CN111999341B - Flexible thermal conductivity detection device and method based on micro-nano optical fiber - Google Patents
Flexible thermal conductivity detection device and method based on micro-nano optical fiber Download PDFInfo
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Abstract
The invention discloses a flexible thermal conductivity detection device and method based on micro-nano optical fibers. The flexible thermal conductivity detection device comprises a thermal conductivity sensor, a light source and a controller, wherein the thermal conductivity sensor utilizes a flexible thermal conductivity packaging material to coat a micro-nano optical fiber and a flexible heater for heat conduction, the thermal conductivity sensor and the controller form a closed temperature control feedback loop, the flexible thermal conductivity packaging material is utilized as a coating of the micro-nano optical fiber, and based on the coupling of a strong evanescent field of light transmitted in the micro-nano optical fiber and the thermo-optical effect of a coating packaging material, the single flexible thermal conductivity sensor realizes the miniaturized integration of temperature measurement and temperature regulation functions under the regulation and control of the controller, can realize the accurate evaluation of the thermal conductivity of an object to be detected without adding other extra modules, has the remarkable light weight characteristic, has the remarkable advantages of high sensitivity, high response speed, no electromagnetic radiation interference and the like, and is more suitable for application in extreme and special environments.
Description
Technical Field
The invention relates to micro-nano optical fiber sensing and thermal conductivity detection, and belongs to the field of optical fiber sensing.
Background
In the internet of things and the 5G era, the touch sensor has wide application prospects in robots, health medical treatment, intelligent manufacturing and basic scientific research. The temperature sense is an important component of the sense of touch and is an important basis for recognizing the world and realizing material identification of human beings. At present, the flexible touch sensor with the temperature detection function mainly adopts the electrical principle, and the response time, the resolution, the working range and the anti-electromagnetic interference performance of the flexible touch sensor are difficult to meet the requirements of an intelligent robot on a high-performance temperature sensor. How to convert the temperature information into the thermal conductivity information of the object to be measured and further distinguish the material of the object is an urgent need for the development of intelligent robots and is also a huge challenge for researchers.
The traditional thermal conductivity detection method comprises a steady state method and a transient state method, wherein the steady state method is to measure the heat quantity, the temperature gradient and the like flowing through a sample to calculate the thermal conductivity of the sample after the temperature distribution of the sample to be detected is stable. The heat conductivity is measured by using the balance condition that the heat transfer rate is equal to the heat dissipation rate in the stable heat transfer process. The steady state method has the advantages of clear principle, simple model and the like, but the method has harsh experimental conditions and longer measurement time. Transient methods transfer heat to the sample by emitting a heat source while measuring the temperature-time response of the sample. In contrast, the transient method is widely used in practice due to its simple operation, short measurement time, and many kinds of measurable samples (e.g. liquid, powder, gel). However, at present, most thermal conductivity sensors based on the transient method adopt rigid structures, including rigid heat sources, temperature probes and packaging materials. In some environments with strong electromagnetic interference, the accuracy of the temperature probe based on the electrical principle cannot be guaranteed. And thus have limited applications in wearable, robotic, and smart manufacturing scenarios. The thermal conductivity sensor made of the fully flexible material and resisting electromagnetic interference is developed, and has important application value in the field of touch perception.
The micro-nano optical fiber is a waveguide with the diameter of the waist area close to or smaller than the wavelength of transmission light, when the light is transmitted in the micro-nano optical fiber, a part of energy exists in a medium outside the optical fiber in the form of an evanescent field, and the micro-nano optical fiber has the characteristics of smooth surface, good diameter uniformity, high mechanical performance, strong optical field constraint, strong evanescent field, surface field enhancement effect and the like, and has important application prospect in the field of optical sensing. When the fiber core of the micro-nano optical fiber is packaged by the flexible polymer with the low refractive index and the high thermo-optic coefficient, the output light intensity of the micro-nano optical fiber is sensitively changed along with the change of the temperature of the flexible polymer, so that the flexible polymer packaged micro-nano optical fiber can be used for temperature measurement. When the flexible polymer packaging micro-nano optical fiber is in contact with a measured object and temperature difference exists, the temperature information of the measured object can be obtained by measuring the change of the output optical signal of the micro-nano optical fiber in real time, and the thermal conductivity information of the measured object can be obtained by analyzing a temperature change curve. In order to simulate the constant body temperature of a human, a flexible heater is integrated with the micro-nano optical fiber temperature sensor, so that the temperature sensor keeps constant temperature higher than the ambient temperature when not in contact with a measured object. When the temperature sensor is contacted with a measured object with the temperature being the ambient temperature, the heating film stops working, and the thermal conductance of the measured object is calculated by measuring a cooling curve when the sensor is contacted with the measured object. The temperature sensor has the characteristics of high precision, electromagnetic interference resistance and low cost, is suitable for being applied to the touch perception of an intelligent robot, and is beneficial to realizing the material identification of a measured object by acquiring the thermal conductance of an object.
Disclosure of Invention
The invention aims to provide a flexible thermal conductivity detection device based on micro-nano optical fibers aiming at the defects of the prior art.
In order to realize the purpose, the technical scheme adopted by the invention is as follows: the flexible thermal conductivity detection device based on the micro-nano optical fiber comprises a thermal conductivity sensor, a light source and a controller; the thermal conductivity sensor comprises a flexible thermal conductivity packaging object, a micro-nano optical fiber and a flexible heater, the flexible heater comprises a flexible thermal conductivity film and a conductive coating plated on the flexible thermal conductivity film, a waist region of the micro-nano optical fiber and the flexible heater are packaged in the flexible thermal conductivity packaging object, and the refractive index of the flexible thermal conductivity packaging object is smaller than that of a fiber core of the micro-nano optical fiber; the controller comprises a central processing unit, an optical signal detection module and a temperature control module, wherein an unstretched region at one end of the micro-nano optical fiber is connected with the output end of the light source, an unstretched region at the other end of the micro-nano optical fiber is connected with the optical signal detection module, the central processing unit is respectively connected with the optical signal detection module and the temperature control module, and the temperature control module is electrically connected with the conductive coating; the central processing unit can convert the optical signal from the optical signal detection module into a temperature value, compare the temperature value with a preset target temperature, convert a comparison result into temperature control information and transmit the temperature control information to the temperature control module, and the temperature control module can adjust the temperature of the conductive coating according to the received temperature control information so that the temperature value converted by the central processing unit is constant at the preset target temperature; when the temperature value converted by the central processing unit is constant at a preset target temperature, and the flexible heat-conducting packaging object is attached to the object to be detected, the central processing unit can instruct the temperature control module to stop working, and when the converted temperature value is reduced to a threshold value, the time required from the stop of the working of the temperature control module to the reduction of the temperature value to the threshold value is calculated, wherein the threshold value is smaller than the target temperature and larger than the temperature of the object to be detected.
Furthermore, the transition region of the micro-nano optical fiber is encapsulated in the flexible heat-conducting encapsulant.
Furthermore, the unstretched region of the micro-nano optical fiber is encapsulated in the flexible heat-conducting encapsulant.
Furthermore, the central processing unit of the invention can substitute the calculated time required for reducing the temperature value to the threshold value from the stop of the temperature control module into the relation between the thermal conductivity measured by the standard sample calibration method and the temperature reduction time to obtain the thermal conductivity of the object to be measured.
Furthermore, the thermo-optic coefficient of the flexible heat-conducting packaging material is more than or equal to 1 multiplied by 10 -5 RIU/℃。
The method for detecting the thermal conductivity of the object by using the flexible thermal conductivity detection device based on the micro-nano optical fiber comprises the following steps:
the method comprises the following steps: the central processing unit presets and stores a target temperature, wherein the target temperature is higher than the temperature of an object to be measured;
step two: the central processing unit converts the optical signal from the optical signal detection module into a temperature value, compares the temperature value with a preset target temperature, converts a comparison result into temperature control information and transmits the temperature control information to the temperature control module, and the temperature control module adjusts the temperature of the conductive coating according to the received temperature control information so that the temperature value converted by the central processing unit is constant at the preset target temperature;
step three: attaching the flexible heat-conducting packaging object to an object to be measured in a state that the temperature value converted by the central processing unit is constant at a preset target temperature, and instructing the temperature control module to stop working by the central processing unit;
step four: when the temperature value converted by the central processing unit is reduced to the threshold value, the central processing unit calculates the time required from the stop of the temperature control module to the reduction of the temperature value to the threshold value; substituting the time into a relational expression of the thermal conductivity measured by using a standard sample calibration method and the cooling time to obtain the thermal conductivity of the object to be measured; the threshold is less than the target temperature and greater than the temperature of the object to be measured.
The other method for detecting the thermal conductivity of the object by using the flexible thermal conductivity detection device based on the micro-nano optical fiber comprises the following steps:
the method comprises the following steps: the central processing unit presets and stores a target temperature, wherein the target temperature is higher than the temperature of an object to be measured;
step two: the central processing unit converts the optical signal from the optical signal detection module into a temperature value, compares the temperature value with a preset target temperature, converts a comparison result into temperature control information and transmits the temperature control information to the temperature control module, and the temperature control module adjusts the temperature of the conductive coating according to the received temperature control information so that the temperature value converted by the central processing unit is constant at the preset target temperature;
step three: attaching the flexible heat-conducting packaging object to an object to be measured in a state that the temperature value converted by the central processing unit is constant at a preset target temperature, and instructing the temperature control module to stop working by the central processing unit;
step four: when the temperature value converted by the central processing unit is reduced to the threshold value, the central processing unit calculates the time required from the stop of the temperature control module to the reduction of the temperature value to the threshold value; the central processor substitutes the time into a relational expression of the thermal conductivity measured by using a standard sample calibration method and the cooling time to obtain the thermal conductivity of the object to be measured; the threshold is less than the target temperature and greater than the temperature of the object to be measured.
Compared with the prior art, the invention has the following beneficial effects:
(1) Structurally, the thermal conductivity sensor coats the micro-nano optical fiber and the flexible heater by using the flexible thermal conductivity packaging material for heat conduction, and the thermal conductivity sensor and the controller form a closed temperature control feedback loop, so that the single flexible thermal conductivity sensor realizes the miniaturized integration of temperature measurement and temperature regulation functions under the regulation and control of the controller, can realize the accurate evaluation of the thermal conductivity of an object to be measured without adding other extra modules, and has the remarkable light weight characteristic; compared with the traditional rigid sensor structure, the sensor is more suitable for the coupling of wearable devices, robots, human-like tactile perception devices and the like.
(2) In the detection principle, the flexible heat-conducting packaging material is used as the cladding of the micro-nano optical fiber, and the flexible heat-conducting packaging material in the heat-conducting sensor can be contacted with an object to be detected and accurately measure the temperature change in the heat transfer process based on the coupling of the strong evanescent field of the transmission light in the micro-nano optical fiber and the thermo-optical effect of the cladding packaging material; compared with the existing electric sensing device, the sensor has the remarkable advantages of high sensitivity, high response speed, no electromagnetic radiation interference and the like, and is more suitable for application in extreme and special environments.
(3) Under the condition that the temperature value obtained by conversion of the central processing unit is constant at the preset target temperature (Temp 1), once the object to be measured is attached to the flexible heat conduction packaging object, the flexible heat conduction packaging object deforms, so that the waist region of the micro-nano optical fiber is bent, the loss is increased, the transmittance is reduced, the optical signal transmitted to the optical signal detection module by the micro-nano optical fiber is changed instantly, the central processing unit instructs the temperature control module to automatically stop working due to mutation of the received optical signal, the measurement error caused by manual operation is avoided, and the measurement precision is improved. In the prior art, a heat source is stopped being heated manually, and the manual operation of the heat source is usually performed for a period of time after an object to be measured is attached to a flexible heat-conducting packaging material, so that a measurement error caused by manual operation is generated.
(4) The thermal conductivity detection device has the advantages of simple structure, low cost, high measurement precision, good repeatability, convenience for mass production and manufacture, and good market application prospect.
Drawings
Fig. 1 is a schematic structural view of a thermal conductivity sensor, wherein fig. 1a and 1b are a schematic overall structural view and a schematic partial exploded view of the thermal conductivity sensor, respectively;
FIG. 2 is a schematic structural diagram of a micro-nano optical fiber;
FIG. 3 is a schematic view of a flexible heater;
FIG. 4 is a process of packaging the micro-nano optical fiber and the flexible heater in a flexible heat-conducting packaging material;
FIG. 5 is an overall schematic diagram of a micro-nano fiber-based flexible thermal conductivity detection device;
FIG. 6 is a schematic diagram of the controller;
fig. 7 is a graph showing a temperature drop curve of the flexible heat-conducting encapsulant of the thermal conductivity sensor after contacting with the dut made of different materials.
Wherein, 1-thermal conductivity sensor; 2-a light source; 3-a controller; 11-a flexible thermally conductive encapsulant; 12-micro nano optical fiber; 13-a flexible heater; 121-one end of the unstretched zone; 122-waist region; 123-the other end of the unstretched zone; 131-a flexible heat conducting film; 132-a conductive coating; 31-optical signal detection module interface; 32-temperature control module interface; 33-conducting wire.
Detailed Description
The invention is described in detail below with reference to the figures and the specific embodiments, but the invention is not limited thereto.
As shown in fig. 5, the flexible thermal conductivity detection device based on micro-nano optical fiber of the present invention includes a thermal conductivity sensor 1, a light source 2 and a controller 3. As shown in fig. 1a and 1b, the thermal conductivity sensor 1 includes a flexible thermal conductive encapsulant 11, a micro-nano optical fiber 12, and a flexible heater 13. The light source 2 adopts a stable light source of a halogen tungsten lamp with a wave band of 300-2600 nm. As shown in fig. 6, the controller 3 includes a central processing unit, an optical signal detection module, and a temperature control module.
As shown in fig. 2, the micro-nanofiber 12 includes unstretched regions 121 and 123 at two ends and a waist region 122 in the middle, and a transition region between the waist region 122 and the unstretched regions 121 and 123. The diameter of the waist region 122 is close to or less than the wavelength of the transmitted light and may typically be from 100nm to 5 μm.
As shown in fig. 3, the flexible heater 13 includes a flexible heat conductive film 131 and an electrically conductive coating 132 plated on the flexible heat conductive film. The flexible thermal conductive film 131 is preferably made of Polyimide (PI) polymer material, and the conductive coating 132 is preferably made of metal and alloy material such as gold, silver, copper, or conductive polymer material such as ethylenedioxythiophene (PEDOT) and Polyaniline (PANI).
As shown in fig. 1, the waist region 122 of the micro-nano optical fiber 12, the transition region of the micro-nano optical fiber 12, and the parts of the unstretched regions 121 and 123 at the two ends of the micro-nano optical fiber 12 and the flexible heater 13 are encapsulated in the flexible heat conducting encapsulant 11. Wherein the flexible thermally conductive encapsulant 11 acts as a cladding for the waist region 122. It should be noted that, in the case of generating the necessary evanescent field around the waist region 122 when transmitting light in the micro-nano optical fiber 12, as an embodiment of the present invention, the flexible heat-conducting encapsulant 11 may encapsulate only the waist region 122 of the micro-nano optical fiber 12; the factors such as actual conditions, requirements, convenience of the manufacturing process and the like can also be considered, the flexible heat-conducting packaging material 11 extends from the waist region 122 to two ends for packaging the micro-nano optical fiber 12, the transition region of the micro-nano optical fiber 12 is packaged together, or the transition region and a part of the unstretched region of the micro-nano optical fiber 12 are packaged together. Usually, for the convenience of the packaging process, the waist region 122 of the micro-nano optical fiber 12, the transition region of the micro-nano optical fiber 12, and a part of the unstretched regions 121 and 123 at two ends of the micro-nano optical fiber 12 are often packaged in the flexible heat-conducting packaging material 11 together.
The process of encapsulating the micro-nano optical fiber 12 and the flexible heater 13 in the flexible heat-conducting encapsulant 11 is sequentially shown in fig. 4a to 4 e: (a) Dripping 0.3ml of PDMS colloid on a clean glass slide, standing, spin-coating to form a film, and curing at 80 ℃ for 20 minutes; (b) Placing the stretched micro-nano optical fiber 12 above the PDMS film in a U shape; (c) Dripping 0.3ml of PDMS colloid to cover the waist region 122, the transition region, a part of the unstretched region 121 and a part of the unstretched region 123 of the micro-nano optical fiber 12, standing, flattening and curing at 80 ℃ for 20 minutes; (d) The flexible heater 13 is placed above the PDMS film, and the conductive coating 132 and the lead 33 are fixedly connected through soldering; (e) 0.3ml of PDMS gel was applied dropwise, allowed to stand, and spread flat and cured at 80 ℃ for 20 minutes.
The refractive index of the flexible heat-conducting encapsulant 11 is smaller than that of the fiber core of the micro-nano optical fiber 12. As a preferred embodiment of the present invention, when the thermo-optic coefficient of the flexible heat-conducting encapsulant 11 is greater than or equal to 1 × 10 -5 When RIU/DEG C is achieved, the output light intensity of the micro-nano optical fiber 12 is sensitively changed along with the change of the temperature of the flexible heat conducting packaging material 11. When the thermo-optic coefficient of the flexible heat-conducting encapsulant 11 is less than 1 × 10 -5 The thermal conductivity sensor 1 also has sensing capability at RIU/deg.C. The flexible heat-conducting encapsulant 11 is preferably a Polydimethylsiloxane (PDMS) polymer material with a thermo-optic coefficient of 4.5 × 10 -4 RIU/DEG C, refractive index of 1.4.
As shown in fig. 5, an unstretched region 121 at one end of the micro-nano fiber 12 is connected to an output end of the light source 2, an unstretched region 123 at the other end of the micro-nano fiber 12 is connected to an optical signal detection module interface 31 of the controller 3, and the optical signal detection module detects a temperature sensed by a waist region 122 of the micro-nano fiber. The light source 2 generates an optical signal, and the optical signal is received by an optical signal detection module of the controller 3 through the micro-nano optical fiber 12. As shown in fig. 6, the central processing unit in the controller 3 is connected to the optical signal detection module and the temperature control module, respectively. The temperature control module interface 32 is connected to the conductive coating 132 of the flexible heater 13 by a wire 33.
The central processor converts the optical signal (for example, parameter information such as intensity, phase or spectrum) from the optical signal detection module into a temperature value, compares the temperature value with a preset target temperature (the target temperature should be higher than the ambient temperature), converts the comparison result into temperature control information, and transmits the temperature control information to the temperature control module, and the temperature control module can adjust the temperature of the conductive coating 132 according to the received temperature control information so that the temperature value converted by the central processor is constant at the preset target temperature; under the state that the temperature value obtained by the central processing unit is constant at the preset target temperature, when the flexible heat-conducting packaging object 11 is attached to the object to be detected, the flexible heat-conducting packaging object 11 deforms, so that the waist region 122 of the micro-nano optical fiber 12 is bent, the loss is increased, the transmittance is reduced, the optical signal transmitted to the optical signal detection module by the micro-nano optical fiber 12 is changed instantly, the central processing unit instructs the temperature control module to automatically stop working due to the fact that the received optical signal changes suddenly, in addition, the central processing unit calculates the time required for stopping working from the temperature control module until the temperature value is reduced to the threshold value when the temperature value converted by the central processing unit is reduced to the threshold value, wherein the threshold value is smaller than the preset target temperature and is larger than the temperature of the object to be detected.
As an embodiment of the present invention, the central processing unit converts the light intensity from the optical signal detection module and calculates to obtain a temperature value sensed by the waist region 122 of the micro-nano fiber; in order to enable the temperature value calculated by the central processing unit to reach the preset target temperature value and keep the temperature value constant, the central processing unit can calculate the duty ratio of a duty ratio adjustable (PWM) square wave signal through a proportional-integral-derivative (PID) algorithm according to the temperature value obtained by conversion and the preset target temperature value, and outputs the PWM square wave signal to the temperature control module. The temperature control module can adjust the voltage applied across the conductive coating 132 according to the PWM square wave signal, and further adjust the output power of the conductive coating 132, thereby driving the conductive coating 132 to heat up. Along with the temperature rise of the conductive coating 132, the flexible packaging material 11 and the waist region 122 of the micro-nano optical fiber packaged by the flexible packaging material also rise in temperature until the temperature value calculated by the central processing unit reaches the set target temperature value and keeps constant. At this moment, the flexible heat-conducting packaging material 11 can be attached to the object to be detected, and then the central processing unit detects the change of the light intensity signal and automatically instructs the temperature control module to stop working. When the temperature value converted by the central processing unit is reduced to the threshold value, the central processing unit calculates the time delta T from the stop of the temperature control module to the reduction of the temperature value to the threshold value. As a preferred embodiment of the present invention, the central processing unit may further substitute the calculated time required for the temperature value to decrease to the threshold value from the time when the temperature control module stops working into the relational expression between the thermal conductivity measured by the standard sample calibration method and the temperature decrease time, so as to obtain the thermal conductivity of the object to be measured.
The working principle of the detection device of the invention is as follows: the light source 2 generates an optical signal and transmits the optical signal in the micro-nano optical fiber 12 of the thermal conductivity sensor 1. When an optical signal passes through the waist region 122 of the micro-nano fiber 12, a strong evanescent field is generated at the interface between the core and the cladding of the micro-nano fiber 12. When the temperature of the flexible heat-conducting encapsulant 11 changes, its refractive index changes accordingly due to thermo-optic properties. As a cladding material of the waist region 122 of the micro-nano fiber 12, the refractive index change of the flexible heat-conducting encapsulant 11 may affect the evanescent field of the micro-nano fiber 12, thereby changing the characteristic parameters (including but not limited to intensity, phase, spectrum, polarization state, etc.) of the optical signal. The controller 3 controls the flexible heater 13 packaged in the flexible heat-conducting packaging material 11 to heat, so that the flexible heat-conducting packaging material 11 reaches the target temperature and is higher than the ambient temperature. In the process that the flexible heat-conducting encapsulant 11 is in contact with the object to be tested and heat transfer is generated, the controller 3 monitors the temperature change condition of the flexible heat-conducting encapsulant 11 in the heat transfer process by detecting optical signals transmitted in the micro-nano optical fiber 12, and analysis of the heat conductivity of the object to be tested can be realized.
The following describes a method for detecting the thermal conductivity of a target object to be detected by using the thermal conductivity detection device according to a specific embodiment, and specifically includes the following steps:
the method comprises the following steps: the target temperature of the temperature control module is preset to be Temp1 (for example, 50 ℃), and the target temperature is higher than the temperature of the object to be measured.
Step two: the central processing unit converts the optical signal from the optical signal detection module into a temperature value, compares the temperature value with a preset target temperature, converts the comparison result into temperature control information and transmits the temperature control information to the temperature control module, the temperature control module adjusts the temperature of the conductive coating 132 according to the received temperature control information, so that the temperature value converted by the central processing unit is constant at a preset target temperature Temp1;
step three: attaching the flexible heat-conducting packaging object 11 to an object to be measured in a state that the temperature value converted by the central processing unit is constant at a preset target temperature Temp1, and instructing the temperature control module to stop working by the central processing unit;
step four: when the temperature value converted by the central processing unit is reduced to a threshold value Temp2 (Temp 2 is between a preset target temperature and the temperature of the object to be measured, for example, temp2 is 30 ℃), the central processing unit calculates the time Δ T required for the temperature control module to stop working until the temperature value is reduced to the threshold value, and the time Δ T is substituted into the relational expression between the thermal conductivity measured by the standard sample calibration method and the cooling time, so that the thermal conductivity of the object to be measured can be obtained. It should be noted that, in the present invention, the central processing unit may not calculate Δ T and the thermal conductivity of the object to be measured, but calculate Δ T manually and substitute Δ T into the relationship between the thermal conductivity measured by the standard sample calibration method and the cooling time to obtain the thermal conductivity of the object to be measured.
Fig. 7 shows a temperature reduction curve of the flexible heat-conducting encapsulant 11 of the thermal conductivity sensor 1 after contacting with the objects to be tested of different materials.
The material of the object to be detected detectable by the thermal conductivity detection device of the present invention includes, but is not limited to, 304 stainless steel, glass, nylon, PVC plastic, wood, etc.
The thermal conductivity detection device simulates human touch perception, and conducts heat through the flexible thermal conductivity packaging object 11, the micro-nano optical fiber 12 packaged by the flexible thermal conductivity packaging object and the flexible thermal conductivity film 131 no matter in the process that the thermal conductivity sensor 1 is heated to the target temperature or during the thermal conductivity detection of the object to be detected. In the heat transfer process, when an optical signal is transmitted in the micro-nano optical fiber 12, the strong evanescent field of the waist region 122 of the micro-nano optical fiber 12 is mutually coupled with the thermo-optical characteristics of the flexible heat-conducting encapsulant 11 covering the strong evanescent field, and the change of the refractive index of the flexible heat-conducting encapsulant 11 can influence the evanescent field of the micro-nano optical fiber 12, so that the characteristic parameters of the optical signal are changed, thereby accurately transmitting the temperature change conditions of the conductive coating 132 and the object to be detected to the optical signal detection module, converting the optical signal into a temperature value by the central processing unit, and realizing the accurate evaluation of the heat conductivity of the sample to be detected. Further, the heat output of the conductive coating 132 is regulated by the controller 3 during the temperature rise of the thermal conductivity sensor 1 itself. The electric conduction coating 132 as a heat source is packaged in the flexible heat conduction packaging object 11, and the temperature information of the electric conduction coating 132 is transmitted to the controller 3 through the flexible heat conduction film 131, the flexible heat conduction packaging object 11 and the micro-nano optical fiber 12, so that the thermal conduction sensor 1 utilizes the flexible heat conduction packaging object 11 to coat the waist region 122 of the micro-nano optical fiber 12 and the flexible heater 13, thereby realizing the heat conduction function, and the electric conduction coating 132, the flexible heat conduction film 131, the flexible heat conduction packaging object 11, the micro-nano optical fiber 12 and the controller 3 in the thermal conduction sensor 1 jointly form a closed temperature feedback loop, so that the single and flexible thermal conduction sensor 1 realizes the miniaturized integration of the temperature measurement and temperature regulation functions under the regulation and control of the controller 3, can realize the accurate evaluation of the thermal conduction performance of the object to be measured without adding other extra modules, has smaller heat capacity, the temperature rises and falls rapidly, and the rate and efficiency of thermal conduction analysis can be improved. When the flexible heat-conducting packaging object 11 is in contact with an object to be detected, the central processing unit can automatically trigger the temperature control module to stop working according to the change of the optical signal, so that errors caused by manual operation are avoided. In addition, the detection device has the characteristics of flexibility and light weight, and can be applied to wider application scenes.
Claims (5)
1. A flexible thermal conductivity detection device based on micro-nano optical fibers is characterized by comprising a thermal conductivity sensor (1), a light source (2) and a controller (3); the thermal conductivity sensor (1) comprises a flexible thermal conductivity packaging object (11), a micro-nano optical fiber (12) and a flexible heater (13), wherein the flexible heater (13) comprises a flexible thermal conductivity film (131) and a conductive coating (132) plated on the flexible thermal conductivity film, a waist region (122) of the micro-nano optical fiber (12) and the flexible heater (13) are packaged in the flexible thermal conductivity packaging object (11), and the refractive index of the flexible thermal conductivity packaging object (11) is smaller than that of a fiber core of the micro-nano optical fiber (12); the controller (3) comprises a central processing unit, an optical signal detection module and a temperature control module, wherein an unstretched region (121) at one end of the micro-nano optical fiber (12) is connected with the output end of the light source (2), an unstretched region (123) at the other end of the micro-nano optical fiber is connected with the optical signal detection module, the central processing unit is respectively connected with the optical signal detection module and the temperature control module, and the temperature control module is electrically connected with the conductive coating (132); the central processing unit can convert the optical signal from the optical signal detection module into a temperature value, compare the temperature value with a preset target temperature, convert a comparison result into temperature control information and transmit the temperature control information to the temperature control module, and the temperature control module can adjust the temperature of the conductive coating (132) according to the received temperature control information so that the temperature value converted by the central processing unit is constant at the preset target temperature; when the temperature value obtained by conversion of the central processing unit is constant at a preset target temperature, and the flexible heat-conducting packaging object (11) is attached to the object to be detected, the central processing unit can instruct the temperature control module to stop working, calculate the time required by the temperature control module to stop working until the temperature value is reduced to a threshold value when the temperature value obtained by conversion is reduced to the threshold value, and substitute the time into a relational expression of the heat conductivity coefficient and the cooling time obtained by a standard sample calibration method to obtain the heat conductivity coefficient of the object to be detected, wherein the threshold value is smaller than the target temperature and larger than the temperature of the object to be detected.
2. The micro-nano optical fiber-based flexible thermal conductivity detection device according to claim 1, wherein: the transition region of the micro-nano optical fiber (12) is further packaged in the flexible heat-conducting packaging material (11).
3. The micro-nano fiber-based flexible thermal conductivity detection device according to claim 2, wherein: and an unstretched region of the micro-nano optical fiber (12) is also packaged in the flexible heat-conducting packaging material (11).
4. The micro-nano optical fiber-based flexible thermal conductivity detection device according to any one of claims 1 to 3, wherein: the thermo-optic coefficient of the flexible heat-conducting packaging material (11) is more than or equal to 1 multiplied by 10 -5 RIU/°C。
5. A method of testing the thermal conductivity of an object using the apparatus of any one of claims 1 to 3, comprising the steps of:
the method comprises the following steps: the central processing unit presets and stores a target temperature, wherein the target temperature is higher than the temperature of an object to be measured;
step two: the central processing unit converts the optical signal from the optical signal detection module into a temperature value, compares the temperature value with a preset target temperature, converts a comparison result into temperature control information and transmits the temperature control information to the temperature control module, and the temperature control module adjusts the temperature of the conductive coating according to the received temperature control information so that the temperature value converted by the central processing unit is constant at the preset target temperature;
step three: attaching the flexible heat-conducting packaging object to an object to be measured in a state that the temperature value converted by the central processing unit is constant at a preset target temperature, and instructing the temperature control module to stop working by the central processing unit;
step four: when the temperature value converted by the central processing unit is reduced to the threshold value, the central processing unit calculates the time required from the stop of the temperature control module to the reduction of the temperature value to the threshold value; substituting the time into a relational expression of the thermal conductivity measured by using a standard sample calibration method and the cooling time to obtain the thermal conductivity of the object to be measured; the threshold is less than the target temperature and greater than the temperature of the object to be measured.
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