CN211178305U

CN211178305U - Thin film strain gauge for elastomer strain measurement

Info

Publication number: CN211178305U
Application number: CN201922029109.9U
Authority: CN
Inventors: 齐红丽; 吴昊; 马相龙; 吴承勇; 林杰俊
Original assignee: 704th Research Institute of CSIC
Current assignee: 704th Research Institute of CSIC
Priority date: 2019-11-21
Filing date: 2019-11-21
Publication date: 2020-08-04
Anticipated expiration: 2029-11-21

Abstract

The utility model relates to a film strain gauge for measuring the strain of an elastomer, wherein an insulating isolation layer, a strain sensitive layer and a protective layer in the film strain gauge are all prepared on the elastomer, wherein the insulating isolation layer is prepared on the surface of the elastomer and is used for the electrical insulation between the whole film strain gauge and elastic alloy; the strain sensitive layer is prepared above the insulating isolation layer and used for measuring strain; the protective layer is prepared on the strain sensitive layer, and is provided with a lead electrode exposed out of the strain sensitive layer, so that the strain sensitive layer is protected from being influenced by the external environment, and the phenomena of aging, corrosion and the like of the strain sensitive layer are avoided. The utility model discloses a film strainometer is different from the tradition and pastes formula resistance strain gauge, need not introduce the paste agent to avoided the problem that hysteresis and creep are big, and had simple structure, the precision is high, the fast advantage of response speed, the elastomer of having prepared film strainometer more can satisfy other metering device's strain measurement demand.

Description

Thin film strain gauge for elastomer strain measurement

Technical Field

The utility model relates to a film strainometer, in particular to film strainometer of its small meeting an emergency of direct preparation in elastomer surface measurement.

Background

Strain measurement techniques have found widespread use in many fields. On the one hand, the most of the measurements of physical quantities such as force, torque, speed and acceleration can be converted into indirect measurements of strain, so that the strain sensor becomes the core of most measuring instruments on the market at present. On the other hand, the structure and the principle are simple, the performance is stable and reliable, and the use is convenient. Among all the strain measurement techniques, the most common resistive strain sensor based on metal materials is the following measurement principle: when the geometric shape (length or width) of the sensitive material is changed due to external physical quantity (such as force, speed, torque and the like), the resistance of the material is changed, and the actual strain size and the change of the object to be measured can be obtained by acquiring and amplifying electric signals caused by the resistance change. The principle is simple and easy to realize, and the strain of the tested sample can be obtained only by analyzing the resistance value change of the sensitive material, so that the method is widely applied.

The existing resistance-type strain sensor mainly uses a paste-type resistance strain gauge, and has the advantages of small additional mass, high precision, high response speed, capability of simultaneously performing dynamic and static measurement and the like. When the device is used, the strain foil is only needed to be pasted on an object to be measured, a certain amplifying or compensating circuit can be formed, and finally, a strain foil signal wire is led out to carry out measurement. But the use of the strain gauge needs to be closely attached to an object to be measured through glue, and the strain gauge is manually operated in a laboratory and is subjected to curing treatment. The strain gauge and an object to be measured are combined by glue, so that a plurality of problems are caused, and firstly, due to the introduction of the adhesive, the strain gauge has the defects of large hysteresis and creep deformation; secondly, the current high-quality adhesive is imported, and the difference of the quality of various adhesives influences the measuring effect of the strain gauge.

In order to overcome the disadvantages of the above-mentioned bonded resistance strain gauge, a new thin film strain gauge based on a thin film processing technology has been developed in recent years. The film strain gauge is prepared by in-situ preparing a sensitive material and a shape structure thereof on the surface of an object to be measured by utilizing film preparation processes such as evaporation, deposition, sputtering and the like. Therefore, the thin film strain gauge and the object to be measured are not fixed by using the adhesive glue any more, but are combined by strong atoms formed between the thin film strain gauge and the object to be measured, and the problems of creep aging, hysteresis and the like existing when the adhesive glue is used for insulation are solved. On the other hand, the thickness of the film strain gauge is in the micrometer or even nanometer level, the sensitivity, the measurement precision and the response speed of the film strain gauge are further improved on the basis of the adhesive resistance strain gauge, and the tiny structure can not influence the mechanical characteristics of the testing environment. Therefore the utility model discloses to naval special environmental condition, provide a film strainometer based on resistance strain effect, the elastomer that the simultaneous design is fit for the deposition film to proper position preparation film strainometer on the elastomer can realize the quick stable measurement that the elastomer is met an emergency.

Through the research on the prior art, the research on the thin film strain gauge is found, and the research results of the electronics technology university are most representative in China, for example, the university of electronics technology thesis "research on TaN thin film strain gauge for turbine blade strain measurement", "research on NiCr thin film strain gauge for turbine blade strain measurement", and the like, and the liuhao et al "research on PdCr thin film resistance strain gauge and high temperature strain sensitivity thereof", and the like, and the researched thin film strain gauges are all used for the strain measurement of the turbine blade in the high temperature situation. The utility model provides a film strainometer for elastomer measurement mainly is preparation film strainometer on the elastomer alloy, and the elastomer that the preparation has the film strainometer can regard as the strain measurement component use of other measuring equipment, and its theory of operation, structural style, suitable object all are different from the above-mentioned film strainometer who is applied to turbine blade that is mentioned.

Disclosure of Invention

The utility model discloses a to the demand of strain measurement of elastomer alloy, provide a film strainometer for elastomer strain measurement, based on the film strainometer of film processing technique, the film strainometer of preparation on the elastomer can be applied to other metering device, and the resistance value through film strainometer on the analysis elastomer changes, provides the accurate strain value of elastomer for the device, and then obtains the required physical quantity that awaits measuring of metering device.

The technical scheme of the utility model is that: a thin film strain gauge for measuring the strain of an elastic body comprises the elastic body, an insulating isolation layer, a strain sensitive layer and a protective layer, wherein the insulating isolation layer, the strain sensitive layer and the protective layer are all prepared on the elastic body; the strain sensitive layer is prepared above the insulating isolation layer and used for measuring strain; the protective layer is prepared on the strain sensitive layer, and is provided with a lead electrode exposed out of the strain sensitive layer, so that the strain sensitive layer is protected from being influenced by the external environment, and the phenomena of aging, corrosion and the like of the strain sensitive layer are avoided.

Further, the strain sensitive layer comprises an electrode, a transition grid, a sensitive grid and a transverse grid, wherein the electrode is used for leading out an electric signal of the strain sensitive layer with the resistance value changing; the electrode is connected with a sensitive grid through a transition grid, the sensitive grid is used for sensing resistance change caused by strain, and the sensitive grid is formed by a plurality of long and thin strip-shaped structures and is used for reflecting the resistance change caused by strain in the longitudinal direction to the maximum extent; the sensing grids are connected through the transverse grids, the transverse grids play a role in connecting the sensing grids, so that the overall size of the strain sensing layer is reduced, and the transverse grids are in short-circuit structures and can reduce the transverse effect of the film strain gauge.

Further, when the elastic body is deformed due to external physical quantity, the length of the sensitive grid in the strain sensitive layer is extended or shortened, and the resistance of the strain sensitive layer is changed according to the resistance strain effect, so that the resistance under the action of unknown physical quantity is output, and a strain value under the action of corresponding physical quantity is obtained according to the relationship between the resistance and the strain.

Furthermore, a signal wire is welded on an electrode of the strain sensitive layer, an electric signal generated by the film strain gauge is transmitted to the measuring circuit through the signal wire, and the measuring circuit performs temperature compensation and amplification processing, so that adverse effects of the environment on a strain measuring result are avoided.

The beneficial effects of the utility model reside in that:

the utility model discloses a film strain gauge for elastomer strain measurement is different from the tradition and pastes formula resistance strain gauge, need not introduce the paste agent to avoided lags and the big problem of creep, and had simple structure, the precision is high, the fast advantage of response speed, the elastomer of having prepared the film strain gauge more can satisfy other metering device's strain measurement demand.

Drawings

FIG. 1 is a cross-sectional view of a thin film strain gauge on elastomer;

FIG. 2 is a top view of a thin film strain gage on elastomer structure;

fig. 3 is a schematic diagram of a thin film strain gauge.

Detailed Description

The present invention will be further explained with reference to the accompanying drawings and examples.

As shown in FIGS. 1 and 2, the utility model discloses a film strain gauge for elastomer strain measurement, including elastomer 1, insulating isolation layer 2, strain sensitive layer 3 and protective layer 4. The insulation isolation layer 2, the strain sensitive layer 3 and the protective layer 4 are all prepared on the elastic body, wherein the insulation isolation layer 2 is prepared on the surface of the elastic body 1 and is used for electrical insulation between the whole thin film strain gauge and the elastic alloy; the strain sensitive layer 3 is prepared above the insulating isolation layer 2 and used for measuring strain; the protective layer 4 is prepared on the strain sensitive layer 3, and a lead electrode of the strain sensitive layer 3 needs to be exposed, so as to protect the strain sensitive layer 3 from being influenced by the external environment and avoid the phenomena of aging, corrosion and the like of the strain sensitive layer 3.

As shown in fig. 3, the strain sensitive layer 3 includes an electrode 5, a transition gate 6, a sensitive gate 7 and a lateral gate 8. The electrode 5 is used for leading out an electric signal of the change of the resistance value of the strain sensitive layer; the transition gate 6 structurally plays a role in reducing local stress; the sensitive grid 7 is a main structure for sensing resistance change caused by strain, and the structure of the sensitive grid is designed to be a long and thin strip shape, so that the resistance change caused by strain in the longitudinal direction can be reflected to the maximum extent; the transverse grating 8 serves to connect the individual sensitive gratings so as to reduce the overall size of the strain sensitive layer 3, while the transverse grating 8 should be designed as a short-circuited structure in order to reduce the lateral effects of the thin film strain gauge.

And signal wires are welded on the electrodes of the strain sensitive layer 3, an electric signal generated by the film strain gauge is transmitted to the measuring circuit through the signal wires, and the measuring circuit performs temperature compensation and amplification treatment, so that adverse effects of the environment on a strain measuring result are avoided.

The thin film strain gauge for measuring the elastic body strain can be prepared by the following preparation method, and comprises the following steps:

firstly, polishing the surface of an elastomer 1 substrate;

secondly, covering a layer of polymer on the polished elastomer substrate in the first step by adopting a spin coating method to form an insulating isolation layer 2, wherein the polymer can be electrophoretic paint;

and thirdly, realizing patterning by using a mask sputtering method or a lift-off method, and depositing a film by using a magnetron sputtering method. Sputtering an alloy film on the upper surface of the insulating isolation layer 2 formed in the second step to obtain a strain sensitive layer 3, wherein the alloy film can be selected from Cr/NiCr, Cr/CuNi and the like, the thickness of the Cr as an adhesive layer is 10-30 nm, and the thicknesses of the CuNi and the NiCr are flexibly selected between 200-500 nm;

and fourthly, covering a protective layer 4 on the strain sensitive layer 3 formed in the third step by using a spin coating method, and exposing the lead electrode by using an etching method to obtain the film strain gauge.

When the elastic body deforms under the action of unknown physical quantity, the resistance of the thin film strain gauge prepared on the surface of the elastic body is changed. Specifically, when an elastic body is deformed due to an external physical quantity, the structure of the strain sensitive layer 3 of the film strain gauge changes, the length of the sensitive grid 7 in the strain sensitive layer 3 is elongated or shortened according to the direction of the external action, and the resistance is calculated according to the formula (1):

in the formula, R is the resistance of the strain sensitive layer 3, rho is the resistivity of the material used by the strain sensitive layer 3, L is the total length of the structure to which the strain sensitive layer 3 belongs and can be approximated by multiplying the length of a sensitive grid by the number of the sensitive grid, and S is the thickness of the prepared strain sensitive layer, the change of the length of the sensitive grid can cause the resistance of the strain sensitive layer 3 to change, so that the resistance under the action of unknown physical quantity is output, and the strain value under the action of the corresponding physical quantity can be obtained by analyzing the relationship between the resistance and the strain.

Claims

1. A thin film strain gauge for measuring elastic body strain comprises an elastic body, an insulating isolation layer, a strain sensitive layer and a protective layer, and is characterized in that: the insulation isolation layer, the strain sensitive layer and the protective layer are all prepared on the elastomer, wherein the insulation isolation layer is prepared on the surface of the elastomer and is used for electrical insulation between the whole thin film strain gauge and the elastic alloy; the strain sensitive layer is prepared above the insulating isolation layer and used for measuring strain; the protective layer is prepared on the strain sensitive layer, and a lead electrode exposed out of the strain sensitive layer is arranged.

2. The thin film strain gauge for elastomeric strain measurement of claim 1, wherein: the strain sensitive layer comprises an electrode, a transition grid, a sensitive grid and a transverse grid, and the electrode is used for leading out an electric signal of the strain sensitive layer with the resistance value changing; the electrode is connected with a sensitive grid through a transition grid, the sensitive grid is used for sensing resistance change caused by strain, and the sensitive grid is formed by a plurality of long and thin strip-shaped structures and is used for reflecting the resistance change caused by strain in the longitudinal direction to the maximum extent; the sensing grids are connected through the transverse grids, the transverse grids play a role in connecting the sensing grids, so that the overall size of the strain sensing layer is reduced, and the transverse grids are in short-circuit structures and can reduce the transverse effect of the film strain gauge.

3. The thin film strain gauge for elastomeric strain measurement of claim 1, wherein: and signal wires are welded on the electrodes of the strain sensitive layer, the electric signals generated by the film strain gauge are transmitted to the measuring circuit through the signal wires, and the measuring circuit performs temperature compensation and amplification treatment.