KR102072991B1 - Wireless sensor by using structural coloration and method for manufacturing the same - Google Patents

Abstract

The present application relates to a wireless sensor capable of measuring physical deformation in a non-contact manner, and a method of manufacturing the same. The wireless sensor according to the present application is a substrate that can be deformed by an external force, and first and second directions on the substrate. The plurality of diffraction grating structures are arranged at regular intervals by a predetermined distance, and the spectrum of light diffracted by the plurality of diffraction grating structures may be shifted in response to the deformation of the substrate.

Description

Wireless sensor using structure color and manufacturing method thereof {WIRELESS SENSOR BY USING STRUCTURAL COLORATION AND METHOD FOR MANUFACTURING THE SAME}

The present application relates to a wireless sensor using a structural color and a method of manufacturing the same.

Sensors for diagnosing the condition of machinery, machined parts, structures, etc. are used to measure physical changes (mechanical deformation, temperature) and changes in the surrounding environment (humidity, pressure). Strain sensors and temperature sensors for measuring physical changes are sensors for measuring physical changes applied to an object to which a sensor is attached, and mainly use a method of detecting strain and temperature changes as electrical signals. In the case of the attached strain sensor and the temperature sensor, an attached electrode is required, and a detection device and a circuit which are electrically connected to the electrode to detect and analyze an electric signal and calculates the mechanical strain and the electric resistance are required. There is a problem that the application field is limited due to the limitations. In the case of the non-contact temperature sensor, there are disadvantages in that the object to be measured is limited or inaccurate, expensive, and the configuration of the device is too large. In addition, in the case of a humidity sensor for measuring a change in the surrounding environment, like the strain sensor and the contact temperature sensor, the humidity change is measured by a method of detecting an electric signal, and thus there is a problem in that the application field is limited due to a complicated configuration and structural limitations. .

In order to overcome this problem, strain sensors, temperature sensors, and humidity sensors with small modules capable of transmitting electric signals have been introduced, but the manufacturing process is complicated and costs are increased by embedding the fine modules in the sensors. There is a problem that the noise error rate is high due to wireless transmission and reception.

The present application is to solve the problem to provide a wireless sensor and a method of manufacturing the same that can obtain physical deformation information through the wavelength of light reflected by the diffraction grating structure.

The wireless sensor according to an example of the present application includes a polymer substrate that can be deformed by an external force, and a plurality of diffraction grating structures arranged at regular intervals on the polymer substrate by a predetermined distance in a first direction and a second direction. The spectrum of light diffracted by the plurality of diffraction grating structures may be changed in response to deformation of the polymer substrate.

Method of manufacturing a wireless sensor according to an embodiment of the present application comprises the steps of preparing a mold, forming a plurality of groove patterns arranged along a first direction and a second direction crossing the first direction on the mold, Filling the plurality of groove patterns with a polymer or a mixture of polymer and reflective material to form a plurality of diffraction grating structures; Stacking a substrate on the mold while adhering to the plurality of diffraction grating structures; And separating the plurality of diffraction grating structures and the substrate from the mold.

The wireless sensor according to an example of the present application includes a polymer substrate that can be deformed by an external force, and a plurality of diffraction grating structures arranged at regular intervals on the polymer substrate by a predetermined distance in a first direction and a second direction. The spectrum of light diffracted by the plurality of diffraction grating structures may be changed in response to deformation of the polymer substrate.

Method of manufacturing a wireless sensor according to an embodiment of the present application comprises the steps of preparing a mold, forming a plurality of groove patterns arranged along a first direction and a second direction crossing the first direction on the mold, And filling a polymer or a mixture of polymer and reflective material in the plurality of groove patterns.

Forming a plurality of diffraction grating structures; Stacking a substrate on the mold while adhering to the plurality of diffraction grating structures; And separating the plurality of diffraction grating structures and the substrate from the mold.

1 is a schematic diagram of a wireless sensor according to an example of the present application.
2A is a schematic diagram illustrating that light is incident and reflected on a diffraction grating according to an example of the present application.
2B is a schematic diagram illustrating that light is diffracted according to a diffraction order when white light is incident on a diffraction grating according to an example of the present application.
3 is a schematic diagram of a cuboid diffraction grating structure of a wireless sensor according to an example of the present application.
4 (a) is a perspective view of a wireless sensor according to another example of the present application, Figure 4 (b) is a cross-sectional view of a wireless sensor according to another example of the present application.
5 is a cross-sectional view illustrating that the wireless sensor is concave or convexly deformed when the temperature / humidity applied to the wireless sensor according to another example of the present application rises or falls.
6 (a) to 6 (e) are diagrams illustrating a method of manufacturing a wireless sensor according to an example of the present application.
7 (a) is a photograph showing a line profile measurement position of a wireless sensor according to an example of the present application.
7 (b) is a line profile graph of a wireless sensor according to an example of the present application.
FIG. 8A is a photograph of a wireless sensor according to various examples of the present application, in which both an incident angle and a reflection angle of light are set to 0 ° and the wireless sensor is photographed.
FIG. 8 (b) is a photograph of the wireless sensor according to various examples of the present application, the incident angle of light is set to 60 °, and the reflection angle is taken at 0 °.
8 (c) shows an incident angle of light to a wireless sensor according to various examples of the present application set to 60 °, and a reflection spectrum is measured at a reflection angle of 0 °.
FIG. 9A illustrates a linear deformation applied to a wireless sensor according to various examples of the present application, and the changed color is measured.
FIG. 9 (b) is a schematic diagram schematically illustrating a change in distance between diffraction grating structures by applying linear deformation according to an example of the present application.
FIG. 10 (a) shows that the uniaxial linear deformation of the wireless sensor is 0%, 10%, 25%, and while the incident light is set to 70 ° and the reflection spectrum is measured at 0 ° according to an example of the present application. At 45%, we measured the color change of the wireless sensor.
FIG. 10 (b) shows the measurement of the reflected spectral wavelength under each condition when the uniaxial linear deformation of the wireless sensor in FIG. 10 (a) is 0%, 10%, 25%, and 45%.
FIG. 10 (c) shows spectral peak values for uniaxial linear deformation of the wireless sensor in FIG. 10 (b).

Advantages and features of the present application, and a method of achieving them will be apparent with reference to the examples described below in detail in conjunction with the accompanying drawings. However, the present application is not limited to the examples disclosed below, but will be implemented in various different forms, only the examples are intended to complete the disclosure of the present application and to those skilled in the art to which the present application belongs. It is provided to fully inform the scope of the invention, and this application is defined only by the scope of the claims.

Shapes, sizes, ratios, angles, numbers, and the like disclosed in the drawings for explaining examples of the present application are exemplary, and thus the present application is not limited to the illustrated items. Like reference numerals refer to like elements throughout. In addition, in describing the present application, when it is determined that the detailed description of the related known technology may unnecessarily obscure the subject matter of the present application, the detailed description thereof will be omitted. In the case where 'comprises', 'haves', 'consists of' and the like mentioned in the present specification are used, other parts may be added unless 'only' is used. In the case where the component is expressed in the singular, the plural includes the plural unless specifically stated otherwise.

In interpreting a component, it is interpreted to include an error range even if there is no separate description.

In the case of the description of the positional relationship, for example, if the positional relationship of the two parts is described as 'on', 'upper', 'lower', 'next to', etc. Alternatively, one or more other parts may be located between the two parts unless 'direct' is used.

In the case of a description of a temporal relationship, for example, if the temporal after-term relationship is described as 'after', 'following', 'after', 'before', or the like, 'directly' or 'direct' This may include cases that are not continuous unless used.

The first, second, etc. are used to describe various components, but these components are not limited by these terms. These terms are only used to distinguish one component from another. Therefore, the first component mentioned below may be a second component within the technical spirit of the present application.

Each of the features of the various examples of the present application may be combined or combined with each other, partly or wholly, and technically various interlocking and driving are possible, and each of the examples may be independently implemented with respect to each other or may be implemented in association with each other. .

Hereinafter, an example according to the wireless sensor of the present application will be described in detail with reference to the drawings.

 1 is a schematic diagram of a wireless sensor according to an example of the present application.

Referring to FIG. 1, a wireless sensor according to an example of the present application may include a substrate 100 and a plurality of diffraction grating structures 200.

The substrate 100 may be a flexible substrate deformable by an external force, or may be a polymer substrate. The substrate 100 according to an example may be made of a polymer material including at least one of polydimethylsiloxane (PDMS), polyimide, polyethylene terephthalate (PET), hydrogel, and ecoflex.

The substrate 100 may be deformed by an external force, for example, may be deformed in at least one of a first direction and a second direction. That is, the polymer substrate may be changed only in the first direction, for example, the X direction, or only in the second direction, for example, the Y direction, or the polymer substrate may be simultaneously deformed in the first and second directions. Can be. In this case, the first direction and the second direction may be defined as directions crossing each other on the same side. In addition, a portion of the polymer substrate is applied with a strain in a positive direction in the first direction, for example, in an X-axis coordinate to the right, and another portion of the polymer substrate is in a negative direction in the first direction, for example X Strain may be applied to the left in axial coordinates so that shear deformation may be applied to the polymer substrate.

The plurality of diffraction grating structures 200 may be regularly arranged on the substrate 100. In detail, the plurality of diffraction grating structures 200 may be regularly arranged at predetermined intervals along a first direction and a second direction crossing the first direction. Here, the first direction may be defined as the X direction, and the second direction may be defined as the Y direction. In this case, the plurality of diffraction grating structures 200 may be arranged to have the same distance in the first direction and the second direction.

The diffraction grating structure 200 may be formed in the form of a structure protruding in a direction perpendicular to one surface, for example, an upper surface of the substrate 100. The diffraction grating structure 200 may have a conical shape in which an upper surface is cut, or may have a shape selected from one of a cuboid, a spherical shape, a cylindrical shape, and a conical shape, but is not limited thereto.

The present application is designed to measure the amount of strain applied to the substrate 100 through the color change of the light reflected after the incident to the plurality of diffraction grating structure 200, the principle thereof with reference to Figures 2a and 2b Let's explain.

2A is a view schematically illustrating that light is incident and reflected on the diffraction grating structure 200 according to an example of the present application, and FIG. 2B is when white light is incident on the diffraction grating structure according to the example of the present application. This is a diagram schematically illustrating that light is reflected according to a diffraction order.

2A and 2B, a plurality of diffraction grating structures 200 on the substrate 100 may diffract incident light, and each diffraction grating structure 200 may be a single one by diffraction of the incident light. Generate a diffraction pattern. At this time, when the diffraction grating has a sufficient number of N numbers, a diffraction pattern generated by the N diffraction gratings generates a simple pattern having a diffraction order by extinction and constructive interference, and the diffraction order is low. Higher intensity of light is observed.

In the wireless sensor according to an example of the present application, preferably, the light incident on the diffraction grating structure 200 is white light or visible light, and the peak spectrum of the light reflected by the diffraction grating structure 200 is visible light. It can be selected among the region wavelengths.

Equation 1 below is a diffraction equation (Diffraction Equation) by the diffraction grating (Diffraction Grating).

[Equation 1]

Where d is the spacing (or pitch) between adjacent diffraction grating structures, θ _i is the angle of incidence, specifically the angle between the incident light and the vertical axis passing through the diffraction grating structure, θ _r is the angle of reflection, Specifically, the angle between the vertical axis passing through the diffraction grating structure and the reflected light, m is the diffraction order, and λ is the wavelength of the reflected light.

At this time, if the light reflected by the diffraction grating structure is observed in the direction perpendicular to the upper surface of the diffraction grating structure, sinθ _r becomes "0", and thus can be approximated as Equation 2 below.

[Equation 2]

In the above equation (2), when the distance (d) of the diffraction grating structure is close to the wavelength (λ), only the diffraction of the low diffraction order (m) is present, and if the diffraction order (m) is fixed, the wavelength (λ) Is changed depending on the diffraction grating spacing d. That is, under the limited conditions as described above, it can be seen that the wavelength λ of the light is changed when the distance d of the diffraction grating structure is changed, and accordingly the wavelength λ of the light is changed accordingly. By measuring the amount of change in the interval (d) (or distance) of can be measured the amount of strain that is ultimately applied to the substrate (100).

In the wireless sensor according to the exemplary embodiment of the present application, the gap between the plurality of diffraction grating structures 200 arranged in the first direction and the second direction on one surface of the substrate 100 by deformation of the substrate 100. The wavelength of the light reflected by the plurality of diffraction grating structures can be shifted thereby. In this case, the deformation of the substrate 100 may be linear deformation, uniaxial deformation, biaxial deformation, or shear deformation, but is not limited thereto.

The spectrum of light reflected by the plurality of diffraction grating structures 200 may shift in response to deformation of the substrate 100. For example, when the uniaxial linear strain of the substrate 100 is 10%, the spectrum of light may be shifted to a longer wavelength by 30 nm compared to the state where no strain is applied, and the substrate 100 When the uniaxial linear strain of is 20%, the spectrum of light can be shifted to longer wavelengths by 60 nm compared to the state where no strain is applied. On the contrary, when the uniaxial linear strain of the substrate 100 is -10%, the spectrum of light can be shifted to a wavelength shorter in the peak spectrum by 30 nm compared to the state where no deformation is applied, and the substrate 100 When the uniaxial linear strain of is -20%, the spectrum of light can shift to a longer wavelength by 60 nm compared to the state where no strain is applied.

As described above, the variation of the gap between the deformation of the substrate 100 and the plurality of diffraction grating structures 200 corresponding thereto shifts the reflected wavelength to a longer wavelength or a shorter wavelength compared to a state where no deformation is applied. If the wavelength is a visible light region can be observed as a change in color.

When the wavelength of the light measured by the wireless sensor according to an example of the present application is a visible light region, the interval of the diffraction grating structure 200 may be estimated by changing the color and observing the peak spectrum, and thus the substrate 100 Strain can be measured. In addition, the wireless sensor according to an example of the present application can measure the physical deformation through the change in color and observation of the peak spectrum through the reflected light, thereby analyzing a separate electrode or electrical signal attached to the wireless sensor No device is required.

An interval of the diffraction grating structure 200 of the wireless sensor according to an example of the present application may be 300 nm to 800 nm.

At this time, the distance between the diffraction grating structure 200 is perpendicular to the substrate 100, the central axis passing through the center of one diffraction grating structure 200 and the other diffraction adjacent to the diffraction grating structure 200 It means the distance of the central axis penetrating the center of the grid structure 200. Here, when the distance between the diffraction grating structure 200 is less than 300nm, there may be a problem that the spectrum of light diffracted by the diffraction grating structure 200 is out of the ultraviolet region and difficult to observe as a change in color. In addition, when the distance between the diffraction grating structure 200 exceeds 800 nm, the spectrum of light diffracted by the diffraction grating structure 200 may be difficult to observe as a change in color out of the infrared region. Accordingly, the interval d of the diffraction grating structure 20 is preferably set to 300 nm to 800 nm.

3 is a schematic diagram when the diffraction grating structure 200 of the wireless sensor according to an example of the present application is a rectangular parallelepiped.

Referring to FIG. 3, the diffraction grating structure 200 of the wireless sensor according to the example of the present application may have a rectangular parallelepiped shape. The diffraction grating structure 200 may be made of the same material as the substrate 100, and in this case, strain measurement applied to the substrate 100 may be easier. The diffraction grating structure 200 includes a matrix part 220 defining its shape. The base portion 220 may be a polymer that can be deformed by an external force, the base portion 220 according to an example is PDMS (Polydimethylsiloxane), polyimide (polyimide), PET (Polyethylene Terephthalate), hydrogel (hydrogel) It may be made of a polymeric material including at least one of) and ecoflex. Therefore, when the substrate 100 is deformed by an external force, the diffraction grating structure 200 may be deformed in response to the deformation of the substrate 100. In addition, the polymer may be a polymer having a high modulus of elasticity so that it may be suitably deformed and recovered by an external force.

The diffraction grating structure 200 may further include a reflective material 210.

The reflective material 210 may be dispersed in the base 220 to provide a predetermined reflectance with respect to incident light. The reflective material 210 may be formed of nanoparticles, and the nanoparticles may include aluminum (Al), titanium (Ti), chromium (Cr), iron (Fe), cobalt (Co), nickel (Ni), and copper ( Cu, Zinc (Zn), Silver (Ag), Indium (In), Tin (Sn), Turnsten (W), Platinum (Pt), Gold (Au), Lead (Pb), alloys thereof and their It may include at least one of the oxides. The metal nanoparticles are preferably metals having a surface plasmon resonance effect, and may be metals having a high reflectance. In addition, since reflection and refraction are caused by the surface plasmon phenomenon, it may be irregularly dispersed in the diffraction grating structure.

The diameter of the nanoparticles may range from 10 nm to 1000 nm, but is not particularly limited thereto.

Nanoparticles having a diameter smaller than 10 nm in diameter are difficult to apply because of high manufacturing costs, and nanoparticles larger than 1000 nm may be difficult to apply because they may damage patterns because they are larger than the surface diffraction grating structure. Therefore, the nanoparticles preferably have a diameter of 10 nm to 1000 nm.

The mass ratio of the nanoparticles 210 to the matrix portion 220 of the diffraction grating structure 200 may be 1:10 to 1: 1000.

When the content of the nanoparticles 210 exceeds the mass ratio, the elasticity of the diffraction grating structure 200 is lowered and the diffraction grating structure 200 and the polymer substrate 100 when the polymer substrate 100 is deformed by an external force. The heterogeneity of the physical properties of) may cause problems of peeling and peeling. When the content of the nanoparticles 210 is less than the mass ratio, the reflection efficiency may be low to obtain a desired diffraction spectral intensity. Accordingly, the mass ratio of the nanoparticles 210 to the matrix portion 220 of the diffraction grating structure 200 is preferably 1:10 to 1: 1000.

The nanoparticles 210 may be included in the substrate 100.

In addition, the wireless sensor according to an example of the present application is attached to the object to measure the strain, when the strain is applied to the object can be seen through the detection of the color change amount of the corresponding strain.

4 (a) is a perspective view of a wireless sensor according to another example of the present application, Figure 4 (b) is a cross-sectional view of a wireless sensor according to another example of the present application.

4 (a) and 4 (b), the wireless sensor according to another example of the present application may further include a functional member 300 disposed on the other surface of the substrate 100.

The functional member 300 is made of a different material from the substrate 100. Specifically, the mechanical deformation due to the change in humidity and / or temperature of the material constituting the functional member 300 is the substrate 100. It may be different from the mechanical deformation caused by the change of humidity and / or temperature of the material constituting the.

5 is a cross-sectional view illustrating a change of a wireless sensor according to another example of the present application with increase or decrease of temperature and / or humidity.

Referring to FIG. 5, when the temperature or humidity is changed, the substrate 100 constituting the wireless sensor may expand or the functional member 300 may contract, thereby diffraction grating structure 200 on the substrate 100. The interval of may increase. On the contrary, when the temperature or humidity is changed, the substrate 100 constituting the wireless sensor may contract or the functional member 300 may expand, thereby reducing the gap of the diffraction grating structure 200 on the substrate 100. can do.

Accordingly, in the wireless sensor according to another example of the present application, the distance between the diffraction grating structure 200 is changed according to the change of temperature and / or humidity, and the wavelength of the light reflected by the diffraction grating structure 200 is shifted to a temperature. And / or the change in humidity can be measured.

When a wireless sensor according to another example of the present application is utilized as a temperature sensor, the thermal expansion coefficient of the material constituting the substrate 100 is different from the thermal expansion coefficient of the material constituting the functional member 300. For example, the substrate 100 and the functional member 300 may include a shape memory polymer having different thermal expansion coefficients. In addition, the substrate 100 and the functional member 300 may be formed of a functionally graded material whose thermal expansion coefficient is gradually increased or decreased. At this time, the substrate (at the bottom of the functional member 300) The coefficient of thermal expansion may be gradually increased or decreased gradually up to the upper surface of 100). In addition, the substrate 100 and the functional member 300 may be made of different metals, so that the substrate 100 and the functional member 300 as a whole has a bimetal structure. It can be achieved.

The shape memory polymer may be restored to an initial shape or changed to a predetermined shape at a specific temperature corresponding to the physical properties (glass transition temperature or melting point) of the shape memory polymer. For example, the substrate 100 and the functional member 300 may include a shape memory polymer having different physical properties, and may exhibit different thermal expansion behaviors with increasing or decreasing temperatures. The functional gradient material and the bimetal may be formed to have different behaviors with each other by mixing or attaching the first member and the second member having different thermal expansion coefficients. Each of the substrate 100 and the functional member 300 may be formed by mixing a material having a relatively high coefficient of thermal expansion and a material having a relatively low coefficient of thermal expansion. In this case, the substrate 100 may be thermally expanded. It is possible to increase the content of the material having a high coefficient and increase the content of the material having a low coefficient of thermal expansion in the functional member 300, or vice versa.

If the wireless sensor according to another example of the present application to be used as a temperature sensor in more detail described as follows.

When the substrate 100 is set to have a first thermal expansion coefficient, the functional member 300 may have a second thermal expansion coefficient different from the first thermal expansion coefficient.

When the first thermal expansion coefficient of the substrate 100 is greater than the second thermal expansion coefficient of the functional member 300, when the temperature is increased in the wireless sensor according to another example of the present application, the volume of the substrate 100 is increased. The expansion rate becomes larger than the volume expansion rate of the functional member 300, so that the wireless sensor according to another example of the present application may be modified to be convex in the direction of the diffraction grating structure 200, correspondingly The spacing between the 200 may increase.

In addition, when the first thermal expansion coefficient of the substrate 100 is greater than the second thermal expansion coefficient of the functional member 300, if the temperature is reduced in the wireless sensor according to another example of the present application, The volume reduction rate becomes greater than the volume reduction rate of the functional member 300, so that the wireless sensor according to another example of the present application may be modified to concave in the direction of the diffraction grating structure 200, correspondingly The spacing between the structures 200 can be reduced.

According to the same principle as above, in a condition in which the first coefficient of thermal expansion of the substrate 100 is smaller than the second coefficient of thermal expansion of the functional member 300, the temperature increases in the wireless sensor according to another example of the present application. The wireless sensor according to another example of the present application may be modified to concave in the direction of the diffraction grating structure 200, and if the temperature is reduced in the wireless sensor according to another example of the present application, the wireless sensor according to another example of the present application It may be deformed to be convex in the direction of the diffraction grating structure 200.

When a wireless sensor according to another example of the present application is utilized as a humidity sensor, the humidity expansion coefficient of the material constituting the substrate 100 is different from the humidity expansion coefficient of the material constituting the functional member 300. For example, the substrate 100 and the functional member 300 may include a hydrogel having different humidity expansion coefficients. In addition, the substrate 100 and the functional member 300 may be made of a functionally graded material that gradually increases or decreases the humidity expansion coefficient. In this case, the substrate (the lower surface of the functional member 300) The humidity expansion coefficient may gradually increase or decrease gradually to the upper surface of 100). In addition, each of the substrate 100 and the functional member 300 may be formed by mixing a material having a relatively high humidity expansion coefficient and a material having a relatively low humidity expansion coefficient, and in this case, the substrate 100 The content of the material having a high humidity expansion coefficient may be increased and the content of the material having a low humidity expansion coefficient may be increased in the functional member 300, or vice versa.

When the wireless sensor according to another example of the present application is utilized as a humidity sensor in more detail described as follows.

When the substrate 100 is set to have a first humidity expansion coefficient, the functional member 300 may have a second humidity expansion coefficient different from the first humidity expansion coefficient.

When the first humidity expansion coefficient of the substrate 100 is greater than the second humidity expansion coefficient of the functional member 300, when the humidity is increased in the wireless sensor according to another example of the present application, the volume of the substrate 100 is increased. The expansion rate becomes larger than the volume expansion rate of the functional member 300, so that the wireless sensor according to another example of the present application may be modified to be convex in the direction of the diffraction grating structure 200, correspondingly The spacing between the 200 may increase.

In addition, when the first humidity expansion coefficient of the substrate 100 is greater than the second humidity expansion coefficient of the functional member 300, if the humidity is reduced in the wireless sensor according to another example of the present application, The volume reduction rate becomes greater than the volume reduction rate of the functional member 300, so that the wireless sensor according to another example of the present application may be modified to concave in the direction of the diffraction grating structure 200, correspondingly The spacing between the structures 200 can be reduced.

According to the same principle as above, when the first humidity expansion coefficient of the substrate 100 is smaller than the second humidity expansion coefficient of the functional member 300, increasing the humidity in the wireless sensor according to another example of the present application The wireless sensor according to another example of the present application may be modified to concave in the direction of the diffraction grating structure 200, and if the humidity is reduced to the wireless sensor according to another example of the present application, the wireless sensor according to another example of the present application It may be deformed to be convex in the direction of the diffraction grating structure 200.

6 (a) to 6 (e) show a flowchart of a method of manufacturing a wireless sensor according to an example of the present application.

6 (a) to 6 (e), the method of manufacturing a wireless sensor according to an example of the present application includes preparing a mold 10, and forming a first direction and the first direction on the mold 10. Forming a plurality of groove patterns 15 arranged along a second direction crossing the first direction, and a mixed precursor including polymers and metal nanoparticles on a mold on which the plurality of groove patterns 15 are formed. It can be prepared by a method comprising the steps of applying and shaping, thereby preparing a wireless sensor comprising a diffraction grating structure.

First, the mold 10 is prepared as shown in FIG. 6 (a). The mold 10 may be a ceramic material such as silicon or silicon carbide, or may be an alloy material such as stainless steel, but is not limited thereto.

Next, as shown in FIG. 6B, a plurality of groove patterns 15 are formed on the mold 10 along a first direction and a second direction crossing the first direction.

The forming of the plurality of groove patterns 15 is a step of defining a formation space of the diffraction grating structure formed in a subsequent step. The plurality of groove patterns 15 may be formed using a process capable of irregular or regular nano pattern processing, and the applicable processes may include a nano cutting process by a mechanical process and a focused ion beam (FIB) device. It can be formed through the ion beam milling (milling) process, in this case, the interval between the plurality of groove patterns 15 can be determined according to the milling cycle of the focusing ion beam. The method of manufacturing the wireless sensor according to the present application may form the groove pattern 15 in the mold 10 by precision micromachining without using a lithography process requiring expensive equipment such as a mask. The spacing and shape of the subsequently formed diffraction grating structure can be controlled.

Next, a plurality of diffraction grating structures are formed by filling a polymer in the groove pattern 15 or a mixture including a polymer and nanoparticles as shown in FIG. 6 (c). The reflective material may include nanoparticles.

The process of filling the polymer and nanoparticles is as follows.

First, nanoparticles and flexible polymers are prepared, which are then evenly stirred in an organic solvent such as ethanol or alcohol. Next, the organic solvent is evaporated, a curing agent is added to prepare a mixed precursor, and the prepared mixed precursor is filled into the groove pattern 15 and then molded.

In addition, prior to performing the filling step, in order to easily perform the process of Figure 6 (e) to be described later, it may further comprise the step of applying a release agent (parting agent) on the mold (10).

Next, as shown in FIG. 6 (d), the substrate 100 is laminated on the mold 10. The substrate 100 may be stacked using the same polymer as the polymer filled in the groove pattern 15. The lamination process may further include a heat treatment process, and the diffraction grating structure filled in the groove pattern 15 and the substrate 100 are adhered through the heat treatment process. More specifically, the polymer included in the diffraction grating structure and the polymer constituting the substrate 100 may be bonded to each other by the heat treatment process.

Next, as shown in FIG. 6E, the substrate 100 is separated from the mold 10. In this case, the polymer or the polymer and the reflective material filled in the groove pattern 15 of the mold 10 are also separated from the substrate 100 so that the diffraction grating structure 200 is formed on the substrate 100. Get a wireless sensor.

In the method of manufacturing a wireless sensor according to an example of the present application, the polymer may be a polymer deformable by an external force. The polymer may be formed of a polymer material including at least one of polydimethylsiloxane (PDMS), polyimide, polyethylene terephthalate (PET), hydrogel, and ecoflex.

In the method of manufacturing a wireless sensor according to an example of the present application, the nanoparticles are aluminum (Al), titanium (Ti), chromium (Cr), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), silver (Ag), indium (In), tin (Sn), tungsten (W), platinum (Pt), gold (Au), lead (Pb), alloys thereof and their It may include at least one of the oxide, the metal nanoparticles are preferably a metal having a surface plasmon resonance effect, it may be a metal having a high reflectivity. In addition, since reflection is caused by the surface plasmon phenomenon, it may be irregularly dispersed in the diffraction grating structure. In addition, the polymer may be a polymer having a high elasticity so that it can be properly modified by an external force.

The diameter of the metal nanoparticles may be in the range of 10nm to 1000nm, but is not particularly limited thereto.

Nanoparticles having a diameter smaller than 10 nm in diameter are difficult to apply because of high manufacturing costs, and nanoparticles larger than 1000 nm may be difficult to apply because they may damage patterns because they are larger than the surface diffraction grating structure. Therefore, the nanoparticles preferably have a diameter of 10 nm to 1000 nm.

In the method of manufacturing a wireless sensor according to an example of the present application, the interval between the groove patterns 15 may be 300 nm to 800 nm.

In this case, the interval of the groove pattern 15 means a distance between the central axis penetrating the center of one groove pattern 15 and the central axis penetrating the center of another groove pattern 15 adjacent thereto. . Here, when the interval between the groove pattern 15 is less than 300nm, there may be a problem that the spectrum of light diffracted by the diffraction grating structure subsequently formed is out of the ultraviolet region and difficult to observe due to the change of color. In addition, when the interval between the groove patterns 15 exceeds 800 nm, a spectrum of light diffracted by the diffraction grating structure subsequently formed may be difficult to observe due to a change in color out of the infrared region. Accordingly, the interval of the groove pattern 15 is preferably set to 300nm to 800nm.

Although not shown, after the step of separating from the mold, the functional member 300 described above is attached to the other surface of the substrate 100 on which the diffraction grating structure 200 is not formed, and thus, in FIGS. 4A and 4B. It is possible to manufacture a wireless sensor according to.

Hereinafter, the present application will be described in more detail with reference to the following examples.

First example

First, a silicon wafer having a thickness of 700 μm having a size of 20 mm × 20 mm was prepared. Next, a pattern was fabricated by scanning the silicon wafer once with a milling time of 0.08 seconds under a 625pA condition to form a pattern for a single diffraction grating structure using a focused ion beam (FIB) device. And milling was repeated while the milling interval was adjusted to have a spacing of 460 nm in the second direction and a depth of about 100 nm, thereby fabricating a silicon wafer mold.

Next, in order to prepare a diffraction grating structure and a polymer substrate including metal nanoparticles and a polymer that can be modified by external force, the cobalt (Co) nanoparticles having a 25 nm diameter and the PDMS liquid precursor solution are agitated. A polymer composite solution was prepared.

Next, the metal nanoparticle-PDMS liquid precursor solution prepared before the mold was applied and solidified, and then a wireless sensor having a cross section of 50 μm × 50 μm was prepared.

2nd example

In the first example, the wireless sensor was prepared in the same manner except that the milling cycle interval of the focused ion beam was changed to 520 nm when performing etching using the focused ion beam apparatus.

Third example

In the first example, a wireless sensor was prepared in the same manner except that the milling cycle interval of the focused ion beam was changed to 600 nm when performing etching using the focused ion beam apparatus.

4th example

In the first example, the wireless sensor was prepared in the same manner except that the milling cycle interval of the focused ion beam was changed to 670 nm when performing etching using the focused ion beam apparatus.

5th example

In the first example, the wireless sensor was prepared in the same manner except that the milling cycle interval of the focused ion beam was changed to 690 nm when performing etching using the focused ion beam apparatus.

6th example

In the first example, the wireless sensor was prepared in the same manner except that the milling cycle interval of the focused ion beam was changed to 750 nm when performing etching using the focused ion beam apparatus.

7th example

In the first example, the wireless sensor is prepared by the same preparation except that a 300 μm thick functional member made of an inclined functional material of an aluminum (Al) and aluminum nitride (AlN) composite is disposed on the other surface of the substrate. It was.

FIG. 7 (a) is a photograph of an upper surface of the wireless sensor prepared by the third example with an atomic force microscopy (AFM) device, and FIG. 7 (b) is a line measured along line A in FIG. 7 (a). Profile graph.

Referring to FIG. 7 (a), it can be seen that the wireless sensor prepared by the third example is formed by separating each diffraction grating structure as a result of observing through an AFM device. Referring to FIG. 7B, the distance between the pitches of the diffraction grating structures was measured at about 602 nm, and the diffraction grating structures were measured to have a height of about 100 nm.

Hereinafter, the present application will be described in more detail with reference to the following experimental examples.

Measurement Setup

In order to set up the measurement conditions according to the incident light and the diffraction angle, the experiment was performed by variously changing the incident angle and measurement angle of the white light source.

FIG. 8 (a) is a photograph taken by setting the incident light to 0 ° on the wireless sensor prepared by Examples 2 to 4 and photographing the wireless sensor at 0 °, and FIG. 6B is prepared by the second to fourth examples. The incident light on the wireless sensor is set to 60 °, and the picture is taken by the wireless sensor at 0 °.

Referring to FIG. 8A, when the incident angle of the incident light is 0 ° and the measurement angle of the wireless sensor is 0 °, the wireless sensor prepared by Examples 2 to 4 differ only in the intensity of the diffraction wavelength. As a result, there is little color change observed in the wireless sensor.

On the other hand, referring to Figure 8 (b), when the incident angle of the incident light is 60 °, the measurement angle of the wireless sensor is 0 °, the wireless sensor prepared by the second example to the fourth example is the interval of the diffraction grating structure It can be seen that the observed color changes with the change of.

8 (c) shows that the incident angle is set to 60 ° and the reflection spectrum is measured at 0 ° in the wireless sensor prepared by the second to fourth examples.

 Referring to 8 (c), the grating period d of the diffraction grating structure of the wireless sensor prepared by Examples 2 to 4 is the peak of the spectrum spectroscopy by the diffraction grating structure is the diffraction order (m). When 1) is "1", the distance d and the diffraction wavelength λ of the diffraction grating structure of the wireless sensor according to the example of the present application may satisfy the following equation (3).

[Equation 3]

At this time, the wireless sensor prepared by Examples 1 to 6 based on Equation 3 has a diffraction order (m) of 1, an incident angle of incident light is 60 °, and a measurement angle of diffraction wavelength is 0 °. The peak wavelength of the spectrum corresponding thereto may be calculated as shown in Table 1 below.

Color Wavelength λ (wavelength, nm) d (nm) Red 650 750 Orange 600 690 Yellow 580 670 Green 520 600 Blue 450 520 Violet 400 460

Referring to FIG. 8 (c) and Table 1, it can be seen that there is only a slight difference between the theoretical wavelength peak value calculated by Equation 1 and the actually measured wavelength peak value of about 10-20 nm. By changing the spacing of the grating structure it was confirmed that the wavelength of the light reflected by the wireless sensor according to an example of the present application is shifted (shifted), thereby changing the observed color.

Linear Deformation Application Experiment

FIG. 9 (a) is a photograph in which strain is applied to a wireless sensor prepared in Examples 1 to 6 in one direction and the color changed by the strain is measured. FIG. 9 (b) is a diffraction grating due to application of strain. It is a schematic diagram which shows that the distance between structures is changed.

Referring to FIG. 9 (a), when linear deformation is applied in one direction to the wireless sensor prepared by the first to sixth examples, the wireless sensor prepared by the first to sixth examples is observed. It can be seen that the changed color is compared with the initial state. In particular, the wireless sensor prepared by the third example was green in the initial state, and yellow after linear deformation was applied in one direction. As a result, when linear deformation is applied in one direction to the wireless sensor according to an example of the present application as shown in FIG. 9 (b), the distance d of the diffraction grating structure of the wireless sensor increases, and thus the diffraction wavelength observed. The peak value of can be shifted to long wavelengths.

Fig. 10 (a) shows that the uniaxial linear deformation of the wireless sensor is 0%, 10%, 25%, and 45 while the incident light is set to 70 ° and the reflection spectrum is measured at 0 ° prepared by the second example. It is a measure of the color change of the wireless sensor, set to%.

Referring to FIG. 10A, when the uniaxial linear deformation of the wireless sensor prepared by the second example is 0%, it can be seen that the wireless sensor emits blue light, and the uniaxial linear of the wireless sensor prepared by the second example is shown. When the deformation is 10%, it can be seen that the wireless sensor emits green light. When the uniaxial linear deformation of the wireless strain sensor prepared by the second example is 25%, the wireless sensor emits yellow light. In addition, when the uniaxial linear deformation of the wireless sensor prepared by the second example is 45%, it can be seen that the wireless sensor emits red light. Through this, it can be seen that as the uniaxial linear strain increases in the experimental conditions, the length of the observed wavelength gradually increases correspondingly.

FIG. 10 (b) shows the measurement of the reflected spectral wavelength under each condition when the uniaxial linear deformation of the wireless sensor in FIG. 10 (a) is 0%, 10%, 25%, and 45%.

Referring to FIG. 10B, as the uniaxial linear deformation of the wireless sensor prepared by the first example is set to 0%, 10%, 25%, and 45% under the foregoing experimental conditions, the peak wavelengths of the spectral spectrum are 445 nm and 498 nm, respectively. As can be seen shifted to 571nm and 645nm.

FIG. 10C illustrates the theoretical and measured values of spectral peak values for uniaxial linear deformation of the wireless sensor in FIG. 10B.

Referring to FIG. 10C, it can be seen that the wavelength peak value of the measured value shifts in the long wavelength direction of about 10 to 20 nm compared to the theoretical value, but it can be seen that the theoretical value and the measured value generally correspond well. .

Although the examples of the present application have been described in more detail with reference to the accompanying drawings, the present application is not necessarily limited to these examples, and various modifications can be made without departing from the spirit of the present application. Therefore, the examples disclosed in the present application are not intended to limit the technical spirit of the present application, but to describe the present invention, and the scope of the technical spirit of the present application is not limited thereto. Therefore, it should be understood that the examples described above are exemplary in all respects and not restrictive. The scope of protection of the present application should be interpreted by the claims, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present application.

100: substrate
200: diffraction grating structure
210: nanoparticle
220: base
300: functional member
10: Mold
15: home pattern

Claims (22)

A substrate deformable by an external force; And
A plurality of diffraction grating structures arranged on one surface of the substrate along a first direction and a second direction crossing the first direction,
The spectrum of light diffracted by the plurality of diffraction grating structures shifts in response to deformation of the substrate,
The substrate is made of a polymer material including at least one of polydimethylsiloxane (PDMS), polyimide (polyimide), polyethylene terephthalate (PET), hydrogel, and ecoflex,
The diffraction grating structure is made of the same material as the substrate, the wireless sensor. The method of claim 1,
And a spectrum of light diffracted by the plurality of diffraction grating structures shifts in response to a change in spacing of the diffraction grating structure according to deformation of the substrate. The method of claim 1,
The plurality of diffraction grating structures are made of a structure protruding in a vertical direction from one surface of the substrate, the wireless sensor. The method of claim 1,
And the plurality of diffraction grating structures are arranged at equal intervals in the first direction and the second direction. The method of claim 1,
The distance of the diffraction grating structure is 300 nm to 800 nm, the wireless sensor. delete delete The method of claim 1,
And the diffraction grating structure further comprises a reflective material. The method of claim 8,
And the reflective material is irregularly dispersed within the diffraction grating structure. The method of claim 8,
The reflective material comprises nanoparticles. The method of claim 10,
The nanoparticles are aluminum (Al), titanium (Ti), chromium (Cr), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), silver (Ag), indium A wireless sensor comprising at least one of (In), tin (Sn), turnsten (W), platinum (Pt), gold (Au), lead (Pb), alloys thereof, and oxides thereof. The method of claim 10,
The nanoparticles have a diameter of 10 to 1000 nm, the wireless sensor. The method of claim 8,
Wherein the mass ratio of nanoparticles to polymer material of the diffraction grating structure is from 1:10 to 1: 1000. The method of claim 1,
Further comprising a functional member disposed on the other surface of the substrate,
Wherein said functional member differs in mechanical strain from said substrate in response to changes in humidity or temperature. The method of claim 14,
The substrate and the functional member include a hydrogel having different mechanical strains due to changes in humidity. The method of claim 14,
The substrate and the functional member include a shape memory polymer having different mechanical strains with respect to temperature. The method of claim 14,
The substrate and the functional member include a functional inclined material in which the mechanical strain gradually changes due to a humidity change or a temperature change, and the mechanical strain gradually increases or decreases from the lower surface of the functional member to the upper surface of the substrate. . Preparing a mold;
Forming a plurality of groove patterns on the mold arranged along a first direction and a second direction crossing the first direction;
Filling a plurality of groove patterns with a polymer or a mixture of a polymer and a reflective material to form a plurality of diffraction grating structures;
Stacking a substrate on the mold while adhering to the plurality of diffraction grating structures; And
Separating the plurality of diffraction grating structures and the substrate from the mold. The method of claim 18,
The forming of the plurality of groove patterns is performed by a nano cutting process or a focused ion beam process. The method of claim 18,
In the process of filling the polymer and the reflective material, after preparing the flexible polymer and the metal nanoparticles, the mixture is stirred in an organic solvent, the organic solvent is evaporated and a curing agent is added to prepare a mixed precursor, and the prepared mixed precursor is filled in the groove pattern. Method of producing a wireless sensor, comprising the step of forming after. The method of claim 18,
Further comprising applying a release agent on the mold prior to forming the plurality of diffraction grating structures. 19. The method of claim 18, further comprising attaching a functional member on the other surface of the substrate on which the diffraction grating structure is not formed after the step of separating from the mold, wherein the functional member is in accordance with a change in humidity or temperature. A method of manufacturing a wireless sensor, wherein the mechanical strain from the substrate is different.

Images