Planar tensile testing device for flexible materials

Abstract

This utility model relates to the field of medical device testing, and more specifically, to a planar tensile testing device using flexible materials. It includes a tensile device capable of applying tensile force and a testing device. The tensile device includes a base and multiple tensile components mounted on the base. The testing device includes a testing host, a stress sensor, and an impedance sensor connected to the testing host. By applying tensile force to a flexible thin-film electrode using the tensile device to achieve planar tensile testing, the testing device measures the tensile force experienced by the flexible thin-film electrode and the impedance value at the electrode points, thereby evaluating the safety, comfort, signal stability, and long-term reliability of the flexible thin-film electrode.

Description

Technical Field

[0001] This utility model relates to the field of medical device testing, and more specifically, to a planar tensile testing device using flexible technology materials. Background Technology

[0002] Flexible thin-film electrodes are electrodes that combine flexibility and thin-film properties. They typically consist of a flexible substrate, a conductive layer, a functional layer, and an encapsulation layer. The flexible substrate provides mechanical support, ensuring the electrode can be bent and stretched. The conductive layer is the core functional layer, directly responsible for the acquisition or stimulation of electrical signals, providing the conduction path for the electrical signals, and must balance high conductivity and flexibility. The functional layer is designed for specific applications. The encapsulation layer protects the electrode from environmental corrosion (sweat, oxygen), improving durability. Flexible thin-film electrodes are typically on the micrometer scale in thickness, lightweight, suitable for attachment to irregular surfaces, and can be bent, folded, or stretched. They maintain low resistance and high electrochemical activity under bending, folding, or stretching conditions, making them suitable for wearable devices, flexible electronics, biomedicine, and other fields.

[0003] In recent years, flexible thin-film electrodes have become a research hotspot in the field of wearable physiological monitoring due to their ultra-thinness, stretchability, and high conformability. Flexible thin-film electrodes are typically fabricated using flexible substrate materials combined with highly conductive materials. They adapt to the complex curvature and dynamic movements of human skin, closely conforming to the skin, reducing motion artifacts, and improving signal acquisition stability. In flexible electrocardiogram (ECG) monitoring, low-impedance contact is achieved through microstructure design or conductive polymer coatings, allowing for stable ECG signal acquisition without the need for gels. Furthermore, flexible electrodes can integrate wireless transmission modules to achieve remote dynamic ECG monitoring, suitable for long-term management of cardiovascular disease patients. In flexible electromyography (EMG) monitoring, flexible thin-film electrodes, with their excellent mechanical adaptability, can stretch and contract with the skin without detaching, ensuring the continuity and accuracy of EMG signals. In flexible body temperature monitoring, flexible temperature sensors can be fabricated using ultra-thin thermistoric or thermoelectric materials to create large-area arrays, enabling real-time dynamic monitoring of skin temperature, which has significant application value in areas such as fever early warning and sports medicine. In flexible ultrasound monitoring, flexible materials are combined with ultrasound electronic devices, and a stretchable transducer deformation array is used to enable signals to penetrate the skin and achieve tissue imaging monitoring, or the Doppler effect is used to measure blood flow velocity and achieve arterial / venous signal monitoring.

[0004] Flexible thin-film electrodes are worn on the user's skin during use. The dynamic deformation of human skin (such as joint bending, muscle contraction, and respiratory movements) causes repeated deformation. Therefore, it is necessary to test the mechanical and electrical properties of the flexible thin-film electrodes under stretching, as well as the quality of the acquired signals, to ensure stable, reliable, and safe operation in practical applications. Flexible thin-film electrodes are used in products such as flexible ECG, flexible electromyography, flexible body temperature measurement, and flexible ultrasound. However, there is no dedicated testing device for measuring the mechanical and electrical properties of flexible thin-film electrodes under stretching. Utility Model Content

[0005] The present invention aims to overcome at least one defect (deficiency) of the prior art and provide a planar tensile testing device using flexible technology materials to solve the problem of the lack of devices on the market for testing the mechanical and electrical properties of flexible thin film electrodes under tension.

[0006] The technical solution adopted by this utility model is a planar tensile testing device using flexible technical materials, including a tensile device capable of applying tensile force and a testing device. The tensile device includes a base and multiple tensile components disposed on the base. The testing device includes a testing host, a stress sensor and an impedance sensor connected to the testing host.

[0007] The mechanical properties of flexible thin-film electrodes are related to their safety, comfort, signal stability, and long-term reliability during use, and typically involve their mechanical strength, elasticity, and durability. Different users and different application sites will stretch the thin-film electrodes to varying degrees. Mechanical property testing can verify whether flexible wearable devices can adaptively adjust and ensure they are not easily torn or permanently deformed.

[0008] The impedance of the electrode points of a thin-film electrode directly affects signal quality and system performance. During stretching and expansion, not only should the impedance of a single electrode point be within the specified range, but the impedance of all electrode points should also be as consistent as possible. If the impedance is too high, it will cause signal attenuation and increased noise. Impedance imbalance will cause large differences in signal amplitude between different channels, affecting spatial resolution and causing signal distortion. Impedance testing can also reflect the contact state between the electrode point and biological tissue.

[0009] When in use, the stretching device applies a tensile force to the flexible thin film electrode, causing the flexible thin film electrode to be stretched. The stress sensor is set on the stretching device to test the tensile force experienced by the flexible thin film electrode when it is stretched, and the impedance sensor is set on the thin film electrode to test the impedance change of the electrode point when the flexible thin film electrode is stretched.

[0010] Furthermore, the plurality of stretching components are arranged radially and symmetrically.

[0011] The radially symmetrical structure can apply tensile forces simultaneously from multiple directions, simulating the complex stress states that materials may encounter in practical applications and avoiding localized stress concentrations caused by uniaxial stretching. The symmetrical arrangement ensures uniform stress on the thin-film electrodes in each stretching direction, more realistically reflecting the material's performance in dynamic environments, such as wearable devices. Symmetrical stretching prevents the electrodes from breaking conductive paths due to excessive local deformation, such as crack propagation, thus allowing for a more accurate assessment of the impact of strain on electrical parameters such as impedance. For flexible circuits, radial stretching can test the signal fidelity of electrodes under uniform deformation, preventing noise or impedance abrupt changes introduced by asymmetrical stretching.

[0012] Furthermore, there are 4-6 tensioning components.

[0013] When thin-film electrodes are worn on the surface of human skin, they may be stretched in multiple directions rather than simply uniaxially. Setting up 4-6 stretching components can create a uniform tensile force field in the plane, such as biaxial or triaxial strain, avoiding localized stress concentrations caused by uniaxial stretching and more realistically simulating the mechanical response of flexible thin-film electrodes under complex deformation. Simultaneous stretching by multiple components can uniformly distribute strain, preventing the breakage of conductive paths due to excessive local stretching, thus enabling more accurate measurement of impedance changes or signal transmission attenuation. Furthermore, the 4-6 stretching components are compatible with common sample shapes, such as square, circular, and hexagonal, facilitating standardized preparation and clamping, and reducing sample edge effects. The design of setting up 4-6 stretching components achieves uniformity and controllability of mechanical loading, comprehensive monitoring of electrical performance, and a balance between equipment efficiency and cost in flexible thin-film electrode testing, taking into account both scientific rigor and engineering practicality.

[0014] Furthermore, the stretching assembly includes a motion device and a clamping device disposed on the motion device.

[0015] The clamping device is used to clamp and fix the film, and the motion device is used to drive the clamping device to move, thereby applying a tensile force to the film and stretching the film electrode.

[0016] Furthermore, the motion device includes a guide rail, a connecting block, and a motor. The connecting block is mounted on the guide rail and can move along the guide rail, while the motor is mounted on the connecting block.

[0017] The clamping device is mounted on the connecting block. The motor provides power to the connecting block, enabling it to move along the guide rail, thereby moving the clamping device to apply a tensile force to the film and stretch the film electrode.

[0018] Furthermore, the clamping device is provided with a soft material.

[0019] The soft material is placed on the clamping surface of the clamping device. A hard material clamping surface is prone to damaging the thin-film electrode. Using a soft material, such as rubber, silicone, or polyurethane, as the clamping surface can prevent the thin-film electrode from being damaged by the clamping device. On the other hand, compared with hard materials, the friction between soft materials and thin-film electrodes is greater.

[0020] Furthermore, the base is also equipped with biomimetic bone and skin.

[0021] Bionic bone skin can mimic the mechanical properties of human tissues, such as elasticity, viscoelasticity, and flexibility, helping researchers observe the mechanical behavior (e.g., fracture strength, ductility, fatigue life) of thin-film electrodes under stretching, bending, or torsion in similar real-world applications, such as wearable devices. Thin-film electrodes may develop cracks, impedance changes, or broken conductive pathways when stretched; the dynamic deformation environment provided by bionic skin can more realistically reflect the electrical performance of electrodes under repeated deformation. In summary, the main purpose of bionic bone skin is to simulate real human bodies or biological environments, thereby more accurately evaluating the mechanical and electrical properties of thin-film electrodes under dynamic and complex conditions.

[0022] Furthermore, the bionic bone skin is positioned in the middle of the base.

[0023] When the flexible thin-film electrode is stretched, it is stretched symmetrically along multiple axes, with the central region experiencing more uniform stress. By placing the bionic bone and skin in the middle of the base, it corresponds precisely to the central region of the flexible thin-film electrode during the stretch test, making the test results more accurate.

[0024] Furthermore, the bionic bone skin is provided with patches that can conduct analog signals.

[0025] When using flexible thin-film electrodes, it is crucial to ensure the integrity of the signal transmission path. If the mechanical connection of the electrodes is unreliable, breakage or detachment may occur during isotropic stretching, leading to signal interruption, waveform distortion, and other problems. By using a patch that conducts analog signals, the electromechanical coupling performance of flexible wearable devices can be tested—that is, how mechanical deformation affects the integrity of the signal transmission path—revealing structural defects such as cracked solder joints or broken connecting wires causing signal interruption. The contact state between the patch and the electrode points of the thin-film electrode also affects the electrode's impedance value.

[0026] Furthermore, there are multiple patches capable of conducting analog signals.

[0027] In wearable devices, the conductive layer can be configured as a monolithic conductive layer or a partitioned multi-part conductive layer, depending on specific application requirements, signal acquisition targets, and mechanical adaptability. To improve the reliability and redundancy of signal acquisition and achieve high spatial resolution signal mapping, flexible thin-film electrodes often employ multi-electrode arrays, with multiple patches used in conjunction. Secondly, when a flexible thin-film electrode is stretched, the strain in different regions may vary, such as low strain at the center and high strain at the edges. Under different strains, the flexible electrode may experience localized conductive path failure due to microcracks, delamination, or material inhomogeneity during stretching. Multiple patches can monitor the conductivity status of the conductive layer in different regions in real time. Stretching may cause the contact interface between the patch and the electrode to peel off; data from multiple patches can help distinguish between electrode breakage and interface debonding. Multiple patches can also test the impact of different regions on electrical performance under different strains. Furthermore, multiple small patches are easier to adhere to irregular human body parts (such as the ribcage and joints) than a single large electrode, reducing contact impedance fluctuations caused by wrinkles and better adapting to complex human body surfaces and dynamic deformations.

[0028] Compared with existing technologies, the advantages of this invention are as follows: By applying tensile force to the flexible thin-film electrode through a stretching device, planar stretching is achieved. The tensile force and impedance values ​​at the electrode points are then measured using a testing device, thereby evaluating the safety, comfort, signal stability, and long-term reliability of the flexible thin-film electrode. The stretching device includes multiple stretching components arranged radially and symmetrically to ensure uniform force on the thin-film electrode in each stretching direction. This also prevents the conductive path from breaking due to excessive local deformation, thus allowing for a more accurate assessment of the impact of stretching on electrical parameters such as impedance. Since the thin-film electrode may be stretched in multiple directions during use, 4-6 stretching components are used to stretch it simultaneously in multiple directions, avoiding local stress concentration caused by uniaxial stretching and more realistically simulating the mechanical response of the flexible thin-film electrode under complex deformation. Furthermore, the 4-6 stretching components are compatible with common sample shapes, such as square, round, and hexagonal, facilitating standardized preparation and clamping and reducing sample edge effects. The base also features a biomimetic skeletal skin, primarily designed to simulate the real human body or biological environment, thereby more accurately evaluating the mechanical and electrical properties of the thin-film electrodes under dynamic and complex conditions. The biomimetic skeletal skin also includes patches that conduct analog signals, connecting to the electrode points on the thin-film electrodes. By inputting analog signals to these patches, the electromechanical coupling performance of the thin-film electrodes can be tested—that is, how mechanical deformation affects the integrity of signal transmission, exposing structural defects. Multiple patches are provided to simulate the contact conditions between the test electrode points and different areas of the scalp. Attached Figure Description

[0029] Figure 1 This is a structural diagram of the present invention.

[0030] Figure 2 This is a structural diagram of the tensioning device of this utility model.

[0031] Figure 3 This is a structural diagram of the tensioning component of this utility model.

[0032] Figure 4 This is a structural diagram of the present invention in use. Detailed Implementation

[0033] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the scope of this invention. To better illustrate the following embodiments, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0034] like Figure 1 , Figure 2 As shown, a planar tensile testing device using flexible materials includes a tensile device 1 capable of applying tensile force and a testing device 2. The tensile device 1 includes a base 11 and multiple tensile components 12 disposed above the base 11. The testing device 2 includes a testing host 21, a stress sensor 22 connected to the testing host 21, and an impedance sensor 23. The multiple tensile components 12 are arranged radially and symmetrically. Preferably, there are 4 to 6 tensile components 12, allowing simultaneous tensile testing in multiple directions. This avoids local stress concentration caused by uniaxial tensile testing, more realistically simulates the mechanical response of the flexible thin-film electrode 3 under complex deformation, and is compatible with common sample shapes such as square, round, and hexagonal, facilitating standardized preparation and clamping, and reducing sample edge effects.

[0035] like Figure 2 , Figure 3 As shown, the stretching assembly 12 includes a motion device 121 and a clamping device 122 disposed on the motion device 12. The motion device includes a guide rail 1211, a connecting block 1212, and a motor 1213. The guide rail 1211 is mounted on the base 11 via a bracket (not shown). The connecting block 1212 is disposed on the guide rail 1211 and can move along the guide rail 1211. The motor 1213 is disposed on the connecting block 1212 and provides power to the connecting block 1212, enabling it to move along the guide rail 1211. The clamping device 122 is fixed on the connecting block 1212, and the clamping surface of the clamping device 122 is provided with a soft material to prevent the thin film electrode 3 from being damaged by the clamping device 122 and to increase the friction between the clamping material 122 and the thin film electrode 3, making the clamping more secure.

[0036] like Figure 1 , Figure 2As shown, a biomimetic skeletal skin 13 is disposed in the middle of the base 11, which can simulate the mechanical properties of human tissue, such as elasticity, viscoelasticity, and flexibility, to help researchers observe the thin-film electrode 3 in similar real-world usage scenarios, thereby more accurately evaluating the mechanical and electrical properties of the thin-film electrode 3 under dynamic and complex conditions. Multiple patches 14 that can conduct simulated signals are also disposed on the biomimetic skeletal skin 13, so as to test the influence of different regions of the thin-film electrode 3 on the electrical properties under different strains.

[0037] like Figure 4 As shown, in use, the clamping device 122 clamps the edge or corner of the flexible thin-film electrode 3. A stress sensor 22 is mounted on the clamping device 122, and an impedance sensor 23 is mounted on the upper surface of the flexible thin-film electrode 3 and connected to the electrode point 31. The lower surface of the flexible thin-film electrode 3 contacts the bionic bone skin 13 and the patch 14 on the bionic bone skin 13. An analog signal is then input to the patch 14, controlling the stretching device 12 to expand outwards, thereby stretching the flexible thin-film electrode 3.

[0038] This testing device can test the tensile force of the flexible thin film electrode 3, the impedance of the electrode point 31, or the electromechanical coupling performance individually, or it can be combined with other devices for simultaneous testing.

[0039] This testing device can be used for destructive testing of the flexible thin-film electrode 3, that is, stretching the flexible thin-film electrode 3 until it fails and testing the tensile force it experiences upon failure. This tests the ultimate tensile strength of the flexible thin-film electrode 3 and evaluates its mechanical reliability, safety, and durability.

[0040] Alternatively, the flexible thin-film electrode 3 can be extended to a point where the simulated signal from patch 14 cannot be detected at electrode point 31, and the tensile force it experiences at this point can be tested. This test is used to evaluate its mechanical-electrical coupling failure threshold, that is, to determine when the flexible thin-film electrode 3 will experience signal interruption due to structural damage under mechanical stress. By simultaneously monitoring the tensile force and signal interruption, the cause of failure can be distinguished. For example, if the signal drops suddenly but is not completely interrupted, the cause may be poor contact at the electrode point; if the signal is completely interrupted but there is no visible damage, the cause may be a breakage of the internal conductive layer of the thin-film electrode 3, such as solder joint detachment; if the signal interruption is accompanied by material fracture, the cause may be insufficient mechanical strength of the thin-film electrode 3 or the wire.

[0041] The device can also extend the flexible thin-film electrode 3 to a certain set tension and test the signal change under this tension. This tests whether the flexible thin-film electrode 3 can transmit signals normally under fixed deformation.

[0042] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the technical solution of this utility model, and are not intended to limit the specific implementation of this utility model. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the claims of this utility model should be included within the protection scope of the claims of this utility model.

Claims

1. A planar tensile testing device for applying a flexible technical material, characterized in that It includes a tensile device capable of applying tensile force and a testing device. The tensile device includes a base and multiple tensile components disposed on the base. The testing device includes a testing host, a stress sensor and an impedance sensor connected to the testing host.

2. The planar tensile test device for applying flexible technical materials according to claim 1, characterized in that The multiple tensioning components are arranged radially and symmetrically.

3. The planar tensile test device for applying flexible technical materials according to claim 2, characterized in that There are 4-6 tensioning components.

4. A planar tensile testing device for flexible technical materials according to any one of claims 1 to 3, characterized in that The stretching assembly includes a motion device and a clamping device disposed on the motion device.

5. The planar tensile test device for applying flexible technical materials according to claim 4, characterized in that The motion device includes a guide rail, a connecting block, and a motor. The connecting block is mounted on the guide rail and can move along the guide rail. The motor is mounted on the connecting block.

6. The planar tensile test device for applying flexible technical materials according to claim 4, characterized in that The clamping device is provided with a soft material.

7. The planar tensile test device employing a flexible technical material according to any one of claims 1 to 3, characterized in that The base also features bionic bone and skin.

8. The planar tensile test device for applying flexible technical materials according to claim 7, characterized in that The bionic bone and skin structure is positioned in the middle of the base.

9. The planar tensile test device for applying flexible technical materials according to claim 8, characterized in that The bionic bone skin is equipped with patches that can conduct analog signals.

10. The planar tensile test device for applying flexible technical materials according to claim 9, characterized in that There are multiple patches that can conduct analog signals.

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