Optical fiber probe for measuring micro force on cell surface and manufacturing method of optical fiber probe

Abstract

The invention discloses an optical fiber probe for measuring cell surface micro force, which is characterized in that a fiber core is arranged in the center of a single-mode fiber, a sensing structure is positioned at one end of the single-mode fiber, the sensing structure comprises a spring part and a stress part, the stress part and the end surface of the fiber core are oppositely arranged, and an FP cavity is formed between the stress part and the fiber core; the spring part is located between the stress part and the end face of the single-mode optical fiber, and two ends of the spring part are respectively connected with the stress part and the single-mode optical fiber. According to the optimally designed optical fiber probe for measuring the micro force on the cell surface, the FP cavity is combined with the spring structure, the sensitivity and the accuracy of micro stress measurement are effectively improved, micro force can be detected through the stress part, the detection accuracy is high, the detection range is wide, the stability is high, and therefore more accurate measurement data are provided for cell mechanical property research. The invention further discloses a manufacturing method of the optical fiber probe for measuring the micro-force on the cell surface.

Description

Technical Field

[0001] The invention relates to the technical field of cell surface micro-force measurement, and in particular to an optical fiber probe for cell surface micro-force measurement and a manufacturing method thereof. Background Art

[0002] In modern biomedical research and clinical diagnosis, the mechanical properties of cells and their relationship with diseases have received increasing attention. The mechanical properties of cells (such as deformability, stiffness, adhesion, etc.) have an important impact on biological processes such as cell function, tissue development, wound healing, and tumor invasion. Therefore, accurately measuring the microstress of cell surfaces has become a hot issue in biomedical research.

[0003] The mechanical properties of cells can be evaluated by a variety of methods, mainly including the stiffness and deformation ability of cells. The stiffness of cells is usually closely related to the cytoskeletal structure (such as microtubules and microfilaments) within the cell. At the same time, changes in the mechanical properties of cells are often closely related to the progression and prognosis of tumors, which makes cell mechanical measurements have potential application value in early diagnosis and treatment monitoring of cancer.

[0004] In the measurement of cell mechanical properties, fiber optic sensing technology has attracted wide attention due to its advantages such as high sensitivity, easy integration and miniaturization. As an important fiber optic sensor, fiber Fabry-Perot (FP) sensor has the characteristics of small size, high precision, corrosion resistance, anti-electromagnetic interference, easy networking, simple principle, fast response and wide detection range. Its application in chemical production, geological exploration, medical and health, biomedicine and other fields has been increasingly valued, especially in the fields of life sciences, and is widely used in the field of microstress measurement. The sensor is based on the principle of interference. The mechanical properties of the cell tissue surface interface affect the function of the cell. The occurrence of many diseases is accompanied by obvious changes in the mechanical properties of the cell tissue surface interface. Therefore, the model relationship between disease and cell mechanical properties can be established by detecting the microstress of the cell tissue surface interface, and the changes in physical quantities such as stress or pressure can be obtained by measuring the phase change of light. For example, in the detection of cancer-related microstress, the mechanical deformation ability and stiffness of the cell are two more important mechanical parameters. The mechanical deformation ability of cancer cells affects the invasive ability of cancer cells, and usually generates piconewton to nanonewton forces during the invasion process; and the stiffness of the cell can be directly used as the basis for distinguishing normal cells from cancer cells.

[0005] With the development of fiber optic sensor technology, various new sensors have emerged. Placing the fiber optic microstress detection probe on the biological surface interface of the simulated in vitro culture environment can effectively detect cell pathology, etc. Liao Changrui and others from Shenzhen University prepared a door-shaped single-probe microstress sensor on the end face of a single-mode optical fiber. The sensor initially achieved the measurement of the Young's modulus of polydimethylsiloxane, butterfly antennae and human hair (Zou, Mengqiang, Changrui Liao, Shen Liu, CongXiong, Cong Zhao, Jinlai Zhao, Zongsong Gan et al. "Fiber-tip polymer clamped-beam probe for high-sensitivity nanoforce measurements." Light: Science & Applications 10, no. 1 (2021): 171.). In 2023, Liao Changrui and others from Shenzhen University prepared a fiber optic cantilever probe on the end face of the optical fiber. By changing the geometric structure parameters of the micro-cantilever, the stiffness of the probe was adjusted to realize the detection of the mechanical properties of biological cells (Zou, Mengqiang, Changrui Liao, Yanping Chen, Lei Xu, Shuo Tang, Gaixia Xu, Ke Ma et al. "3D printed fiber-optic nanomechanical bioprobe." International Journal of Extreme Manufacturing 5, no. 1 (2023): 015005.), but its deformation ability is limited.

[0006] However, although fiber optic sensors have shown good performance in micro-stress measurement, their disadvantages such as complex manufacturing, insufficient sensitivity, poor adaptability, and long response time limit their potential for wider applications. First, traditional fiber optic sensors are relatively complex in structural design, especially in the manufacturing process of micro-nano structures, which often requires high technical requirements and precision equipment. Secondly, existing fiber optic sensors are not ideal in detection sensitivity and response speed, especially when it is necessary to detect small changes, they may be affected by noise and environmental interference.

[0007] In addition, many existing sensors use solid-state materials as sensing elements, which limits their application in microstress detection to a certain extent, because the stiffness and elastic deformation capacity of solid-state materials often cannot meet the requirements of microstress measurement on the surface interface of biological cells. Moreover, existing sensors are also limited in their adaptability to the cell microenvironment, especially in multiple cell types or tissues, and cannot be universally used.

[0008] In cell biology and medical research, the influence of microstress on cell surface interface on biological processes such as cell growth, differentiation, migration and death has been paid more and more attention. Real-time monitoring of microstress on cell surface interface can better understand the biological behavior of cells and provide important basis for early diagnosis and treatment of diseases.

[0009] In recent years, researchers have conducted a large number of experimental studies on microstress at cell interfaces. The interaction between cells and their microenvironment is an important factor affecting cell behavior. Changes in microstress can not only reflect the mechanical properties of cells, but also reveal functional changes of cells under different physiological and pathological conditions. Therefore, the development of a highly sensitive and stable microstress measurement tool has become an urgent need in biomedical research. Summary of the invention

[0010] In order to solve the technical problems existing in the background technology, the present invention provides an optical fiber probe for measuring micro-force on the cell surface and a manufacturing method thereof.

[0011] The present invention proposes an optical fiber probe for measuring micro-forces on a cell surface, comprising: a single-mode optical fiber and a sensing structure, wherein the single-mode optical fiber has a core at its center, the sensing structure is located at one end of the single-mode optical fiber, the sensing structure comprises a spring portion and a force-bearing portion, the force-bearing portion is arranged opposite to an end face of the core and an FP cavity is formed therebetween, the spring portion is located between the force-bearing portion and the end face of the single-mode optical fiber and both ends are connected to the two respectively.

[0012] Preferably, the force-bearing portion comprises a force-bearing plate.

[0013] Preferably, the force-bearing plate has a needle head on a side away from the spring portion.

[0014] Preferably, the spring wire diameter of the spring part is D, the pitch is greater than 3D, and the effective number of turns is less than 5 turns.

[0015] Preferably, the sensing structure is made of photoresist.

[0016] In the present invention, the proposed fiber optic probe for measuring micro-forces on the cell surface has a core at the center of the single-mode optical fiber, a sensing structure is located at one end of the single-mode optical fiber, and the sensing structure includes a spring portion and a force-bearing portion, the force-bearing portion is arranged relative to the end face of the core and forms an FP cavity between the two, and the spring portion is located between the force-bearing portion and the end face of the single-mode optical fiber and the two ends are respectively connected to the two. The fiber optic probe for measuring micro-forces on the cell surface with the above-mentioned optimized design combines the FP cavity with the spring structure, effectively improving the sensitivity and accuracy of microstress measurement, and can detect tiny forces through the force-bearing portion, with high detection accuracy, wide detection range, and strong stability, thereby providing more accurate measurement data for the study of cell mechanical properties.

[0017] The present invention also provides a method for making an optical fiber probe for measuring micro-force on the cell surface, comprising the following steps:

[0018] Glue is dispensed on the end face of the single-mode optical fiber, and the glue-dispensed single-mode optical fiber is cured to form a glue structure, and then the glue structure is processed into a polymer structure having the spring part and the force-bearing part through two-photon polymerization using a femtosecond laser, and finally the polymer structure is baked and developed in a developer to obtain a sensing structure.

[0019] Preferably, the method further includes pre-processing the single-mode optical fiber before dispensing the glue: using an optical fiber cutter to cut the end of the single-mode optical fiber flat and using an optical fiber fusion splicer to perform end face discharge processing.

[0020] Preferably, the curing treatment of the optical fiber after the glue is dispensed is specifically, baking the single-mode optical fiber after the glue is dispensed, first baking at 60-70° C. for 10-20 minutes, and then baking at 90-100° C. for 40-50 minutes.

[0021] Preferably, the polymerized structure is baked, specifically, at 60-70° C. for 10-20 min, and then at 85-95° C. for 35-45 min.

[0022] The present invention proposes a method for making a fiber optic probe for measuring micro-force on the cell surface. The method is simple, the sensing structure of the obtained fiber optic micro-needle is compact, not easy to deform, the connection position structure with the fiber end face is firm, the sensitivity is high, and the fiber optic micro-needle has good mechanical properties and is not easy to break. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic structural diagram of an embodiment of a fiber optic probe for measuring micro-forces on a cell surface proposed by the present invention.

[0024] Figure 2 This is a schematic diagram of the sensing structure of an embodiment of a fiber optic probe for measuring micro-force on a cell surface proposed by the present invention. DETAILED DESCRIPTION

[0025] like Figure 1 and 2 As shown, Figure 1 This is a schematic structural diagram of an embodiment of a fiber optic probe for measuring micro-force on a cell surface proposed by the present invention. Figure 2 This is a schematic diagram of the sensing structure of an embodiment of a fiber optic probe for measuring micro-force on a cell surface proposed by the present invention.

[0026] Reference Figure 1 and 2The present invention proposes an optical fiber probe for measuring micro-force on the cell surface, comprising: a single-mode optical fiber 1 and a sensing structure, wherein the single-mode optical fiber 1 has a core 11 at the center, and the sensing structure is located at one end of the single-mode optical fiber 1. The sensing structure comprises a spring portion 21 and a force-bearing portion, wherein the force-bearing portion is arranged opposite to the end face of the core 11 and a FP cavity is formed therebetween, and the spring portion 21 is located between the force-bearing portion and the end face of the single-mode optical fiber 1 and the two ends are connected to the two respectively.

[0027] In the specific working process of the fiber optic probe for measuring micro-force on the cell surface of this embodiment, the force-bearing part at one end of the sensing structure at the end of the single-core optical fiber is brought into contact with the cell surface, and the micro-force change on the cell surface can be sensitively detected through the spring structure, and the distance between the force-bearing part and the end face of the optical fiber is changed, thereby causing the length of the FP cavity to change. The optical signal enters the FP cavity through the core of the single-mode optical fiber, and the cell surface particles are accurately detected through the change in the length of the FP cavity.

[0028] The fiber Fabry-Perot (FP) cavity sensor has the advantages of simple detection principle, large detection range, and linear response. At the same time, compared with the cantilever beam structure, the micro-spring structure has a greater elastic deformation capacity, which can achieve precise control of the probe stiffness in a larger range, further improving the accuracy of micro-stress measurement.

[0029] In the specific signal processing process, the free spectral range (FSR) can be used to calculate the effective cavity length of the Fabry-Perot (FP) cavity sensor. Therefore, the effective cavity length of the Fabry-Perot (FP) cavity sensor can be obtained by measuring the FSR of the Fabry-Perot (FP) interferometer at the tip of the optical fiber.

[0030]

[0031] Where λ is the tilt wavelength, n represents the average RI in the cavity, and L is the cavity length. Therefore, the effective cavity length of the FP cavity sensor (L) is:

[0032]

[0033] At the same time, the FP cavity can be simplified as a double-beam light interference. During the detection process, the reflected light intensity can be calculated as:

[0034]

[0035] Where I1 and I2 are the reflection intensities from the upper and lower surfaces 1 and 2 of the middle cavity, is the initial phase of interference, L is the cavity length, and n is the refractive index of the hollow cavity.

[0036] From formula (1), we can get that when the cosine term When it is equal to an odd multiple of π, the reflected light intensity reaches the minimum value, that is:

[0037]

[0038] Where m is an integer. When the cavity length is a constant, the corresponding relationship between the wavelength drift and the average RI change of the FP cavity is as follows:

[0039]

[0040] Among them, Δn is the refractive index change of the medium in the microcavity, and Δλ is the wavelength drift caused by the refractive index change. From this, all the required characteristic parameters can be calculated.

[0041] In this embodiment, the proposed fiber optic probe for measuring micro-forces on the cell surface has a core at the center of the single-mode optical fiber, and the sensing structure is located at one end of the single-mode optical fiber. The sensing structure includes a spring portion and a force-bearing portion, the force-bearing portion is arranged relative to the end face of the core and forms an FP cavity between the two, and the spring portion is located between the force-bearing portion and the end face of the single-mode optical fiber and the two ends are respectively connected to the two. The fiber optic probe for measuring micro-forces on the cell surface with the above-mentioned optimized design combines the FP cavity with the spring structure, effectively improving the sensitivity and accuracy of microstress measurement, and can detect tiny forces through the force-bearing portion, with high detection accuracy, wide detection range, and strong stability, thereby providing more accurate measurement data for the study of cell mechanical properties.

[0042] In a specific embodiment of the force-bearing part, the force-bearing part includes a force-bearing plate 22. When in contact with the cell, the spring is stressed through the entire plate body, and can capture signal changes more sensitively. Furthermore, the force-bearing plate 22 has a needle 23 on the side away from the spring part 21. When the cell size is small, or when detecting a cell among multiple cells, the needle can accurately contact the surface of the specified cell. In the specific design, the needle can be set in the middle of the force-bearing plate to ensure the consistency of the force on the spring.

[0043] In order to ensure the detection sensitivity and mechanical strength, in the specific design of the sensing structure, the spring wire diameter of the spring part 21 is D, the pitch is greater than 3D, and the effective number of turns is less than 5 turns. Through the optimized design of the structure, the sensing structure is guaranteed to have excellent mechanical properties and be able to withstand certain external impacts without being easily broken. This not only increases the service life of the sensor, but also reduces the risk of failure in practical applications, ensuring high stability in long-term experiments or dynamic monitoring.

[0044] In a specific design, a single-mode optical fiber with a cladding of 125μm and a core radius of 85μm is selected. The sensing structure is a spring structure with a spring wire diameter of 8μm, a spring inner diameter of 54μm, a spring outer diameter of 62μm, an effective number of turns of 2 turns, a pitch of 30μm, and a total height of 60μm. The force plate above the spring has a disk structure with a disk radius of 62.5μm, a thickness of 10μm, and a micro-nano structure with a needle radius of 5μm and a height of 5μm.

[0045] In actual design, a functional material layer can be coated on the surface of the sensing structure to achieve the measurement of multi-dimensional cell parameters. For example, magnetic materials can be evenly sputtered onto the device surface by magnetron sputtering or fluorescent substances such as rhodium can be evenly distributed onto the device surface to measure fluid viscosity, cell viscosity, molecular activity, etc.

[0046] The present invention also provides a method for manufacturing the above-mentioned optical fiber probe for measuring micro-force on the cell surface, comprising the following steps:

[0047] Glue is dispensed on the end face of the single-mode optical fiber 1, and the glued single-mode optical fiber 1 is cured to form a glue structure, and then the glue structure is processed into a polymer structure having the spring part 21 and the force-bearing part through two-photon polymerization using a femtosecond laser, and finally the polymer structure is baked and developed in a developer to obtain a sensing structure.

[0048] Specifically, the single-mode optical fiber 1 is pre-processed before dispensing: the end of the single-mode optical fiber 1 is cut flat using a fiber cleaver and the end face is discharged using a fiber fusion splicer.

[0049] In a specific operation mode, the sensing structure 2 is prepared by using photoresist. SU-8 photoresist can be used for dispensing under an optical microscope. Then, the optical fiber after dispensing is cured, specifically, the single-mode optical fiber 1 after dispensing is baked, first at 60-70°C for 10-20min, and then at 90-100°C for 40-50min. Preferably, it is baked at 65°C for 15min, and then at 95°C for 45min.

[0050] Then, it is placed on a femtosecond laser processing platform for two-photon polymerization micro-nano processing. Specifically, the position of the optical fiber fixing fixture is adjusted so that the end face of the single-mode optical fiber is flush with the three-dimensional displacement moving platform, and the femtosecond laser equipment is used to perform two-photon polymerization to prepare the required micro-nano structure.

[0051] Finally, the polymerized structure is baked, specifically, at 60-70°C for 10-20 minutes, and then at 85-95°C for 35-45 minutes. Preferably, it is baked at 65°C for 15 minutes, and then at 90°C for 40 minutes. After baking, it is placed in a developer for development. The sensing structure is compact and not prone to deformation. The micro-nano structure in contact with the end face of the optical fiber is firm and has high sensitivity. The sensing structure prepared by this method has good mechanical properties and effectively prevents breakage. The structure also has high sensitivity, good mechanical properties and deformation resistance.

[0052] In the selection of materials, the photoresist used in this embodiment is SU-8GM1075, which is composed of EPON SU-8 resin, glucoside (GBL) solvent and triaryl sulfonium salt as a photosensitizer. Other polymers that can be absorbed by the human body can also be used, such as: hyaluronic acid, chitosan, polyvinyl pyrrolidone, chondroitin sulfate gelatin and starch, etc. These materials have good compatibility with human tissues, can reduce rejection and inflammation, thereby reducing the risk of complications after implantation. Degradability is another key advantage. These polymers can be degraded into small molecules or monomers under the action of acids, alkalis or enzymes in the body, and are eventually metabolized into carbon dioxide and water, thereby avoiding the need for secondary surgery to remove the implant. These advantages will make the fiber end face drum-shaped Fabry-Perot (FP) cavity sensor proposed by the present invention have various applications in the medical field.

[0053] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An optical fiber probe for measuring micro-forces on a cell surface, characterized in that: include: A single-mode optical fiber (1) and a sensing structure, wherein the single-mode optical fiber (1) has a core (11) at its center, and the sensing structure is located at one end of the single-mode optical fiber (1). The sensing structure comprises a spring portion (21) and a force-bearing portion, wherein the force-bearing portion is arranged opposite to an end face of the core (11) and an FP cavity is formed between the two. The spring portion (21) is located between the force-bearing portion and the end face of the single-mode optical fiber (1) and the two ends are respectively connected to the two.

2. The optical fiber probe for measuring micro-force on the cell surface according to claim 1, characterized in that: The force-bearing part comprises a force-bearing plate (22).

3. The optical fiber probe for measuring micro-force on the cell surface according to claim 2, characterized in that: The force-bearing plate (22) has a needle head (23) on one side away from the spring portion (21).

4. The optical fiber probe for measuring micro-force on the cell surface according to claim 1, characterized in that: The spring wire diameter of the spring part (21) is D, the pitch is greater than 3D, and the effective number of turns is less than 5 turns.

5. The optical fiber probe for measuring micro-force on the cell surface according to claim 1, characterized in that: The sensing structure is prepared by using photoresist.

6. A method for making an optical fiber probe for measuring micro-force on a cell surface according to any one of claims 1 to 5, characterized in that: The following steps are involved: Glue is dispensed on the end face of the single-mode optical fiber (1), and the glue-dispensed single-mode optical fiber (1) is cured to form a glue structure, and then the glue structure is processed into a polymerized structure having the spring portion (21) and the force-bearing portion by two-photon polymerization using a femtosecond laser, and finally the polymerized structure is baked and developed in a developer to obtain a sensing structure.

7. The manufacturing method according to claim 6, characterized in that: The method also includes pre-processing the single-mode optical fiber (1) before dispensing the glue: using an optical fiber cutter to cut the end of the single-mode optical fiber (1) flat and using an optical fiber fusion splicer to perform end face discharge processing.

8. The manufacturing method according to claim 6, characterized in that: The curing treatment of the optical fiber after the glue application is specifically to bake the single-mode optical fiber (1) after the glue application, first baking it at 60-70° C. for 10-20 minutes, and then baking it at 90-100° C. for 40-50 minutes.

9. The manufacturing method according to claim 6, characterized in that: The polymer structure is baked, specifically, at 60-70° C. for 10-20 min, and then at 85-95° C. for 35-45 min.

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