CN111999341B - Flexible thermal conductivity detection device and method based on micro-nano optical fiber - Google Patents

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

A flexible thermal conductivity detection device and method based on micro-nano optical fiber

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 technique

In the era of the Internet of Things and 5G, tactile sensors have broad application prospects in robotics, health care, intelligent manufacturing, and basic scientific research. The sense of temperature is an important part of the sense of touch, and an important basis for human beings to recognize the world and realize material recognition. At present, flexible tactile sensors with temperature detection function mainly use electrical principles, and their response time, resolution, working range and anti-electromagnetic interference performance are difficult to meet the needs of intelligent robots for high-performance temperature sensors. How to convert the temperature information into the thermal conductivity information of the measured object, and then distinguish the material of the object is an urgent need for the development of intelligent robots, and it is also a huge challenge for researchers.

The traditional thermal conductivity detection methods include steady-state method and transient method. Among them, the steady-state method refers to calculating the thermal conductivity of the sample by measuring the heat and temperature gradient flowing through the sample after the temperature distribution of the sample to be tested is stable. . It uses the equilibrium condition that the heat transfer rate is equal to the heat dissipation rate in the steady heat transfer process to measure the thermal conductivity. The steady-state method has the advantages of clear principle and simple model, but its experimental conditions are harsh and the measurement time is long. During the measurement of the transient method, a heat source is sent to transfer heat to the sample, and the temperature-time response of the sample is measured at the same time. In contrast, the transient method is widely used in practice due to its simple operation, short measurement time, and various types of samples that can be measured (such as liquid, powder, and gel). However, the current thermal conductivity sensors based on the transient method mostly use rigid structures, including rigid heat sources, temperature probes and packaging materials. Moreover, in some environments with strong electromagnetic interference, the accuracy of temperature probes based on electrical principles cannot be guaranteed. Therefore, the application in scenarios such as wearables, robots and intelligent manufacturing is limited. The development of thermal conductivity sensors with fully flexible materials and anti-electromagnetic interference has important application value in the field of tactile perception.

The micro-nano fiber is a waveguide whose waist diameter is close to or smaller than the wavelength of the transmitted light. When light is transmitted in the micro-nano fiber, a considerable part of the energy exists in the medium outside the fiber in the form of evanescent field. It has a smooth surface, The characteristics of good diameter uniformity, high mechanical properties, strong optical field confinement, strong evanescent field and surface field enhancement effect have important application prospects in the field of optical sensing. When the core of the micro-nano-fiber is encapsulated with a low-refractive-index flexible polymer with a high thermo-optic coefficient, the output light intensity of the micro-nano-fiber changes sensitively with the temperature of the flexible polymer, so the flexible polymer-encapsulated micro-nano-fiber can For temperature measurement. When the flexible polymer-encapsulated micro-nano fiber is in contact with the measured object and there is a temperature difference, by measuring the change of the output optical signal of the micro-nano fiber in real time, not only can the temperature information of the measured object be obtained, but also by analyzing the temperature change curve, it can be obtained Thermal conductivity information of the measured object. In order to imitate the constant body temperature of human beings, a flexible heater is integrated with the micro-nano fiber optic temperature sensor, so that the temperature sensor maintains a constant temperature higher than the ambient temperature when it is not in contact with the measured object. When the temperature sensor is in contact with the measured object at ambient temperature, the heating film stops working, and the thermal conductivity of the measured object is calculated by measuring the temperature drop curve when the sensor is in contact with the measured object. The temperature sensor of the present invention has the characteristics of high precision, anti-electromagnetic interference, and low cost, and is suitable for tactile perception of intelligent robots. By obtaining the thermal conductance of objects, it is helpful to realize the material identification of the measured objects.

Contents of the invention

The purpose of the present invention is to provide a flexible thermal conductivity detection device based on micro-nano optical fiber to address the deficiencies of the prior art.

In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: the flexible thermal conductivity detection device based on the micro-nano optical fiber of the present invention includes a thermal conductivity sensor, a light source and a controller; the thermal conductivity sensor includes a flexible thermal conductivity package, a micro-nano The optical fiber and the flexible heater, the flexible heater includes a flexible heat-conducting film and a conductive coating plated on the flexible heat-conducting film, the waist region of the micro-nano optical fiber and the flexible heater are encapsulated in the flexible heat-conducting package, the flexible heat-conducting package The refractive index of the object is less than the refractive index of the core of the micro-nano fiber; the controller includes a central processing unit, an optical signal detection module and a temperature control module, and the unstretched area at one end of the micro-nano fiber is connected to the output end of the light source, The unstretched area at the other end 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 optical signal of the module is converted into a temperature value and compared with the preset target temperature, and then the comparison result is converted into temperature control information and transmitted to the temperature control module. The temperature control module can adjust the electrical conductivity according to the received temperature control information. The temperature of the coating, so that the temperature value converted by the central processor is constant at the preset target temperature; when the temperature value converted by the central processor is constant at the preset target temperature, when the flexible heat-conducting package When it is attached to the object to be measured, the central processing unit can instruct the temperature control module to stop working, and when the converted temperature value drops to the threshold value, calculate the time required from the temperature control module to stop working until the temperature value drops to the threshold value, so The threshold is less than the target temperature and greater than the temperature of the object to be measured.

Furthermore, the transition region of the micro-nano optical fiber is also encapsulated in the flexible heat-conducting package of the present invention.

Further, the unstretched region of the micro-nano optical fiber is also encapsulated in the flexible heat-conducting package of the present invention.

Further, the central processing unit of the present invention can also substitute the calculated time from the stop of the temperature control module to the time required for the temperature value to drop to the threshold value into the thermal conductivity measured by using the standard sample calibration method and the cooling time. In the relational expression, the thermal conductivity of the object to be measured is obtained.

Further, the thermo-optic coefficient of the flexible heat-conducting package of the present invention is greater than or equal to 1×10 ^-5 RIU/°C.

A method for detecting the thermal conductivity of an object using the micro-nano optical fiber-based flexible thermal conductivity detection device of the present invention comprises the following steps:

Step 1: The central processing unit presets and stores the target temperature, and the target temperature is higher than the temperature of the object to be measured;

Step 2: The central processor converts the optical signal from the optical signal detection module into a temperature value and compares the temperature value with the preset target temperature, and then converts the comparison result into temperature control information and transmits it to the temperature control module. The module adjusts the temperature of the conductive coating according to the received temperature control information, so that the temperature value converted by the central processor is constant at the preset target temperature;

Step 3: When the temperature value converted by the central processing unit is constant at the preset target temperature, attach the flexible heat-conducting package to the object to be measured, and the central processing unit instructs the temperature control module to stop working;

Step 4: When the temperature value converted by the central processing unit drops to the threshold value, the central processing unit calculates the time required for the temperature control module to stop working until the temperature value drops to the threshold value; substitute this time into the standard sample calibration method to measure The thermal conductivity of the object to be measured is obtained from the obtained relationship between the thermal conductivity and the cooling time; the threshold value is less than the target temperature and greater than the temperature of the object to be measured.

Another method for detecting the thermal conductivity of an object using the micro-nano optical fiber-based flexible thermal conductivity detection device of the present invention includes the following steps:

Step 1: The central processing unit presets and stores the target temperature, and the target temperature is higher than the temperature of the object to be measured;

Step 2: The central processor converts the optical signal from the optical signal detection module into a temperature value and compares the temperature value with the preset target temperature, and then converts the comparison result into temperature control information and transmits it to the temperature control module. The module adjusts the temperature of the conductive coating according to the received temperature control information, so that the temperature value converted by the central processor is constant at the preset target temperature;

Step 3: When the temperature value converted by the central processing unit is constant at the preset target temperature, attach the flexible heat-conducting package to the object to be measured, and the central processing unit instructs the temperature control module to stop working;

Step 4: When the temperature value converted by the central processing unit drops to the threshold value, the central processing unit calculates the time required for the temperature control module to stop working until the temperature value drops to the threshold value; the central processing unit substitutes this time into the standard sample used The thermal conductivity of the object to be measured is obtained from the relationship between the thermal conductivity measured by the calibration method and the cooling time; the threshold value is less than the target temperature and greater than the temperature of the object to be measured.

Compared with the prior art, the present invention has the following beneficial effects:

(1) Structurally, the thermal conductivity sensor of the present invention uses a flexible thermally conductive package to coat the micro-nano optical fiber and the flexible heater for heat conduction, and the thermal conductivity sensor forms a closed temperature control feedback loop with the controller, thus, a single , The flexible thermal conductivity sensor realizes the miniaturized integration of temperature measurement and temperature adjustment functions under the control of the controller, and can realize accurate evaluation of the thermal conductivity of the object to be measured without adding other additional modules, and has significant lightweight features; Compared with the traditional rigid sensor structure, it is more suitable for the coupling of device applications such as wearables, robots and human-like tactile perception.

(2) In terms of detection principle, the present invention uses a flexible heat-conducting package as the cladding of the micro-nano fiber, and based on the coupling of the strong evanescent field of the transmitted light in the micro-nano fiber and the thermo-optic effect of the cladding packaging material, the thermal The flexible heat-conducting package in the conductivity sensor is in contact with the object to be measured and the temperature change is accurately measured during the heat transfer process; compared with the existing electrical sensing device, it has high sensitivity, fast response speed, and no interference from electromagnetic radiation. Advantages, more suitable for applications in extreme and special environments.

(3) When the temperature value converted by the central processing unit is constant at the preset target temperature (Temp1), once the object to be measured is attached to the flexible heat-conducting package, the flexible heat-conducting package will deform, causing the micro-nano fiber The waist area is bent, the loss increases, and the transmittance decreases, resulting in an instantaneous change in the optical signal transmitted by the micro-nano fiber to the optical signal detection module. The central processing unit orders the temperature control module to automatically stop due to a sudden change in the received optical signal. Work, avoid the measurement error caused by human operation, and improve the measurement accuracy. In the prior art, the heating of the heat source is stopped manually, and the manual operation often occurs after a period of time after the object to be measured is bonded to the flexible heat-conducting package, resulting in measurement errors caused by human operation.

(4) The thermal conductivity detection device of the present invention has the advantages of simple structure, low cost, high measurement accuracy and good repeatability, which is convenient for large-scale production in batches and has good market application prospects.

Description of drawings

Figure 1 is a schematic structural diagram of a thermal conductivity sensor, wherein Figure 1a and Figure 1b are a schematic diagram of the overall structure of the thermal conductivity sensor and a schematic diagram of the disassembly of each part;

Fig. 2 is the structural representation of micro-nano fiber;

Fig. 3 is a structural schematic diagram of a flexible heater;

Figure 4 is the process of encapsulating micro-nano optical fiber and flexible heater in a flexible heat-conducting package;

5 is an overall schematic diagram of a flexible thermal conductivity detection device based on micro-nano optical fibers;

Fig. 6 is the structural representation of controller;

Fig. 7 is a temperature drop curve after the flexible heat conduction package of the thermal conductivity sensor is in contact with the test objects of different materials.

Among them, 1-thermal conductivity sensor; 2-light source; 3-controller; 11-flexible heat-conducting package; 12-micro-nano optical fiber; 13-flexible heater; 121-one end of the unstretched area; 122-waist area; 123-the other end of the unstretched area; 131-flexible heat-conducting film; 132-conductive coating; 31-optical signal detection module interface; 32-temperature control module interface; 33-wire.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments, but the present invention is not limited.

As shown in FIG. 5 , the micro-nano fiber-based flexible thermal conductivity detection device of the present invention includes a thermal conductivity sensor 1 , a light source 2 and a controller 3 . As shown in FIG. 1a and FIG. 1b , the thermal conductivity sensor 1 includes a flexible thermally conductive package 11 , a micro-nano optical fiber 12 and a flexible heater 13 . The light source 2 is a stable light source of a tungsten-halogen lamp with a wavelength of 300-2600nm. 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-nano fiber 12 includes unstretched regions 121 , 123 at both ends, a waist region 122 in the middle, and a transition region between the waist region 122 and the unstretched regions 121 , 123 . The diameter of the waist region 122 is close to or smaller than the wavelength of the transmitted light, usually 100 nm-5 μm.

As shown in FIG. 3 , the flexible heater 13 includes a flexible heat-conducting film 131 and a conductive coating 132 plated on the flexible heat-conducting film. The flexible heat-conducting film 131 can be preferably made of polyimide (PI) polymer material, and the conductive coating 132 is preferably metal and alloy materials such as gold, silver, copper, or conductive polymer materials such as ethylenedioxythiophene (PEDOT) and polyaniline (PANI). material.

As shown in Figure 1, the waist region 122 of the micro-nano fiber 12, the transition region of the micro-nano fiber 12, and the parts of the unstretched regions 121, 123 at both ends of the micro-nano fiber 12 and the flexible heater 13 are packaged in a flexible heat-conducting package within 11. Wherein, the flexible heat-conducting package 11 is used as a cladding of the waist region 122 . It should be noted that, in the case that the necessary evanescent field can be generated around the waist region 122 when the light is transmitted in the micro-nano optical fiber 12, as an embodiment of the present invention, the flexible heat-conducting package 11 can only encapsulate the micro-nano optical fiber 12 The waist region 122 of the nano-optical fiber 12; factors such as the actual situation and requirements and the convenience of the manufacturing process can also be considered, and the packaging of the micro-nano optical fiber 12 by the flexible heat-conducting package 11 is extended from the waist region 122 to both ends, and the micro-nano optical fiber 12 The transition zone of the micro-nano fiber 12 is packaged together, or the transition zone of the micro-nano fiber 12 and a part of the unstretched zone are packaged together. Commonly, for the convenience of the packaging process, the waist region 122 of the micro-nano fiber 12, the transition region of the micro-nano fiber 12, and a part of the unstretched regions 121 and 123 at both ends of the micro-nano fiber 12 are often packaged in a flexible thermally conductive package 11.

The process of encapsulating the micro-nano optical fiber 12 and the flexible heater 13 in the flexible heat-conducting package 11 is shown in Figure 4a to Figure 4e in sequence: (a) Drop-coat 0.3ml of PDMS colloid on a clean glass slide, spin-coat after standing Form a film and cure at 80°C for 20 minutes; (b) place the stretched micro-nano optical fiber 12 in a U shape on top of the PDMS film; (c) drop-coat 0.3ml of PDMS colloid to cover the waist area of the micro-nano optical fiber 12 122, a part of the transition zone and the unstretched zone 121, and a part of the unstretched zone 123, after standing still, lay it flat and then cure it at 80°C for 20 minutes; (d) place the flexible heater 13 on the PDMS film, and conduct the conductive coating The connection between the layer 132 and the wire 33 is fixed by soldering; (e) 0.3 ml of PDMS colloid is drip-coated, it is laid flat after standing, and then cured at 80° C. for 20 minutes.

The refractive index of the flexible heat-conducting package 11 is smaller than that of the 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 package 11 is greater than or equal to 1×10 ^-5 RIU/°C, the output light intensity of the micro-nano optical fiber 12 changes with the temperature of the flexible heat-conducting package 11 sensitive. When the thermo-optic coefficient of the flexible thermally conductive package 11 is less than 1×10 ^-5 RIU/°C, the thermal conductivity sensor 1 also has sensing capability. The flexible thermally conductive package 11 is preferably made of polydimethylsiloxane (PDMS) polymer material, with a thermo-optic coefficient of 4.5×10 ^-4 RIU/°C and a refractive index of 1.4.

As shown in Figure 5, the unstretched region 121 at one end of the micro-nano fiber 12 is connected to the output end of the light source 2, and the unstretched region 123 at the other end of the micro-nano fiber 12 is connected to the optical signal detection module interface 31 of the controller 3 connected, the temperature sensed by the waist region 122 of the micro-nano fiber is detected by the optical signal detection module. The light source 2 generates an optical signal, passes through the micro-nano optical fiber 12 , and is received by the optical signal detection module of the controller 3 . 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 through a wire 33 .

The central processing unit converts the optical signal (for example, parameter information such as intensity, phase or spectrum) from the optical signal detection module into a temperature value and compares the temperature value with the preset target temperature (the target temperature should be higher than the ambient temperature) , and then convert the comparison result into temperature control information and transmit it to the temperature control module. 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 a preset value. Set the target temperature; when the temperature value converted by the central processing unit is constant at the preset target temperature, when the flexible heat-conducting package 11 is attached to the object to be measured, the flexible heat-conducting package 11 is deformed, causing The waist region 122 of the micro-nano optical fiber 12 bends, the loss increases, and the transmittance decreases, which causes the optical signal transmitted by the micro-nano optical fiber 12 to the optical signal detection module to change instantaneously, and the central processing unit is interrupted due to a sudden change in the received optical signal. Instruct the temperature control module to automatically stop working, and the central processing unit calculates the time required from the temperature control module to stop working until the temperature value drops to the threshold when the converted temperature value drops to the threshold value, wherein the threshold value is less than the preset The target temperature and greater than the temperature of the object to be measured.

As an embodiment of the present invention, the central processor converts the light intensity from the optical signal detection module and calculates the temperature value sensed by the waist region 122 of the micro-nano optical fiber; Set the target temperature value and keep it constant, the central processor can calculate the duty cycle adjustable (PWM) through the "proportional-integral-derivative" (PID) algorithm according to the converted temperature value and the preset target temperature value The duty cycle of the square wave signal, and output the PWM square wave signal to the temperature control module. The temperature control module can adjust the voltage applied to both ends of the conductive coating 132 according to the PWM square wave signal, and then adjust the output power of the conductive coating 132, thereby driving the conductive coating 132 to heat up. As the temperature of the conductive coating 132 rises, the temperature of the waist region 122 of the flexible package 11 and the encapsulated micro-nano fiber also rises accordingly until the temperature value calculated by the central processing unit reaches the set target temperature value and remains constant. At this time, the flexible heat-conducting package 11 can be pasted on the object to be tested, 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 converted temperature value drops to the threshold value, the central processing unit calculates the time ΔT required from the temperature control module to stop working until the temperature value drops to the threshold value. As a preferred embodiment of the present invention, the central processing unit can further substitute the calculated time from the temperature control module stop working until the temperature value drops to the threshold value into the thermal conductivity and cooling time measured by the standard sample calibration method In the relational formula, the thermal conductivity of the object to be measured is obtained.

The working principle of the detection device of the present invention is that the light source 2 generates an optical signal and transmits it in the micro-nano optical fiber 12 of the thermal conductivity sensor 1 . When the optical signal passes through the waist region 122 of the micro-nano fiber 12 , a strong evanescent field will be generated at the interface between the core and the cladding of the micro-nano fiber 12 . When the temperature of the flexible thermally conductive package 11 changes, its refractive index will change accordingly due to thermo-optical characteristics. As the cladding material of the waist region 122 of the micro-nano fiber 12, the change in the refractive index of the flexible heat-conducting package 11 will affect the evanescent field of the micro-nano fiber 12, thereby changing the characteristic parameters of the optical signal (including but not limited to intensity, phase, spectrum and polarization state, etc.). The controller 3 controls the heating of the flexible heater 13 packaged in the flexible heat-conducting package 11, so that the flexible heat-conducting package 11 reaches a target temperature and is higher than the ambient temperature. During the process of heat transfer between the flexible heat-conducting package 11 and the object to be measured, the controller 3 monitors the temperature change of the flexible heat-conducting package 11 during the heat transfer process by detecting the optical signal transmitted in the micro-nano optical fiber 12, It can realize the analysis of the thermal conductivity of the object to be measured.

The method of using the thermal conductivity detection device of the present invention to detect the thermal conductivity of the target object to be tested is described below with specific examples, which specifically includes the following steps:

Step 1: Preset the target temperature of the temperature control module as Temp1 (for example, 50° C.), which is higher than the temperature of the object to be measured.

Step 2: The central processor converts the optical signal from the optical signal detection module into a temperature value and compares the temperature value with the preset target temperature, and then converts the comparison result into temperature control information and transmits it to the temperature control module. The 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 the preset target temperature Temp1;

Step 3: When the temperature value converted by the central processing unit is constant at the preset target temperature Temp1, attach the flexible heat-conducting package 11 to the object to be measured, and the central processing unit instructs the temperature control module to stop working;

Step 4: When the temperature value converted by the central processing unit drops to the threshold Temp2 (Temp2 is between the preset target temperature and the temperature of the object to be measured, for example, Temp2 is 30° C.), the central processing unit can calculate the temperature automatically. The time ΔT required for the temperature control module to stop working until the temperature value drops to the threshold value is substituted into the relationship between the thermal conductivity and the cooling time measured by the standard sample calibration method, and the thermal temperature of the object to be measured can be obtained. Conductivity. It should be noted that, in the present invention, instead of calculating ΔT and the thermal conductivity of the object to be measured by the central processing unit, ΔT is manually calculated and ΔT is substituted into the thermal conductivity measured by the standard sample calibration method and In the relational expression of the cooling time, the thermal conductivity of the object to be measured is obtained.

Refer to FIG. 7 for the temperature drop curves of the flexible heat-conducting package 11 of the thermal conductivity sensor 1 after contacting the test objects of different materials.

The material of the object to be tested that can be detected by the thermal conductivity detection device of the present invention includes, but is not limited to, 304 stainless steel, glass, nylon, PVC plastic, wood, and the like.

The thermal conductivity detection device of the present invention imitates human's tactile perception, whether it is in the process of heating up the temperature of the thermal conductivity sensor 1 itself to the target temperature, or when the thermal conductivity detection of the object to be measured is performed, the flexible thermal conductivity package 11 and its packaging The micro-nano optical fiber 12 and the flexible heat-conducting film 131 conduct heat. In the process of heat transfer, when the optical signal is transmitted in the micro-nano fiber 12, the strong evanescent field of the waist region 122 of the micro-nano fiber 12 is coupled with the thermo-optical characteristics of the flexible heat-conducting package 11 covering it, and the flexible heat-conducting The change of the refractive index of the package 11 will affect the evanescent field of the micro-nano fiber 12, and then change the characteristic parameters of the optical signal, so as to accurately transmit the temperature change of the conductive coating 132 and the object to be measured to the optical signal detection module, Then the central processor converts the optical signal into a temperature value to realize accurate evaluation of the thermal conductivity of the sample to be tested. In addition, during the heating process of the thermal conductivity sensor 1 itself, the heat output of the conductive coating 132 is regulated by the controller 3 . Since the conductive coating 132 as a heat source is packaged in the flexible thermally conductive package 11, the temperature information of the conductive coating 132 is transmitted to the controller 3 via the flexible thermally conductive film 131, the flexible thermally conductive package 11, and the micro-nano optical fiber 12, thus, The thermal conductivity sensor 1 utilizes the flexible thermal conductive package 11 to coat the waist region 122 and the flexible heater 13 of the micro-nano optical fiber 12 to realize the heat conduction function, and the conductive coating 132 in the thermal conductivity sensor 1, the flexible thermal conductive film 131, the flexible The thermally conductive package 11 and the micro-nano optical fiber 12 together with the controller 3 form a closed temperature feedback loop, so that the single, flexible thermal conductivity sensor 1 realizes the miniaturization of the temperature measurement and temperature regulation functions under the control of the controller 3 Integrated, no need to add other additional modules to achieve accurate evaluation of the thermal conductivity of the object to be measured. It has a small heat capacity, and the temperature rises and falls rapidly, which can improve the rate and efficiency of thermal conductivity analysis. When the flexible heat-conducting package 11 is in contact with the object to be measured, the central processing unit can automatically trigger the temperature control module to stop working according to the change of the optical signal, so as to avoid errors caused by human operation. In addition, the detection device of the present invention has the characteristics of flexibility and light weight, and can be applied to a wide range of application scenarios.

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.

Images