Cascade type micro-spherical lens imaging structure and preparation method thereof

Abstract

The invention discloses a cascaded micro-spherical lens imaging structure and a preparation method thereof. The structure is composed of a barium titanate (BTG) microsphere array and a polystyrene (PS) microsphere array. The preparation method comprises the following steps: 1, preparing a PS microsphere array by using a gravity self-assembly method; 2, dropping the BTG solution on a slide provided with a PS microsphere array; and 3, spin-coating PDMS and heating to obtain the PDMS thin film embedded with the BTG microsphere and PS microsphere array. According to the invention, the magnifying power of microsphere imaging can be improved, a sample with a smaller period can be identified, and the imaging resolution of the system can be improved. The advantages of the method in the aspect of imaging performance fully show that the method has a wide application prospect in the field of super-resolution imaging.

Description

Technical Field

[0001] This invention relates to the field of microsphere-assisted microscopy imaging technology in super-resolution imaging, specifically to a cascaded microsphere lens imaging structure and its fabrication method. Background Technology

[0002] Since its invention in the late 16th century, the optical microscope has undergone numerous improvements and has been successfully applied in fields such as biology and medicine to observe objects invisible to the naked eye. With the advancement and development of biology and medicine, the observed samples have become increasingly detailed, leading to higher demands on imaging resolution. The Abbe criterion provides researchers with two feasible methods to improve resolution: reducing the incident light wavelength λ and increasing the numerical aperture NA. Based on these two ideas, researchers have explored various experimental methods to enhance the imaging performance of microscopes, such as using immersion oil immersion to increase the numerical aperture of the optical system, and using ultraviolet light sources to reduce the incident light wavelength. However, these methods have not significantly improved resolution. Meanwhile, many new microscopic imaging techniques have emerged, including scanning electron microscopy, probe scanning microscopy, and fluorescence imaging microscopy. Among them, scanning electron microscopy requires spraying a layer of metal onto the sample surface to improve the sample's conductivity, and then scanning the sample in a vacuum environment. Therefore, this method cannot observe living biological tissues. Probe scanning microscopy requires reading information from the sample surface through a probe and then transmitting it to a computer for calculation and imaging. Therefore, this method takes too long to image and cannot observe the sample in real time. Fluorescence imaging microscopy can only image specific samples, and the process of labeling the sample can also cause some damage to the sample, so it cannot meet all imaging needs.

[0003] In recent years, researchers have also discovered a novel super-resolution imaging technique: microsphere-assisted microscopy. Microspheres possess the ability to amplify and focus light beams in the near field. By placing them on the sample surface, they can couple evanescent waves containing precise information about the sample, propagating these evanescent waves to the far field to achieve super-resolution imaging. Therefore, microsphere-assisted microscopy can not only achieve high resolution under white light illumination but also perform real-time observation and imaging of samples, making it valuable for observing biological samples and possessing broad application prospects. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a cascaded microsphere lens imaging structure and its fabrication method.

[0005] To achieve the above objectives, in a first aspect, the present invention proposes a cascaded microsphere lens imaging structure, which mainly consists of a single barium titanate BTG microsphere with a diameter of 20 μm and an array of polystyrene PS microspheres with a diameter of 200 nm or 250 nm.

[0006] In a second aspect, the present invention provides a method for fabricating the above-mentioned cascaded microsphere lens imaging structure, comprising the following steps:

[0007] 1. Cut the glass slides into long and short pieces, immerse them in a solution of concentrated sulfuric acid and hydrogen peroxide in a ratio of 3:1 for 30 minutes, rinse them with plasma water, and dry them in an oven.

[0008] 2. Dilute the 10% PS microsphere solution with deionized water at a ratio of 1:18 to prepare a microsphere solution with a lower concentration. Vibrate the solution in an ultrasonic oscillator for 5 minutes to make the PS microspheres disperse evenly.

[0009] 3. Use an uncut glass slide as a base, place the short slide on the base, and place the long slide on the short slide. Fix them with 4 clips to form a wedge-shaped groove with an included angle of 4° in the middle.

[0010] 4. Use a syringe to draw up the prepared PS microsphere solution and inject it into the wedge-shaped groove. Then, place the substrate upside down in an incubator. Under the influence of gravity and liquid tension, the water in the solution will evaporate and deposit on the surface of the long film, thus obtaining a PS microsphere array.

[0011] 5. Drop the BTG solution onto a long sheet equipped with a PS microsphere array, use a heating plate to dry the moisture, and spin coat PDMS in a spin coater;

[0012] 6. After standing for 24 hours, use a heating plate to cure the PDMS film to obtain a PDMS film embedded with BTG microspheres and PS microsphere arrays.

[0013] Furthermore, the parameters of the insulated box are set to control the temperature at 3-5℃ and the humidity at 60%-70%.

[0014] Furthermore, the rotation speed of the homogenizer is set to 500 r / min, and the time is 40 s.

[0015] Beneficial effects: First, the method for preparing the cascaded microsphere lens imaging structure disclosed in this invention is simple to operate, requires simple instruments, has excellent results, high stability and good repeatability;

[0016] Second, the cascaded microsphere lens imaging structure proposed in this invention can not only improve the imaging magnification, but also improve the resolution of microsphere imaging, provide clearer imaging of samples, and identify samples with shorter identification cycles.

[0017] Third, the cascaded microsphere lens imaging structure proposed in this invention can perform real-time observation and imaging of samples, which has important application value in the field of biological sample observation technology. Attached Figure Description

[0018] Figure 1This is a schematic diagram of the single microsphere structure A;

[0019] Figure 2 This is a schematic diagram of the cascaded microsphere structure B. Detailed Implementation

[0020] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. These embodiments are implemented based on the technical solutions of the present invention, and it should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0021] Example 1:

[0022] Single microsphere imaging structure sample A, such as Figure 1 As shown, the preparation process is as follows:

[0023] Step S01: Cut the glass slide into 2.5cm × 4cm pieces, prepare a solution of concentrated sulfuric acid and hydrogen peroxide in a 3:1 ratio, and soak for 30 minutes. After soaking, rinse with deionized water and dry in an oven.

[0024] Step S02: Drop the prepared BTG solution with a diameter of 20μm and a refractive index of n=1.92 onto the surface of the long film, use a heating plate to heat and dry the moisture, spin coat PDMS, set the spin coater speed to 500r / min, and the time to 40s.

[0025] Step S03: After spin coating of PDMS, let the long film stand for 24 hours, then heat it with a heating plate for 1 hour to cure the PDMS film.

[0026] Step S04: Peel off the PDMS film embedded with BTG microspheres and attach it to the sample surface.

[0027] The prepared single-microsphere imaging structure A was used to observe the Blu-ray disc. As the distance between the objective lens and the sample decreased, the magnification continuously increased, and the image gradually became clearer and then blurred again. When z = 38 μm, the imaging magnification of the sample by the single-microsphere structure was approximately 5.2 × 10⁻⁶.

[0028] Cascaded microsphere structure sample B, such as Figure 2 As shown, the preparation process is as follows:

[0029] Step S11: First, PS microsphere arrays are prepared using a gravity self-assembly method.

[0030] Step S12: Drop the BTG solution onto a long sheet equipped with a PS microsphere array, use a heating plate to heat and dry the moisture, spin coat PDMS, set the spin coater speed to 500 r / min, and the time to 40 s.

[0031] Step S13: Let stand for 24 hours (mainly to allow PDMS to better penetrate the microsphere arrangement layer and ensure that the array is peeled off together when the PDMS film layer is peeled off), then heat with a heating plate for 1 hour to cure the PDMS film.

[0032] Step S14: Peel off the PDMS film embedded with BTG microspheres and PS microsphere arrays and attach it to the sample surface.

[0033] The prepared cascaded microsphere imaging structure B was used to observe the Blu-ray disc. As the distance between the objective lens and the sample decreased, the magnification increased. The image gradually became clearer and then blurred again. When z = 38 μm, the imaging magnification of the sample by the cascaded microsphere structure B was about 6.5 × 10⁻⁶.

[0034] In this embodiment, comparing the imaging results of a single microsphere structure A and a cascaded microsphere structure B, it can be seen that the imaging magnification of the cascaded microsphere structure is greater than that of the single microsphere structure. The cascaded microsphere structure further improves the magnification of microsphere imaging.

[0035] Example 2:

[0036] The preparation process of single microsphere structure sample C is as follows:

[0037] Step S21: Prepare a PS microsphere array with a diameter of 250 nm using a gravity self-assembly method.

[0038] Step S22: A 30nm aluminum film and a 10nm SiO film are deposited on the surface of the PS microsphere array using a vacuum thermal evaporation machine as the sample to be tested.

[0039] Step S23: Drop the BTG solution onto the sample surface, use a heating plate to dry the moisture, spin coat PDMS, set the spin coater speed to 1500 r / min, and the time to 40 s.

[0040] Step S24: Heat the PDMS film for 1 hour using a heating plate to cure it.

[0041] The prepared single-microsphere imaging structure sample C was used to observe the sample with a smaller measurement period. During the microscope focal length adjustment, the microspheres could image the sample within the focal plane range of 25-55 μm. During this process, the sample array began to be clearly observed at approximately 35 μm of the focal plane, and the imaging result changed from clear to blurry at 45 μm of the focal plane. The imaging magnification of the structure on the sample was approximately 8.2-11.4×.

[0042] The preparation process of cascaded microsphere structure sample D is as follows:

[0043] Step S31: Prepare a PS microsphere array with a diameter of 250 nm using a gravity self-assembly method.

[0044] Step S32: A 30nm aluminum film and a 10nm SiO film are deposited on the surface of the microsphere array using a vacuum thermal evaporation machine as the sample to be tested.

[0045] Step S33: On the sample coated with the thin film, a PS microsphere array with the same period as the sample is prepared by gravity self-assembly.

[0046] Step S34: Drop the BTG solution onto the sample surface, use a heating plate to heat and dry the moisture, spin coat PDMS, set the spin coater speed to 1500 r / min, and the time to 40 s.

[0047] Step S35: Heat the PDMS film for 1 hour using a heating plate to cure it.

[0048] The prepared cascaded microsphere imaging structure D was used to observe the sample with a smaller observation period. During microscope focus adjustment, the microspheres could image the sample within the focal plane range of 30-60 μm. In this process, the sample array was observed at approximately 40 μm of the focal plane, and the imaging result changed from clear to blurry at 50 μm of the focal plane. The magnification of the sample imaged by structure D was approximately 10.6-13.6 × 10⁻⁶.

[0049] In this embodiment, the sample is a 250nm PS microsphere array. The magnification of a single microsphere imaging structure is approximately 8.2-11.4×, and the magnification of a cascaded microsphere imaging structure is approximately 10.6-13.6×. Calculations show that the magnification of the cascaded microsphere imaging structure is approximately 1.25 times that of the single microsphere imaging structure, indicating that the magnification of the cascaded microsphere imaging structure is higher than that of the single microsphere imaging structure.

[0050] Example 3:

[0051] Based on Example 2, the observed sample was replaced with a smaller 200nm PS microsphere array. During microscope focus adjustment, structure C could not image the sample and could not clearly distinguish the hexagonally packed microsphere array. With structure D, the microspheres could image the sample within the 30-45μm range during microscope focus adjustment. During this process, the sample array was initially observed at approximately 35μm of the focal plane, and the image became blurry at 40μm. The magnification of the sample image from structure D was approximately 12.5-13.7×.

[0052] In this embodiment, the cascaded microsphere imaging structure D can identify a PS microsphere array with a period of 200nm, while the single microsphere imaging structure C cannot identify a PS microsphere array with a period of 200nm. The lateral magnification of the microspheres in the cascaded microsphere imaging structure is higher than that in the single microsphere imaging structure, and the imaging resolution of the system is also higher than that of the single microsphere imaging structure.

[0053] The above description is merely a preferred embodiment of the present invention. It should be noted that for those skilled in the art, other parts not specifically described are existing technology or common knowledge. Several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A cascaded microsphere lens imaging structure, characterized in that, It consists of an array of barium titanate BTG microspheres and polystyrene PS microspheres.

2. The cascaded microsphere lens imaging structure as described in claim 1, characterized in that, The barium titanate BTG microspheres have a diameter of 20 μm, and the polystyrene PS microspheres have a diameter of 200 nm or 250 nm.

3. A method for fabricating a cascaded microsphere lens imaging structure, characterized in that, Includes the following steps:

1. Cut the glass slides into long and short pieces, immerse them in a solution of concentrated sulfuric acid and hydrogen peroxide in a ratio of 3:1 for 30 minutes, rinse them with plasma water, and dry them in an oven.

2. Dilute the 10% PS microsphere solution with deionized water at a ratio of 1:18 to prepare a microsphere solution with a lower concentration. Vibrate the solution in an ultrasonic oscillator for 5 minutes to make the PS microspheres disperse evenly.

3. Use an uncut glass slide as a base, place the short slide on the base, and place the long slide on the short slide. Fix them with 4 clips to form a wedge-shaped groove with an included angle of 4° in the middle.

4. Use a syringe to draw up the prepared PS microsphere solution and inject it into the wedge-shaped groove. Then, place the substrate upside down in an incubator. Under the influence of gravity and liquid tension, the water in the solution will evaporate and deposit on the surface of the long film, thus obtaining a PS microsphere array.

5. Drop the BTG solution onto a long sheet equipped with a PS microsphere array, use a heating plate to dry the moisture, and spin coat PDMS in a spin coater; 6. After standing for 24 hours, use a heating plate to cure the PDMS film to obtain a PDMS film embedded with BTG microspheres and PS microsphere arrays.

4. The method for fabricating a cascaded microsphere lens imaging structure as described in claim 3, characterized in that, The parameters of the insulated box are set to control the temperature at 3-5℃ and the humidity at 60%-70%.

5. The method for fabricating a cascaded microsphere lens imaging structure as described in claim 3, characterized in that, The speed of the homogenizer was set to 500 r / min and the time was 40 s.

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