Ion detection method

Abstract

The embodiment of the invention provides an ion detection method. The ion detection method comprises the following steps: preparing a glass chip; processing the chip, and filling the chip with liquid crystal to obtain a liquid crystal optical flow control chip; preparing a to-be-detected solution of sodium ions with target concentration; placing the liquid crystal optical flow control chip on an ion detection device; extracting the to-be-detected liquid to form a to-be-detected sample, and injecting the to-be-detected sample onto the liquid crystal optical flow control chip; collecting a polarized image of the liquid crystal optical flow control chip based on a preset frequency; performing liquid crystal-related optical feature extraction on the polarized light image; and calculating and determining the concentration of the target ions in the to-be-detected liquid based on the extracted characteristics. The method provided by the invention can be fast and accurate, and is low in cost.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of ion detection, and in particular to an ion detection method. Background Art

[0002] Ion detection plays an indispensable role in environmental protection, health diagnosis, food safety, industrial control and scientific research. For example, sodium ions are common cations in nature and are widely present in the human body, environment and industrial systems. In the biomedical field, sodium ions play a vital role in maintaining osmotic pressure, acid-base balance and regulation of extracellular fluid in the human body; in water bodies and soil, the content of sodium ions can be used as an important indicator of water and soil quality; in food and drinking water safety, sodium is a common component, and excessive sodium intake may lead to health problems such as high blood pressure; in the chemical and pharmaceutical industries, the detection of sodium ions helps monitor the progress of chemical reactions and product purity during the production process. Therefore, it is crucial to accurately and quickly detect sodium ion concentrations.

[0003] Micromachining technology refers to the optimized design, processing, assembly, system integration and application technology of sub-millimeter and micron-scale components and parts or systems composed of these components. It has the characteristics of miniaturization, mass production and low cost. It has played a huge role in promoting modern life and production, and has spawned a number of emerging industries.

[0004] Existing ion detection methods include ion selective electrode method, atomic absorption spectroscopy, fiber optic sensing method, electrochemical sensing method and other technologies.

[0005] (1) Ion-selective electrode method. The ion-selective electrode method is based on a selective membrane that can produce an electrochemical response to specific ions (such as sodium ions). When the membrane comes into contact with sodium ions in the solution, it will produce a potential change related to the sodium ion concentration. By measuring the potential generated by the electrode and using the corresponding calibration curve, the concentration of sodium ions in the solution can be determined. This method is simple, fast and highly selective, but the electrode life is limited and requires regular calibration.

[0006] (2) Atomic absorption spectroscopy. Atomic absorption spectroscopy is a method of heating a sample to a high temperature to atomize ions (such as sodium ions), then irradiating the sample with light of a specific wavelength, measuring the absorption intensity of the light by sodium atoms, and calculating the concentration of sodium ions. This method has high sensitivity and accuracy and is suitable for the detection of low-concentration samples, but the instrument is expensive and the sample pretreatment is troublesome.

[0007] (3) Fiber optic sensing. Fiber optic sensors use optical fibers coated with specific ion (such as sodium ion) recognition molecules on the end face. When sodium ions react with recognition molecules, the optical signal (such as fluorescence, absorption or refractive index) in the optical fiber changes. The sodium ion concentration is measured by detecting the change in the optical signal. This method has high sensitivity and is suitable for remote monitoring, but the design and manufacture of fiber optic sensors are relatively complex and require expensive optical monitoring equipment.

[0008] (4) Electrochemical sensing. Electrochemical sensors use the redox reaction or potential change of ions (such as sodium ions) on the electrode surface to detect their concentration. These sensors can quantitatively analyze the concentration of sodium ions through signals such as conductivity and redox potential. This method has high sensitivity and fast response, but it is easily affected by the environment and the instrument needs to be calibrated regularly.

[0009] Although many advances have been made in ion detection technology, there are still some challenges.

[0010] Liquid crystal is a physical state between liquid and crystal, sometimes called the fourth state of matter. It retains the fluidity and continuity of liquid, and exhibits the physical, chemical, optical and other anisotropies of crystal. Liquid crystal molecules are considered to be an excellent detection technology because they can respond to external stimuli with high sensitivity, convert the molecular arrangement caused by physical and chemical binding events between molecules into optical signal output, and can be easily observed through a polarizing microscope. Compared with traditional sensing technology, it avoids cumbersome sample processing, complex operating steps and reliance on large and expensive equipment. Summary of the invention

[0011] The invention provides a fast, accurate and low-cost ion detection method.

[0012] In order to solve the above technical problems, an embodiment of the present invention provides an ion detection method, comprising:

[0013] preparing a glass chip;

[0014] Processing the chip and filling it with liquid crystal to obtain a liquid crystal optofluidic chip;

[0015] preparing a test solution having a target concentration of sodium ions;

[0016] Placing the liquid crystal optofluidic chip on an ion detection device;

[0017] Extracting the test liquid to form a test sample, and injecting the test sample into the liquid crystal optofluidic chip;

[0018] Collecting a polarized image of the liquid crystal optofluidic chip based on a preset frequency;

[0019] Extracting optical features of liquid crystal from the polarized image;

[0020] The concentration of the target ions in the test solution is determined based on the extracted features.

[0021] In some embodiments, the preparation of the glass chip comprises:

[0022] determining an array pattern of liquid crystal;

[0023] preparing a photolithography mask based on the array pattern;

[0024] The glass chip is prepared by processing a high-transmittance glass substrate using micromachining technology and a photolithography mask.

[0025] In some embodiments, the method of processing a high-transmittance glass substrate using micromachining technology and a photolithography mask includes:

[0026] Spin coating an anchor layer on the high light transmittance glass substrate;

[0027] heating the anchor layer and performing ion etching treatment;

[0028] The high light-transmittance glass substrate after etching is subjected to photolithography processing based on the photolithography template.

[0029] In some embodiments, the photolithography process includes spin coating of photoresist, pre-baking, exposure, post-baking, development, and hardening.

[0030] In some embodiments, the chip is processed and filled with liquid crystal to obtain a liquid crystal optofluidic chip, including:

[0031] cutting the chip;

[0032] The cut chips are placed in an evaporating dish for vacuum treatment;

[0033] The vacuumed chip is filled with liquid crystal.

[0034] In some embodiments, the method further comprises:

[0035] Place the chip filled with liquid crystal on a hot plate and let it stand;

[0036] The chip is tilted after being left to stand, so that the excess liquid crystal flows relative to the chip under the influence of gravity, thereby obtaining a liquid crystal optofluidic chip.

[0037] In some embodiments, the method further comprises:

[0038] The chip is subjected to wettability characterization so that the chip is in a suitable wettability state during the process of preparing the liquid crystal optofluidic chip.

[0039] In some embodiments, the step of preparing a test solution having a target concentration of sodium ions comprises:

[0040] preparing a solution of an amphiphilic anionic surfactant (taking sodium dodecyl sulfate as an example) with a target concentration;

[0041] Prepare the ion solution to be tested (taking sodium chloride solution as an example);

[0042] The amphiphilic anionic surfactant sodium dodecyl sulfate solution and sodium chloride solution are mixed to prepare a test solution.

[0043] In some embodiments, the collecting of the polarization image of the liquid crystal optofluidic chip based on a preset frequency includes:

[0044] The polarization image of the liquid crystal optofluidic chip is collected at a frequency of not less than 3 images collected per second, based on an interval between two adjacent collection moments being not less than 4 seconds.

[0045] In some embodiments, extracting optical features of liquid crystal from the polarized image includes:

[0046] Determine the collection time;

[0047] The brightness information of the polarized image is extracted. The liquid to be tested contains sodium ions. Different sodium ion concentrations can make the brightness of the polarized image different.

[0048] Based on the disclosure of the above embodiments, it can be known that the beneficial effects of the embodiments of the present invention include preparing a liquid crystal optofluidic chip through micromachining technology, and combining an artificial intelligence algorithm to achieve quantitative detection of sodium ions. The liquid crystal optofluidic chip used in the method of this embodiment has low preparation cost, is easy to mass produce, and is not easily affected by the external environment. At the same time, when the liquid crystal optofluidic chip is used to detect sodium ions, the response time is fast, and by adjusting the chip parameters, the ion detection range can be adjusted, and a wide range of ions can be adjusted.

[0049] Other features and advantages of the present application will be described in the following description, and partly become apparent from the description, or be understood by practicing the present application. The purpose and other advantages of the present application can be realized and obtained by the structures specifically pointed out in the written description, claims, and drawings.

[0050] The technical solution of the present application is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0052] Figure 1 Schematic diagram of the process of the ion detection method in an embodiment of the present invention.

[0053] Figure 2 It is a schematic flow chart of an ion detection method in another embodiment of the present invention.

[0054] Figure 3 It is a schematic flow chart of an ion detection method in another embodiment of the present invention.

[0055] Figure 4 This is a polarized picture of the liquid crystal optofluidic chip in the embodiment of the present invention in air. DETAILED DESCRIPTION

[0056] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings, but are not intended to limit the present invention.

[0057] It should be understood that various modifications may be made to the embodiments disclosed herein. Therefore, the following description should not be considered as limiting, but merely as an example of an embodiment. Other modifications within the scope of the present disclosure will occur to those skilled in the art.

[0058] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the general description of the present disclosure given above and the detailed description of the embodiments given below, serve to explain the principles of the present disclosure.

[0059] These and other characteristics of the invention will become apparent from the following description of a preferred form of embodiment given as a non-limiting example, with reference to the accompanying drawings.

[0060] It should also be understood that, although the invention has been described with reference to some specific examples, those skilled in the art will be able to realize many other equivalent forms of the invention that have the characteristics recited in the claims and are therefore within the scope of protection defined thereby.

[0061] The above and other aspects, features and advantages of the present disclosure will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

[0062] Specific embodiments of the present disclosure are described hereinafter with reference to the accompanying drawings; however, it should be understood that the disclosed embodiments are merely examples of the present disclosure, which may be implemented in a variety of ways. Well-known and / or repeated functions and structures are not described in detail to avoid obscuring the present disclosure with unnecessary or redundant details. Therefore, the specific structural and functional details disclosed herein are not intended to be limiting, but merely serve as a basis and representative basis for the claims to teach those skilled in the art to use the present disclosure in a variety of ways with substantially any suitable detailed structure.

[0063] This specification may use the phrases "in one embodiment," "in another embodiment," "in a further embodiment," or "in other embodiments," all of which may refer to one or more of the same or different embodiments according to the present disclosure.

[0064] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0065] like Figure 1 As shown, an embodiment of the present invention provides an ion detection method, comprising:

[0066] S1: Preparation of glass chip;

[0067] S2: processing the chip and filling it with liquid crystal to obtain a liquid crystal optofluidic chip;

[0068] S3: preparing a test solution having a target concentration of sodium ions;

[0069] S4: placing the liquid crystal optofluidic chip on an ion detection device;

[0070] S5: extracting the test liquid to form a test sample, and injecting the test sample into the liquid crystal optofluidic chip;

[0071] S6: collecting a polarized image of the liquid crystal optofluidic chip based on a preset frequency;

[0072] S7: extracting optical features of liquid crystal from the polarized image;

[0073] S8: Determine the concentration of the target ions in the test solution based on the extracted features.

[0074] For example, the detection device includes a polarizing microscope, and under the polarizing microscope, when the liquid to be tested is added, its optical image can be transformed from a dark field to a bright stripe texture. At this time, the image collected under the polarizing microscope is called a polarizing image (POM). When the method based on the present embodiment is used to detect ions in the liquid to be tested, the principle based on the anionic surfactant component in the liquid to be tested can make the liquid crystal molecules in the liquid crystal optofluidic chip have a parallel / tilt angle arrangement. On the contrary, when there are ions in the liquid to be tested at the interface of the liquid crystal optofluidic chip, due to the coupling effect between the components contained in the liquid to be tested and the ions to be tested, the liquid to be tested at the interface will produce a charge shielding effect, resulting in more surfactant molecules in the liquid to be tested being distributed at the interface, so a series of optical images of different color textures can be observed through a polarizing microscope. And different concentrations of ionic solutions have different effects on the response time of the liquid to be tested at the interface and the brightness of the optical picture, so the optical features of the polarized image obtained can be extracted by an artificial intelligence deep learning algorithm, so as to analyze and calculate based on the extracted features, and then realize the quantitative detection of the concentration of the target ion. For example, detecting positive ions such as sodium ions, potassium ions, aluminum ions, or the salinity of seawater, etc., the specific details are uncertain.

[0075] Based on the above content, it can be seen that the beneficial effects of this embodiment include preparing a liquid crystal optofluidic chip through micromachining technology and combining it with an artificial intelligence algorithm to achieve quantitative detection of sodium ions. The liquid crystal optofluidic chip used in the method of this embodiment has low preparation cost, is easy to mass produce, and is not easily affected by the external environment. At the same time, when using a liquid crystal optofluidic chip to detect sodium ions, the response time is fast, and by adjusting the chip parameters, the ion detection range can be adjusted, and a wide range of ions can be adjusted.

[0076] In one embodiment, if Figure 2 As shown, the preparation of the glass chip comprises:

[0077] S9: determining an array pattern of liquid crystal;

[0078] S10: preparing a photolithography mask based on the array pattern;

[0079] S11: Processing a high-transmittance glass substrate using micromachining technology and a photolithography mask to prepare a glass chip.

[0080] Furthermore, if Figure 3 As shown, the method of processing a high light transmittance glass substrate using micromachining technology and a photolithography mask plate includes:

[0081] S12: spin coating an anchor layer on the high light transmittance glass substrate;

[0082] S13: heating the anchor layer and performing ion etching treatment;

[0083] S14: performing photolithography on the etched high-transmittance glass substrate based on the photolithography template.

[0084] The photolithography process includes spin coating of photoresist, pre-baking, exposure, post-baking, development, and hardening.

[0085] After the chip is prepared, the chip is processed and filled with liquid crystal to obtain a liquid crystal optofluidic chip, including:

[0086] S15: cutting the chip;

[0087] S16: placing the cut chip into an evaporating dish for vacuum treatment;

[0088] S17: filling the vacuumed chip with liquid crystal.

[0089] Furthermore, the method further comprises:

[0090] S18: placing the chip filled with liquid crystal on a hot plate and letting it stand;

[0091] S19: Tilt the chip after it has been left to stand so that excess liquid crystal flows relative to the chip due to gravity, thereby obtaining a liquid crystal optofluidic chip.

[0092] Furthermore, the method further comprises:

[0093] S20: performing wetting characterization on the chip, so that the chip is in a suitable wetting state during the process of preparing the liquid crystal optofluidic chip.

[0094] That is, in order to ensure the smooth progress of each of the above steps and the filling of the liquid crystal on the chip, the wettability of the chip state during the preparation process is characterized in this embodiment.

[0095] Taking the detection of the salinity of seawater as an example, the preparation of a test solution having a target concentration of sodium ions in this embodiment includes:

[0096] S21: preparing a sodium dodecyl sulfate solution of an amphiphilic anionic surfactant having a target concentration;

[0097] S22: preparing a sodium chloride solution;

[0098] S23: Mixing the amphiphilic anionic surfactant sodium dodecyl sulfate solution and sodium chloride solution to prepare a test solution.

[0099] Taking a sodium dodecyl sulfate (SDS) solution of an amphiphilic anionic surfactant having a target concentration as an example, the SDS solution is mixed with a series of NaCl solutions of different concentrations to obtain a test solution, wherein the concentration of the NaCl solution is not fixed and can be any concentration that can be used for detection. When detecting ions, the test solution is used to detect sodium ions in the solution.

[0100] When collecting polarized images, collecting the polarized images of the liquid crystal optofluidic chip based on a preset frequency includes:

[0101] S24: collecting polarized images of the liquid crystal optofluidic chip at a frequency where the interval between two adjacent collection moments is not less than 4 seconds and the number of images collected per second is not less than 3.

[0102] For example, the acquisition setting is 5 frames per second, and a total of 4 seconds of polarization images are acquired, or the acquisition setting is 7, 8, etc. frames per second for acquisition, and the specific frequency is not unique.

[0103] The extracting optical features of liquid crystal from the polarized image includes:

[0104] S25: Determine the collection time;

[0105] S26: extracting brightness information of the polarized image. The test liquid contains sodium ions. Different sodium ion concentrations can make the brightness of the polarized image different.

[0106] During the test, when there is an optimized concentration of amphiphilic anionic surfactant sodium dodecyl sulfate solution (SDS) at the interface of the liquid crystal optofluidic chip, it can be observed under a polarizing microscope that the optical image changes from a dark field to a bright stripe texture. At this time, the image collected under a polarizing microscope is called a polarizing image. At this time, SDS causes the liquid crystal molecules to be arranged at a parallel / tilted angle. On the contrary, when there is a mixed solution of SDS and sodium chloride (NaCl) at the interface (i.e., the test solution), due to the coupling effect between SDS and sodium ions, the SDS at the interface produces a charge shielding effect, resulting in more SDS distributed at the interface, so a series of optical images with different color textures can be observed. Different concentrations of NaCl solutions have different effects on information such as the response time of SDS at the interface and the brightness of the optical picture. Therefore, the characteristic values ​​can be extracted through an artificial intelligence deep learning algorithm, thereby realizing quantitative detection of the salinity of seawater.

[0107] Specifically, in one application example, a layer of anchoring layer Hyf is spin-coated on a cleaned high-transmittance glass substrate. lon (spin coating parameters can be but not limited to 500rpm, 18s, 500rpm; 1500rpm, 60s, 1500rpm, and the anchor layer thickness can be but not limited to 150nm), then heated (for example, can be but not limited to 120℃, 10min), and then reactive ion etching (etching parameters can be but not limited to O2, 15W, 20s). In this embodiment, SU82015 photoresist is selected for spin coating (photolithography parameters can be but not limited to 500rpm, 5s, 300rpm; 2500rpm, 30s, 300rpm, and the thickness of the glue layer can be but not limited to H=16.5μm), pre-baking (for example, can be but not limited to 95℃, 4min), exposure (for example, can be but not limited to 7s); post-baking (95℃, 5min), development (for example, can be but not limited to glycol formaldehyde acetate (PGMEA), 4min), and hardening (for example, can be but not limited to 150℃, 30min). The chip parameters finally obtained are: width W1 = 80 μm, thickness H = 16.5 μm. The specific parameters are not limited, and the chip parameters obtained are different when the above parameters are used differently.

[0108] Next, the obtained chip is cut, and the cutting size can be but not limited to 18mm×18mm. Finally, the cut chip is placed in an evaporating dish for vacuum treatment, for example, for 30 minutes, and then filled with liquid crystal, for example, 20μL of liquid crystal, and then immediately placed on a hot plate at 40°C (it can be other temperatures higher than the clearing point of the liquid crystal) for a period of time, for example, for 30 minutes, and then the chip is tilted at an angle of 30° so that the excess liquid crystal relies on gravity to stay, and finally a liquid crystal optofluidic chip is obtained.

[0109] In the preparation process of the chip, the wettability characterization is preferably performed on the results obtained in each step of the preparation. First, the cleaned glass substrate has a large amount of hydroxyl groups on the surface, and the contact angle with water can be as low as 21.1°, so the anchor layer is spin-coated on this optical substrate. However, since the anchor layer is a fluorine-containing polymer, the contact angle with water can reach 117.5°. In order to spin-coat the photoresist on this surface and make its surface hydrophilic, the anchor layer can be treated so that when its contact angle with water reaches 103.6°, the SU-8 photoresist can be successfully spin-coated on the anchor layer. After the photolithography is completed, the process of hardening the film simultaneously causes the anchor layer to heat reflux to the initial stable state, and the contact angle can return to 117.6°, and the contact angle with the liquid crystal is 48.4°. At the same time, the contact angles of the photoresist with water and liquid crystal are 100.2° and 81.3° respectively. When this parameter is reached, it is considered that the chip can be successfully prepared.

[0110] The optical characterization of the liquid crystal optofluidic chip can be determined by placing the prepared liquid crystal optofluidic chip under an orthogonal polarization microscope for observation. The polarized image observed is as follows: Figure 4 As shown. Since the chip is vertically anchored in the air, a black polarized image can be observed through a microscope.

[0111] When sodium ion detection is performed, first 30 μM SDS aqueous solution is mixed with sodium chloride aqueous solution of different concentrations (sodium chloride aqueous solution of 21 concentrations is used in the present embodiment) in equal volumes, for example, the concentrations of sodium chloride solution are 0, 2.0300, 4.1616, 6.0508, 8.2092, 10.2892, 12.5158, 14.2106, 16.5194, 18.0808, 20.3180, 21.9744, 23.4468, 26.3522, 28.152, 30.2158, 32.2162, 34.532, 35.9776, 38.4232, 39.3148, 41.5956 wt ‰. In the present embodiment, each sodium chloride concentration is subjected to 6 groups of experiments, and the effective time for the collection of each group of experiments is 4 s. The images collected at the following 19 concentrations (0, 2.0300, 4.1616, 8.2092, 10.2892, 12.5158, 14.2106, 18.0808, 20.3180, 21.9744, 23.4468, 26.3522, 28.152, 32.2162, 34.532, 35.9776, 38.4232, 39.3148, 41.5956 wt‰) were used as standard data sets and input into the self-developed deep learning algorithm for training. The coefficient of determination R 2 It can reach 0.9962. Then the three concentrations outside the standard data set (6.0508, 16.5194, 30.2158wt‰) were input into the trained model for prediction. The detection range can reach 0-41.5956wt‰, and the response time is 4s. The overall parameters and effects are excellent. In addition, the SDS concentration is adjustable, and one SDS concentration corresponds to a detection range and an optimal response time. The above implementation case only lists the case where the SDS concentration is 30μM, and the corresponding detection range is 0-41.5956wt‰, and the response time is 4s.

[0112] In one embodiment, the parameters of the chip (side length W1, spacing W2, thickness H and shape of the microstructure) are adjustable. Different chip parameters correspond to an optimal ion detection range. This implementation case only lists the parameters of the microstructure being a square, with a side length of 80 μm, a spacing of 40 μm, and a thickness of 16.5 μm.

[0113] The above embodiments are only exemplary embodiments of the present invention and are not intended to limit the present invention. The protection scope of the present invention is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present invention within the essence and protection scope of the present invention, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present invention.

Claims

1. An ion detection method, characterized in that: include: preparing a glass chip; Processing the chip and filling it with liquid crystal to obtain a liquid crystal optofluidic chip; preparing a test solution having a target concentration of sodium ions; Placing the liquid crystal optofluidic chip on an ion detection device; Extracting the test liquid to form a test sample, and injecting the test sample into the liquid crystal optofluidic chip; Collecting a polarized image of the liquid crystal optofluidic chip based on a preset frequency; Extracting optical features of liquid crystal from the polarized image; The concentration of the target ions in the test solution is determined based on the extracted features.

2. The ion detection method according to claim 1, characterized in that: The method for preparing a glass chip comprises: determining an array pattern of liquid crystal; preparing a photolithography mask based on the array pattern; The glass chip is prepared by processing a high-transmittance glass substrate using micromachining technology and a photolithography mask.

3. The ion detection method according to claim 2, characterized in that: The method of processing a high light transmittance glass substrate by using micro-machining technology and a photolithography mask plate comprises: Spin coating an anchor layer on the high light transmittance glass substrate; heating the anchor layer and performing ion etching treatment; The high light-transmittance glass substrate after etching is subjected to photolithography processing based on the photolithography template.

4. The ion detection method according to claim 3, characterized in that: The photolithography process includes spin coating of photoresist, pre-baking, exposure, post-baking, development, and hardening.

5. The ion detection method according to claim 1, characterized in that: The chip is processed and filled with liquid crystal to obtain a liquid crystal optofluidic chip, comprising: cutting the chip; The cut chips are placed in an evaporating dish for vacuum treatment; The vacuumed chip is filled with liquid crystal.

6. The ion detection method according to claim 5, characterized in that: The method further comprises: Place the chip filled with liquid crystal on a hot plate and let it stand; The chip is tilted after being left to stand, so that the excess liquid crystal flows relative to the chip under the influence of gravity, thereby obtaining a liquid crystal optofluidic chip.

7. The ion detection method according to claim 1, characterized in that: The method further comprises: The chip is subjected to wettability characterization so that the chip is in a suitable wettability state during the process of preparing the liquid crystal optofluidic chip.

8. The ion detection method according to claim 1, characterized in that: The method of preparing a test solution having a target concentration of sodium ions comprises: preparing a sodium dodecyl sulfate solution of an amphiphilic anionic surfactant having a target concentration; Prepare sodium chloride solution; The amphiphilic anionic surfactant sodium dodecyl sulfate solution and sodium chloride solution are mixed to prepare a test solution.

9. The ion detection method according to claim 1, characterized in that: The collecting of the polarized image of the liquid crystal optofluidic chip based on a preset frequency includes: The polarization image of the liquid crystal optofluidic chip is collected at a frequency of not less than 3 images collected per second, based on an interval between two adjacent collection moments being not less than 4 seconds.

10. The ion detection method according to claim 1, characterized in that: The extracting optical features of liquid crystal from the polarized image includes: Determine the collection time; The brightness, color and texture information of the polarized image are extracted. The liquid to be tested contains sodium ions. Different sodium ion concentrations can make the brightness, color or texture of the polarized image different.

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