticles grow on the CNTs. At this time, since the CNT has a structure like a skein, a plurality of empty spaces 22a may be provided therein (see FIG. 5). Therefore, after completion of the electroplating, a plurality of gold nanoparticles grow on the CNT and combine with the surrounding gold nanoparticles to form the island portion 121, and the empty space 22a of the CNT forms the island portion 121 A curved crack 120a is formed between them.

Accordingly, when an external force is applied to the substrate layer 110, the area of the crack 120a widens or narrows, and the contact area between the island portions 121 changes, and the island portion 121 according to the change in the contact area ) It is possible to measure the external force applied to the base layer 110 by measuring the electrical change.

5 is a flow chart of a method for manufacturing a strain measuring sensor according to an embodiment of the present invention, and FIG. 6 is a diagram schematically illustrating a process for implementing the method for manufacturing a strain measuring sensor shown in FIG. 5, and FIG. 7 is a diagram showing an electroplating apparatus for forming a conductive thin film layer on a substrate layer in FIG. 5 .

In this embodiment, a description will be made focusing on differences from the previous embodiment.

5 to 7, the method of manufacturing a strain measuring sensor (S100) includes providing a conductive wire on one surface of a substrate (S110), forming a base layer (S120), and removing the base layer from the substrate. It may include separating (S130), growing metal nanoparticles on the conductive wire (S140), and forming a conductive thin film layer on the substrate layer (S140).

In the step of providing a conductive wire on one surface of the substrate (S110), the conductive wire 22 is spray-coated on one surface of the substrate 130 made of a silicon (Si) wafer to form a conductive wire 22 on one surface of the substrate 130. ) can be provided. Here, the conductive wire 22 provided on the substrate 130 may include at least one of CNT, silver nano wire, graphene, or graphite.

The step of providing a conductive wire on one surface of the substrate (S110) may further include a step of preparing a pretreated substrate 130 by cleaning the silicon wafer before spray-coating the conductive wire 22 (S111).

In the step of forming the substrate layer (S120), a liquid polymer material is coated on one surface of the substrate 130 to form the substrate layer 110 with the conductive wire 22 interposed between the substrate 130 and the substrate 130. there is. Here, the conductive wire 22 may be provided to have a nano-sized diameter, and the polymer material may include polydimethylsiloxane (PDMS), polyimide (PI), polyehtylene-terephthalate (PET), polyether sulfone (PES), and PEN ( polyethylene naphthalate), PMMA (PolymethymethAcrylate), PC (Polycarbonate), and Ecoflex.

For example, the step of forming the substrate layer (S120) is a process of spin-coating a liquid polymer material on the substrate 130 provided with the conductive wire 22, and curing the polymer material to form the conductive wire 22 on one surface. A part of may include a process of obtaining the fixed base layer 110. Here, the reason for using the liquid polymer material as the base layer 110 is to harden a part of the conductive wire 22 while being inserted into the polymer material, so that when the base layer 110 is separated from the substrate 130 This is to prevent the conductive wire 22 from escaping from the base layer 110 .

In the step of separating the substrate layer from the substrate ( S130 ), the substrate layer 110 having the conductive wire 22 fixed to one surface may be separated from the substrate 130 using a physical method or a chemical method. Here, the step of separating the base layer from the substrate (S130) may include separating the base layer 110 from the substrate 130 and then cutting the base layer 110 into a desired size and shape (S131). there is. Accordingly, it is possible to obtain a base layer 110 having a desired size and shape, and the conductive wire 22 may be fixed to one surface of the base layer 110 thus obtained.

In the step of growing metal nanoparticles on the conductive wire (S140), as shown in FIG. 6, after immersing the substrate layer 110 in a solution containing metal ions, an electrochemical process using the conductive wire 22 is actively performed. Metal nanoparticles 21 may be grown on the conductive wire 22 through a deposition process. Here, the electrochemical deposition process may include at least one of an electrodeposition method, an electroplating method, an electrophorethic deposition method, and an electroless plating method.

Meanwhile, as the density of the metal nanoparticles 21 per unit area increases, sensitivity and sensing range can be improved. That is, as the size of the metal nanoparticles 21 grown on the CNT is small and the distribution (number) per unit area increases, sensitivity and sensing range can be improved by responding to minute vibrations. The density control of the metal nanoparticles 21 is achieved by controlling at least one of the time of the electrochemical deposition process and the magnitude of the electric field applied during the electrochemical deposition process in the step of growing the metal nanoparticles on the conductive wire (S140). can

In the step of forming the conductive thin film layer on the substrate layer (S140), the conductive thin film layer 120 having irregular curved patterns of cracks 120a is formed on the substrate layer 110 by using the growth of metal nanoparticles 21. can do. That is, the conductive thin film layer 120 including the island portion 121 and the crack 120a is formed on the substrate layer 110 through the growth of metal nanoparticles 21 using electroplating, so that the strain measurement sensor 100 ) can be obtained.

For example, when electroplating is performed after immersing the substrate layer 110 in a solution containing gold (Au) ions, CNT provided on one side of the substrate layer 110 is used as an electrode, and gold (Au) on the CNT ) nanoparticles grow. Therefore, if this is used, gold nanoparticles grow on the CNT and combine with the surrounding gold nanoparticles to form the island portion 121, and the space 22a formed inside the CNT causes the gold (Au) nanoparticles to grow. If not yet combined, this space 22a forms a crack 120a. At this time, due to the skein-shaped CNT structure, the space 22a is formed in a curved shape, and thus, the crack 120a may also be formed in a curved shape.

As such, as the curved cracks 120a are provided between the island portions 121, the cracks 120a having a wider distribution are formed than in the conventional strain measuring sensor 1 in which straight cracks 20a are formed. And, due to the increased distribution of cracks 120a, it is possible to improve the sensitivity and sensing range of the strain measuring sensor 100 without an intermediate layer.

Meanwhile, the area of the crack 120a may be controlled according to the amount of the conductive wire 22 provided on the substrate 130 . For example, as the amount of conductive wires 22 provided on the same substrate 130 increases, the space 22a between the conductive wires 22 becomes more dense, which reduces the distribution (number) of cracks 120a. can increase Conversely, as the amount of the conductive wires 22 decreases, the space 22a between the conductive wires 22 becomes coarser, which may reduce the distribution (number) of cracks 120a. That is, when the amount of conductive wire 22 is controlled, the distribution of cracks 120a can be increased. However, when more conductive wires 22 are provided than necessary, the spaces 22a formed in the conductive wires 22 are too dense, so that when the metal nanoparticles 21 grow, the surrounding metal nanoparticles 21 Since cracks 120a may not be formed by combining both, it is important to properly control the amount of the conductive wire 22 in consideration of this point.

8(a) is a conventional strain measuring sensor 1 manufactured using a sputtering device, and it can be seen that cracks are formed in one direction. On the other hand, in the case of the strain measuring sensor 100 according to the present invention, as shown in FIG. 8(b), it can be confirmed that the crack is formed in a curved shape. In addition, in the case of the strain measuring sensor 100 according to the present invention, since the distribution of cracks per unit area is more formed, it can have a wider sensing range than the conventional strain measuring sensor 1.

9 is a diagram showing an example in which the strain measuring sensor according to the present invention is applied to wearable devices, and FIG. 10 is a diagram showing an example in which the strain measuring sensor according to the present invention is applied to a sound recognition device.

Referring to FIG. 9 , the strain measurement sensor 100 according to the present invention may be installed in a wearable device such as a mask or glove to measure a signal caused by a user's cough or movement. In addition, as shown in FIG. 10 , it may be used as an acoustic perception device by measuring vibrations caused by sound waves.

As described above, in the case of the strain measuring sensor 100 according to the present invention, since the conductive thin film layer 120 having the crack 120a can be formed on the substrate layer 110 by a simple method such as electroplating, Compared to the manufacturing process of the conductive thin film layer 20 using a conventional sputtering device, the manufacturing time can be shortened, and manufacturing cost can be reduced because expensive equipment is not required.

In addition, as the conductive thin film layer 120 deposited on the substrate layer 110 has a crack 120a having a curved pattern, the strain is measured without providing an intermediate layer between the substrate layer 110 and the thin film layer 120. The sensitivity and sensing range of the sensor 100 may be improved.

In addition, since the conductive thin film layer 120 is prepared by growing metal nanoparticles 21 on the conductive wire 22 using the conductive wire 22 as an electrode during electroplating, the time of electroplating and the applied electric field When controlling the size of the size and density of the metal nanoparticles 21 can be controlled. That is, since the sensing range increases as the size of the metal nanoparticles 21 decreases, the strain measurement sensor 100 having a wide sensing range can be manufactured when the time and the size of the electric field are appropriately controlled during electroplating.

In addition, since the external force applied to the strain measuring sensor 100 can be measured by measuring the electrical change of the conductive thin film layer 120, it can be applied to a wearable device to measure a biosignal or movement.

The present invention has been described with reference to an embodiment shown in the accompanying drawings, but this is only exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. You will be able to. Therefore, the true protection scope of the present invention should be defined only by the appended claims.

included in the text

Claims

A base layer formed of a flexible material; and

a conductive thin film layer provided on one side of the substrate layer and formed with cracks having at least one pattern of irregular straight lines or irregular curves;

Strain measurement sensor comprising a.
According to claim 1,

The conductive thin film layer includes a plurality of island portions formed by growing metal nanoparticles on a conductive wire coated on one surface of the base layer, and the crack is formed between the island portions by a space between the conductive wires. measuring sensor.
According to claim 2,

The conductive wire is a strain measuring sensor comprising at least one of CNT, silver nano wire, graphene or graphite.
According to claim 2,

When an external force is applied to the base layer, the area of the crack widens or narrows to change the contact area between the island parts, and the electrical change of the island part according to the change in the contact area is measured and applied to the base layer Strain measurement sensor that measures the external force.
According to claim 1,

The conductive thin film layer is deposited and formed on the base layer using an electrochemical deposition process including at least one of an electroporation method, an electroplating method, an electrophorethic deposition method, and an electroless plating method. Strain measuring sensor.
providing a conductive wire on one side of the substrate;

coating one surface of the substrate with a liquid polymer material to form a substrate layer with the conductive wire interposed therebetween;

Separating the base layer on which the conductive wire is fixed on one side of the substrate from the substrate;

growing metal nanoparticles on the conductive wire through an electrochemical deposition process actively using the conductive wire after immersing the substrate layer in a solution containing metal ions; and

forming a conductive thin film layer having at least one pattern of cracks among irregular straight lines and irregular curves on the base layer by using the growth of the metal nanoparticles;

Method of manufacturing a strain measuring sensor comprising a.
According to claim 6,

Forming the base layer,

spin-coating the liquid polymer material on the substrate provided with the conductive wire;

A method of manufacturing a strain measuring sensor comprising a step of curing the polymer material to obtain a substrate layer on one surface of which a portion of the conductive wire is fixed.
According to claim 6,

Separating the substrate layer from the substrate,

After separating the base layer from the substrate, the manufacturing method of the strain measuring sensor further comprising the step of cutting the base layer into a desired size and shape.
According to claim 6,

Growing metal nanoparticles on the conductive wire,

A method of manufacturing a strain measuring sensor in which the size and density of the metal nanoparticles are controlled by controlling at least one of the time of the electrochemical deposition process and the size of the electric field.
According to claim 6,

A method of manufacturing a strain measuring sensor capable of controlling the distribution of the cracks according to the amount of the conductive wire provided on the substrate.
According to claim 6,

The method of manufacturing a strain measuring sensor, wherein the electrochemical deposition process includes at least one of an electrodeposition method, an electroplating method, an electrophorethic deposition method, and an electroless plating method.
According to claim 6,

The polymer material includes one selected from polydimethylsiloxane (PDMS), polyimide (PI), polyehtylene-terephthalate (PET), polyether sulfone (PES), polyethylene naphthalate (PEN), polymethymethacrylate (PMMA), polycarbonate (PC), and Ecoflex. Manufacturing method of strain measuring sensor.
According to claim 6,

The conductive wire is a method of manufacturing a strain measuring sensor comprising at least one of CNT, silver nano wire, graphene or graphite.