CN210811072U - Tensile stress sensor and bending sensor - Google Patents

Abstract

The utility model relates to a tensile stress sensor, which comprises a first conductive fiber and a second conductive fiber, wherein the second conductive fiber is wound on the first conductive fiber to form at least one contact part between the first conductive fiber and the second conductive fiber; the area of the contact portion changes with the state that the second conductive fiber is stretched by an external force. The tensile stress sensor has the advantages of small volume, enough response, real-time monitoring, compatibility with the existing textile technology and convenience in wearing. The utility model discloses still relate to a crooked sensing device, including at least one tensile type stress sensor and flexible basement, tensile type stress sensor sets up on the flexible basement, second conductive fiber receives the crooked effect of flexible basement is tensile. The bending sensing device has the advantages of being washable, not easy to fall off, resistant to motion interference, high in resolution, high in sensitivity and compatible with the existing textile technology.

Description

Tensile stress sensor and bending sensor

Technical Field

The utility model relates to a stress sensing field especially relates to a tensile type stress sensor and crooked sensing device.

Background

Stress sensors have important applications in many aspects, such as national defense engineering and civil medical treatment, and the shadow of stress sensing can be seen everywhere, and with the development of society, the requirement on the precision of stress sensing is higher and higher.

The current stress sensing technology is mainly based on capacitance type, piezoelectric type, resistance type or friction electrification effect, etc., and most of the sensors use pressure-sensitive rubber, organic semiconductor materials, conductive polymers, etc. which are sensitive to pressure and can generate corresponding response, however, the materials have obvious disadvantages, namely large volume and insufficient response, which brings inconvenience to stress measurement.

In recent years, the skilled person has reported several types of flexible stress sensor technologies: the plain cotton fabric (CPCF) based on carbon fiber reported by MingchaoZhang et al has excellent performance in detecting human body movement through experiments; the Carbonized Silk Fabric (CSFS) material reported by Chunya Wang et al can detect large and fine human motions, which is suitable for making superelastic and highly sensitive strain sensors. Although these reported materials have excellent properties, the following problems still exist: the sensor is not sensitive enough and often requires a significant amount of deformation to produce a detectable change (e.g., resistance, capacitance, etc.).

For the above reasons, it is an urgent need for development of intelligent wearable electronic products to develop a stress sensor that has a small volume and a relatively large response with only a small amount of deformation.

SUMMERY OF THE UTILITY MODEL

Based on this, the utility model aims at providing a tensile type stress sensor, but it has small, the response is enough big, real-time supervision and compatible and the convenient advantage of dressing with current textile technology.

The utility model adopts the following technical scheme:

a tensile stress sensor comprises a first conductive fiber and a second conductive fiber, wherein the second conductive fiber is wound on the first conductive fiber to form at least one contact part between the first conductive fiber and the second conductive fiber; when viewed from a radial cross section of the first conductive fiber at the contact portion, an angle between two central axes of the second conductive fiber respectively positioned at two sides of the contact portion is less than 90 degrees; the area of the contact portion changes with the state that the second conductive fiber is stretched by an external force.

The working principle of the tensile stress sensor is as follows: when the second conductive fiber is stretched under the action of external force, the larger the external force is, the larger the area of the contact part between the first conductive fiber and the second conductive fiber is, and the smaller the resistance between the contact parts between the first conductive fiber and the second conductive fiber is; the smaller the external force is, the smaller the area of the contact part between the first conductive fiber and the second conductive fiber is, and the larger the resistance between the contact parts between the first conductive fiber and the second conductive fiber is; therefore, the change of the resistance can be measured to reflect the tensile stress of the second conductive fiber, so that the tensile stress can be sensed and detected.

The utility model discloses a tensile type stress sensor adopts two conductive fiber preparation to form, simple structure, because conductive fiber's diameter can reach very little, possess the flexibility and can weave, consequently tensile type stress sensor's volume can reach very little, facilitates the use, can also be compatible with current weaving technology and textile material fully, solves the problem that can only "wear" can not "wear" that current wearable equipment exists, simultaneously, resistance between two conductive fiber is enough big to tensile stress's response in the tensile type stress sensor, only needs trace deformation just can produce the resistance response that can be detected, so this tensile type stress sensor sensitivity is high to can real-time supervision.

The stretching type stress sensor can be used for monitoring the limb movement amplitude, and when the limb restores to the original state, the resistance of the stretching type stress sensor can also restore to the original state, so that the stretching type stress sensor is good in restorability and high in stability.

Further, when the second conductive fibers are not stretched by external force, the area of the contact part is the smallest, and at the moment, the first conductive fibers and the second conductive fibers are kept tightened to prevent the contact part from disappearing, so that the stress can be timely detected.

Furthermore, two ends of the first conductive fiber are fixed, and two ends of the second conductive fiber are fixed, so that the first conductive fiber and the second conductive fiber are always kept in a tightened state, and the disappearance of contact parts caused by relative displacement between the first conductive fiber and the second conductive fiber is avoided.

Furthermore, the first conductive fibers are arranged straightly, and two ends of the first conductive fibers are fixed respectively; the second conductive fiber is wound on the first conductive fiber, two ends of the second conductive fiber are folded in half, a contact part between the first conductive fiber and the second conductive fiber is formed, and two ends of the second conductive fiber are fixed together; the first conductive fibers and the second conductive fibers are perpendicular to each other to form a T-shaped structure. Experiments prove that after the second conductive fiber is stretched or bent for multiple times, the first conductive fiber and the second conductive fiber are not easy to generate relative displacement, the initial resistance is stable and unchanged, and the measurement error is smaller.

Furthermore, fluffy structures are respectively arranged on the contact parts of the first conductive fibers and the second conductive fibers; the lofty structure comprises a plurality of conductive fiber filaments with a plurality of interstices between the plurality of conductive fiber filaments. Technical effects

Further, the first conductive fiber is made of carbon, metal or conductive polymer material; the second conductive fiber is made of carbon, metal or conductive high polymer materials.

Another object of the present invention is to provide a bending sensor device, which includes any one of the above-mentioned tensile stress sensors and a flexible substrate, wherein the tensile stress sensors are disposed on the flexible substrate, and both ends of the first conductive fibers and both ends of the second conductive fibers are fixed on the flexible substrate; the second conductive fibers are stretched by the bending of the flexible substrate.

The working principle of the bending sensing device is as follows: when the flexible substrate is bent to stretch the second conductive fibers, the greater the bending degree of the flexible substrate is, the greater the stretching effect on the second conductive fibers is, the greater the area of the contact parts between the first conductive fibers and the second conductive fibers is, and the smaller the resistance between the contact parts between the first conductive fibers and the second conductive fibers is; the smaller the bending degree of the flexible substrate is, the smaller the stretching effect of the flexible substrate on the second conductive fibers is, the smaller the area of the contact part between the first conductive fibers and the second conductive fibers is, and the larger the resistance between the contact parts of the first conductive fibers and the second conductive fibers is; therefore, the bending state of the flexible substrate can be reflected by measuring the change of the resistance, and the sensing and the detection of the bending state are realized.

Crooked sensing device adopts foretell tensile type stress sensor as sensing unit, adopts flexible basement to bear tensile type stress sensor and implement crooked, and it can be used for the monitoring to limbs motion bending amplitude, for example is used for measuring the joint at the bending angle of 0-180 scope to when limbs resume original state, its resistance also can resume to original state, and restorability is good, and stability is high.

Crooked sensing device have can wash, be difficult for droing, anti motion interference, resolution ratio height, sensitivity height and with the compatible advantage of current textile technology.

Further, the bending sensing device comprises at least two tensile stress sensors connected in series or in parallel.

Preferably, the tensile stress sensors are connected in series with each other; in each tensile stress sensor, the first conductive fiber is arranged straightly, and two ends of the first conductive fiber are fixed respectively; the second conductive fiber is wound on the first conductive fiber, two ends of the second conductive fiber are folded in half, a contact part between the first conductive fiber and the second conductive fiber is formed, and two ends of the second conductive fiber are fixed together; the first conductive fibers and the second conductive fibers are perpendicular to each other to form a T-shaped structure.

Experiments prove that after the second conductive fiber is stretched or bent for multiple times, the first conductive fiber and the second conductive fiber are not easy to generate relative displacement, the initial resistance of the tensile stress sensor is stable and unchanged, and the measurement error of the bending angle is smaller; meanwhile, the tensile stress sensors connected in series can obtain larger resistance change, so that a stronger response signal is obtained on a circuit, and the detection sensitivity is improved.

Furthermore, the flexible substrate is a flexible circuit board, which is beneficial to the integration and miniaturization of the device.

For a better understanding and an implementation, the present invention is described in detail below with reference to the accompanying drawings.

Drawings

Fig. 1 is a schematic diagram of a basic structure of a tensile stress sensor according to the present invention;

FIG. 2 is a schematic view taken along line A-A of FIG. 1;

fig. 3 is a schematic view of a first conductive fiber or a second conductive fiber with a bulky structure;

fig. 4 is a schematic diagram of the tensile stress sensor with a fluffy structure according to the present invention;

fig. 5 is a schematic diagram of the basic structure of the bending sensor device of the present invention;

fig. 6 is a schematic structural view of the tensile stress sensor of embodiment 1;

fig. 7 is a schematic structural view of a tensile stress sensor of embodiment 2;

fig. 8 is a schematic structural view of a tensile stress sensor according to embodiment 3;

fig. 9 is a schematic structural view of a tensile stress sensor according to embodiment 4;

FIG. 10 is a schematic structural view of a bending sensor apparatus according to embodiment 5;

FIG. 11 is a schematic view showing the bending of the bending sensor device according to embodiment 5;

FIG. 12 is a graph of resistance versus bending angle for the bending sensor device of example 5;

FIG. 13 is a graph showing the results of a bending cycle test of the bending sensor device of example 5;

FIG. 14 is a schematic structural diagram of one embodiment of the bend sensor apparatus of example 6;

FIG. 15 is a schematic structural diagram of another embodiment of the bend sensor apparatus of example 6;

FIG. 16 is a side view of the bending sensor apparatus according to embodiment 6;

FIG. 17 is a schematic structural view of a bending sensor apparatus according to embodiment 7;

fig. 18 is a schematic view of bending of the bending sensor device according to embodiment 7, in which fig. 18(a) is a schematic view of the bending sensor device at a bending angle of 0 °, fig. 18(b) is a schematic view of the bending sensor device at a bending angle of 60 °, and fig. 18(c) is a schematic view of the bending sensor device at a bending angle of 90 °;

FIG. 19 is a schematic structural view of a bending sensor apparatus according to embodiment 8;

fig. 20 is a schematic structural view of the bending sensor device according to embodiment 9, in which fig. 20(a) is a schematic structural view seen from the front surface of the flexible substrate, and fig. 20(b) is a schematic structural view seen from the back surface of the flexible substrate 20 e.

Detailed Description

Please refer to fig. 1, which is a schematic diagram of a basic structure of a tensile stress sensor according to the present invention.

The utility model discloses a tensile type stress sensor 10, including first conductive fiber 11 and second conductive fiber 12, second conductive fiber 12 wind in on the first conductive fiber 11, form at least one contact site 13 between first conductive fiber 11 and the second conductive fiber 12, fig. 1 shows that second conductive fiber 12 winds and forms a contact site 13 on first conductive fiber 11, but the quantity of contact site 13 is not limited to one, can be two or more. The area of the contact portion 13 changes with a change in the state in which the second conductive fiber 12 is stretched by an external force, and the direction of the arrow in fig. 1 indicates the stretching direction.

As shown in fig. 2, when viewed in a radial cross section of the first conductive fiber 11 at each contact point 13, an angle α between two central axes of the second conductive fiber 12 on both sides of each contact point 13 is smaller than 90 °.

The working principle of the tensile stress sensor 10 is as follows: when the second conductive fiber 12 is stretched by an external force (the arrow direction in fig. 1 indicates the stretching direction), the larger the external force is, the larger the area of the contact portion 13 between the first conductive fiber 11 and the second conductive fiber 12 is, and the smaller the resistance between the contact portion 13 between the first conductive fiber 11 and the second conductive fiber 12 is; the smaller the external force is, the smaller the area of the contact portion 13 between the first conductive fiber 11 and the second conductive fiber 12 is, the larger the resistance between the contact portion 13 between the first conductive fiber 11 and the second conductive fiber 12 is; therefore, the magnitude of the tensile stress of the second conductive fiber 12 can be reflected by measuring the change of the resistance, so that the sensing and the detection of the tensile stress are realized.

In order to detect the occurrence of tensile stress in time, in one embodiment, when the second conductive fibers 12 are not stretched by an external force, the first conductive fibers 11 and the second conductive fibers 12 are kept as tight as possible to prevent the contact portions 13 from disappearing, and the area of the contact portions 13 is minimized.

In order to keep the first conductive fiber 11 and the second conductive fiber 12 always in a tight state and avoid the loss of the contact portion 13 due to the relative displacement between the two, in one embodiment, both ends of the first conductive fiber 11 are fixed, and both ends of the second conductive fiber 12 are also fixed.

In order to further improve the sensitivity of the sensing, as a preferred embodiment, as shown in fig. 3 to 4, the first conductive fibers 11 and the second conductive fibers 12 are respectively provided with fluffy structures 14 at the contact portions 13; the fluffy structure 14 comprises a plurality of conductive fiber filaments 140, a plurality of gaps exist among the plurality of conductive fiber filaments 140, and the number of the conductive fiber filaments 140 is preferably not less than ten; the conductive fiber filaments 140 in the bulky structure 14 of the first conductive fibers 11 and the conductive fiber filaments 140 in the bulky structure 14 of the second conductive fibers 12 are in contact with each other to form a plurality of conductive channels, and the total area of contact between the conductive channels is the area of the contact portion 13;

therefore, although the state of the second conductive fibers 12 stretched by the external force is slightly changed (the direction of the arrow in fig. 4 indicates the stretching direction), the number of the gaps between the conductive fiber filaments 140 in the fluffy structure 14 can be changed, so that the number of the formed conductive paths is changed, that is, the area of the contact portion 13 is changed correspondingly, thereby facilitating the detectable change of the resistance between the contact portions 13 of the first conductive fibers 11 and the second conductive fibers 12;

therefore, the first conductive fiber 11 and the second conductive fiber 12 with the fluffy structure 14 respectively are adopted to form the tensile stress sensor, so that the change of the area of the contact part 13 along with the change of the tensile state of the second conductive fiber 12 is more obvious, the sensitivity of induction is improved, and the effective induction and detection of the tiny tensile stress are realized.

Specifically, as shown in fig. 3, the conductive fiber filament 140 of the first conductive fiber 11 is arranged along the axial direction of the first conductive fiber 11, and both ends thereof are connected to the first conductive fiber 11; the conductive fiber filaments 140 in the second conductive fiber 12 are arranged along the axial direction of the second conductive fiber 12, and both ends of the conductive fiber filaments are connected with the second conductive fiber 12; however, the direction of the conductive fiber filament 140 is not limited thereto, and may be different directions perpendicular to the side surface of the first conductive fiber 11 or the second conductive fiber 12 where the conductive fiber filament is located.

Specifically, the first conductive fibers 11 are made of carbon, metal or a conductive polymer material, the second conductive fibers 12 are made of carbon, metal or a conductive polymer material, and the conductive fiber filaments 140 in the bulky structure 14 are made of carbon, metal or a conductive polymer material. In addition, the lengths and diameters of the first conductive fibers 11 and the second conductive fibers 12 are not limited, depending on the actual needs.

In the tensile stress sensor of the present invention, the second conductive fibers are wound around the first conductive fibers in a plurality of ways, and the respective arrangement of the first conductive fibers and the second conductive fibers is also in a plurality of ways, including the configurations described in the following embodiments 1 to 4, but the tensile stress sensor of the present invention is not limited to the configurations of these embodiments 1 to 4.

Please refer to fig. 5, which is a schematic diagram of a basic structure of a bending sensor according to the present invention.

The bending sensing device B of the present invention comprises at least one tensile stress sensor 10 and a flexible substrate 20, wherein the tensile stress sensor 10 is disposed on the flexible substrate 20, and both ends of the first conductive fibers 11 and both ends of the second conductive fibers 12 are fixed on the flexible substrate 20; the second conductive fibers 12 are stretched by the bending of the flexible substrate 20, and the arrows in fig. 5 indicate the bent state.

The working principle of the bending sensing device B is as follows: when the flexible substrate 20 is bent to stretch the second conductive fibers 12 (the arrow in fig. 5 indicates a bent state), the greater the degree of bending of the flexible substrate 20, the greater the stretching effect on the second conductive fibers 12, the greater the area of the contact portions 13 between the first conductive fibers 11 and the second conductive fibers 12, and the smaller the resistance between the contact portions 13 of the first conductive fibers 11 and the second conductive fibers 12; the smaller the bending degree of the flexible substrate 20 is, the smaller the stretching effect on the second conductive fibers 12 is, the smaller the area of the contact part 13 between the first conductive fibers 11 and the second conductive fibers 12 is, and the larger the resistance between the contact part 13 of the first conductive fibers 11 and the second conductive fibers 12 is; therefore, the bending state of the flexible substrate 20 can be reflected by measuring the change of the resistance, and the sensing and the detection of the bending state are realized.

In order to detect the bending state of each portion of the flexible substrate 20, in one embodiment, the bending sensing device B includes at least two tensile stress sensors 10 connected in series or in parallel, where the series is formed by connecting the resistances between the first conductive fibers 11 and the second conductive fibers 12 in each tensile stress sensor 10 in series by a connection circuit, and the parallel is formed by connecting the resistances between the first conductive fibers 11 and the second conductive fibers 12 in each tensile stress sensor 10 in parallel by a connection circuit; in a preferred embodiment, the tensile stress sensors 10 are connected in series, which is beneficial for obtaining larger resistance variation.

The flexible substrate 20 is insulating, with thickness and material depending on the actual requirements. To facilitate integration and miniaturization of the device, the flexible substrate 20 is a flexible circuit board in one embodiment.

For better packaging and protection, in one embodiment, the bending sensor device B further includes an insulating flexible protective film covering the flexible substrate 20 and the tensile stress sensor 10, and the thickness and material of the flexible protective film are determined according to actual needs.

Specifically, two or more of the tensile stress sensors 10 may be disposed on the same surface of the flexible substrate 20, so as to measure the state of the flexible substrate 20 bending toward the other surface, as shown in fig. 5; or may be respectively disposed on both surfaces of the flexible substrate 20 to implement the measurement of the state of the flexible substrate 20 bending toward any one surface thereof.

In the bending sensor device of the present invention, the arrangement of the tensile stress sensors on the flexible substrate is various, and the connection between two or more tensile stress sensors is also various, including the configurations described in the following embodiments 5 to 9, but the bending sensor device of the present invention is not limited to the configurations of the embodiments 5 to 9.

Example 1: tensile stress sensor

As shown in fig. 6, the tensile stress sensor 10a of the present embodiment includes a first conductive fiber 11a and a second conductive fiber 12a, where the first conductive fiber 11a is disposed straight and both ends thereof are fixed respectively; the second conductive fiber 12a is wound on the first conductive fiber 11a, and two ends of the second conductive fiber are folded in half to form a contact part 13 between the first conductive fiber 11a and the second conductive fiber 12a, and two ends of the second conductive fiber 12a are fixed together; the first conductive fibers 11a and the second conductive fibers 12a are perpendicular to each other to form a T-shaped structure; the area of the contact portion 13 changes according to a state in which the second conductive fiber 12a is stretched by an external force.

Example 2: tensile stress sensor

As shown in fig. 7, the tensile stress sensor 10b of the present embodiment includes a first conductive fiber 11b and a second conductive fiber 12b, wherein the first conductive fiber 11b is disposed in a straight manner, and two ends of the first conductive fiber 11b are fixed respectively; the second conductive fiber 12b is wound around the first conductive fiber 11b to form a contact portion 13 between the first conductive fiber 11b and the second conductive fiber 12b, and two ends of the second conductive fiber 12b are fixed respectively; the area of the contact portion 13 changes according to a state in which the second conductive fiber 12b is stretched by an external force.

Example 3: tensile stress sensor

As shown in fig. 8, the tensile stress sensor 10c of the present embodiment includes a first conductive fiber 11c and a second conductive fiber 12c, both ends of the first conductive fiber 11c being folded in half and fixed together; the second conductive fiber 12c is wound around the first conductive fiber 11c, and two ends of the second conductive fiber are folded in half, so as to form a contact portion 13 between the first conductive fiber 11c and the second conductive fiber 12c, and two ends of the second conductive fiber 12c are fixed together.

The first conductive fiber 11c is stretched in a direction opposite to the direction in which the second conductive fiber 12c is stretched by an external force, and when the first conductive fiber 11c is stretched, the second conductive fiber 12c is also stretched, and when the second conductive fiber 12c is stretched, the first conductive fiber 11c is also stretched, whereby the area of the contact portion 13 changes according to the state in which the first conductive fiber 11c and the second conductive fiber 12c are stretched by an external force.

Example 4: tensile stress sensor

As shown in fig. 9, the tensile stress sensor 10d of the present embodiment includes a first conductive fiber 11d and a second conductive fiber 12d, where the first conductive fiber 11d is disposed straight and both ends of the first conductive fiber are fixed respectively; the second conductive fiber 12d is spirally wound on the first conductive fiber 11d to form more than one contact portion 13 between the first conductive fiber 11d and the second conductive fiber 12 d; both ends of the second conductive fiber 12d are fixed respectively; the total area of the contact portions 13 changes according to a state in which the second conductive fibers 12d are stretched by an external force.

Example 5: bending sensor

As shown in fig. 10, the bending sensing apparatus B1 of the present embodiment includes the tensile type stress sensor 10a of embodiment 1 and a flexible substrate 20 a.

The flexible substrate 20a is a flexible circuit board, two surfaces of which are a front surface and a back surface, respectively, and fig. 10 shows the front surface of the flexible substrate 20 a; the flexible substrate 20a is provided with three through holes 201, 202 and 203, and the front surface thereof is provided with wires 31 and 32, and the wires 31 and 32 may be copper wires.

The tensile stress sensor 10a is arranged on the front surface of the flexible substrate 20a, wherein two ends of the first conductive fiber 11a are respectively fixed on the front surface of the flexible substrate 20a through silver paste, and the end parts of the two ends of the first conductive fiber 11a respectively penetrate out of the through holes 201 and 202 to the back surface of the flexible substrate 20 a; both ends of the second conductive fiber 12a are fixed together on the front surface of the flexible substrate 20a by silver paste, and both ends of the second conductive fiber 12a penetrate out to the back surface of the flexible substrate 20a from the through hole 203 together.

One end of the lead 31 is electrically connected to two ends of the first conductive fiber 11a, and the other end is a free end led out of the flexible substrate 20 a; one end of the lead wire 32 is electrically connected to two ends of the second conductive fiber 12a, and the other end is a free end led out of the flexible substrate 20 a. Specifically, the lead 31 may be fixedly connected to the silver paste at both ends of the first conductive fiber 11a without being in direct contact with the first conductive fiber 11 a; the lead wire 32 may be fixedly connected to the silver paste at both ends of the second conductive fiber 12a without being in direct contact with the second conductive fiber 12 a. The resistance between the free end of the lead 31 and the free end of the lead 32 is the resistance of the bending sensor B1.

The through holes 201, 202 and 203 are provided on the flexible substrate 20a for the ends of the first conductive fibers 11a and the second conductive fibers 12a to pass through, so that when the tensile stress sensor 10a is mounted on the front surface of the flexible substrate 20a, the ends of the first conductive fibers 11a and the second conductive fibers 12a are pulled from the back surface of the flexible substrate 20a to tighten the first conductive fibers 11a and the second conductive fibers 12a as much as possible.

The purpose of selecting the silver adhesive is that on one hand, the silver adhesive has an adhesive effect and can fix two ends of the first conductive fiber 11a and the second conductive fiber 12a, so that the first conductive fiber 11a and the second conductive fiber 12a are kept in a tightened state, and the disappearance of the contact part 13 caused by the relative displacement of the two is avoided; on the other hand, the silver paste has a conductive function, and the wires 31 and 32 are connected with the silver paste, so that non-contact electrical connection between the wire 31 and the first conductive fiber 11a and between the wire 32 and the second conductive fiber 12a can be realized, and measurement errors caused by stretching of the first conductive fiber 11a or the second conductive fiber 12a when the wires 31 and 32 move can be avoided.

As shown in FIG. 11, the relationship between the resistance of the bending sensor B1 and the bending angle β of the present embodiment was measured, specifically, the angle formed when the side of the flexible substrate 20a divided by the center line L1 was bent in the back direction was used as the bending angle β of the bending sensor B1, the bending angle β was in the range of 0-180 degrees, the center line L1 was perpendicular to the second conductive fibers 12a, the change in resistance of the bending sensor B1 was obtained by measuring the resistance value between the free end of the conductive wire 31 and the free end of the conductive wire 32;

as shown in fig. 12, it can be seen that the resistance and the bending angle β (in the range of 0-90 °) are substantially linear, indicating that the bending sensor device B1 has good sensing performance and can well use electrical signals to indicate the bending angle.

In order to verify the bending recovery performance of the bending sensor device B1, the bending sensor device B1 was mounted on the index finger joint of the robot and contacted with the index finger joint by the back surface of the flexible substrate 20a, as also shown in fig. 11, the index finger joint was bent a plurality of times at different bending angles β, and after each bending stay for a certain period of time, the bending sensor device B1 was restored to the original straight state, and the resistance of the bending sensor device B1 was detected in real time, thereby performing a bending cycle test;

the test result is shown in fig. 13, which shows a resistance curve of the bending sensing device B1 in a change process of a bending angle β of 0 ° → 10 ° → 0 ° → 15 ° → 0 ° → 5 ° → 90 ° → 45 ° → 0 °, and it can be seen that the bending sensing device B1 can still return to an original resistance after a plurality of bending, which illustrates its feasibility for detecting a bending angle of a joint in motion, and has good stability and sensitivity.

Example 6: bending sensor

As shown in fig. 14 to 16, the bending sensing device B2 of the present embodiment includes three tensile- type stress sensors 10a, 10a', and 10a "of embodiment 1, a flexible substrate 20B, and a flexible protective film 50.

The flexible substrate 20b is a flexible circuit board, and both surfaces thereof are a front surface and a back surface, respectively, and fig. 14 and 15 show the front surface of the flexible substrate 20 b.

The three tensile stress sensors 10a, 10a' and 10a ″ are all disposed on the front surface of the flexible substrate 20b, and specifically, each of the tensile stress sensors is mounted on the flexible substrate 20b in the same manner as the tensile stress sensor 10a in example 5 on the flexible substrate 20a, that is, two ends of the first conductive fiber and the second conductive fiber thereof are fixed on the front surface of the flexible substrate 20b by silver paste, and end portions of the two ends of the first conductive fiber and the second conductive fiber respectively penetrate out of the through holes on the flexible substrate 20b to the back surface thereof.

The three tensile stress sensors 10a, 10a' and 10a ″ are connected in series with each other.

Specifically, as shown in fig. 14, the three tensile stress sensors 10a, 10a ', and 10a ″ are arranged in a row and aligned up and down, and the directions of the T-shaped structures formed by the three tensile stress sensors 10a, 10a', and 10a ″ are uniform; wherein, two ends of the second conductive fiber 12a of the tensile stress sensor 10a are electrically connected with one end of the first conductive fiber 11a 'of the tensile stress sensor 10a' through a conducting wire 33, two ends of the second conductive fiber 12a 'of the tensile stress sensor 10a' are electrically connected with one end of the first conductive fiber 11a "of the tensile stress sensor 10 a" through a conducting wire 34, two ends of the second conductive fiber 12a "of the tensile stress sensor 10 a" are connected with one end 35 of the conducting wire, one end of the first conductive fiber 11a of the tensile stress sensor 10a is connected with one end of a conducting wire 36, the resistance between the other end of the conducting wire 35 and the other end of the conducting wire 36 is the resistance of the bending sensing device B2, and a resistance can be connected between the other end of the conducting wire 35 and the other end of the conducting wire 36, to measure the resistance; the leads 33, 34, 35 and 36 are all copper wires;

alternatively, as shown in fig. 15, the three tensile stress sensors 10a, 10a' and 10a ″ are arranged in a row and aligned left and right, and the directions of the T-shaped structures formed by two adjacent tensile stress sensors are opposite; wherein, one end of the first conductive fiber 11a of the tensile stress sensor 10a is electrically connected to one end of the first conductive fiber 11a 'of the tensile stress sensor 10a' through the printed circuit 41, two ends of the second conductive fiber 12a 'of the tensile stress sensor 10a' are electrically connected to one end of the first conductive fiber 11a "of the tensile stress sensor 10 a" through the printed circuit 42, two ends of the second conductive fiber 12a "of the tensile stress sensor 10 a" are connected to one end of the printed circuit 43, two ends of the second conductive fiber 12a of the tensile stress sensor 10a are connected to one end of the printed circuit 44, and the resistance between the other end of the printed circuit 43 and the other end of the printed circuit 44 is the resistance of the bending sensing device B2; the printed circuits 41, 42, 43 and 44 are all silver layers.

As shown in fig. 16, the bending sensor device B2 can be regarded as having a three-layer structure, which includes, from top to bottom, a flexible protective film 50, a sensing layer 60, and a flexible substrate 20B; wherein, the three tensile stress sensors 10a, 10a' and 10a ″ can be regarded as constituting the sensing layer 60, and the flexible protection film 50 is covered on the front surface of the flexible substrate 20b and the sensing layer 60 to play a role of encapsulation protection.

Example 7: bending sensor

As shown in fig. 17, the bending sensing apparatus B3 of the present embodiment includes two tensile type stress sensors 10e, 10f and a flexible substrate 20 c.

Each of the tensile type stress sensors has substantially the same structure as the tensile type stress sensor 10a of embodiment 1, except that: the second conductive fibers of the two tensile stress sensors 10e and 10f share one conductive fiber 12ef, the conductive fiber 12ef is perpendicular to the first conductive fibers 11e and 11f of the two tensile stress sensors 10e and 10f, respectively, and forms a T-shaped structure with the first conductive fibers 11e and 11f of the two tensile stress sensors 10e and 10f, respectively, and both ends of the conductive fiber 12ef are fixed, respectively.

The flexible substrate 20c is a flexible circuit board, two surfaces of which are a front surface and a back surface, respectively, and fig. 17 shows the front surface of the flexible substrate 20 c; six through holes 204, 205, 206, 207, 208 and 209 are arranged on the flexible substrate 20c, and the front surface thereof is provided with the leads 37 and 38, and the leads 37 and 38 can be copper wires.

The two tensile stress sensors 10e and 10f are disposed on the front surface of the flexible substrate 20c and aligned up and down, and the directions of the T-shaped structures formed by the two tensile stress sensors 10e and 10f are opposite.

Specifically, two ends of the first conductive fiber 11e of the tensile stress sensor 10e are respectively fixed on the front surface of the flexible substrate 20c through silver paste, and the ends of the two ends of the first conductive fiber 11e respectively penetrate out of the through holes 204 and 205 to the back surface of the flexible substrate 20 c; two ends of the first conductive fiber 11f of the tensile stress sensor 10f are respectively fixed on the front surface of the flexible substrate 20c through silver paste, and the end parts of the two ends of the first conductive fiber 11f respectively penetrate out of the through holes 206 and 207 to the back surface of the flexible substrate 20 c; the ends of the two ends of the conductive fiber 12ef are respectively passed out from the through holes 208,209 to the back surface of the flexible substrate 20 c.

One end of the lead 37 is electrically connected to two ends of the first conductive fiber 11e of the tensile stress sensor 10e, and the other end is a free end led out of the flexible substrate 20 c; one end of the lead 38 is electrically connected to two ends of the first conductive fiber 11f of the tensile stress sensor 10f, and the other end is a free end led out of the flexible substrate 20 c. Specifically, the lead wire 37 may be fixedly connected to the silver paste at both ends of the first conductive fiber 11e without being in direct contact with the first conductive fiber 11 e; the lead 38 may be fixedly connected to the silver paste at both ends of the first conductive fiber 11f without being in direct contact with the first conductive fiber 11 f. Thus, the two tensile stress sensors 10e and 10f are connected in series by the common conductive fiber 12ef, and the resistance between the free end of the conductive wire 37 and the free end of the conductive wire 38 is the resistance of the bending sensor B3.

In the bending sensor apparatus B3 of the present embodiment, when the side of the flexible substrate 20c divided by the center line L2 is bent toward the back, the conductive fiber 12ef is stretched, and the resistances of the two tensile stress sensors 10e and 10f are changed, so as to respond to the change of the bending state, the center line L2 is perpendicular to the middle of the conductive fiber 12 ef. Referring to fig. 18, fig. 18(a), 18(B) and 18(c) show the bending sensor apparatus B3 at bending angles of 0 ° (no bending), 60 ° and 90 °, respectively.

Example 8: bending sensor

As shown in fig. 19, the bending sensing apparatus B4 of the present embodiment includes two tensile- type stress sensors 10a, 10a' of embodiment 1 and a flexible substrate 20 d.

The flexible substrate 20d is a flexible circuit board, and both surfaces thereof are a front surface and a back surface, respectively, and fig. 19 shows the front surface of the flexible substrate 23 d.

The two tensile stress sensors 10a and 10a' are both disposed on the front surface of the flexible substrate 20d, and specifically, the mounting manner of each tensile stress sensor on the flexible substrate 20d is the same as that of the tensile stress sensor 10a in the flexible substrate 20a in example 5, that is, the two ends of the first conductive fiber and the second conductive fiber are fixed on the front surface of the flexible substrate 20d by silver paste, and the ends of the two ends of the first conductive fiber and the second conductive fiber respectively penetrate out of the through holes on the flexible substrate 20d to the back surface thereof.

The two tensile stress sensors 10a, 10a' are connected in parallel. Specifically, the two tensile stress sensors 10a and 10a 'are arranged in a left-right alignment manner, and the directions of the T-shaped structures formed by the two tensile stress sensors 10a and 10a' are consistent; wherein one end of the first conductive fiber 11a of the tensile stress sensor 10a and one end of the first conductive fiber 11a 'of the tensile stress sensor 10a' are connected together by a printed circuit 45, two ends of the second conductive fiber 12a of the tensile stress sensor 10a and two ends of the second conductive fiber 12a 'of the tensile stress sensor 10a' are connected together by a printed circuit 46, and a resistance between the printed circuit 45 and the printed circuit 46 is a resistance of the bending sensor B4; the printed circuits 45 and 46 are both silver layers.

Example 9: bending sensor

As shown in fig. 20, the bending sensing apparatus B5 of the present embodiment includes two tensile- type stress sensors 10a, 10g of embodiment 1 and a flexible substrate 20 e.

The flexible substrate 20e is a flexible circuit board, and two surfaces thereof are a front surface and a back surface, respectively, fig. 20(a) shows the front surface of the flexible substrate 20e, and fig. 20(b) shows the back surface of the flexible substrate 20 e; the flexible substrate 20e is provided with six through holes 201', 202', 203', 204', 205 'and 206', and the front surface thereof is provided with the leads 31 'and 32', and the back surface thereof is provided with the leads 33 'and 34', and the leads may be copper wires.

The two tensile type stress sensors 10a and 10g are provided on the front and back surfaces of the flexible substrate 20e, respectively.

Specifically, as shown in fig. 20(a), the tensile stress sensor 10a is mounted on the flexible substrate 20e in the same manner as the tensile stress sensor 10a in the flexible substrate 20a in example 5, that is, two ends of the first conductive fiber 11a and the second conductive fiber 12a are fixed on the front surface of the flexible substrate 20e by silver paste, and the end portions of the two ends of the first conductive fiber 11a respectively penetrate out from the through holes 201' and 202 ' on the flexible substrate 20e to the back surface thereof, and the end portions of the two ends of the second conductive fiber 12a penetrate out from the through hole 203' on the flexible substrate 20e to the back surface thereof; meanwhile, one end of the lead 31' is electrically connected to two ends of the first conductive fiber 11a, and the other end is a free end led out of the flexible substrate 20 e; one end of the lead wire 32' is electrically connected to both ends of the second conductive fiber 12a, and the other end thereof is a free end led out of the flexible substrate 20 e.

Specifically, as shown in fig. 20(b), in the tensile stress sensor 10g, two ends of a first conductive fiber 11g and a second conductive fiber 12g are fixed on the back surface of a flexible substrate 20e by silver paste, and ends of two ends of the first conductive fiber 11g respectively penetrate out from through holes 204' and 205 ' on the flexible substrate 20e to the front surface thereof, and ends of two ends of the second conductive fiber 12g penetrate out from a through hole 206' on the flexible substrate 20e to the front surface thereof; meanwhile, one end of the lead 33' is electrically connected to two ends of the first conductive fiber 11g, and the other end is a free end led out of the flexible substrate 20 e; one end of the lead wire 34' is electrically connected to both ends of the second conductive fiber 12g, and the other end thereof is a free end led out of the flexible substrate 20 e.

The two tensile stress sensors 10a and 10g are insulated from each other, and thus the two tensile stress sensors 10a and 10g independently measure, respectively, in which the tensile stress sensor 10a measures a state in which the flexible substrate 20e is bent in a rear direction thereof, and the tensile stress sensor 10g measures a state in which the flexible substrate 20e is bent in a front direction thereof, so that the bending sensor B5 can be used to measure a bending angle of more than 180 °.

The above-mentioned embodiments only represent some embodiments of the present invention, and the description thereof is specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention.

Claims (10)

1. A tensile stress sensor, characterized by: the conductive fiber comprises a first conductive fiber and a second conductive fiber, wherein the second conductive fiber is wound on the first conductive fiber to form at least one contact part between the first conductive fiber and the second conductive fiber; when viewed from a radial cross section of the first conductive fiber at the contact portion, an angle between two central axes of the second conductive fiber respectively positioned at two sides of the contact portion is less than 90 degrees; the area of the contact portion changes with the state that the second conductive fiber is stretched by an external force.

2. The tensile stress sensor of claim 1, wherein: when the second conductive fiber is not stretched by an external force, the area of the contact part is minimum.

3. The tensile stress sensor of claim 2, wherein: the two ends of the first conductive fiber are fixed, and the two ends of the second conductive fiber are fixed.

4. The tensile stress sensor of claim 3, wherein: the first conductive fibers are arranged straightly, and two ends of the first conductive fibers are fixed respectively; the second conductive fiber is wound on the first conductive fiber, two ends of the second conductive fiber are folded in half, a contact part between the first conductive fiber and the second conductive fiber is formed, and two ends of the second conductive fiber are fixed together; the first conductive fibers and the second conductive fibers are perpendicular to each other to form a T-shaped structure.

5. The tensile stress sensor of any of claims 1 to 4, wherein: the first conductive fibers and the second conductive fibers are respectively provided with fluffy structures at the contact parts; the lofty structure comprises a plurality of conductive fiber filaments with a plurality of interstices between the plurality of conductive fiber filaments.

6. The tensile stress sensor of any of claims 1 to 4, wherein: the first conductive fiber is made of carbon, metal or conductive high polymer material; the second conductive fiber is made of carbon, metal or conductive high polymer materials.

7. A bend sensing device, characterized by: comprising at least one tensile stress sensor according to any one of claims 1 to 6 and a flexible substrate on which the tensile stress sensor is disposed, both ends of the first conductive fiber and both ends of the second conductive fiber being fixed; the second conductive fibers are stretched by the bending of the flexible substrate.

8. The bend sensing device of claim 7, wherein: comprises at least two tensile stress sensors connected in series or in parallel.

9. The bend sensing device of claim 8, wherein: the tensile stress sensors are connected in series; in each tensile stress sensor, the first conductive fiber is arranged straightly, and two ends of the first conductive fiber are fixed respectively; the second conductive fiber is wound on the first conductive fiber, two ends of the second conductive fiber are folded in half, a contact part between the first conductive fiber and the second conductive fiber is formed, and two ends of the second conductive fiber are fixed together; the first conductive fibers and the second conductive fibers are perpendicular to each other to form a T-shaped structure.

10. The bend sensing device according to any one of claims 7-9, wherein: the flexible substrate is a flexible circuit board.

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