CN112213815B - Flexible force-induced luminescent optical fiber, preparation method thereof and large strain sensing application device - Google Patents
Flexible force-induced luminescent optical fiber, preparation method thereof and large strain sensing application device Download PDFInfo
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/30—Sulfur-, selenium- or tellurium-containing compounds
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L83/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
- C08L83/04—Polysiloxanes
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/32—Optical coupling means having lens focusing means positioned between opposed fibre ends
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/30—Sulfur-, selenium- or tellurium-containing compounds
- C08K2003/3009—Sulfides
- C08K2003/3036—Sulfides of zinc
Abstract
The invention discloses a flexible force-induced luminescent fiber, a preparation method thereof and a large strain sensing application device. The flexible mechanoluminescence optical fiber comprises a matrix optical fiber, a mechanoluminescence sensing layer and a protective layer; the matrix optical fiber has a fiber core-cladding structure, which comprises a fiber core and a cladding, wherein the cladding is wrapped outside the fiber core; the mechanoluminescence sensing layer is compounded on the outer side of the cladding of the matrix optical fiber; the protective layer is wrapped outside the force-induced luminescence sensing layer; the mechanoluminescence sensing layer directly generates mechanoluminescence with corresponding intensity under the action of external force without continuous excitation of a power supply or a light source, and the mechanoluminescence is collected through the matrix optical fiber and transmitted to a far end along the matrix optical fiber for detection and demodulation. The flexible mechanoluminescence optical fiber prepared by compounding the mechanoluminescence material and the elastomer material integrates the sensing and transmission functions, can realize the axial collection and conduction of fluorescence, further effectively improves the collection efficiency and the measurement accuracy of the fluorescence, and realizes the functions of in-situ real-time fluorescence monitoring and strain sensing.
Description
Technical Field
The invention belongs to the field of optical fiber sensing, and particularly relates to a flexible force-induced luminescent optical fiber, a preparation method thereof and a large-strain sensing application device.
Background
Mechanoluminescence (mechanolimescent) is a material that releases energy externally in the form of light when subjected to mechanical stimuli such as pressure, impact, friction, etc. Because the energy conversion between force and light can be realized, the material has wide application prospect in the fields of force-induced driving lighting sources, building structure health monitoring, human body movement monitoring and the like. At present, according to the type of mechanical stimulation on a material, a mechanoluminescence material can be divided into three categories of deformation luminescence, fracture luminescence and friction luminescence, and the deformation luminescence can be divided into elastic deformation luminescence and plastic deformation luminescence, wherein the elastic deformation luminescence has the characteristics of luminescence recoverability and good linear relation between the luminescence intensity and the load size, so that the elastic mechanoluminescence material has a good application value (Progress in Materials science.2019,103, 678-742) in the fields of stress strain sensing, imaging and the like, and a novel scheme is provided for stress strain detection.
Meanwhile, as the demand of people for flexible wearable strain sensors is increasingly urgent, a great deal of research work is currently put into the design and development of the flexible stress strain sensor made of the mechanoluminescence material (adv.funct.mater.2018,28,1803168), but the existing technical scheme still has the following problems. Firstly, most research schemes are to compound the mechanoluminescence material and the elastomer together to prepare a film or fibrous sample, and then to directly detect fluorescence in a local area of the surface of the sample by using a fluorescence spectrometer or a CCD camera, such as the existing patents 201610556644.8, 201710478128.2, 201811004066.2, etc., in the technical schemes disclosed by the above schemes, the sample only has a sensing function and cannot integrate a conduction function, and most of the sensing characteristic display depends on the off-line measurement of a laboratory commercial fluorescence measurement device, so that the integration level of the whole sensing system is low, and the realization of advanced sensing functions such as in-situ real-time, on-line monitoring, wearable, etc. is greatly limited. Secondly, most of the existing technical schemes directly rely on the end face of the commercial optical fiber to collect fluorescence on the surface of the sensing unit, but the fluorescence itself has non-directivity and the collection angle of the end face of the optical fiber is limited, the fluorescence collection method described above causes low fluorescence collection efficiency, thus causing large errors in fluorescence measurement, and in addition, most of the mechanoluminescence materials have low luminous efficiency and weak intensity, and these problems also directly affect the detection of fluorescence signals in nature. In order to solve the above problems, the ideal flexible stress-strain sensor for the mechanoluminescence material not only needs a reasonable structural design to realize the function of integration of sensing and transmission, but also needs a reliable and efficient fluorescence collection mode to meet the requirement of accurate quantitative measurement.
The optical fiber sensor, especially the flexible optical fiber sensor (such as the prior patents 201811325073.2, 201710595128.0, etc.), has the characteristics of stretch and bending, small size, easy integration, electromagnetic interference resistance, etc., can integrate the sensing and transmission functions, and can be used for collecting and transmitting fluorescence. Based on the problems of the mechanoluminescence material strain sensing and the advantages of the flexible optical fiber sensing, the mechanoluminescence material and the elastomer are compositely designed into an optical fiber structure to axially collect fluorescence so as to maximally realize the sensing application of the optical fiber structure. However, the axial collection of fluorescence on the conventional optical fiber is difficult, and the structural design and preparation difficulty is high, so that related research reports are few, and therefore, the development of a simple and effective flexible mechanoluminescence optical fiber compounded by a mechanoluminescence material and an elastomer is very significant. Meanwhile, the wearable large-strain optical fiber sensing application technology developed by relying on the flexible force luminescent optical fiber also has practical significance. The device of the material and the introduction of the optical fiber structure make the practical application potential of the mechanoluminescence material huge.
Disclosure of Invention
The invention aims to provide a preparation method of a flexible force-emitting optical fiber and a large-strain optical fiber sensing application device based on the flexible force-emitting optical fiber, which can be used for the aspects of real-time monitoring of human body large movement, multi-path large-strain measurement, distributed measurement, implanted strain monitoring and the like.
The purpose of the invention is realized by at least one of the following technical solutions.
A flexible mechanoluminescence optical fiber comprises a matrix optical fiber, a mechanoluminescence sensing layer and a protective layer;
the matrix optical fiber has a fiber core-cladding structure, which comprises a fiber core and a cladding, wherein the cladding is wrapped outside the fiber core; the mechanoluminescence sensing layer is compounded on the outer side of the cladding of the matrix optical fiber; the protective layer is wrapped outside the force-induced luminescence sensing layer;
the mechanoluminescence sensing layer directly generates mechanoluminescence with corresponding intensity under the action of external force without continuous excitation of a power supply or a light source, and the mechanoluminescence is collected through the matrix optical fiber and transmitted to a far end along the matrix optical fiber for detection and demodulation.
Furthermore, in the matrix optical fiber, the refractive index of the fiber core is greater than that of the cladding, the diameter of the fiber core is 200-1000 μm, the thickness of the cladding is 5-100 μm, the length of the matrix optical fiber is 1-10cm, and the numerical aperture is 0.2-0.6, so that the fluorescence generated by the mechanoluminescence sensing layer can be efficiently collected and transmitted at the interface of the fiber core and the cladding in a total internal reflection mode; the matrix optical fiber is made of an elastomer, wherein the elastomer comprises polysiloxane, organic silicon rubber, soft unsaturated polyurethane, polystyrene elastomer, polyolefin elastomer, polyamide elastomer, polylactic acid-glycolic acid copolymer, polyethylene glycol diacrylate or alginic acid;
the mechanoluminescence sensing layer is prepared by compounding a mechanoluminescence material and a polydimethylsiloxane material, is coated on the outer side of the cladding and is prepared into a cylindrical or flaky shape coaxial with the matrix optical fiber; the mechanoluminescence material is elastic mechanoluminescence fluorescent powder, namely in the elastic deformation range of a substrate, the light emission of the mechanoluminescence fluorescent powder has recoverability, and the luminous intensity and the stress strain magnitude are in a regular linear relation and comprise transition metal ion or rare earth ion doped oxides, sulfides, phosphates, aluminates, silicates, nitric oxides and oxysulfides; the thickness of the mechanoluminescence sensing layer is 50-300 mu m;
the protective layer is made of polydimethylsiloxane material, is coated on the outer side of the mechanoluminescence sensing layer and is made into a cylindrical or flaky shape coaxial with the matrix optical fiber, and the thickness of the cylindrical or flaky shape is 10-200 mu m.
The preparation method of the flexible force-induced luminescent fiber comprises the following steps:
s1, preparing a matrix optical fiber;
s2, preparing a mechanoluminescence sensing layer;
s3, preparing a protective layer.
Further, in step S1, the preparation of the matrix optical fiber adopts a sleeving method, which specifically includes the following steps:
s1.1, injecting a transparent elastomer with the refractive index of 1.4-1.6 into the sleeve, carrying out polymerization curing at 25-120 ℃, and taking out the transparent elastomer by a stripping method to obtain a fiber core of the matrix optical fiber;
s1.2, dipping another elastomer solvent with the refractive index lower than that of the fiber core on the surface of the fiber core prepared in the step S1.1, and preparing a uniform cladding by adopting a spin coating method.
Further, in step S2, in the preparation of the mechanoluminescence sensing layer, the doping of the mechanoluminescence material includes single doping or mixed doping, and is respectively applied to single-point or multi-point large strain sensing;
when single doping is adopted, the specific steps are as follows:
s2.1.1, weighing a polydimethylsiloxane solvent with required mass, wherein the solvent consists of a prepolymer and a crosslinking agent, and the mixing ratio of the prepolymer to the crosslinking agent is 10:1-30: 1;
s2.1.2, after mixing evenly, doping 25-85 wt% of certain mechanoluminescence material, stirring evenly and fully, then placing in vacuum environment for defoaming treatment;
s2.1.3, dipping the prepared matrix optical fiber in the mixed solution prepared in step S2.1.2, and finally preparing the uniform single-doping force luminous sensing layer by a spin coating method, a sleeving method or a flat-plate film scraping method;
further, when the mixed doping is adopted, the double doping is adopted, namely, when two kinds of mechanoluminescence materials are mixed, the specific steps are as follows:
s2.2.1, weighing the required mass of the mechanoluminescence material and the polydimethylsiloxane solvent respectively, wherein the total impurity content ratio of the mechanoluminescence material is 25-85 wt%, the mixing ratio range of the two mechanoluminescence materials is 10:0-0:10, and the mixing ratio range of the prepolymer and the cross-linking agent in the polydimethylsiloxane solvent is 10:1-30: 1;
s2.2.2, fully stirring the two kinds of mechanoluminescence materials prepared in the step S2.2.1 and a polydimethylsiloxane solvent to obtain a uniform mixed solution, and placing the mixed solution in a vacuum environment for defoaming treatment;
s2.2.3, dipping the prepared matrix optical fiber into the mixed solution obtained in step S2.2.1, and finally preparing the uniform double-doping force luminescence sensing layer by a spin coating method, a sleeving method or a flat-plate film scraping method;
the doping forms of more than two kinds of mechanoluminescence materials are the same, and the proportion of various mechanoluminescence materials is only required to be regulated and controlled.
Further, in step S3, the process of preparing the protective layer specifically includes the following steps:
s3.1, weighing a polydimethylsiloxane solvent with required mass, wherein the mixing ratio of a prepolymer to a cross-linking agent in the polydimethylsiloxane solvent is 10:1-20:1, fully and uniformly stirring, and then placing in a vacuum environment for defoaming treatment;
s3.2, preparing a cylindrical or flaky protective layer on the outer side of the mechanoluminescence sensing layer obtained in the step S2 by adopting a rotary coating method or a flat-plate film scraping method, wherein the protective layer needs to be cured and formed at the temperature of 25-120 ℃.
The large strain sensing application device based on the flexible force-emitting optical fiber comprises a sensing device and a signal demodulation part; the sensing device comprises a flexible force-induced luminescence optical fiber sensing unit, a band-pass filter, a coupling lens, a photoelectric detector and a signal processing unit; the flexible force-emitting optical fiber sensing unit comprises a flexible force-emitting optical fiber;
the flexible force-induced luminescence optical fiber sensing unit is fixed on the surface of human skin or a wearing device, optical signals generated in the force-induced luminescence sensing layer are transmitted in a matrix optical fiber through total reflection and are coupled and connected to a band-pass filter, external environment light is filtered out, then obtained fluorescence signals are connected to a coupling lens, fluorescence in all directions is focused and then connected to a photoelectric detector, real-time fluorescence intensity is measured through rapid conversion of the photoelectric detector, finally, measured and converted data are input to a signal processing unit for further conversion and amplification, the measured strain condition is demodulated according to the real-time fluorescence intensity, and the final data can be transmitted to a mobile phone or a computer terminal through Wifi, Bluetooth or a serial port, so that the purpose of real-time monitoring is achieved.
Further, the large strain sensing applications include single point detection and multi-point detection, the single point detection corresponds to a single doped mechanoluminescence fiber, using a band pass filter; the multipoint detection corresponds to a mixed doped mechanoluminescence fiber, and the combined band-pass filter is used, so that switching can be performed according to a required waveband.
Furthermore, the signal demodulation part comprises single-path signal demodulation and multi-path signal demodulation, wherein a single sensing unit, namely a single flexible force-emitting optical fiber, is corresponding to the single-path signal demodulation and can be realized by using one photoelectric detector; the multi-channel distributed sensing network formed by the cascade connection and the parallel connection of the plurality of sensing units, namely the plurality of flexible force-emitting optical fibers, corresponds to multi-channel signal demodulation, can be simplified into a plurality of independent sensing units for processing, and realizes the demodulation of signals through an optical switch or a plurality of discrete detectors.
The invention has the following specific beneficial effects:
1. the flexible mechanoluminescence optical fiber prepared by compounding the mechanoluminescence material and the elastomer material integrates the sensing and transmission functions, can realize the axial collection and conduction of fluorescence, further effectively improves the collection efficiency and the measurement accuracy of the fluorescence, and realizes the functions of in-situ real-time fluorescence monitoring and strain sensing.
2. The flexible force-emitting optical fiber is anti-electromagnetic interference, electrically insulated, small in size, soft, stretchable, bendable and biocompatible, can be in good contact with human skin, is easy to weave and integrate into a wearable device or directly stick to the surface of the human skin, and can be used in the fields of monitoring the motion of different parts of a human body (especially monitoring the large motion of the human body), implanted strain monitoring and the like in real time.
3. The sensing device and the signal demodulation mode adopted by the developed large-strain optical fiber sensing application technology based on the flexible force luminous optical fiber are simple, the sensing layer can realize single-path multipoint distributed large-strain sensing monitoring by adopting sectional type mixed doping, and different sensing units can be cascaded and carry out multi-path signal monitoring in parallel to realize multi-position large-strain monitoring.
Drawings
FIG. 1 is a schematic diagram of a flexible mechanoluminescence optical fiber prepared in example 1, in which the mechanoluminescence sensing layer was single-doped;
in the figure: 1-a fiber core; 2-a cladding layer; 3-a sensing layer; 4-a protective layer;
FIG. 2 is a schematic diagram of a flexible mechanoluminescence optical fiber prepared in example 2, in which the mechanoluminescence sensing layer is mixed doped;
FIG. 3 is a schematic diagram of a single-point and multi-point distributed large strain sensing application technology based on a flexible force luminescent fiber;
FIG. 3a is a schematic diagram of a single-point large strain sensing application device based on a single-doped photoluminescent fiber;
FIG. 3b is a schematic diagram of a multi-point large strain sensing application device based on a multi-doped photoluminescent fiber;
fig. 4 is a technical schematic diagram of a multi-part large strain sensing application based on a flexible force-emitting optical fiber.
FIG. 4a is a schematic diagram of single-channel signal detection and demodulation;
FIG. 4b is a schematic diagram of multi-channel signal detection and demodulation using multiple optical switches;
fig. 4c is a schematic diagram of multi-channel signal detection and demodulation by using a plurality of photodetectors.
Detailed Description
The following detailed description of the embodiments of the present invention is provided with reference to the accompanying drawings and examples, but not intended to limit the invention thereto.
Example 1:
a flexible mechanoluminescence optical fiber, as shown in FIG. 1, comprises a matrix optical fiber, a mechanoluminescence sensing layer 1.3 and a protective layer 1.4;
the matrix optical fiber has a fiber core-cladding structure, and comprises a fiber core 1.1 and a cladding 1.2, wherein the cladding 1.2 is wrapped outside the fiber core 1.1; the mechanoluminescence sensing layer 1.3 is compounded on the outer side of a cladding 1.2 of the matrix optical fiber; the protective layer 1.4 is wrapped outside the mechanoluminescence sensing layer 1.3;
the mechanoluminescence sensing layer 1.3 directly generates mechanoluminescence with corresponding intensity under the action of external force without continuous excitation of a power supply or a light source, and the mechanoluminescence is collected by the matrix optical fiber and transmitted to a far end along the matrix optical fiber for detection and demodulation.
In the embodiment, in the matrix optical fiber, the refractive index of the fiber core 1 is greater than that of the cladding 1.2, the diameter of the fiber core 1.1 is 300 μm, the thickness of the cladding 1.2 is 80 μm, and the length of the matrix optical fiber is 10cm, so that fluorescence generated by the mechanoluminescence sensing layer can be efficiently collected and transmitted at the interface of the fiber core and the cladding in a total internal reflection mode; in this embodiment, the elastomer selected is Polydimethylsiloxane (PDMS);
in the mechanoluminescence sensing layer 1.3, a mechanoluminescence material and a polydimethylsiloxane material are compounded to prepare the mechanoluminescence sensing layer, and the mechanoluminescence sensing layer is coated on the outer side of the cladding layer 1.2 and made into a cylindrical or flaky shape coaxial with the matrix optical fiber; the mechanoluminescence material is elastic mechanoluminescence fluorescent powder, namely, in the elastic deformation range of a substrate, the light emission has recoverability, and the luminous intensity and the stress strain magnitude are in a regular linear relationship, and the mechanoluminescence material comprises oxides, sulfides, phosphates, aluminates, silicates, nitric oxides and sulfur oxides doped with transition metal ions or rare earth ions2+、ZnS:Cu+、ZnS:Mn2+、LiNbO3:Pr3+、CaZnOS:Mn2+、SrAl2O4:Eu2+Etc.; the thickness of the mechanoluminescence sensing layer 1.3 is 220 μm;
the protective layer 1.4 is made of polydimethylsiloxane material, is coated on the outer side of the mechanoluminescence sensing layer 1.3, and is made into a cylindrical or flaky shape coaxial with the matrix optical fiber, and the thickness of the cylindrical or flaky shape is 10-200 mu m.
Example 2:
the preparation method of the flexible force-induced luminescent fiber comprises the following steps:
s1, preparing a matrix optical fiber;
the preparation of the matrix optical fiber adopts a sleeving method, and specifically comprises the following steps:
s1.1, in the embodiment, the selected elastomer is Polydimethylsiloxane (PDMS), wherein the PDMS is composed of a prepolymer A and a cross-linking agent B, and the mixing ratio is 5: 1; firstly weighing A and B with required mass, fully mixing the A and the B uniformly, placing the mixture in a vacuum environment for defoaming treatment, injecting the solution into a polytetrafluoroethylene sleeve mold (with the length of 10cm and the inner diameter of 300 mu m), curing the solution for 1 hour at 80 ℃, and taking out the cured fiber core by a stripping method.
S1.2, in this example, the fiber core is horizontally rotated at 3000rpm by a rotating motor, the surface of the fiber core is uniformly coated with a layer of PDMS solvent by centrifugal force, the mixture ratio of the prepolymer A of the PDMS solvent and the cross-linking agent B is 20:1, the refractive index is lower than that of the solution in the step S1.1, and then the mixture is cured at 80 ℃ for 40 minutes to obtain the matrix optical fiber with the fiber core-cladding structure, the diameter of the fiber core is 300 μm, the thickness of the cladding is 80 μm, wherein the thickness of the cladding can be controlled by the rotating speed of the rotating motor.
S2, preparing a mechanoluminescence sensing layer;
in the preparation of the mechanoluminescence sensing layer, the doping of the mechanoluminescence material comprises single doping or mixed doping, and the single doping or mixed doping is respectively applied to single-point or multi-point large strain sensing; in this embodiment, single doping is employed, and the specific steps are as follows:
s2.1.1, weighing a polydimethylsiloxane solvent with required mass, wherein the solvent consists of a prepolymer and a crosslinking agent, and the mixing ratio of the prepolymer to the crosslinking agent is 10: 1;
s2.1.2, after mixing evenly, doping 50-70 wt% of certain mechanoluminescence material, stirring evenly and fully, then placing in vacuum environment for defoaming treatment;
s2.1.3, dipping the prepared matrix optical fiber in the mixed solution prepared in step S2.1.2, then sheathing the matrix optical fiber with a silica gel sleeve (length 1cm, inner diameter 600 μm) to repeatedly move horizontally at a constant speed to uniformly coat the mixed solution on the surface of the cladding, or directly coating a layer of the mixed solution on the surface of the cladding by using a spin coating method, and then curing at 80 ℃ for 40 minutes to obtain the single-doping photoluminescence sensing layer with the thickness of 220 μm.
S3, preparing a protective layer;
in this embodiment, the method for preparing the protective layer by using a flat-plate film-scraping method specifically includes the following steps:
s3.1, weighing a polydimethylsiloxane solvent with required mass, wherein the mixing ratio of a prepolymer to a cross-linking agent in the polydimethylsiloxane solvent is 20:1, fully and uniformly stirring, and then placing in a vacuum environment for defoaming treatment;
s3.2, horizontally placing the optical fiber in the step S2 on a clean flat plate die, slowly pouring the solution prepared in the step S3.1 from one end of the optical fiber and uniformly moving the optical fiber to the other end to enable the solution to cover the whole optical fiber, uniformly scraping the solution from one end to the other end by using a film scraper with a scraping surface of 250 mu m, finally curing the solution at 80 ℃ for 40 minutes, trimming an edge area and taking down the flexible force-induced luminescent optical fiber;
example 3:
the preparation of a mixed doped flexible mechanoluminescence fiber, in which the preparation of the host fiber and the protective layer is the same as that of example 2 and is not repeated, taking double doping as an example, the preparation steps of the mechanoluminescence sensing layer are as follows:
s2.2.1 weighing the required mass of the mechanoluminescence material and the polydimethylsiloxane solvent respectively, wherein the mechanoluminescence material selected in the embodiment is ZnS: Cu2+With ZnS: Mn2+The matrix is polydimethylsiloxane solvent, wherein the total doping amount ratio of the mechanoluminescence material is 60%, the mixing ratio of prepolymer of the polydimethylsiloxane solvent to the cross-linking agent is 10:1, the mixing ratio of prepolymer to the cross-linking agent in the polydimethylsiloxane solvent is 10:1, a series of mechanoluminescence materials with different ratios are prepared, and ZnS is ZnS, Cu is2+With ZnS: Mn2+The ratio of the materials is 10:0, 3:7, 5:5, 7:3 and 0:10 respectively, a series of ratios of the mechanoluminescence materials are weighed and respectively mixed with the dimethyl silicone polymer solvent uniformly, and the mixture is placed in a vacuum environment for defoaming treatment;
s2.2.2, fully stirring and uniformly mixing the prepared mechanoluminescence materials with the polydimethylsiloxane solvent in a series of proportions to obtain mixed solutions with different proportions, and placing the mixed solutions in a vacuum environment for defoaming treatment;
s2.2.3, in the embodiment, the segmented preparation is carried out by using a sleeving method, the sleeving is sleeved at different positions of the matrix optical fiber along the axis, the distance between the different positions is 0-3cm, the mixed solution with different proportions in the step S2.2.2 is injected at the different positions, and the uniform double-doping force luminescence sensing layer is prepared after polymerization, solidification and molding are carried out at 25-120 ℃ and demoulding is carried out;
to obtain uniform double-doped photoluminescenceThe sensing layer, as shown in FIG. 2, is made of ZnS: Cu in the region2+With ZnS: Mn2+The ratio of ZnS to Cu in the region is 3:72+With ZnS: Mn2+The mixture ratio of (A) to (B) is 7: 3;
the doping forms of more than two kinds of mechanoluminescence materials are the same, and the proportion of various mechanoluminescence materials is only required to be regulated and controlled.
Example 4:
the large strain sensing application device based on the flexible force-emitting optical fiber comprises a sensing device and a signal demodulation part; as shown in fig. 3a and 3b, the sensing device includes a flexible force-induced luminescence optical fiber sensing unit, a band-pass filter 2.4, a coupling lens 2.5, a photodetector 2.6 and a signal processing unit;
the flexible force-emitting optical fiber sensing unit comprises a flexible force-emitting optical fiber 2.1, an optical fiber interface 2.2 and a cassette 2.3; the signal processing unit comprises a circuit board 2.8, a signal conversion and amplification module 2.9, an A/D module 2.10 and a micro control unit 2.11;
the flexible force-induced luminescence optical fiber sensing unit is fixed on the skin surface of a human body or a wearing device, a flexible force-induced luminescence optical fiber 2.1 is connected to an optical fiber interface 2.2 at one end of a cassette 2.3, an optical signal generated by a force-induced luminescence sensing layer is transmitted in a substrate optical fiber through total reflection and is coupled and connected to a band-pass filter 2.4 embedded in the cassette 2.3, the obtained fluorescence signal is connected to a coupling lens 2.5 after external environment light is filtered out, fluorescence in each direction is focused and then connected to a photoelectric detector 2.6, real-time fluorescence intensity is measured through rapid conversion of the photoelectric detector 2.6, and measured and converted data is input to a signal processing unit through a lead 2.7; in the signal processing unit, the measured and converted data are input into a signal conversion and amplification module 2.9 and an A/D module 2.10 which are arranged on a circuit board 2.8 for amplification and conversion, finally, the measured strain condition is demodulated through a micro control unit 2.11 which is arranged on the circuit board 2.8 according to the real-time fluorescence intensity, and the final data can be transmitted to a mobile phone or a computer terminal through Wifi, Bluetooth or a serial port, so that the purpose of real-time monitoring is achieved.
The large strain sensing applications include single point detection and multi-point detection, as shown in FIG. 3a, which showsThe application scene is strain real-time detection of a single joint area, single-point detection corresponds to a single-doped mechanoluminescence fiber, a band-pass filter is used, and in the embodiment, the single-doped mechanoluminescence fiber adopts a mechanoluminescence material of ZnS to Cu2+(ii) a As shown in fig. 3b, the application scenario shown in the figure is strain real-time detection of multiple joint regions, multi-point detection corresponds to a mixed doped mechanoluminescence fiber, and a combined band-pass filter is used, which can be switched according to a desired band2+、ZnS:Mn2+。
In this embodiment, the flexible mechanoluminescence fiber 2.1 is under the action of tensile force, and the mechanoluminescence material ZnS: Cu in the mechanoluminescence sensing layer2+The fluorescence peak of the fluorescent material is 517nm, ZnS is Mn2+The fluorescence peak intensity is 585nm, and when the tensile strain is increased, the fluorescence peak intensity can be gradually and linearly increased along with the increase of the strain, so that the relation between the fluorescence peak intensity and the tensile strain can be calibrated, and the in-situ real-time and on-line monitoring and sensing application aiming at single-point and multi-point stress strain is realized. In addition, the fluorescence intensity of the flexible force-induced luminescence optical fiber sensing unit can be recovered to a stable state during detection under the cyclic loading of more than 1000 times, and the stability of long-term cyclic use of the sensing device in the embodiment is proved.
Example 5:
the signal demodulation part comprises single-path signal demodulation and multi-path signal demodulation, wherein a single sensing unit, namely a mechanoluminescence optical fiber, corresponds to the single-path signal demodulation and can be realized by using a photoelectric detector, as shown in fig. 4 a; a plurality of sensing units, namely a multi-channel distributed sensing network formed by cascading and paralleling a plurality of flexible force-emitting optical fibers, are corresponding to multi-channel signal demodulation, can be simplified into a plurality of independent sensing units for processing, and realize the demodulation of signals through an optical switch or a plurality of discrete detectors, as shown in fig. 4b and 4 c; the multi-path signal detection shown in fig. 4b is time-sharing detection, and signal detection of different paths needs to be switched; the multi-channel signal detection shown in fig. 4c is simultaneous detection, and the signal detection of different channels can be performed synchronously.
In this embodiment, as shown in fig. 4a, 4b, and 4c, the large strain sensing application device based on the flexible force-emitting optical fiber includes a signal processing unit 3.1, a wire 3.2, a photodetector 3.3, a coupling lens 3.4, a band-pass filter 3.5, a commercial multimode optical fiber 3.6, an optical switch 3.7, and a flexible force-emitting optical fiber 3.8, and a specific signal transmission path of single-path sensing is as follows: when the flexible mechanoluminescence fiber 3.8 generates strain, fluorescence generated by the mechanoluminescence material is collected by the matrix fiber and transmitted at the fiber core-cladding interface in a total reflection mode, and then the fluorescence is coupled to the photoelectric detector 3.3 to realize the conversion of an optical signal to an electric signal, and finally the amplification, the conversion and the acquisition analysis of the signal are further completed through the signal processing unit 3.1, wherein the demodulation of the multi-path sensing signal can be realized through the optical switch 3.7 or by using a discrete detector.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.
Claims (8)
1. A flexible mechanoluminescence optical fiber characterized by comprising a substrate optical fiber, a mechanoluminescence sensing layer (1.3) and a protective layer (1.4);
the matrix optical fiber has a fiber core-cladding structure and comprises a fiber core (1.1) and a cladding (1.2), wherein the cladding (1.2) is wrapped outside the fiber core (1.1); the mechanoluminescence sensing layer (1.3) is compounded on the outer side of a cladding (1.2) of the matrix optical fiber; the protective layer (1.4) is wrapped outside the mechanoluminescence sensing layer (1.3);
the mechanoluminescence sensing layer (1.3) directly generates mechanoluminescence with corresponding intensity under the action of external force without continuous excitation of a power supply or a light source, collects the mechanoluminescence through the matrix optical fiber and transmits the mechanoluminescence to a far end along the matrix optical fiber for detection and demodulation;
the preparation method of the flexible mechanoluminescence fiber comprises the following steps:
s1, preparing a matrix optical fiber;
s2, preparing a mechanoluminescence sensing layer; in the preparation of the mechanoluminescence sensing layer, the doping of the mechanoluminescence material comprises mixed doping and is applied to multipoint large-strain sensing; when double doping is adopted, namely two kinds of mechanoluminescence materials are mixed, the specific steps are as follows:
s2.2.1, weighing the required mass of the mechanoluminescence material and the polydimethylsiloxane solvent respectively, wherein the total impurity content ratio of the mechanoluminescence material is 25-85 wt%, the mixing ratio range of the two mechanoluminescence materials is 10:0-0:10, and the mixing ratio range of the prepolymer and the cross-linking agent in the polydimethylsiloxane solvent is 10:1-30: 1;
s2.2.2, fully stirring the two kinds of mechanoluminescence materials prepared in the step S2.2.1 and a polydimethylsiloxane solvent to obtain a uniform mixed solution, and placing the mixed solution in a vacuum environment for defoaming treatment;
s2.2.3, dipping the prepared matrix optical fiber into the mixed solution obtained in step S2.2.1, and finally preparing the uniform double-doping force luminescence sensing layer by a spin coating method, a sleeving method or a flat-plate film scraping method;
the doping forms of more than two kinds of mechanoluminescence materials are the same, and the proportion of various mechanoluminescence materials is only required to be regulated and controlled;
s3, preparing a protective layer.
2. The flexible mechanoluminescence fiber according to claim 1, characterized in that in the host fiber, the refractive index of the core (1.1) is larger than that of the cladding (1.2), the diameter of the core (1.1) is 200-1000 μm, the thickness of the cladding (1.2) is 5-100 μm, the length of the host fiber is 1-10cm, the numerical aperture is 0.2-0.6, and the fluorescence generated by the mechanoluminescence sensing layer is collected and transmitted at the core-cladding interface in the form of total internal reflection; the matrix optical fiber is made of an elastomer, wherein the elastomer comprises polysiloxane, organic silicon rubber, soft unsaturated polyurethane, polystyrene elastomer, polyolefin elastomer, polyamide elastomer, polylactic acid-glycolic acid copolymer, polyethylene glycol diacrylate or alginic acid;
the mechanoluminescence sensing layer (1.3) is prepared by compounding a mechanoluminescence material and a polydimethylsiloxane material, is coated on the outer side of the cladding (1.2) and is made into a cylindrical or sheet shape coaxial with the matrix optical fiber; the mechanoluminescence material is elastic mechanoluminescence fluorescent powder, namely in the elastic deformation range of a substrate, the light emission of the mechanoluminescence fluorescent powder has recoverability, and the luminous intensity and the stress strain magnitude are in a regular linear relation and comprise transition metal ion or rare earth ion doped oxides, sulfides, phosphates, aluminates, silicates, nitric oxides and oxysulfides; the thickness of the mechanoluminescence sensing layer (1.3) is 50-300 mu m;
the protective layer (1.4) is made of polydimethylsiloxane material, is coated on the outer side of the mechanoluminescence sensing layer (1.3), and is made into a cylindrical or flaky shape coaxial with the matrix optical fiber, and the thickness of the cylindrical or flaky shape is 10-200 mu m.
3. A method of making a flexible mechanoluminescence fiber according to claim 1, characterized by comprising the steps of:
s1, preparing a matrix optical fiber;
s2, preparing a mechanoluminescence sensing layer; in the preparation of the mechanoluminescence sensing layer, the doping of the mechanoluminescence material comprises mixed doping and is applied to multipoint large-strain sensing; when double doping is adopted, namely two kinds of mechanoluminescence materials are mixed, the specific steps are as follows:
s2.2.1, weighing the required mass of the mechanoluminescence material and the polydimethylsiloxane solvent respectively, wherein the total impurity content ratio of the mechanoluminescence material is 25-85 wt%, the mixing ratio range of the two mechanoluminescence materials is 10:0-0:10, and the mixing ratio range of the prepolymer and the cross-linking agent in the polydimethylsiloxane solvent is 10:1-30: 1;
s2.2.2, fully stirring the two kinds of mechanoluminescence materials prepared in the step S2.2.1 and a polydimethylsiloxane solvent to obtain a uniform mixed solution, and placing the mixed solution in a vacuum environment for defoaming treatment;
s2.2.3, dipping the prepared matrix optical fiber into the mixed solution obtained in step S2.2.1, and finally preparing the uniform double-doping force luminescence sensing layer by a spin coating method, a sleeving method or a flat-plate film scraping method;
the doping forms of more than two kinds of mechanoluminescence materials are the same, and the proportion of various mechanoluminescence materials is only required to be regulated and controlled;
s3, preparing a protective layer.
4. The method for preparing a flexible mechanoluminescence fiber according to claim 3, wherein in step S1, the preparation of the matrix optical fiber is carried out by a jacketing method, specifically comprising the steps of:
s1.1, injecting a transparent elastomer with the refractive index of 1.4-1.6 into the sleeve, carrying out polymerization curing at 25-120 ℃, and taking out the transparent elastomer by a stripping method to obtain a fiber core of the matrix optical fiber;
s1.2, dipping another elastomer solvent with the refractive index lower than that of the fiber core on the surface of the fiber core prepared in the step S1.1, and preparing a uniform cladding by adopting a spin coating method.
5. The method for preparing a flexible mechanoluminescence fiber according to claim 4, wherein when the mixed doping is adopted, the process of preparing the protective layer in step S3 specifically includes the steps of:
s3.1, weighing a polydimethylsiloxane solvent with required mass, wherein the mixing ratio of a prepolymer to a cross-linking agent in the polydimethylsiloxane solvent is 10:1-20:1, fully and uniformly stirring, and then placing in a vacuum environment for defoaming treatment;
s3.2, preparing a cylindrical or flaky protective layer on the outer side of the mechanoluminescence sensing layer obtained in the step S2 by adopting a rotary coating method or a flat-plate film scraping method, wherein the protective layer needs to be cured and formed at the temperature of 25-120 ℃.
6. The large strain sensing application device based on the flexible mechanoluminescence optical fiber according to claim 1, characterized by comprising a sensing device and a signal demodulating portion; the sensing device comprises a flexible force-induced luminescence optical fiber sensing unit, a band-pass filter, a coupling lens, a photoelectric detector and a signal processing unit; the flexible force-emitting optical fiber sensing unit comprises a flexible force-emitting optical fiber;
the flexible force-induced luminescence optical fiber sensing unit is fixed on the surface of human skin or a wearing device, optical signals generated in the force-induced luminescence sensing layer are transmitted in a matrix optical fiber through total reflection and are coupled and connected to a band-pass filter, external environment light is filtered out, then obtained fluorescence signals are connected to a coupling lens, fluorescence in all directions is focused and then connected to a photoelectric detector, real-time fluorescence intensity is measured through rapid conversion of the photoelectric detector, finally, measured and converted data are input to a signal processing unit for further conversion and amplification, the measured strain condition is demodulated according to the real-time fluorescence intensity, and the final data can be transmitted to a mobile phone or a computer terminal through Wifi, Bluetooth or a serial port, so that the purpose of real-time monitoring is achieved.
7. The device for large strain sensing application based on flexible mechanoluminescence optical fiber according to claim 6, wherein the large strain sensing application comprises single point detection and multi-point detection, the single point detection corresponds to single doped mechanoluminescence optical fiber, and band-pass filter is used; the multipoint detection corresponds to a mixed doped mechanoluminescence fiber, and the combined band-pass filter is used, so that switching can be performed according to a required waveband.
8. The device for applying large strain sensing based on flexible mechanoluminescence fiber according to claim 6, wherein the signal demodulating part comprises single-path signal demodulation and multi-path signal demodulation, wherein a single sensing unit, i.e. a single flexible mechanoluminescence fiber, is realized by using a photodetector corresponding to the single-path signal demodulation; the multi-channel distributed sensing network formed by the cascade connection and the parallel connection of the plurality of sensing units, namely the plurality of flexible force-emitting optical fibers, corresponds to multi-channel signal demodulation, can be simplified into a plurality of independent sensing units for processing, and realizes the demodulation of signals through an optical switch or a plurality of discrete detectors.
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| CN113047045B (en) * | 2021-03-29 | 2022-05-10 | 中国科学院深圳先进技术研究院 | Flexible optical fiber and preparation method and application thereof |
| CN113292856B (en) * | 2021-05-19 | 2022-06-10 | 清华大学 | Mechanoluminescence device and method for producing same |
| CN113604925B (en) * | 2021-07-09 | 2022-11-04 | 东华大学 | Self-driven interactive photoelectric sensing yarn and preparation and application thereof |
| CN114001637B (en) * | 2021-10-29 | 2024-03-29 | 上海应用技术大学 | Preparation method of elastic stress luminous conductive strain sensor with dual-core sheath structure |
| CN114171704A (en) * | 2021-12-08 | 2022-03-11 | Tcl华星光电技术有限公司 | Flexible display panel and preparation method thereof |
| CN114754912A (en) * | 2022-04-15 | 2022-07-15 | 云南师范大学 | Optical fiber carbon quantum dot pressure detection system |
| CN114910199B (en) * | 2022-05-09 | 2023-08-18 | 北京纳米能源与系统研究所 | Touch sensor, preparation method and information acquisition method |
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