KR20220063634A - Strain sensor fabricating method and the strain sensor fabricated by the same - Google Patents

Abstract

A strain sensor manufacturing method of the present invention comprises: a substrate provision step of providing a substrate having a plurality of protrusion units; a first inclined deposition step of depositing a deposition material on the substrate with a first inclination angle; and a second inclined deposition step of depositing a deposition material on the substrate with a second inclination angle. According to the strain sensor manufacturing method and a strain sensor manufactured by using the same according to the present invention, crack alignment and density is significantly improved to greatly increase sensibility and secure excellent durability.

Description

Strain sensor manufacturing method and strain sensor manufactured using the same

The present invention relates to a strain sensor manufacturing method and a strain sensor manufactured using the same, and more particularly, to a crack-based strain sensor manufacturing method with improved sensitivity through aligned cracks, and a strain sensor manufactured using the same.

A strain sensor (or strain gauge) refers to a sensor that measures strain strain. Strain sensors are being applied to wearable devices such as smart watches and smart insoles, or healthcare devices that measure various biometric information such as heart rate, blood pressure, EEG, ECG, and EMG. Furthermore, the range of application of the strain sensor is continuous, such as being applied to human motion detection for extracting body motion information or a human-machine interface that performs various controls using the same. is being expanded to

1 shows a measurement principle for each type of strain sensor. The strain sensor has a resistive-type shown in (a) of FIG. 1 and a capacitive-type shown in (b).

The resistive type measures the strain rate of the conductive material by extracting a change in resistance through electrodes provided on both sides of the conductive material through an electrical change at both ends as the conductive material is deformed.

The capacitive type is based on the amount of change in capacitance between electrodes due to deformation (increase or decrease in thickness) of the dielectric (eg, increase in capacitance due to decrease in the distance (d) between electrodes due to decrease in dielectric thickness). Measure the strain.

2 is a graph comparing gauge factors for each type of strain sensor. The gauge factor is defined as the relative change in resistance/capacitance compared to applied strain. A large gauge factor means a large change in resistance or capacitance at the same strain, and based on this, sensitivity can be determined. As shown in Figure 2, compared to the capacitive type ([1], [2], [3]), the resistive type ([4], [5], [6], [7], [8] It can be seen that the gauge factor of ]) is significantly larger.

In addition, among the resistive types, a crack based strain sensor has been in the spotlight due to its high sensitivity.

However, crack-based strain sensors have a problem in that it is difficult to generate nano-period aligned cracks, and thus sensitivity is lowered.

3 to 7 are diagrams for explaining the mechanism and problems of the conventional crack-based strain sensor. As shown in FIG. 3 , in the crack-based strain sensor, when a strain is applied, the crack spreads and the resistance increases, and the magnitude of the strain is calculated using the amount of change in the resistance. However, as shown in the photo of FIG. 3 , non-uniform and misaligned cracks inevitably cause a decrease in sensitivity.

As shown in FIG. 4 , when a strain is applied to an unaligned crack and when a strain is applied to an aligned crack, even if the same strain is applied, the measured resistance change amount may be different. The resistance change measured in aligned cracks is larger than the resistance change measured in unaligned cracks, which means that the aligned cracks have a greater sensitivity.

On the other hand, in the conventional crack-based strain sensor, cracks were formed using a platinum (Pt) film on a flexible polymer (PUA) as shown in FIG. . Furthermore, when a metal other than platinum (Pt) (eg, Au) is used, the shape of the crack becomes more messy as shown in FIG.

6 shows a stress concentration structure in which lattice-shaped cracks are formed. Even in this case, cracks are not perfectly aligned, and high sensitivity cannot be expected because the crack density is low. As such, it is not easy to perfectly align cracks, and furthermore, it is difficult to expect an increase in the density of cracks with current technology.

On the other hand, a metal coating for forming cracks is made on the flexible substrate, and the adhesive force for bonding the substrate and the metal becomes an important variable in determining whether or not cracks are formed. As shown on the left of FIG. 7, when bonding Au on PDMS, the adhesive force is weak, so it does not matter, but when bonding Au on PUA as in the right of FIG. The cracks are not properly aligned because they are not concentrated in the thin film and are relieved by the flexible substrate. In other words, the adhesive force between the metal thin film and the flexible substrate has a great effect in manufacturing aligned cracks whose resistance is changed by the change of strain. Because there are too many factors to be considered, such as (temperature, humidity, etc.), the existing crack manufacturing method has limitations, and R&D is required to improve it.

The present invention has been devised in view of the technical needs described above, and an object of the present invention is to provide a method for manufacturing a highly sensitive crack-based strain sensor with improved crack alignment and density, and a strain sensor manufactured using the same. .

A method for manufacturing a strain sensor according to the present invention for achieving the above object comprises: providing a substrate providing a substrate having a plurality of protrusions; a first inclined deposition step of depositing a deposition material having a first inclination angle with respect to the substrate; and a second inclined deposition step of depositing a deposition material having a second inclination angle with respect to the substrate.

The method may further include a vertical deposition step of depositing the deposition material in a direction perpendicular to the substrate.

The method may further include a stress application step of generating cracks in the deposition layer formed on the substrate by applying stress.

In addition, the substrate may be a nanograting substrate in which a plurality of linear protrusions are spaced apart from each other by a predetermined interval.

In addition, the crack may be formed in a straight line along a straight valley positioned between the plurality of straight protrusions.

In addition, in the step of applying the stress, a linear crack may be formed on the deposition layer by bending or stretching the substrate to space the plurality of linear protrusions apart.

In addition, the substrate may be made of a flexible material.

In addition, the step of providing the substrate may include: forming a flexible material layer on the Si nano grating substrate; and transferring the grating pattern by removing the Si nano grating substrate.

The method may further include forming a base layer on the flexible material layer.

In addition, the amount of the deposition material penetrating into the valleys between the protrusions may be less than the amount of the deposition material deposited on the upper surface or the upper surface of the protrusions.

In addition, the size of the crack generated on the substrate may decrease from the substrate toward the upper portion of the deposition layer.

On the other hand, the strain sensor according to the present invention for achieving the above object may be manufactured by the strain sensor manufacturing method.

According to the method for manufacturing a strain sensor according to the present invention and a strain sensor manufactured using the same, since the alignment and density of cracks can be greatly improved, the sensitivity can be significantly increased.

1 shows a measurement principle for each type of strain sensor.
2 is a graph comparing gauge factors for each type of strain sensor.
3 is a view for explaining the operation of a crack-based strain sensor.
4 is a view for explaining a difference in sensitivity according to the alignment degree of cracks.
5 is a view for explaining the limitations of the coating material selection of the conventional crack-based strain sensor.
6 is a view for explaining a problem according to the crack density and misalignment structure of the conventional crack-based strain sensor.
7 is a view for explaining the problems of the conventional crack-based strain sensor manufacturing using a stress application method with respect to the bonded substrate and the conductive material.
8 is a schematic diagram for explaining the operation of the strain sensor manufactured by the strain sensor manufacturing method according to the present invention.
9A to 9D are flowcharts illustrating various embodiments of a method for manufacturing a strain sensor according to the present invention.
10 is a view for explaining the principle of generating cracks aligned in a straight line on a substrate in the strain sensor manufacturing method according to the present invention.
11 shows the sequence of the strain sensor manufacturing method according to the present invention.
12 shows aligned cracks on a strain sensor according to the present invention.
13A is an enlarged view of the crack of the strain sensor according to the present invention.
13B is a graph showing the thickness of the deposited layer of the strain sensor according to the present invention and the width of the crack.
14 shows that the strain sensor manufacturing method according to the present invention can be manufactured using various materials.
15 is an experiment for confirming whether the strain sensor according to the present invention operates.
16 is a graph illustrating a resistance change rate according to a strain applied to a sensor.
17 is a graph showing measurement results when strains in opposite directions are applied.
18 is a graph showing the sensitivity of the strain sensor according to the present invention compared to the sensor of the prior art.
19A shows a state in which a biosignal is measured through the strain sensor according to the present invention.
19B is a graph showing the measurement result of the biosignal measured in FIG. 18B.
20 shows another sequence of a method for manufacturing a strain sensor according to the present invention.
21 is a durability test result of the strain sensor according to the present invention.

The invention will be described in detail with reference to the accompanying drawings, which show specific embodiments in which the invention may be practiced. With respect to specific embodiments shown in the accompanying drawings, description is given in sufficient detail to enable those skilled in the art to practice the present invention. Embodiments other than the specific embodiment are different from, but need not be mutually exclusive of. In addition, it should be understood that the detailed description given below is not intended to be taken in a limiting sense.

BRIEF DESCRIPTION OF THE DRAWINGS The detailed description of a particular embodiment shown in the accompanying drawings is read in conjunction with the accompanying drawings, which are considered to be part of the entire description of the invention. References to directions or directions are for convenience of description only, and are not intended to limit the scope of the present invention in any way.

Specifically, terms indicating a position such as "down, up, horizontal, vertical, upper, lower, upward, downward, upper, lower", or derivatives thereof (eg, "horizontally, downwardly, upwardly") etc.) should be understood with reference to both the drawings and related descriptions being described. In particular, these relative words are only for convenience of description.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. 8 is a schematic diagram for explaining the operation of the strain sensor manufactured by the strain sensor manufacturing method according to the present invention.

In the strain sensor manufactured by the method for manufacturing a strain sensor according to the present invention, as shown in FIG. 8 , cracks arranged in a line are formed on the substrate. In the normal state, the reference resistance (R _releasing ) is measured, and when a predetermined stress (pressure, etc.) is applied and both ends are bent, a crack opens and the resistance rises. That is, the resistance (R _bending ) in a state in which the strain is applied is greater than the reference resistance (R _releasing ), and according to the magnitude of the change value of the resistance (R _bending -R _releasing ), the magnitude of the applied strain can be calculated. .

As shown in FIG. 8, the strain sensor manufactured by the strain sensor manufacturing method according to the present invention includes a substrate in which a plurality of linear protrusions are formed side by side, that is, formed in parallel at a predetermined interval. The substrate may be a nanograting substrate.

A straight trough exists between the plurality of straight protrusions formed on the substrate, and as the straight ribs are widened, cracks formed in the deposition material are widened. Cracks formed in the deposition material may also be formed side by side along a straight valley by being deposited through the manufacturing method proposed in the present invention. Accordingly, as shown in FIG. 8 , it is possible to form straight-line aligned cracks.

9A to 9D are flowcharts illustrating various embodiments of a method for manufacturing a strain sensor according to the present invention.

(Example 1)

As shown in FIG. 9A , in the first embodiment of the method for manufacturing a strain sensor according to the present invention, a substrate provided with a plurality of protrusions is provided ( S110 ). As described above, the substrate may be a nanograting substrate in which a plurality of linear protrusions are spaced apart from each other at predetermined intervals.

Thereafter, a deposition material is deposited at a first inclination angle with respect to the substrate (S120). The first inclination angle is an angle between 0° and 90°, and step S120 may be performed by spraying the deposition material obliquely to the substrate.

Thereafter, a deposition material is deposited with a second inclination angle with respect to the substrate ( S130 ). The second inclination angle is an angle between 90° and 180°, and step S130 may be performed by spraying the deposition material obliquely on the substrate in a direction opposite to that of step S120.

In other words, both the first inclination angle and the second inclination angle are angles between 0° and 90°, and may refer to angles formed by extending diagonally in opposite directions with respect to the surface on which the substrate is placed. Aligned cracks may be generated only by the first gradient deposition ( S120 ) and the second gradient deposition ( S130 ) described above.

(Second embodiment)

As shown in FIG. 9B , in the second embodiment of the method for manufacturing a strain sensor according to the present invention, a substrate provided with a plurality of protrusions is provided ( S210 ). As described above, the substrate may be a nanograting substrate in which a plurality of linear protrusions are spaced apart from each other at predetermined intervals.

Thereafter, a deposition material is deposited at a first inclination angle with respect to the substrate (S220). The first inclination angle is an angle between 0° and 90°, and step S120 may be performed by spraying the deposition material obliquely to the substrate.

Thereafter, a deposition material is deposited at a second inclination angle with respect to the substrate ( S230 ). The second inclination angle is an angle between 90° and 180°, and step S230 may be performed by spraying the deposition material obliquely on the substrate in a direction opposite to that of step S220.

Finally, the step of applying the stress is performed (S240). Specifically, by bending or stretching both sides of the substrate, cracks are generated in the deposition layer formed on the substrate (S240). In step S240, a linear crack is formed on the deposition layer by bending the substrate (flexible substrate) to separate the plurality of linear protrusions. As a result, cracks are formed in a straight line along the line of the straight valleys positioned between the plurality of straight projections. Step S240 may be performed when a film layer covering the entirety of the film is generated without a complete crack on the substrate by the first gradient deposition ( S220 ) and the second gradient deposition ( S230 ). By step S240, it is possible to generate a linear crack in the film layer.

(Example 3)

A third embodiment of the method for manufacturing a strain sensor according to the present invention first provides a substrate provided with a plurality of protrusions (S310). As described above, the substrate may be a nanograting substrate in which a plurality of linear protrusions are spaced apart from each other at predetermined intervals.

Thereafter, a deposition material is deposited with a first inclination angle with respect to the substrate ( S320 ). The first inclination angle is an angle between 0° and 90°, and step S120 may be performed by spraying the deposition material obliquely to the substrate.

Thereafter, a deposition material is deposited with a second inclination angle with respect to the substrate (S330). The second inclination angle is an angle between 90° and 180°, and step S330 may be performed by spraying the deposition material obliquely on the substrate in a direction opposite to that of step S320.

After the first gradient deposition in step S320 and the second gradient deposition in step S330 are completed, a vertical deposition step of depositing the deposition material in a vertical direction with respect to the substrate is performed (S340).

Although the nanogap can be manufactured through the first gradient deposition ( S320 ) and the second gradient deposition ( S330 ), it is possible to obtain finely aligned cracks and control the thickness through the vertical deposition ( S340 ).

(Example 4)

A fourth embodiment of the method for manufacturing a strain sensor according to the present invention first provides a substrate having a plurality of protrusions (S410). As described above, the substrate may be a nanograting substrate in which a plurality of linear protrusions are spaced apart from each other at predetermined intervals.

Thereafter, a deposition material is deposited at a first inclination angle with respect to the substrate (S420). The first inclination angle is an angle between 0° and 90°, and step S420 may be performed by spraying the deposition material obliquely to the substrate.

Thereafter, a deposition material is deposited at a second inclination angle with respect to the substrate (S430). The second inclination angle is an angle between 90° and 180°, and step S430 may be performed by spraying the deposition material obliquely on the substrate in a direction opposite to that of step S420.

After the first gradient deposition in step S420 and the second gradient deposition in step S430 are completed, a vertical deposition step of depositing the deposition material in a vertical direction with respect to the substrate is performed (S440).

When the first inclined deposition (S420), the second inclined deposition (S430), and the vertical deposition (not shown) are performed, cracks do not occur on the substrate and a film layer completely covering the surface of the substrate can be formed. In this case, the method may further include generating cracks by applying stress to the substrate ( S450 ). That is, by bending or stretching the substrate (flexible substrate) to make a distance between the plurality of linear protrusions where stress is concentrated, the first inclined deposition (S420), the second inclined deposition (S430) and the vertical deposition (not shown) ) to form cracks in the film layer formed by Of course, the cracks are formed in a straight line aligned along the straight valley lines located between the straight projections.

10 is a view for explaining the principle of generating cracks aligned in a straight line on a substrate in the strain sensor manufacturing method according to the present invention. As shown in FIG. 10 , the width of the plurality of linear protrusions formed on the substrate may be about 150 nm in nano size. The width of the plurality of straight valleys defined by this may also have a size similar to the width of the straight protrusion, and may be larger or smaller than the width according to an embodiment.

When deposition is performed on a protrusion having a very small width, such as a straight protrusion, an atomic shadowing effect occurs. This is a physical phenomenon in which the deposition material is not newly interposed between the deposited parts, and the deposition material is intensively deposited only on the originally protruding area (polycrystalline island), forming shadowing areas hatched in FIG. it can be seen that In this case, the amount of the deposition material penetrating into the valleys between the protrusions is less than the amount of the deposition material deposited on the upper surface or the upper surface of the protrusions.

The method for manufacturing a strain sensor according to the present invention generates aligned cracks through an appropriate combination of a plurality of gradient deposition processes, additional vertical deposition processes, and strain application processes. That is, by depositing only around the tip of the straight protrusion on the substrate, it is possible to form aligned cracks on the plurality of straight valleys.

On the other hand, in the above, since a substrate having a straight protrusion is used, it has been described to obtain a straight crack aligned on the valley part. In the same principle, a substrate having protrusions of a specific pattern (zigzag, curved line, etc.) may be used, and if cracks are generated in the same way as above for a substrate of a specific pattern, the pattern of cracks is also the pattern of the substrate (more specifically, a pattern of valleys between protrusions formed on the substrate). That is, the present invention is an invention for forming aligned cracks, and the pattern is not necessarily limited to a straight line.

11 shows the sequence of the strain sensor manufacturing method according to the present invention. First, (a) to (c) of FIG. 11 corresponds to the step of providing the substrate ( S110 ) of FIG. 9 .

First, a rigid Si nanograting substrate is prepared. Although the width of the protrusion of the Si nanograting substrate is shown to be 150 nm, it is not necessarily limited thereto.

The pattern is transferred to a flexible material on the Si nanograting substrate. 11 illustrates a flexible material in which PUA is laminated on PET, but is not limited thereto. When the flexible material is printed on the Si nanograting substrate, a flexible substrate as shown in FIG. 11C is formed. Since the width of the protrusion of the substrate prepared in (a) of FIG. 11 was 150 nm, the width of the trough of the flexible substrate generated in (c) of FIG. 11 may be 150 nm. That is, by varying the width of the protrusion of the substrate prepared in (a) of FIG. 11 , it is possible to change the width of the valley of the flexible substrate.

That is, the step of providing the substrate includes forming a flexible material layer on the Si nano grating substrate and transferring the grating pattern by removing the Si nano grating substrate. However, the method may further include forming a base layer on the flexible material layer between the steps.

Thereafter, the first gradient deposition is performed as shown in FIG. 11(d). The first gradient deposition corresponds to the gradient deposition in step S120 of FIG. 9 . The deposition step is a step of depositing a deposition material by spraying the deposition material at a predetermined angle in an incident direction of one or the other side of the protrusion of the flexible substrate.

The deposition may be performed by PVD (Physical Vapor Deposition). PVD is a deposition method that converts energy applied to a material into kinetic energy so that the material becomes movable and accumulates on a substrate. It can be divided into deposition and the like.

Briefly describing each deposition method, thermal evaporation vacuum deposition is a method of forming a thin film on a substrate at a relatively low temperature by vaporizing it by applying high heat to a material source in a vacuum state. Electron beam deposition is a method of forming a thin film on a substrate by supplying electric current to a filament and inducing the emitted electron beam into a magnetic field by a magnet to focus electron collision on the deposition material. In sputtering deposition, when ionized atoms are accelerated and collide with a material, when the collision energy is greater than the binding energy of the material surface, atoms are ejected from the surface using sputtering. It is a method of forming a thin film by depositing on The deposition used in the method for manufacturing the strain sensor according to the present invention is not limited to any specific method.

When the first inclined deposition is performed, it can be seen that the deposition is more biased in the right direction (a surface close to the inclined deposition (spray) direction) of the upper surface of the protrusion as shown in FIG. 11(d).

As shown in (e) of Figure 11, a second gradient deposition is performed. The second gradient deposition corresponds to the gradient deposition in step S130 of FIG. The second gradient deposition may also be performed by PVD (Physical Vapor Deposition) described above. In the second gradient deposition, the deposition material is sprayed in a direction opposite to the spraying direction in the first gradient deposition.

When the second inclined deposition is performed, it can be seen that this time, the deposition is more biased toward the left side of the upper surface of the protrusion (a surface close to the inclined deposition (spraying) direction), as shown in FIG. 11E .

Finally, vertical deposition is performed as shown in FIG. 11(f). The vertical deposition is performed by spraying a deposition material in a direction perpendicular to the substrate, and a third deposition layer is formed on the first deposition layer by the first gradient deposition and the second deposition layer stacked thereon. Accordingly, it is possible to form straight cracks at regular intervals along the straight valley line.

12 shows aligned cracks on a strain sensor according to the present invention. As shown in (a) of FIG. 12 , when the strain sensor is viewed from the top, it can be seen that cracks arranged in a line are formed.

Meanwhile, as shown in (b) of FIG. 12 , the first/second deposition layer formed by the first gradient deposition/second gradient deposition and the third deposition layer formed by the vertical deposition thereon can be confirmed, and a straight valley line It can be seen that delicate cracks are formed along the

13A is an enlarged view of the crack of the strain sensor according to the present invention. When the width of the valley portion of the flexible substrate is approximately 150 nm, cracks of about 45 nm occurred in the first/second deposition layer formed by the first/second gradient deposition, and approximately 4.5 nm in the third deposition layer formed by vertical deposition. of cracks were formed. That is, the size of the crack formed on the deposition layer gradually decreased from the bottom to the top.

13B is a graph showing the thickness of the deposition layer and the width of the crack. As the thickness of the deposition layer increases through a plurality of depositions, the crack width tends to decrease. Using this, it was confirmed that cracks of 10 nm or less can be sufficiently formed.

14 shows various materials used in a method for manufacturing a strain sensor according to the present invention. As described in FIG. 5, the conventional crack-based strain sensor has a problem of being dependent on the coating material. However, in the present invention, since the crack formation process is not affected or less affected by the adhesive force between the flexible substrate and the conductive film, various materials such as Pt, ITO, and Cu may be used. In particular, as shown in FIG. 14A , the deposition material of the first gradient deposition and the deposition material of the second gradient deposition may be different. Even when any material was employed, it was possible to confirm the uniformly aligned straight-line cracks.

15 is an experiment for confirming whether the strain sensor according to the present invention operates. When electrodes were installed at both ends of the strain sensor with aligned cracks and strain was applied periodically, it was confirmed that the resistance change was dramatically changed in the strain applied state and the released state.

16 is a graph showing the resistance change rate according to the magnitude of the strain. It was confirmed that the magnitude of the strain and the resistance change rate are proportional to each other, and accordingly, it can be seen that the strain sensor according to the present invention can sufficiently operate as a sensor.

17 is a graph showing measurement results when strains in opposite directions are applied. In the above, if a mechanism for cracking cracks by bending the strain sensor from both sides was used, in FIG. 17, a mechanism for narrowing cracks by bending the strain sensor in the opposite direction is used.

Even in this case, as shown in FIG. 17 , it was confirmed that the resistance decreased whenever a pressing force was applied. That is, it was confirmed that the strain sensor according to the present invention can detect the magnitude of the strain with high sensitivity no matter which direction the strain is applied.

18 is a graph showing the sensitivity of the strain sensor according to the present invention compared to the sensor of the prior art. As shown in (a) of FIG. 18 , in the strain sensor according to the present invention, the resistance change rate (ΔR/R ₀ ) with respect to a very low strain of 0.3 (%) is measured around 200%. As shown in (b) of FIG. 18 , compared with the conventional strain sensors of [1] to [5], it was confirmed that they had high sensitivity even to very low strains.

19A is a diagram illustrating a state in which a biosignal is measured through a strain sensor according to the present invention, and FIG. 18B is a graph illustrating a result of measuring a biosignal.

As shown in FIG. 19A , when the strain sensor according to the present invention is attached to a person's neck and an electrode is connected to measure a signal, a change in resistance as shown in FIG. 19B could be confirmed.

The upper graph of FIG. 19B is the measurement result (resistance change) before exercise, and the lower graph of FIG. 19B is the measurement result (resistance change) after exercise. Comparing this, it was confirmed that it was possible to measure up to the intensity along with the period of the pulse.

20 shows another sequence of the strain sensor manufacturing method according to the present invention. A process corresponding to the step of providing the substrate of FIGS. 9A to 9D described above will be omitted and described.

First, after preparing a flexible nano-grating substrate (FIG. 20 (a)), a first gradient deposition is performed (FIG. 20 (b)). The first gradient deposition corresponds to the first gradient deposition ( S120 , S220 , S320 , and S420 ) of FIGS. 9A to 9D . The deposition step is a step of depositing a deposition material by spraying the deposition material at a predetermined angle in an incident direction of one or the other side of the protrusion of the flexible substrate.

The deposition may be performed by PVD (Physical Vapor Deposition). PVD is a deposition method that converts energy applied to a material into kinetic energy so that the material becomes movable and accumulates on a substrate. It can be divided into vapor deposition, and any vapor deposition method may be employed for the manufacturing method according to the present invention, and in some cases, vapor deposition may be performed using a method other than those described herein. When the first inclined deposition is performed, it can be seen that the deposition is more biased toward the right side of the upper surface of the protrusion (a surface close to the inclined deposition (spraying) direction).

Thereafter, a second gradient deposition is performed (FIG. 20(c)). The second gradient deposition corresponds to the gradient deposition in the second gradient deposition steps S130, S230, S330, and S430 of FIGS. 9A to 9D . The second gradient deposition may also be performed by PVD (Physical Vapor Deposition) described above. In the second gradient deposition, the deposition material is sprayed in a direction opposite to the spraying direction in the first gradient deposition. When the second inclined deposition is performed, it can be seen that this time, deposition is more biased toward the left side of the upper surface of the protrusion (a surface close to the inclined deposition (spraying) direction).

Next, vertical deposition is performed (FIG. 20(d)). The vertical deposition corresponds to the vertical deposition (S340 and S440) of FIGS. 9C and 9D. That is, the deposition material is sprayed in a direction perpendicular to the substrate, and a third deposition layer is formed on the first deposition layer by the first gradient deposition and the second deposition layer stacked thereon.

At this time, if cracks are not formed in the third deposition layer by vertical deposition, cracks are formed by applying stress to both ends of the substrate and tearing the deposition layer as shown in FIG. 20E . As for the deposition layer formed on the valley line, a very thin deposition layer is formed by the above-described atomic shadowing effect. Accordingly, when both ends of the flexible substrate are bent, the straight protrusions are widened, and the connection of the deposition layer on the valley line is broken, and cracks are formed along the valley line. Accordingly, it is possible to obtain a strain sensor in which a crack of a predetermined width is formed.

21 is a durability test result of the strain sensor according to the present invention. The motion of applying 0.26% of strain to the strain sensor and releasing it was repeated approximately 20,000 times. As a result, despite the continuous operation, the result value (resistance change rate) showed a constant pattern with no significant difference. This proves that the durability of the sensor using cracks formed by two times of gradient deposition and one round of vertical deposition is very high, and suggests that it can be directly applied to various products.

According to the method for manufacturing a strain sensor according to the present invention and a strain sensor manufactured using the same, since the alignment and density of cracks can be greatly improved, the sensitivity can be significantly increased. In addition, as demonstrated in FIG. 21 , since durability of the strain sensor can be secured, it may be applied to various products.

In the above, the embodiment has been mainly described, but this is only an illustration and does not limit the present invention, and those of ordinary skill in the art to which the present invention pertains are not exemplified above in the range that does not depart from the essential characteristics of the present embodiment. It can be seen that various modifications and applications are possible. For example, each component specifically shown in the embodiment can be implemented by modification. And differences related to such modifications and applications should be construed as being included in the scope of the present invention defined in the appended claims.

100: nanograting substrate (nanograting substrate)
R _releasing : resistance when no crane is applied
R _bending : resistance when strain is applied

Claims (12)

A substrate providing step of providing a substrate provided with a plurality of protrusions;
a first inclined deposition step of depositing a deposition material having a first inclination angle with respect to the substrate; and
and a second inclined deposition step of depositing a deposition material having a second inclination angle with respect to the substrate. According to claim 1,
A method of manufacturing a strain sensor further comprising a vertical deposition step of depositing a deposition material in a direction perpendicular to the substrate. 3. The method of claim 1 or 2,
The method of manufacturing a strain sensor further comprising a stress applying step of applying stress to generate cracks in the deposition layer formed on the substrate. 4. The method of claim 3,
The method for manufacturing a strain sensor, wherein the substrate is a nanograting substrate in which a plurality of linear protrusions are spaced apart from each other at predetermined intervals. 5. The method of claim 4,
The crack is a strain sensor manufacturing method that is formed in a straight line along a straight valley located between the plurality of straight protrusions. 6. The method of claim 5,
The stress applying step is a strain sensor manufacturing method of forming a linear crack on the deposition layer by bending or stretching the substrate to make the distance between the plurality of linear protrusions. According to claim 1,
The substrate is a strain sensor manufacturing method made of a flexible material. According to claim 1,
The step of providing the substrate,
forming a flexible material layer on the Si nano grating substrate; and
Strain sensor manufacturing method comprising a; removing the Si nano grating substrate to transfer the grating pattern. 9. The method of claim 8,
The strain sensor manufacturing method further comprising; forming a base layer on the flexible material layer. According to claim 1,
The amount of the deposition material penetrating into the valleys between the protrusions is less than the amount of the deposition material deposited on the upper surface or the upper side of the protrusions. According to claim 1,
A method of manufacturing a strain sensor in which the size of the crack generated on the substrate becomes smaller toward an upper portion of the deposition layer formed on the substrate. A strain sensor manufactured by the strain sensor manufacturing method according to claim 1.

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