Flexible optical fiber based on liquid crystal elastomers and methods of preparation and actuation applications

Abstract

The application discloses a flexible optical fiber based on liquid crystal elastomer and a preparation method and an actuating application device thereof. The flexible optical fiber based on liquid crystal elastomer comprises a liquid crystal elastomer core and a transparent elastomer cladding; the liquid crystal elastomer core comprises liquid crystal elastomer and light-responsive material. The preparation method injects a precursor of liquid crystal elastomer and a precursor of transparent elastomer into an inner barrel and an outer barrel of coaxial double barrels respectively, extrudes or prints a columnar body with a core-cladding structure through an extrusion method or a 3D printing method, and solidifies to obtain the flexible optical fiber. The actuating application device comprises a light source, a quartz optical fiber and the flexible optical fiber based on liquid crystal elastomer. The flexible optical fiber based on liquid crystal elastomer can construct a photo-driven device achieving full fiberization, integrates photo-actuation and optical transmission functions, effectively reduces the volume of a traditional actuating device, further realizes real-time, in-situ, remote and accurate actuation, and improves the practicability of the photo-driven device.

Description

Technical Field

[0001] This invention belongs to the field of flexible optical fiber technology, specifically relating to a flexible optical fiber based on liquid crystal elastomer, its preparation method, and its actuation application device. Background Technology

[0002] Flexible actuators possess excellent properties such as foldability, wearability, and interactive comfort, and have important applications in soft robotics, physiological monitoring, bioelectronics, in vivo detection, and smart clothing. In particular, the use of flexible devices in surgery in biomedicine will greatly alleviate patient suffering. Flexible actuators respond to external stimuli and perform corresponding movements, and are generally fabricated from intelligent responsive flexible materials. Among them, optically driven flexible actuators are highly favored due to their significant advantages such as fast response speed, inherent electrical safety, and strong resistance to electromagnetic interference. Liquid crystal elastomers, as the most commonly used optically responsive flexible materials, show promising application prospects due to their advantages such as low environmental requirements, good biocompatibility, and large actuation strain, and are widely used in the fabrication of optically driven flexible actuators.

[0003] Currently, most existing optically driven flexible actuators are driven by spatial light. Although this driving method is low in cost, the use of such flexible actuators is limited in situations where light can only travel in a straight line and is subject to high environmental requirements; otherwise, the light intensity is easily severely lost due to scattering and absorption by the environmental medium. Using optical waveguides will effectively solve the key problems of spatial light driving, enabling remote control and avoiding energy loss (as in the existing invention patent 202110870445.5).

[0004] However, current research and development of optical wave actuators are immature, with limited motion range and single motion modes, making it difficult to meet practical needs. Therefore, developing optical wave actuators with multiple motion modes and a large motion range has significant scientific and application value. The deviceization of liquid crystal elastomer materials and the introduction of fiber optic structures make the practical application potential of optically driven flexible actuators enormous. Summary of the Invention

[0005] To address the problems existing in the prior art, the purpose of this invention is to provide a flexible optical fiber (LCEOF) based on a liquid crystal elastomer, its fabrication method, and an actuation application device, which overcomes the environmental limitations of spatial optical actuation and facilitates its application in fields such as soft robotics, in vivo detection, and assisted operations. The flexible optical fiber based on a liquid crystal elastomer of this invention comprises a photo-driven liquid crystal elastomer core and a flexible cladding, wherein the flexible cladding is made of a transparent elastomer.

[0006] The technical solution adopted in this invention is:

[0007] A flexible optical fiber based on liquid crystal elastomer includes a liquid crystal elastomer core and a transparent elastomer cladding; the liquid crystal elastomer core includes a liquid crystal elastomer and a photoresponsive material.

[0008] Preferably, the transparent elastomer includes one of PDMS, Ecoflex series materials, polyurethane elastomer, hydrogel, and liquid crystal elastomer;

[0009] Preferably, the liquid crystal elastomer is prepared from liquid crystal monomers and chain extenders;

[0010] More preferably, the liquid crystal monomer is an acrylate liquid crystal monomer;

[0011] More preferably, the acrylate liquid crystal monomer is at least one of 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene and 4-(3-acryloyloxypropoxy)benzoic acid-2-methyl-1,4-phenyl ester.

[0012] Preferably, the photoresponsive material is at least one of bismuth(III) compounds, carbon nanomaterials, molecular motors, polydopamine, organic dyes, and azobenzene materials.

[0013] Preferably, the refractive index of the liquid crystal elastomer core is greater than the refractive index of the transparent elastomer cladding; the lengths of the liquid crystal elastomer core and the transparent elastomer cladding are the same.

[0014] Preferably, the diameter of the liquid crystal elastomer core is 130-1000 micrometers; and the thickness of the transparent elastomer cladding is 50-500 micrometers.

[0015] The above-mentioned method for fabricating flexible optical fibers based on liquid crystal elastomers includes the following steps:

[0016] (1) Prepare precursor A of liquid crystal elastomer and precursor B of transparent elastomer respectively. Precursor A of liquid crystal elastomer is composed of liquid crystal monomer, chain extender, photoinitiator, photoresponsive material, catalyst and solvent.

[0017] (2) The precursor A of liquid crystal elastomer and the precursor B of transparent elastomer are injected into the inner barrel and outer barrel of coaxial dual barrel respectively; pressure is applied to the coaxial dual barrel using extrusion or 3D printing to extrude or print a columnar body with a core-encapsulated structure; the core-encapsulated structure includes: a liquid crystal elastomer core and a transparent elastomer cladding.

[0018] (3) The columnar body with core-cladding structure is placed under ultraviolet light for curing to obtain a flexible optical fiber based on liquid crystal elastomer.

[0019] Preferably, the liquid crystal monomer in step (1) is an acrylate liquid crystal monomer;

[0020] More preferably, the acrylate liquid crystal monomer is at least one of 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene (RM82) and 4-(3-acryloyloxypropoxy)benzoic acid-2-methyl-1,4-phenyl ester (RM257).

[0021] Preferably, the chain extender in step (1) is selected from dithiol compounds or trithiol compounds.

[0022] Preferably, the photoinitiator in step (1) is at least one of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, 2-phenylbenzyl-2-dimethylamine-1-(4-morpholinobenzylphenyl)butanone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and benzoyladium dimethyl ether.

[0023] Preferably, the photoresponsive material in step (1) is at least one of bismuth(III) compounds, carbon nanomaterials, molecular motors, polydopamine, organic dyes, and azobenzene materials.

[0024] Preferably, the catalyst in step (1) is at least one of di-n-butylamine, triethylamine, and 1,8-diazabicyclo[5.4.0]undec-7-ene.

[0025] Preferably, the solvent in step (1) is one or two of toluene, dichloromethane, dichloroethane, chloroform, acetone, tetrahydrofuran, and N,N-dimethylformamide.

[0026] Preferably, the precursor B of the transparent elastomer in step (1) includes one of the following: PDMS, Ecoflex series materials, polyurethane elastomer, hydrogel, and liquid crystal elastomer.

[0027] Preferably, the molar ratio of the liquid crystal monomer and the crosslinking agent in step (1) is 0.5 to 2.5:1.

[0028] Preferably, the molar amount of the photoinitiator in step (1) accounts for 0.1% to 5% of the total molar amount of the liquid crystal monomer and crosslinking agent.

[0029] Preferably, the molar amount of the photoresponsive material in step (1) accounts for 0.01% to 5% of the total molar amount of the liquid crystal monomer and crosslinking agent.

[0030] Preferably, the molar amount of the catalyst in step (1) accounts for 0.01% to 5% of the total molar amount of the liquid crystal monomer and crosslinking agent.

[0031] Preferably, the molar ratio of the solvent to the liquid crystal monomer in step (1) is 0.1 to 10:1.

[0032] Preferably, the refractive index of the liquid crystal elastomer core in step (2) is greater than the refractive index of the transparent elastomer cladding.

[0033] Preferably, the liquid crystal elastomer core and the transparent elastomer cladding in step (2) have the same length.

[0034] Preferably, the curing time in step (3) is 1 min to 60 min.

[0035] The actuation application device of the flexible optical fiber based on liquid crystal elastomer of the present invention includes a light source 1, a quartz optical fiber 2, and a flexible optical fiber based on liquid crystal elastomer with a core 3 and a cladding 4 structure; the output end of the light source 1 is connected to the core 3 of the flexible optical fiber based on liquid crystal elastomer through the quartz optical fiber 2; the flexible optical fiber based on liquid crystal elastomer with a core 3 and a cladding 4 structure is the aforementioned flexible optical fiber based on liquid crystal elastomer.

[0036] Preferably, the light source is an LED light source, a semiconductor laser, or a fiber laser.

[0037] Preferably, the wavelength of the light source is across the entire wavelength range.

[0038] The actuation application device based on liquid crystal elastomer flexible optical fiber of the present invention consists of single-channel or multi-channel actuation application devices. In a single-channel actuation application device, a single liquid crystal elastomer-based flexible optical fiber corresponds to a single excitation light source; in a multi-channel actuation application device, multiple liquid crystal elastomer-based flexible optical fibers are arranged in parallel, bundled, or braided to form a flexible optical fiber array, corresponding to multiple excitation light sources, with each excitation light source outputting independently. By adjusting parameters such as input light intensity, wavelength, angle, and polarization, the movement of each flexible optical fiber in the array is controlled, thereby achieving different movement modes, directions, or distances of the optical fiber array.

[0039] A flexible actuator includes or is fabricated from the aforementioned flexible optical fiber actuation device based on a liquid crystal elastomer.

[0040] Compared with the prior art, the beneficial effects of the present invention are:

[0041] (1) The present invention prepares a flexible optical fiber based on liquid crystal elastomer. By coupling ordinary quartz optical fiber with the flexible optical fiber based on liquid crystal elastomer, the excitation light can be efficiently introduced and transmitted, and further effectively realize real-time, in-situ, remote and precise actuation, which greatly improves the practicality of photoactuation device.

[0042] (2) Flexible optical fibers prepared by combining photoresponse materials with liquid crystal elastomers have low optical loss and high optical driving force, and can achieve axial driving. This not only improves the efficiency of excitation light utilization, but also enables information transmission, and it is also easy to eliminate interference from the external environment.

[0043] (3) The flexible optical fiber based on liquid crystal elastomer is encapsulated with transparent elastomer, which improves the stability of the flexible optical fiber and at the same time protects the flexible optical fiber from interference from dust, impurities and other contaminants.

[0044] (4) The present invention can integrate multiple flexible optical fibers based on liquid crystal elastomers to form an array device, which can realize more diverse functions, such as bionic fingers, assisting movement, etc. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the structure of the flexible optical fiber and actuation application device based on liquid crystal elastomer in an embodiment of the present invention;

[0046] Figure 2 This is a graph showing the relationship between strain and excitation light intensity in the flexible optical fiber based on liquid crystal elastomer and the actuation application device of Embodiment 1 of the present invention.

[0047] Figure 3 This is a graph showing the relationship between optical intensity loss and transmission length of the flexible optical fiber based on liquid crystal elastomer in the flexible optical fiber and actuation application device based on liquid crystal elastomer in Embodiment 2 of the present invention.

[0048] Figure 4 This is a schematic diagram of the structure of a multi-channel actuation application device in a flexible optical fiber and actuation application device based on liquid crystal elastomer.

[0049] Figure 1 In the middle: 1—light source, 2—quartz optical fiber, 3—flexible optical fiber core based on liquid crystal elastomer, 4—transparent elastomer cladding. Detailed Implementation

[0050] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0051] Example 1:

[0052] A method for fabricating flexible optical fibers based on liquid crystal elastomers.

[0053] (1) Precursor A for preparing the liquid crystal elastomer: Dissolve 0.5886 g of liquid crystal monomer 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene, 0.1823 g of chain extender 2,2'-(1,2-ethylenedioxy)bis(ethyl mercaptan), 10 μl of toluene solution (0.3 mol / L) of bismuth(III) compound, 0.4 mg of photoinitiator 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylphenylacetone, and 2 mg of catalyst di-n-butylamine in 500 μL of toluene solvent and mix thoroughly. Precursor B for preparing the transparent elastomer: Mix Ecoflex silicone 00-30A and B thoroughly at a mass ratio of 1:1.

[0054] (2) The precursor A of liquid crystal elastomer and the precursor B of transparent elastomer are injected into the inner barrel and outer barrel of the coaxial double barrel respectively; the coaxial double barrel is pressured by extrusion to extrude a columnar core-encapsulated structure with a length of 10cm, a core diameter of 500μm and a cladding thickness of 200μm; the core-encapsulated structure includes: liquid crystal elastomer core and transparent elastomer cladding.

[0055] (3) The columnar body with core-clad structure is placed under ultraviolet light for 3 minutes to cure, and a flexible optical fiber based on liquid crystal elastomer is obtained.

[0056] In this embodiment, the refractive index of the liquid crystal elastomer core in the flexible optical fiber based on the liquid crystal elastomer is greater than the refractive index of the transparent elastomer cladding; the lengths of the liquid crystal elastomer core and the transparent elastomer cladding are the same.

[0057] Example 2:

[0058] A method for fabricating flexible optical fibers based on liquid crystal elastomers.

[0059] (1) Precursor A for preparing the liquid crystal elastomer: Dissolve 1.344 g of liquid crystal monomer 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene, 0.316 g of chain extender ethylene glycol di(3-mercaptopropionate), 0.2 mg of graphene microsheets, 3 mg of photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 6.7 mg of catalyst triethylamine in 1 ml of dichloromethane solvent and mix thoroughly. Precursor B for preparing the transparent elastomer: Mix PDMS monomer and curing agent (SYLGARD 184) thoroughly at a mass ratio of 10:1.

[0060] (2) The precursor A of liquid crystal elastomer and the precursor B of transparent elastomer are injected into the inner barrel and outer barrel of the coaxial dual barrel respectively; using 3D printing, pressure is applied to the coaxial dual barrel to print a columnar core-cladding structure with a length of 15cm, a core diameter of 400μm and a cladding thickness of 100μm; the core-cladding structure includes: a liquid crystal elastomer core and a transparent elastomer cladding.

[0061] (3) The columnar body with core-clad structure is placed under ultraviolet light for 5 minutes to cure, and a flexible optical fiber based on liquid crystal elastomer is obtained.

[0062] In this embodiment, the refractive index of the liquid crystal elastomer core in the flexible optical fiber based on the liquid crystal elastomer is greater than the refractive index of the transparent elastomer cladding; the lengths of the liquid crystal elastomer core and the transparent elastomer cladding are the same.

[0063] Example 3:

[0064] A method for fabricating flexible optical fibers based on liquid crystal elastomers.

[0065] (1) Precursor A for preparing the liquid crystal elastomer: 1.1772 g of liquid crystal monomer 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene, 0.4205 g of chain extender ethylene glycol dihydrothioacetic acid, 0.0032 g of azobenzene, 0.0029 g of photoinitiator 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone,

[0066] 0.0014g of triethylamine catalyst was dissolved in 0.6ml of acetone solvent and mixed thoroughly. Precursor B for the transparent elastomer was prepared by mixing the polyurethane prepolymer and curing agent (Clear Flex 30) at a mass ratio of 1:1.

[0067] (2) The precursor A of liquid crystal elastomer and the precursor B of transparent elastomer are injected into the inner barrel and outer barrel of the coaxial dual barrel respectively; using 3D printing, pressure is applied to the coaxial dual barrel to print a columnar core-cladding structure with a length of 8cm, a core diameter of 300μm and a cladding thickness of 300μm; the core-cladding structure includes: liquid crystal elastomer core and transparent elastomer cladding.

[0068] (3) The columnar body with core-clad structure is placed under ultraviolet light for 10 minutes to cure, and a flexible optical fiber based on liquid crystal elastomer is obtained.

[0069] In this embodiment, the refractive index of the liquid crystal elastomer core in the flexible optical fiber based on the liquid crystal elastomer is greater than the refractive index of the transparent elastomer cladding; the lengths of the liquid crystal elastomer core and the transparent elastomer cladding are the same.

[0070] Example 4:

[0071] Actuation devices based on liquid crystal elastomers and flexible optical fibers, such as Figure 1 As shown, it includes a light source 1, a quartz optical fiber 2, and a flexible optical fiber based on a liquid crystal elastomer with a core 3 and a cladding 4 structure;

[0072] The light source 1 is a semiconductor laser with an output wavelength of 808nm; the quartz fiber 2 is a multimode quartz fiber; the flexible fiber based on liquid crystal elastomer with a core 3 and a cladding 4 structure is the flexible fiber prepared in Example 1.

[0073] The actuation application device described in this embodiment is a single-channel actuation application device, that is, a single flexible optical fiber based on liquid crystal elastomer corresponds to a single excitation light source.

[0074] Example 5:

[0075] Actuation devices based on liquid crystal elastomers and flexible optical fibers, such as Figure 1 As shown, it includes a light source 1, a quartz optical fiber 2, and a flexible optical fiber based on a liquid crystal elastomer with a core 3 and a cladding 4 structure;

[0076] The light source 1 is a fiber laser with an output wavelength of 980nm; the quartz fiber 2 is a multimode quartz fiber; the flexible fiber based on liquid crystal elastomer with a core 3 and a cladding 4 structure is the flexible fiber prepared in Example 2.

[0077] The actuation application device described in this embodiment is a single-channel actuation application device, that is, a single flexible optical fiber based on liquid crystal elastomer corresponds to a single excitation light source.

[0078] Example 6:

[0079] Using the actuation application device based on liquid crystal elastomer flexible optical fiber described in Example 4, a semiconductor laser is activated, and excitation light with a wavelength of 808 nm is input into the liquid crystal elastomer-based flexible optical fiber through a common quartz optical fiber. By adjusting the input power of the excitation light, the axial length of the liquid crystal elastomer-based flexible optical fiber is measured, and a curve showing the relationship between the contraction strain of the liquid crystal elastomer-based flexible optical fiber and the change in excitation light intensity is obtained. Figure 2 As shown.

[0080] Depend on Figure 2 As shown, the shrinkage strain of the flexible optical fiber based on liquid crystal elastomer in Example 4 increases with the increase of the input intensity of the excitation light, with a maximum shrinkage strain of 43%, exhibiting excellent axial optical actuation performance. This demonstrates the feasibility and practicality of the flexible optical fiber based on liquid crystal elastomer as an optical fiber driven flexible actuator.

[0081] Example 7:

[0082] Using the actuation application device based on liquid crystal elastomer flexible optical fiber described in Example 5, a fiber laser with a wavelength of 980nm is activated and input into the liquid crystal elastomer-based flexible optical fiber through a common quartz optical fiber. A power meter is used to collect the remaining light intensity after the laser passes through the liquid crystal elastomer-based flexible optical fiber. The relationship curve and fitting curve between the light intensity loss and the transmission length of the liquid crystal elastomer-based flexible optical fiber are calculated, as shown below. Figure 3 As shown.

[0083] Depend on Figure 3 As shown, the loss of the flexible optical fiber based on liquid crystal elastomer in Example 2 is about 1.36 dB / cm, which shows good axial light transmission performance, demonstrating the feasibility and practicality of the flexible optical fiber based on liquid crystal elastomer of the present invention as a flexible optical fiber.

[0084] Depend on Figure 4 The diagram shows a schematic of a parallel integrated flexible fiber array device based on liquid crystal elastomers in the actuation application device of the present invention. This array device consists of a bundle of four identical liquid crystal elastomer-based flexible fibers, corresponding to multiple excitation sources, each with its own independent output. By adjusting parameters such as the input light intensity, wavelength, angle, and polarization of each liquid crystal elastomer-based flexible fiber, the movement of each flexible fiber in the array can be controlled, enabling the array device to achieve different motion modes, directions, or distances. The liquid crystal elastomer-based flexible fiber and its actuation application device of the present invention greatly expand the practical application range of flexible fibers, providing a high-performance optical waveguide-driven actuation device for multiple fields.

[0085] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any equivalent changes, modifications, or evolutions made by those skilled in the art to the above embodiments using the technical solutions of the present invention shall still fall within the scope of the technical solutions of the present invention.

Claims

1. A liquid crystal elastomer-based flexible optical fiber, characterized by, The flexible optical fiber comprises a liquid crystal elastomer core and a transparent elastomer cladding; the liquid crystal elastomer core comprises a liquid crystal elastomer and a light-responsive material; the refractive index of the liquid crystal elastomer core is greater than the refractive index of the transparent elastomer cladding; the length of the liquid crystal elastomer core is the same as that of the transparent elastomer cladding; and the preparation method of the flexible optical fiber comprises the following steps: injecting a precursor of the liquid crystal elastomer and a precursor of the transparent elastomer into an inner barrel and an outer barrel of a coaxial double-barrel respectively, extruding or printing a columnar body with a core-cladding structure by an extrusion method or a 3D printing method, and solidifying to obtain the flexible optical fiber.

2. The liquid crystal elastomer-based flexible optical fiber according to claim 1, wherein, The transparent elastomer comprises one of PDMS, Ecoflex series materials, polyurethane elastomers, hydrogels and liquid crystal elastomers; the liquid crystal elastomer is prepared from liquid crystal monomers and a chain extender; the liquid crystal monomers are acrylate liquid crystal monomers; the acrylate liquid crystal monomers are at least one of 1,4-bis-[4-(6-acryloyloxyhexyloxy)benzoyloxy]-2-methylbenzene and 4-(3-acryloyloxypropoxy)benzoic acid-2-methyl-1,4-phenyl ester; and the light-responsive material is at least one of trivalent bismuth compounds, carbon nanomaterials, molecular motors, polydopamine, organic dyes and azobenzene materials.

3. The liquid crystal elastomer-based flexible optical fiber of claim 1, wherein, The diameter of the liquid crystal elastomer core is 130-1000 μm; and the thickness of the transparent elastomer cladding is 50-500 μm.

4. A liquid crystal elastomer-based flexible optical fiber actuation application device, characterized by, The flexible optical fiber based on liquid crystal elastomers has a core (3) and a cladding (4) structure; the output end of the light source (1) is connected to the core (3) of the flexible optical fiber based on liquid crystal elastomers through the quartz optical fiber (2); and the flexible optical fiber based on liquid crystal elastomers has the core (3) and the cladding (4) structure as described in any one of claims 1-3.

5. The actuated application device of claim 4, wherein, The actuation application device is composed of single-channel or multi-channel actuation application devices; wherein a single flexible optical fiber based on liquid crystal elastomers in the single-channel actuation application device corresponds to a single-channel excitation light source; The multiple flexible optical fibers based on liquid crystal elastomers in the multi-channel actuation application device are parallel, bundled or woven into a flexible optical fiber array, correspond to multi-channel excitation light sources, and each excitation light source is independently output.

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