CN-122015628-A - Three-dimensional flexible distributed strain sensor and temperature compensation strain interpretation method thereof

CN122015628ACN 122015628 ACN122015628 ACN 122015628ACN-122015628-A

Abstract

The invention discloses a three-dimensional flexible distributed strain sensor and a strain interpretation method for temperature compensation of the sensor, and relates to the technical field of intelligent sensors; the sensor body comprises an Ecoflex flexible matrix, a liquid metal micro-channel network and an annular electrode array, wherein a three-dimensional communication micro-channel structure formed by a three-dimensional printing sacrificial template process is arranged in the Ecoflex flexible matrix, the liquid metal micro-channel network is composed of gallium indium alloy filled in the three-dimensional communication micro-channel structure, and the liquid metal micro-channel network comprises an X-direction micro-channel group extending along an X-direction, a Y-direction micro-channel group extending along a Y-direction and a Z-direction micro-channel group extending along a Z-direction. The invention obviously improves the strain monitoring precision in a complex environment, effectively inhibits errors caused by temperature drift, and has the advantages of high flexibility, strong stability and good adaptability.

Inventors

TIAN CHANGJIN
XIE QINGHE
ZHANG JIANLI
ZHUO JINXIN
LI JIANG
SI JIANGTAO
ZHANG XIAONING
CHENG JINSHENG
LIU XIN
DOU SONGTAO
CUI XINZHUANG
HE GUIPING
GAO KAI
WANG PENG

Assignees

中国建设基础设施有限公司
山东大学
中建山东投资有限公司
中建八局第二建设有限公司
中国建筑土木建设有限公司

Dates

Publication Date: 20260512
Application Date: 20260212

Claims (10)

1. The three-dimensional flexible distributed strain sensor is characterized by comprising a sensor body and a signal conditioning module; the sensor body comprises an Ecoflex flexible matrix, a liquid metal micro-channel network and an annular electrode array, wherein a three-dimensional communication micro-channel structure formed by a three-dimensional printing sacrificial template process is arranged in the Ecoflex flexible matrix, the liquid metal micro-channel network is composed of gallium indium alloy filled in the three-dimensional communication micro-channel structure, the liquid metal micro-channel network comprises an X-direction micro-channel group extending along an X direction, a Y-direction micro-channel group extending along a Y direction and a Z-direction micro-channel group extending along a Z direction, the X direction, the Y direction and the Z direction are mutually orthogonal, the X-direction micro-channel group, the Y-direction micro-channel group and the Z-direction micro-channel group are mutually communicated at a space intersection, the annular electrode array is made of a flexible printed circuit board, the annular electrode array comprises a plurality of electrode units uniformly distributed along the circumferential direction of the Ecoflex flexible matrix, each electrode unit is electrically connected with a corresponding port of the liquid metal micro-channel network, the signal conditioning module comprises a direct digital frequency synthesis signal source, a current injection switching matrix and a phase lock amplification detector, the direct digital frequency synthesis signal source is used for generating excitation signals, the current injection switching matrix is used for detecting the phase-locked phase response signals, and the phase lock-locked response information is extracted by the phase-locked response information of the all-phase-locked electrode array.
2. The three-dimensional flexible distributed strain sensor of claim 1, wherein the annular electrode array comprises thirty-two electrode units.
3. The three-dimensional flexible distributed strain sensor of claim 1, wherein the swept excitation signal generated by the direct digital frequency synthesis signal source covers a low frequency band to a high frequency band.
4. The three-dimensional flexible distributed strain sensor of claim 1, wherein the current injection switching matrix is configured to switch combinations of pairs of excitation electrodes and pairs of measurement electrodes in a pattern in which adjacent electrodes inject current and opposite electrodes measure voltage.
5. A method of strain interpretation based on temperature compensation of a three-dimensional flexible distributed strain sensor as claimed in any of claims 1 to 4, comprising the steps of: Generating a sweep frequency excitation signal through a direct digital frequency synthesis signal source, sequentially traversing all electrode combinations through a current injection switching matrix to finish measurement, acquiring a voltage response amplitude and a voltage response phase through a phase-locked amplification detector, and calculating a complex impedance measured value to obtain a multi-frequency impedance spectrum original data set; step two, performing frequency domain alternating iteration resistance chromatography reconstruction processing based on total variation constraint on the multi-frequency impedance spectrum original data set, and outputting a low-frequency resistivity field distribution image and a high-frequency resistivity field distribution image; calculating temperature field distribution data and temperature compensated resistivity field distribution data according to the low-frequency resistivity field distribution image and the high-frequency resistivity field distribution image; and step four, calculating and outputting X-direction strain field distribution, Y-direction strain field distribution and Z-direction strain field distribution according to the temperature compensated resistivity field distribution data.
6. The method of claim 5, wherein in step one, the swept excitation signal is gradually increased from a start frequency to an end frequency, and after measurement of all electrode combinations is completed at each excitation frequency, all complex impedance measurements corresponding to the current excitation frequency are stored as a frame frequency impedance data, and the frequency impedance data of all excitation frequencies constitute a multi-frequency impedance spectrum raw data set.
7. The method for temperature-compensated strain interpretation according to claim 5, wherein in the second step, the frequency domain alternating iterative resistance chromatography reconstruction process includes the steps of establishing a three-dimensional regular hexahedral mesh model for a monitoring area of the sensor body, dividing the monitoring area into a plurality of regular hexahedral mesh units in an equidistant manner along an X direction, a Y direction and a Z direction respectively, assigning a three-dimensional mesh index to each regular hexahedral mesh unit, establishing a two-channel state register for each regular hexahedral mesh unit, wherein the two-channel state register includes a first channel for storing a low-frequency resistivity estimated value and a second channel for storing a high-frequency resistivity estimated value, extracting a low-frequency impedance data frame and a high-frequency impedance data frame from a multi-frequency impedance spectrum raw data set, and entering a frequency domain alternating iterative main loop, wherein each round of the frequency domain alternating iterative main loop includes a low-frequency channel updating phase, a high-frequency channel updating phase and a total variation smoothing phase which are sequentially executed.
8. The temperature-compensated strain interpretation method according to claim 7, wherein the low-frequency channel updating stage is performed by performing finite element forward electric field solving based on low-frequency resistance estimated values of all regular hexahedral mesh units to obtain a theoretical low-frequency impedance vector, subtracting the theoretical low-frequency impedance vector from a corresponding measured low-frequency impedance vector in a low-frequency impedance data frame element by element to obtain a low-frequency impedance residual vector, performing back projection operation on each residual element in the low-frequency impedance residual vector to determine a main influence unit set corresponding to each residual element, equally dividing the value of each residual element to each regular hexahedral mesh unit in the corresponding main influence unit set as a low-frequency resistance correction increment, summing all accumulated low-frequency resistance correction increments to obtain a low-frequency total correction amount, adding the low-frequency resistance total correction amount to the low-frequency resistance estimated value of the current regular hexahedral mesh unit, and writing the low-frequency resistance total correction amount back to the first channel, and the high-frequency channel updating stage performs high-frequency channel updating on the high-frequency estimated resistance value in the second channel in the same manner as the low-frequency channel updating stage.
9. The method according to claim 7, wherein the total variation smoothing stage is performed by calculating a low-frequency total variation gradient value for each regular hexahedral mesh unit, the low-frequency total variation gradient value being a sum of absolute values of low-frequency resistance difference values of the current regular hexahedral mesh unit in the X direction, the Y direction and the Z direction, dividing all regular hexahedral mesh units into low-frequency high gradient units and low-frequency flat units according to the low-frequency total variation gradient value, performing a low-frequency neighborhood mean smoothing operation for each low-frequency flat unit, taking an arithmetic average of low-frequency resistance estimated values of all neighboring units of the current low-frequency flat unit and the low-frequency resistance estimated values currently stored by the current low-frequency flat unit, and writing back to the first channel, and performing a smoothing operation in the same manner for the high-frequency resistance estimated values in the second channel.
10. The method according to claim 5, wherein in the third step, the low frequency resistivity of the current regular hexahedral mesh unit is subtracted from the high frequency resistivity of the current regular hexahedral mesh unit to obtain a frequency domain resistivity difference, the frequency domain resistivity difference is divided by a unit temperature resistivity change coefficient to obtain a temperature deviation estimate, the temperature deviation estimate is added to an environmental reference temperature value to obtain an absolute temperature estimate, and the product of the temperature deviation estimate and the unit temperature resistivity change coefficient is subtracted from the high frequency resistivity of the current regular hexahedral mesh unit to obtain a temperature compensated resistivity value.

Description

Three-dimensional flexible distributed strain sensor and temperature compensation strain interpretation method thereof Technical Field The invention relates to the technical field of intelligent sensors, in particular to a three-dimensional flexible distributed strain sensor and a temperature compensation strain interpretation method thereof. Background Three-dimensional flexible distributed strain monitoring technology has received increasing attention in recent years in the fields of civil engineering, traffic infrastructure and soft structure health monitoring. Along with the unavoidable generation of multiaxial coupling deformation of roadbeds, large-volume flexible structures and heterogeneous materials in a long-term service process, the strain sensing technology based on the single-axis or plane two-dimensional measurement method is difficult to capture the overall deformation characteristics in longitudinal, transverse and vertical directions at the same time, and particularly difficult to realize real-time identification of roadbed settlement angles, shearing deformation and local stress concentration areas. Therefore, the research of flexible strain sensors capable of forming a continuous distributed response in three dimensions, which can be deformed together with a structural body, is an important direction of development of the prior art. Most of the existing flexible strain sensors adopt metal films, metal nanowires, graphene composite materials or carbon nanotube composite materials as sensitive units, and strain states are estimated through resistance changes. Such material structures generally exhibit in-plane continuous, thickness-limited two-dimensional properties. The sensitive unit is sensitive to stretching or compression along the film surface direction, but has limited response in the thickness direction, so that the X-direction strain component, the Y-direction strain component and the Z-direction strain component which are independent and reliable from each other are difficult to obtain in a three-dimensional space. In order to extend the three-dimensional perceptibility to some extent, some technical solutions attempt to achieve a multidirectional response by stacking multiple layers of thin films or arranging conductive tracks in different directions. However, such structures have limited interlayer bond strength and are prone to delamination, fatigue damage or localized circuit failure under prolonged alternating loading, thereby affecting the continuity and stability of the measurement. Disclosure of Invention The invention aims to provide a three-dimensional flexible distributed strain sensor and a temperature compensation strain interpretation method thereof, which have the advantages of high flexibility, strong stability and good adaptability. In order to solve the technical problems, the invention adopts the following technical scheme: The three-dimensional flexible distributed strain sensor comprises a sensor body and a signal conditioning module, wherein the sensor body comprises an Ecoflex flexible substrate, a liquid metal micro-channel network and an annular electrode array, a three-dimensional communication micro-channel structure formed by a three-dimensional printing sacrificial template process is arranged in the Ecoflex flexible substrate, the liquid metal micro-channel network is composed of gallium indium alloy filled in the three-dimensional communication micro-channel structure, the liquid metal micro-channel network comprises an X-direction micro-channel group extending along an X direction, a Y-direction micro-channel group extending along a Y direction and a Z-direction micro-channel group extending along a Z direction, the X-direction micro-channel group, the Y-direction micro-channel group and the Z-direction micro-channel group are mutually orthogonal, the annular electrode array is made of a flexible printed circuit board, the annular electrode array comprises a plurality of electrode units uniformly distributed along the circumferential direction of the Ecoflex flexible substrate, each electrode unit is electrically connected with a corresponding port of the liquid metal micro-channel structure, the signal conditioning module comprises a direct digital frequency synthesis signal source, a current injection switching matrix and an amplification detector, the signal source is directly connected with the phase-locked frequency synthesis signal source, and the phase-locked frequency amplification detector is used for generating phase-locked frequency signal detection signal amplitude detection matrix. Further, the annular electrode array includes thirty-two electrode units. Furthermore, the sweep frequency excitation signal generated by the direct digital frequency synthesis signal source covers the low frequency band to the high frequency band. Further, the current injection switching matrix is used to switch the combination of the excitation electrode pa