In-situ temperature self-compensated stretchable strain sensor and preparation method thereof

Abstract

This invention relates to the field of strain sensor technology and discloses an in-situ temperature-compensated stretchable strain sensor, comprising: a flexible base layer, a first strain resistor layer, a second strain resistor layer, and an encapsulation layer; the first strain resistor layer is disposed on one side of the flexible base layer, with its curved portions all located on the inner or outer side deviating from the central axis of the flexible base layer; the second strain resistor layer is disposed on the other side of the flexible base layer, with its curved portions also located on the inner or outer side deviating from the central axis of the flexible base layer, and the deviating directions of the first and second strain resistor layers are opposite; the first and second strain resistor layers serve as sensitive resistors, and are externally connected to form a Wheatstone bridge; the encapsulation layer is used to achieve overall encapsulation. This invention can achieve accurate monitoring of pure strain signals in complex temperature-mechanical coupling fields.

Description

Technical Field

[0001] This invention relates to the field of strain sensor technology, specifically to an in-situ temperature self-compensating tensile strain sensor and its fabrication method. Background Technology

[0002] Stretchable strain sensors are typically made by patterning stretchable strain-sensitive materials on an elastic substrate. They detect biomechanical signals or object deformation by measuring changes in the conductive material parameters. Among them, resistive stretchable strain sensors have become a research hotspot in the field of flexible strain sensing due to their advantages such as stable output and good compatibility with conventional acquisition circuits.

[0003] However, in applications involving force-thermal multi-field load coupling, the signal response of resistive strain sensors originates simultaneously from the deformation of the conductive structure caused by mechanical loads and the drift of the material's intrinsic resistance caused by temperature. This results in severe signal crosstalk, causing the output to fail to accurately reflect mechanical strain. Therefore, eliminating temperature interference and acquiring pure mechanical strain signals in dynamic force-thermal coupling environments is a critical challenge that high-precision sensing urgently needs to overcome.

[0004] Existing temperature compensation strategies for resistive strain sensors mainly fall into two categories: the first is intrinsic material compensation, which reduces thermal resistance drift by selecting materials with low temperature coefficients or by doping modification. The second is ex-situ compensation, which introduces one or more independent temperature sensing elements into the sensor structure and uses the temperature response signals of these elements to cancel out temperature interference through differential circuitry or data processing.

[0005] However, intrinsic material compensation is susceptible to the instability of contact resistance in material-dominant sensors, resulting in poor linearity, significant hysteresis, and poor repeatability. It is difficult to stably eliminate temperature drift under wide temperature range or rapid temperature change conditions. Displacement compensation methods are effective in ideal uniform temperature fields, but in actual complex temperature conditions (local heat sources, non-uniform heat dissipation, or the presence of temperature gradients), the large difference in heating between a single compensation element and the strain unit leads to compensation failure. Adding multiple compensation elements will increase the system size and lead complexity, affecting miniaturization and integration. Summary of the Invention

[0006] The purpose of this invention is to provide an in-situ temperature self-compensating tensile strain sensor and its preparation method, in order to solve the technical problems in the prior art where the intrinsic compensation of materials is easily affected by the contact resistance of material-dominant sensors, resulting in poor compensation effect, and where ex-situ compensation methods are prone to compensation failure of a single compensation element under complex temperature conditions, while multiple compensation elements will significantly increase the system volume and lead wire complexity.

[0007] To solve the above-mentioned technical problems, the present invention specifically provides the following technical solution:

[0008] An in-situ temperature self-compensating tensile strain sensor, comprising:

[0009] The flexible base layer is designed with a curved structure.

[0010] The first strain resistance layer is attached to one side of the flexible base layer. In the curved portion, the first strain resistance layer is disposed on the inner or outer side that is offset from the central axis of the flexible base layer.

[0011] The second strain resistance layer is attached to the other side of the flexible base layer. In the curved part, the second strain resistance layer is disposed on the inner or outer side of the flexible base layer away from the central axis of the flexible base layer, and the first strain resistance layer and the second strain resistance layer are offset in opposite directions, so that when the flexible base layer is subjected to stress deformation, the resistance changes of the first strain resistance layer and the second strain resistance layer are equal in magnitude and opposite in direction.

[0012] The first strain resistance layer and the second strain resistance layer serve as sensitive resistors, and two external resistors are connected to form a Wheatstone bridge.

[0013] When the resistance values ​​of the first strain resistor layer and the second strain resistor layer change in the same way, the Wheatstone bridge remains balanced; when the resistance values ​​of the first strain resistor layer and the second strain resistor layer change in opposite ways, the current detection signal of the Wheatstone bridge is output.

[0014] An encapsulation layer is used to encapsulate the flexible base layer, the first strain resistance layer, and the second strain resistance layer as a whole.

[0015] Furthermore, the dimensions and initial resistance values ​​of the first strain resistance layer and the second strain resistance layer at the same position on the flexible base layer are generally equal.

[0016] Furthermore, the flexible base layer, the first strain resistance layer, and the second strain resistance layer are all composed of multiple periodically connected structural units.

[0017] Each of the structural units has at least one curved segment.

[0018] Furthermore, the curved segment is a combination of one or more of the following: circular arc, elliptical arc, and sine curve.

[0019] Furthermore, a first electrode is integrally formed at each end of the first strain resistance layer, and a second electrode is integrally formed at each end of the second strain resistance layer;

[0020] The flexible base layer has an integrally formed electrode base layer at both ends. The first electrode at the same end is attached to one side of the electrode base layer on the corresponding side. Leads are welded to the first electrode and the second electrode and connected to the Wheatstone bridge measurement circuit through the leads for signal transmission.

[0021] Furthermore, the first strain resistance layer and the second strain resistance layer are made of constantan or new constantan.

[0022] Furthermore, the flexible base layer is made of one of polyimide, polyester, phenolic resin, or epoxy resin.

[0023] Furthermore, the encapsulation layer is made of polydimethylsiloxane or Ecoflex series silicone rubber.

[0024] This invention provides a method for fabricating an in-situ temperature self-compensating tensile strain sensor, specifically including the following steps:

[0025] S10, Prepare a flexible base film and two strain resistance conductive plates, and attach the two conductive plates to the two sides of the flexible base film to form a composite laminate.

[0026] S20, using a laser to perform patterned etching on one of the conductive plates according to a preset pattern, forming a first strain resistance layer and the first electrodes at both ends;

[0027] S30, flip the composite laminate to expose the other conductive plate on top, and use a laser to pattern and etch lines on the conductive plate according to a preset pattern to form a second strain resistance layer and the second electrodes at both ends.

[0028] S40 uses a laser to perform laser etching on a flexible base film according to a preset pattern, penetrating the composite laminate to etch out the flexible base and the electrode base at both ends.

[0029] S50, Prepare the encapsulation layer and fix the encapsulation layer to cover the outer surfaces of the first strain resistance layer and the second strain resistance layer.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] This invention sets the first and second strain resistance layers off-axis from the central axis of the flexible substrate, with opposite directions of offset. Combined with the working characteristics of a Wheatstone bridge, when the temperature changes, the first and second strain resistance layers produce the same resistance change, keeping the Wheatstone bridge balanced and thus offsetting the interference caused by temperature drift. When the flexible substrate is subjected to deformation, the first and second strain resistance layers produce opposite resistance changes, and the Wheatstone bridge outputs a current-sensing signal, reflecting pure mechanical strain. This eliminates the need for additional independent temperature sensing elements, achieving temperature self-compensation under complex temperature conditions. Simultaneously, it overcomes the problems of poor linearity, significant hysteresis, and poor repeatability inherent in existing material intrinsic compensation methods, ensuring stable temperature compensation even under complex conditions such as wide temperature ranges and rapid temperature changes. Attached Figure Description

[0032] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0033] Figure 1 A schematic diagram of the layered structure of an in-situ temperature self-compensating tensile strain sensor provided in an embodiment of this application;

[0034] Figure 2 This is a planar schematic diagram of the first strain resistance layer, the second strain resistance layer, and the flexible substrate in an embodiment of the present invention;

[0035] Figure 3 This is a planar schematic diagram of the first strain resistance layer, the second strain resistance layer, the straight segment and the curved segment of the flexible substrate in an embodiment of the present invention;

[0036] Figure 4 This is a diagram showing the connection structure of the first strain gauge layer and the second strain gauge layer connected to the Wheatstone bridge in an embodiment of the present invention.

[0037] Figure 5 This is a process flow diagram of a method for fabricating an in-situ temperature self-compensating tensile strain sensor provided in an embodiment of the present invention.

[0038] The reference numerals in the figure are as follows:

[0039] 1. Flexible base layer; 2. First strain gauge layer; 3. Second strain gauge layer; 4. Encapsulation layer; 5. Wheatstone bridge; 6. Structural unit; 7. First electrode; 8. Second electrode; 9. Electrode base layer;

[0040] 601. Curved section; 602. Straight section. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0042] like Figure 1 , Figure 2 , Figure 4 As shown, the in-situ temperature self-compensating stretchable strain sensor provided in this application comprises: a flexible base layer 1, a first strain resistor layer 2, a second strain resistor layer 3, and an encapsulation layer 4.

[0043] The flexible base layer 1 is designed as a curved structure;

[0044] The first strain resistance layer 2 is attached to one side of the flexible base layer 1. The first strain resistance layer 2 is disposed on the inner or outer side of the flexible base layer 1 in the curved part.

[0045] The second strain resistor layer 3 is attached to the other side of the flexible base layer 1. The second strain resistor layer 3 is disposed on the inner or outer side of the flexible base layer 1 in the curved part, and the first strain resistor layer 2 and the second strain resistor layer 3 are offset in opposite directions, so that when the flexible base layer 1 is subjected to stress deformation, the resistance changes of the first strain resistor layer 2 and the second strain resistor layer 3 are equal in magnitude and opposite in direction.

[0046] The first strain resistance layer 2 and the second strain resistance layer 3 serve as sensitive resistors, and two external resistors are connected to form a Wheatstone bridge 5.

[0047] When the resistance values ​​of the first strain resistor layer 2 and the second strain resistor layer 3 change in the same way, the Wheatstone bridge 5 remains balanced; when the resistance values ​​of the first strain resistor layer 2 and the second strain resistor layer 3 change in opposite ways, the current detection signal of the Wheatstone bridge 5 is output.

[0048] The encapsulation layer 4 is used to encapsulate the flexible base layer 1, the first strain resistance layer 2, and the second strain resistance layer 3 as a whole.

[0049] In this invention, the first strain resistance layer 2 and the second strain resistance layer 3 are offset from the central axis of the flexible base layer 1, and the offset directions are opposite. Combined with the working characteristics of the Wheatstone bridge 5, when the temperature changes, the first strain resistance layer 2 and the second strain resistance layer 3 produce the same resistance change, and the Wheatstone bridge 5 remains balanced, thereby canceling the interference caused by temperature drift. When the flexible base layer 1 is deformed by force, the first strain resistance layer 2 and the second strain resistance layer 3 produce opposite resistance changes, and the Wheatstone bridge 5 outputs a current detection signal, reflecting pure mechanical strain. There is no need to add an additional independent temperature sensing element, realizing temperature self-compensation under complex temperature conditions. At the same time, it gets rid of the problems of poor linearity, obvious hysteresis, and poor repeatability of the intrinsic compensation of existing materials. It can still stably achieve temperature compensation under complex conditions such as wide temperature range and rapid temperature change.

[0050] The following is a detailed explanation: Material-driven sensors operate based on the principle of contact resistance. Through low-temperature coefficient materials or doping modifications, when subjected to external stretching, the unstable reconstruction of the conductive network inside the material causes slight and irreversible shifts in particle spacing, the number of contact points, etc., resulting in continuous random changes in contact resistance. This leads to unstable resistance and an inability to achieve a monotonically ideal correspondence between the resistance value and the applied external force, resulting in poor linearity. In contrast, this solution is based on the principle of non-contact resistance, transforming external tensile strain into the geometric deformation of an integrated strain resistance layer. When subjected to external stretching, there are no unstable contact relationships such as particle spacing or the number of contact points inside the material. Therefore, the resistance change strictly follows the formula for material geometric dimension change, resulting in an excellent linear correspondence between the external force input and the resistance output.

[0051] Hysteresis refers to the phenomenon where a sensor outputs inconsistent resistance values ​​for the same strain during loading (stretching) and unloading (retraction), manifested as the loading curve and unloading curve not coinciding. For existing material-dominated sensors, the conductive microstructure separates or rearranges during loading, and during unloading, due to the hysteresis of the elastic body and friction and adhesion between particles, the microstructure cannot accurately return to its original contact state, resulting in significantly different loading and unloading paths and obvious hysteresis. In contrast, the integrated metal strain gauge layer combined with the flexible base layer 1 in this solution allows the deformation of the strain gauge layer to be entirely dominated by the recoverable elastic deformation of the metal lattice during stretching and retraction. After unloading, the flexible base layer 1 provides a definite and rapid rebound force, enabling the strain gauge layer to accurately restore its original geometry. The loading and unloading paths highly coincide, thus achieving extremely low hysteresis.

[0052] Repeatability refers to the consistency of the output signals when a sensor performs multiple cyclic measurements of the same mechanical strain under identical conditions. For existing material-dominated sensors, the conductive network undergoes irreversible plastic failure or rearrangement after the first stretching, and the contact state continues to evolve in subsequent cycles, leading to baseline drift and sensitivity decay, resulting in poor repeatability. In contrast, in this solution, the integrated metal strain resistor layer structure operates within the elastic strain range, and the metal lattice arrangement is reversible, repeating the exact same physical deformation process in each loading or unloading cycle.

[0053] Material-driven sensors suffer from poor linearity, significant hysteresis, and poor repeatability. This stems from the irreversible rearrangement and contact state evolution of their conductive microstructures during stretching and retraction. Under wide temperature ranges or rapid temperature changes, these variations exacerbate the instability of the microscopic contact interface, causing random fluctuations in contact resistance and thermal stress drift. This further disrupts the already nonlinear signal, making it impossible to establish a reliable temperature drift compensation model. In contrast, this solution employs an integrated continuous metallic strain resistor layer and an off-axis curved laminate structure. The resistance change is entirely based on the recoverable elastic deformation of the material's geometry, without involving any variable contact interface. Therefore, it exhibits extremely high linearity, extremely low hysteresis, and excellent repeatability throughout the entire measurement range. This ensures that the mechanical strain signal itself is pure, monotonic, and highly predictable. Based on this, the first strain resistance layer 2 and the second strain resistance layer 3 are respectively attached to the upper and lower surfaces of the flexible base layer 1 to form a stacked structure, so that the two maintain the same heating temperature under any non-uniform temperature field or rapid temperature change, and the resistance changes the same when heated. After connecting to the Wheatstone bridge 5, the temperature drift as a common mode signal is completely suppressed, thereby achieving stable in-situ temperature self-compensation under wide temperature range and rapid temperature change conditions.

[0054] The first strain resistance layer 2 and the second strain resistance layer 3 are respectively attached to the upper and lower surfaces of the flexible base layer 1. They adopt a stacked arrangement structure in the thickness direction, so that the two are always in the same heat transfer path. This ensures that even under complex working conditions such as temperature gradient, local heating or non-uniform heating, the two can maintain a consistent heating temperature, thus eliminating the failure of the off-site compensation method under complex temperature conditions (local heat source, non-uniform heat dissipation or temperature gradient).

[0055] This embodiment provides an in-situ temperature self-compensating tensile strain sensor, which mainly addresses the temperature drift offset technology for signal crosstalk problems existing in existing resistive tensile strain sensors under force-thermal multi-field coupling conditions.

[0056] Specifically, by setting the flexible base layer 1 as a curved structure, the first strain resistance layer 2 and the second strain resistance layer 3 are attached to its two sides respectively, so that the two strain resistance layers are both deviated from the central axis of the flexible base layer 1 and the deviation direction is opposite. At the same time, the two strain resistance layers are used as sensitive resistors and connected to two external resistors to form a Wheatstone bridge 5. By utilizing the characteristics that the resistance values ​​of the two strain resistance layers change synchronously when the temperature changes, keeping the bridge in balance, and the resistance values ​​of the two strain resistance layers change in opposite directions when subjected to force deformation, the bridge outputs a current detection signal. The automatic cancellation of temperature interference is achieved from the structural design, without the need to add an additional independent temperature sensing element. This avoids the inherent defects of material intrinsic compensation and solves the applicability problem of off-site compensation.

[0057] The first strain resistor layer 2 and the second strain resistor layer 3 are attached to the curved structure of the flexible base layer 1 and are set in a direction opposite to the central axis of the curved structure. This allows the first strain resistor layer 2 and the second strain resistor layer 3 to follow the opposite direction of deformation when the flexible base layer 1 is subjected to stress, thus producing changes in opposite directions.

[0058] Specifically, such as Figure 3 As shown, for example, the curved portion of the first strain resistor layer 2 is set inside the centerline of the flexible base layer 1, and the curved portion of the second strain resistor layer 3 is set outside the centerline of the flexible base layer 1. When the flexible base layer 1 is subjected to tension, the curved portion of the first strain resistor layer 2 is stretched, which increases the resistance, and the curved portion of the second strain resistor layer 3 is compressed, which decreases the resistance. Since the amount of stretching and compression is equal, the increase and decrease in resistance are equal.

[0059] The dimensions and resistance values ​​of the first strain resistance layer 2 and the second strain resistance layer 3 at the same position on the flexible base layer 1 are equal. The purpose is to ensure that the initial resistance values ​​of the first strain resistance layer 2 and the second strain resistance layer 3 are equal, thereby ensuring that the Wheatstone bridge 5 is in a balanced state at the beginning, preventing zero-point drift caused by the difference in initial resistance, and laying the foundation for subsequent temperature interference cancellation and accurate detection of mechanical strain.

[0060] The flexible base layer 1, the first strain resistance layer 2, and the second strain resistance layer 3 are all composed of multiple periodic structural units 6 connected end to end.

[0061] Each structural unit 6 has at least one bending segment 601.

[0062] The curved structure is composed of multiple periodic structural units 6 connected end to end. This structural design has the following technical effects:

[0063] 1. When the sensor is subjected to a large external force, the total deformation applied to the flexible base layer 1 can be evenly distributed to each periodic structural unit 6, effectively avoiding the phenomenon of deformation concentration in local areas, thereby significantly improving the repeatability and linearity of sensor measurements.

[0064] 2. Multiple periodic structural units 6 are connected in series, which can appropriately increase the total resistance of the first strain resistor layer 2 and the second strain resistor layer 3, making it easier to detect the change in resistance of the two strain resistor layers when subjected to force deformation or temperature change, thereby improving the strain detection sensitivity of the sensor.

[0065] 3. The arrangement of multiple periodic structural units 6 can provide a larger sensing area for the sensor, while giving the sensor more flexible size adjustment space. According to the needs of actual application scenarios, the number of periodic structural units 6 can be adjusted to make the sensor adapt to different installation spaces and sensing requirements.

[0066] Among them, the bending section 601 has a large tensile allowance and deformation buffering capacity, which allows the flexible base layer 1 to achieve a large range of tensile deformation through the stretching of the bending section 601 when subjected to tension, thus ensuring the structural integrity and working stability of the sensor under large strain conditions.

[0067] The curved segment 601 is a combination of one or more of the following structures: circular arc, elliptical arc, and sine curve.

[0068] In addition, each structural unit 6 also includes a straight segment 602. When a structural unit 6 contains two curved segments 601, the two curved segments 601 are respectively connected to the two ends of the straight segment 602 and located on both sides of the straight segment 602. The two curved segments 601 have opposite bending directions, and adjacent structural units 6 are smoothly connected through the curved segments 601.

[0069] The first strain resistance layer 2 has a first electrode 7 integrally formed at both ends, and the second strain resistance layer 3 has a second electrode 8 integrally formed at both ends.

[0070] The flexible base layer 1 has an electrode base layer 9 integrally formed at both ends. The first electrode 7 at the same end is attached to one side of the electrode base layer 9 on the corresponding side, and the second electrode 8 at the same end is attached to the other side of the electrode base layer 9 on the corresponding side. Leads are welded to the first electrode 7 and the second electrode 8 and connected to the Wheatstone bridge measurement circuit through the leads for signal transmission.

[0071] The first strain resistance layer 2 and the second strain resistance layer 3 respectively acquire resistance change signals within the characterization area through the first electrode 7 and the second electrode 8.

[0072] Meanwhile, the electrode base layer 9 provides a stable support for the first electrode 7 and the second electrode 8, reducing the impact of electrode position displacement on signal transmission during sensor deformation, ensuring that the Wheatstone bridge 5 can accurately receive the resistance change signals of the two strain resistance layers, and further improving the accuracy of temperature compensation and strain.

[0073] The first strain resistance layer 2 and the second strain resistance layer 3 are made of constantan or new constantan.

[0074] Constantan has the characteristics of stable resistivity, small temperature coefficient of resistance, moderate strain sensitivity coefficient and good long-term stability. It can effectively reduce the impact of temperature drift on detection accuracy and ensure that the strain sensor has high measurement accuracy and working stability under different temperature environments.

[0075] The materials for the first strain gauge layer 2 and the second strain gauge layer 3 can also be selected from gold, aluminum, copper, nickel-chromium alloy, nickel-chromium-aluminum alloy, iron-chromium-aluminum alloy, platinum, and platinum-tungsten alloy. These materials have the characteristics of stable resistivity, small temperature coefficient of resistance, moderate strain sensitivity coefficient and good long-term stability, which can effectively reduce the impact of temperature drift on detection accuracy and ensure that the strain sensor has high measurement accuracy and working stability under different temperature environments.

[0076] The flexible base layer 1 is made of one of polyimide, polyester, phenolic resin, or epoxy resin. These materials have high mechanical strength, excellent flexibility and dimensional stability, providing a stable and reliable support substrate for the first strain resistance layer 2 and the second strain resistance layer 3 on both sides.

[0077] The encapsulation layer 4 is made of polydimethylsiloxane or Ecoflex series silicone rubber. These materials have high elasticity, low modulus, good ductility and biocompatibility. While achieving effective encapsulation protection, they can significantly reduce the constraints on the deformation of the first strain resistor layer 2 and the second strain resistor layer 3, ensure strain transfer efficiency and improve the overall tensile performance and service life of the sensor.

[0078] Furthermore, both the polyimide flexible base layer 1 and the Ecoflex encapsulation layer 4 possess excellent anti-creep and anti-fatigue properties, which can further optimize repeatability.

[0079] This invention provides a method for fabricating an in-situ temperature self-compensating tensile strain sensor, specifically including the following steps:

[0080] S10, Prepare a flexible base film and two strain resistance conductive plates, and attach the two conductive plates to the two sides of the flexible base film to form a composite laminate.

[0081] S20, using a laser to perform patterned etching on one of the conductive plates according to a preset pattern, forming a first strain resistance layer and the first electrodes at both ends;

[0082] S30, flip the composite laminate to expose the other conductive plate on top, and use a laser to pattern and etch lines on the conductive plate according to a preset pattern to form a second strain resistance layer and the second electrodes at both ends.

[0083] S40 uses a laser to perform laser etching on a flexible base film according to a preset pattern, penetrating the composite laminate to etch out the flexible base and the electrode base at both ends.

[0084] S50, Prepare the encapsulation layer and fix the encapsulation layer to cover the outer surfaces of the first strain resistance layer and the second strain resistance layer.

[0085] This invention uses a laser rapid patterning process to replace traditional photolithography, simplifying the complex multi-step process into three laser processing steps. Double-sided patterning can be completed with a single flip, which greatly shortens the preparation cycle, reduces process costs, and facilitates rapid design iteration and customized development.

[0086] Specifically, the laser is an ultraviolet picosecond laser, with a wavelength of 385nm, a repetition frequency of 100-2000 kHz, and a pulse width of 20ps.

[0087] By controlling the laser pulse energy, spot overlap rate, and number of processing steps, the first and second strain resistance layers in S30 and S40 are etched so that the etching depth removes only the first and second strain resistance layers without damaging the flexible substrate, or causing only minor damage to the flexible substrate.

[0088] In this embodiment, the entire preparation process requires only one manual flip, and the rest of the operations are completed automatically by the laser system, which significantly simplifies the process flow. Compared with the traditional photolithography process, this method does not require photoresist, mask and development steps, and the processing time is shortened from more than 10 hours to about 1 hour (based on 10 cm × 10 cm sheet), and it is easy to realize design iteration and mass production.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. All such modifications or substitutions should be covered within the protection scope of this application, and should not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application. Therefore, the protection scope of this application should be determined by the protection scope of the claims.

Claims

1. A self-compensating in-situ temperature tensile strain sensor, characterized in that, have: The flexible base layer (1) is configured as a curved structure; The first strain resistance layer (2) is attached to one side of the flexible base layer (1). The first strain resistance layer (2) is disposed on the inner or outer side of the flexible base layer (1) in the curved part. The second strain resistance layer (3) is attached to the other side of the flexible base layer (1). The second strain resistance layer (3) is located on the inner or outer side of the flexible base layer (1) in the curved part. The first strain resistance layer (2) and the second strain resistance layer (3) are offset in opposite directions. This is so that when the flexible base layer (1) is subjected to stress deformation, the resistance changes of the first strain resistance layer (2) and the second strain resistance layer (3) are equal in magnitude and opposite in direction, thereby achieving temperature compensation in the strain measurement process. The first strain resistance layer (2) and the second strain resistance layer (3) serve as sensitive resistors, and two fixed resistors are connected externally to form a Wheatstone bridge (5). When the resistance values ​​of the first strain resistor layer (2) and the second strain resistor layer (3) change in the same way, the Wheatstone bridge (5) remains balanced; when the resistance values ​​of the first strain resistor layer (2) and the second strain resistor layer (3) change in opposite ways, the current detection signal of the Wheatstone bridge (5) is output. The encapsulation layer (4) is used to encapsulate the flexible base layer (1), the first strain resistance layer (2) and the second strain resistance layer (3) as a whole.

2. The in-situ temperature self-compensating tensile strain sensor according to claim 1, characterized in that, The first strain resistance layer (2) and the second strain resistance layer (3) have the same size and initial resistance value at the same position on the flexible base layer (1).

3. The in-situ temperature self-compensating tensile strain sensor according to claim 1, characterized in that, The curved structure of the flexible base layer (1), the first strain resistance layer (2) and the second strain resistance layer (3) is composed of multiple periodic end-to-end structural units (6); Each of the structural units (6) has at least one curved segment (601).

4. The in-situ temperature self-compensating tensile strain sensor according to claim 3, characterized in that, The curved segment (601) is a combination of one or more of the following: circular arc, elliptical arc, and sine curve.

5. The in-situ temperature self-compensating tensile strain sensor according to claim 1, characterized in that, The first strain resistance layer (2) has a first electrode (7) integrally formed at both ends, and the second strain resistance layer (3) has a second electrode (8) integrally formed at both ends. The flexible base layer (1) has an electrode base layer (9) integrally formed at both ends. The first electrode (7) at the same end is attached to one side of the electrode base layer (9) on the corresponding side, and the second electrode (8) at the same end is attached to the other side of the electrode base layer (9) on the corresponding side. Leads are welded to the first electrode (7) and the second electrode (8) and connected to the Wheatstone bridge measurement circuit through the leads for signal transmission.

6. The in-situ temperature self-compensating tensile strain sensor according to claim 1, characterized in that, The first strain resistance layer (2) and the second strain resistance layer (3) are made of constantan or new constantan.

7. The in-situ temperature self-compensating tensile strain sensor according to claim 1, characterized in that, The flexible base layer (1) is made of one of polyimide, polyester, phenolic resin, or epoxy resin.

8. The in-situ temperature self-compensating tensile strain sensor according to claim 1, characterized in that, The encapsulation layer (4) is made of polydimethylsiloxane or Ecoflex series silicone rubber.

9. A method for fabricating an in-situ temperature self-compensating tensile strain sensor according to claims 1-8, characterized in that, Specifically, the following steps are included: S10, Prepare a flexible base film and two strain resistance conductive plates, and attach the two conductive plates to the two sides of the flexible base film to form a composite laminate. S20, using a laser to perform patterned etching on one of the conductive plates according to a preset pattern, forming a first strain resistance layer and the first electrodes at both ends; S30, flip the composite laminate to expose the other conductive plate on top, and use a laser to pattern and etch lines on the conductive plate according to a preset pattern to form a second strain resistance layer and the second electrodes at both ends. S40 uses a laser to perform laser etching on a flexible base film according to a preset pattern, penetrating the composite laminate to etch out the flexible base and the electrode base at both ends. S50, Prepare the encapsulation layer and fix the encapsulation layer to cover the outer surfaces of the first strain resistance layer and the second strain resistance layer.

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