A cholesteric liquid crystal capsule micro-spectrometer and its usage method

Abstract

The present invention belongs to the technical field of measuring instruments, and is a cholesteric liquid crystal capsule micro-spectrometer and its usage method. The micro-spectrometer includes a core device. The core device is placed at the focal point of an optical microscope, and an external light source is incident on the core device. The core device includes a laser-induced graphene strip and a cholesteric liquid crystal capsule placed at its central position. The spectrometer disperses the cholesteric liquid crystal capsules in a silicone oil matching liquid, and then places the cholesteric liquid crystal capsules at the central position of the prepared laser-induced graphene strip. Based on the thermochromic property of the cholesteric liquid crystal capsules and the property that laser-induced graphene can generate Joule heat under an external bias voltage, the reflection information of the cholesteric liquid crystal capsules is changed. The cholesteric liquid crystal capsule micro-spectrometer is short and compact, low in cost, has high sensitivity, and can achieve fast response.

Description

Technical Field

[0001] The present invention belongs to the technical field of measuring instruments, and is a cholesteric liquid crystal capsule micro-spectrometer and its analysis method. Background Art

[0002] The earliest research on spectra by humans can be traced back to the 17th century when the British physicist Newton used a glass prism to decompose sunlight into seven-color light. In the 1860s, G.R. Kirchhoff and R.W. Bunsen designed and manufactured a spectroscopic device, which was the world's first spectroscopic instrument and laid the preliminary foundation for spectroscopic analysis.

[0003] Spectrometers can be applied in many fields such as biochemical sensing, material analysis, hyperspectral imaging, and light source characterization, and are one of the most powerful and widely used characterization tools in scientific and industrial research. Traditional bench-top laboratory spectrometers are mainly divided into two categories. The first category is spectrometers based on grating spectroscopy. The second category is spectrometers using Michelson interferometers. These bench-top laboratory spectrometer systems can achieve ultra-high resolution and wide spectral range, but they also have high prices and a large number of bulky optical components.

[0004] In many cases, the goal of using a spectrometer is to quickly identify spectral features rather than obtain accurate relative measurements. For example, in application scenarios such as point-of-care health monitoring and marine science research, it is important to obtain immediate on-site results rather than transporting samples to a laboratory for ultra-high resolution analysis. Traditional bench-top laboratory spectrometers cannot play their roles well in these application scenarios, so various handheld mobile portable micro-spectrometers have gradually emerged.

[0005] The general idea of micro-spectrometers is to make a trade-off between size and performance, sacrificing a large number of traditional components to reduce the size of the instrument, and the resolution, dynamic range, signal-to-noise ratio, etc. of micro-spectrometers will be affected accordingly. However, current micro-spectrometers still have defects such as too large volume, high cost, low sensitivity, and slow response speed, and cannot be applied to specific scenarios including the measurement of agricultural products, devices of smart phones, and spectral imaging devices of drones, etc. Summary of the Invention

[0006] In order to solve the defects of existing micro-spectrometers such as too large volume, high cost, low sensitivity, and slow response speed, the present invention provides a cholesteric liquid crystal capsule micro-spectrometer and its usage method. The cholesteric liquid crystal capsule micro-spectrometer is short and concise, has a low cost, has high sensitivity, and can achieve a fast response.

[0007] To achieve the above object, the present invention is realized through the following technical solutions:

[0008] The present invention relates to a cholesteric liquid crystal capsule micro-spectrometer, which includes a core device. The core device is placed at the focal point of the optical microscope of the whole set of microscopic devices, and an external light source is used to irradiate the core device. The core device includes a laser-induced graphene strip and a cholesteric liquid crystal capsule placed at the center of the laser-induced graphene strip. The cholesteric liquid crystal capsule is a temperature-sensitive spherical particle. The temperature-sensitive spherical cholesteric liquid crystal capsules are dispersed in a methyl silicone oil matching liquid to form a liquid crystal solution. The cholesteric liquid crystal capsules are coated on the center position of the laser-induced graphene strip by dipping the PVC hose into the liquid crystal solution. Conductive tapes are respectively pasted on the left and right ends of the laser-induced graphene strip, and the conductive tapes on the left and right sides are connected to a DC regulated power supply to control the heating of the laser-induced graphene strip, so as to change the reflection information of the cholesteric liquid crystal capsules on the laser-induced graphene strip.

[0009] A further improvement of the present invention lies in that: the whole set of microscopic devices consists of an optical microscope, an industrial camera and a display. The color change of the cholesteric liquid crystal capsules is detected by the optical microscope and presented through the display.

[0010] A further improvement of the present invention lies in that: the preparation method of the core device of the cholesteric liquid crystal capsule micro-spectrometer is as follows: a laser is used to perform laser ablation on a polyimide film to fabricate a laser-induced graphene strip with a length of 20 mm and a width of 0.1 mm. The cholesteric liquid crystal capsules are dispersed in a methyl silicone oil matching liquid to form a liquid crystal solution, and the liquid crystal solution is coated on the center position of the laser-induced graphene strip by dipping the PVC hose into the liquid crystal solution.

[0011] The present invention relates to a method for using a cholesteric liquid crystal capsule micro-spectrometer, which includes the following steps:

[0012] Step 1: Place the core device at the focal point of the optical microscope;

[0013] Step 2: Use a light source to irradiate the cholesteric liquid crystal capsules, apply a voltage to the laser-induced graphene strip by using a DC regulated power supply to generate Joule heat, and the cholesteric liquid crystal capsules change color when heated. The reflection information of the cholesteric liquid crystal capsules after heating and color change is photographed and recorded. In this step, the incident range of the light source irradiating the cholesteric liquid crystal capsules is normal incidence when the light source and the horizontally placed core device are perpendicular, or oblique incidence when the light source and the horizontally placed core device form an acute angle. The oblique incidence range is from 89° to 10°.

[0014] Step 3: Select a wavelength in the visible light band of 380 - 750 nm, place a narrow-band filter of this wavelength in front of the light source, repeat Step 1 and Step 2, and photograph, record and analyze them to serve as a library for this band;

[0015] Step 4: Summarize and analyze the data obtained in Step 2 and Step 3, analyze the corresponding relationship between the chromaticity value and wavelength of the cholesteric liquid crystal capsule after heating when an external voltage is applied to the laser-induced graphene strip, and establish a standard image database;

[0016] Step 5: Incident the light to be measured on the cholesteric liquid crystal capsule at the same angle as the light source incident on the cholesteric liquid crystal capsule, change the voltage applied to the laser-induced graphene strip through the knob of the DC regulated power supply, and capture the reflection information of the cholesteric liquid crystal capsule on the laser-induced graphene strip;

[0017] Step 6: Extract the parameter mean of the chromaticity value in the reflection information obtained in Step 5, and compare it one by one with the values in the standard image database established in Step 4, and finally determine the spectral curve of the test light source.

[0018] The beneficial effects of the present invention are as follows: Based on the thermochromic effect of the cholesteric liquid crystal capsule and the characteristic that the laser-induced graphene strip can generate heat when an external bias voltage is applied, the present invention proposes a cholesteric liquid crystal capsule microspectrometer. The microspectrometer is simple to prepare, low in cost, high in sensitivity and fast in response speed;

[0019] At the same time, the present invention also meets the actual application requirements of being portable and easy to operate, and is a microspectrometer with great potential;

[0020] Moreover, the present invention has application prospects in multiple fields such as medical treatment, industry, environment, and aerospace. Description of the Drawings

[0021] Figure 1 is a schematic diagram of the present invention.

[0022] Figure 2 is a schematic diagram of the DC regulated power supply applying an external voltage to the sample.

[0023] Figure 3 is the molecular structure diagram of the laser-induced graphene strip.

[0024] Figure 4 is the corresponding relationship between the external voltage and the chromaticity value of the cholesteric liquid crystal capsule at an oblique incidence of 45°.

[0025] Figure 5 is the corresponding relationship between the external voltage and the chromaticity value of the cholesteric liquid crystal capsule at an oblique incidence of 60°.

[0026] Figure 6 is the corresponding relationship between the external voltage and the chromaticity value of the cholesteric liquid crystal capsule at a normal incidence. Detailed Embodiments

[0027] The embodiments of the present invention will be disclosed below with reference to the drawings. For the sake of clarity, many practical details will be described together in the following description. However, it should be understood that these practical details are not used to limit the present invention. That is to say, in some embodiments of the present invention, these practical details are not necessary.

[0028] The cholesteric liquid crystal capsule micro-spectrometer of the present invention includes a core device. A laser is used to perform laser ablation on a polyimide film to fabricate the laser-induced graphene strip 5 with a length of 20 mm and a width of 0.1 mm. The cholesteric liquid crystal capsules 4 of the temperature-sensitive spherical particles are dispersed in a methyl silicone oil matching liquid to form a liquid crystal solution. The liquid crystal solution is dipped by a PVC hose and coated at the central position on the laser-induced graphene strip 5, thus constituting the core device of the micro-spectrometer of the present invention.

[0029] As Figure 1 shown, the core device 1 is placed at the focus of the optical microscope 2 of the whole set of microscopic devices. An external light source 3 is incident on the core device 1. Conductive tapes 6 are respectively pasted at the left and right ends of the laser-induced graphene strip 5. The conductive tapes 6 are connected to a DC regulated power supply 7 by wires to control the heating of the laser-induced graphene strip 5, change the reflection information of the cholesteric liquid crystal capsules 4 on the laser-induced graphene strip 5, and the color change of the cholesteric liquid crystal capsules 4 is detected by the optical microscope 2 and presented through a display 9.

[0030] As Figure 2 shown, the laser-induced graphene strip 5 is connected to the DC regulated power supply 7 through the conductive tape 6. When a bias voltage is applied, Joule heat is generated, and the heat source is electric heating.

[0031] As Figure 3 shown, the laser-induced graphene strip is a graphene-like product, and the degree of carbonization of the graphene, that is, the degree of similarity between the product and graphene, should be controlled according to methods such as controlling parameters such as speed and power during the manufacturing process.

[0032] As Figure 1 、 2 shown, the present invention also provides a method for using a cholesteric liquid crystal capsule micro-spectrometer. The method for using includes the following steps:

[0033] Step 1: Place the core device 1 at the focus of the optical microscope 2;

[0034] Step 2: Use the light source 3 to irradiate the cholesteric liquid crystal capsules 4, apply a voltage to the laser-induced graphene strip 5 by using the DC regulated power supply 7 to generate Joule heat, the cholesteric liquid crystal capsules 4 are heated and change color, and photograph and record the reflection information of the cholesteric liquid crystal capsules 4 after being heated and changing color;

[0035] Step 3: Select the wavelength in the visible light band of 380 - 750 nm, place a narrow - band filter of this wavelength in front of the light source 3, repeat Step 1 and Step 2, take pictures and records for analysis, and use it as the library for this band;

[0036] Step 4: Summarize and analyze the data obtained in Step 2 and Step 3, analyze the corresponding relationship between the chromaticity value and the wavelength after the cholesteric liquid crystal capsule 4 is heated when a voltage is applied to the laser - induced graphene strip 5, and establish a standard image database;

[0037] Step 5: Incident the light to be measured on the cholesteric liquid crystal capsule 4 at the same angle as the light source 3 incident on the cholesteric liquid crystal capsule 4, change the voltage applied to the laser - induced graphene strip 5 through the knob of the DC regulated power supply 7, and take the reflection information of the cholesteric liquid crystal capsule 4 on the laser - induced graphene strip 5;

[0038] Step 6: Extract the parameter mean value of the chromaticity value in the reflection information obtained in Step 5, and compare it one by one with the values in the standard image database established in Step 4, and finally determine the spectral curve of the test light source.

[0039] Example 1

[0040] As Figure 4 shown, place the cholesteric liquid crystal capsule micro - spectrometer prepared by the present invention in a laboratory at a temperature of 21 °C. The incident range of the light source 3 incident on the cholesteric liquid crystal capsule 4 is set as oblique incidence with an angle of 45°. Under the test light source, the magnitude of the applied voltage has a positive correlation with the chromaticity value of a single cholesteric liquid crystal capsule.

[0041] The cholesteric liquid crystal capsule has good temperature sensitivity, can achieve color change within 0.1 °C, and the thermochromic time is in the millisecond level.

[0042] In this experiment, the state of the cholesteric liquid crystal capsule is recorded every 0.1 V. To ensure that the laser - induced graphene strip and the cholesteric liquid crystal capsule reach a stable thermal equilibrium state, after adjusting the voltage, take the next photo at a time interval of 30 s; when the applied voltage is 0 V, there is no current passing through the laser - induced graphene strip, no heat is generated, and there is no color in the cholesteric liquid crystal capsule; after 30 s, gradually increase the voltage at a sampling interval of 0.1 V and save the image data of the cholesteric liquid crystal capsule at that time; then continue to increase the voltage intensity at the specified time interval and sampling interval in turn. When the applied voltage reaches 2 V, there is red inside the cholesteric liquid crystal capsule; when the applied voltage intensity continues to increase, the temperature of the cholesteric liquid crystal capsule gradually rises, and its reflection wave moves from the long - wave direction to the short - wavelength direction.

[0043] Example 2

[0044] AsFigure 5 As shown in the figure, the cholesteric liquid crystal capsule micro-spectrometer prepared by the present invention is placed in a laboratory at a temperature of 21°C. The incident range of the light source 3 incident on the cholesteric liquid crystal capsule 4 is set as oblique incidence with an angle of 60°. Under the measurement light source, the magnitude of the applied voltage has a positive correlation with the chromaticity value of a single cholesteric liquid crystal capsule. As Figure 5 The corresponding relationship between the applied voltage of the CLCM and hue at an oblique incidence of 60°.

[0045] Example 3

[0046] As Figure 6 shown in the figure, the cholesteric liquid crystal capsule micro-spectrometer prepared by the present invention is placed in a laboratory at a temperature of 21°C, and the light source 3 is perpendicularly incident in a vertical state with the horizontally placed core device 1. Under the measurement light source, the magnitude of the applied voltage has a positive correlation with the chromaticity value of a single cholesteric liquid crystal capsule.

[0047] The present invention uses a microscope system to extract and analyze color information, and then obtains the spectral information of the light source to be measured, which is efficient, practical, and low-cost.

[0048] The above is only the implementation manner of the present invention and is not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the scope of the claims of the present invention.

Claims

1. A cholesteric liquid crystal capsule micro-spectrometer, characterized in that: The cholesteric liquid crystal capsule micro-spectrometer includes a core device (1). The core device (1) is placed at the focal point of an optical microscope (2) of a complete set of microscopic devices, and an external light source (3) is used to irradiate the core device (1). The core device (1) includes a laser-induced graphene strip (5) and a cholesteric liquid crystal capsule (4) placed at the center of the laser-induced graphene strip (5).

2. The cholesteric liquid crystal capsule micro-spectrometer according to claim 1, wherein: The cholesteric liquid crystal capsule (4) is coated at the center of the laser-induced graphene strip (5) by dipping a PVC hose into a liquid crystal solution. Conductive tapes (6) are respectively pasted at the left and right ends of the laser-induced graphene strip (5), and the conductive tapes (6) on the left and right sides are connected to a DC regulated power supply (7) by wires to control the heating of the laser-induced graphene strip (5) and change the reflection information of the cholesteric liquid crystal capsule (4) on the laser-induced graphene strip (5).

3. The cholesteric liquid crystal capsule micro spectrometer according to claim 2, characterized in that: The cholesteric liquid crystal capsule (4) is a temperature-sensitive spherical particle.

4. A cholesteric liquid crystal capsule micro-spectrometer according to claim 2, characterized in that: The laser-induced graphene strip (5) is connected to the DC regulated power supply (7) through the conductive tape (6), and Joule heat is generated when a bias voltage is applied.

5. The cholesteric liquid crystal capsule micro-spectrometer according to claim 1, characterized in that: The complete set of microscopic devices consists of an optical microscope (2), an industrial camera (8), and a display (9). The color change of the cholesteric liquid crystal capsule (4) is detected by the optical microscope (2) and presented through the display (9).

6. A cholesteric liquid crystal capsule micro-spectrometer according to any one of claims 1, characterized in that: The preparation method of the core device (1) is as follows: A laser is used to perform laser ablation on a polyimide film to fabricate the laser-induced graphene strip (5) with a length of 20 mm and a width of 0.1 mm. The cholesteric liquid crystal capsule (4) is dispersed in a methyl silicone oil matching liquid to form a liquid crystal solution, and the liquid crystal solution is coated at the center of the laser-induced graphene strip (5) by dipping a PVC hose into the liquid crystal solution.

7. A method for using a cholesteric liquid crystal capsule micro-spectrometer as described in claim 2 or 4, characterized in that: The usage method of the cholesteric liquid crystal capsule micro-spectrometer includes the following steps: Step 1: Place the core device (1) at the focal point of the optical microscope (2). Step 2: Use the light source (3) to irradiate the cholesteric liquid crystal capsule (4). The DC regulated power supply (7) applies a voltage to the laser-induced graphene strip (5) to generate Joule heat, and the cholesteric liquid crystal capsule (4) changes color when heated. The reflection information of the cholesteric liquid crystal capsule (4) after heating is photographed and recorded. Step 3: Select a wavelength in the visible light band of 380 - 750 nm, place a narrow-band filter of this wavelength in front of the light source (3), repeat Step 1 and Step 2, photograph and record for analysis, and use it as a library for this band. Step 4: Summarize and analyze the data obtained in Step 2 and Step 3, analyze the corresponding relationship between the chromaticity value and the wavelength of the cholesteric liquid crystal capsule (4) after heating when a voltage is applied to the laser-induced graphene strip (5), and establish a standard image database. Step 5: Incident the light to be measured on the cholesteric liquid crystal capsule (4) at the same angle as the light source (3) incident on the cholesteric liquid crystal capsule (4). Change the voltage applied to the laser-induced graphene strip (5) by turning the knob of the DC regulated power supply (7), and capture the reflection information of the cholesteric liquid crystal capsule (4) on the laser-induced graphene strip (5). Step 6: Extract the parameter mean of the chromaticity value in the reflection information obtained in Step 5, and compare it one by one with the values in the standard image database established in Step 4 to finally determine the spectral curve of the light to be measured.

8. The method for using a cholesteric liquid crystal capsule micro spectrometer according to claim 7, characterized in that: In Step 2, the incident range of the light source (3) incident on the cholesteric liquid crystal capsule (4) is the normal incidence where the light source (3) and the horizontally placed core device (1) are in a vertical state.

9. The method for using a cholesteric liquid crystal capsule micro-spectrometer according to claim 7, characterized in that: In Step 2, the incident range of the light source (3) incident on the cholesteric liquid crystal capsule (4) is the oblique incidence where the light source (3) and the horizontally placed core device (1) form an acute angle, and the oblique incidence range is from 89° to 10°.

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