Flexible pressure sensor based on magnetic field and preparation method thereof

Abstract

The invention provides a flexible pressure sensor based on a magnetic field, and a preparation method and a detection method thereof. The flexible pressure sensor based on the magnetic field comprises a gradient magnetoelastomer, a flexible support body, a hard isolation layer and a Hall magnetic sensor, wherein the gradient magnetoelastic body is arranged on the upper side of the flexible supporting body, the hard isolation layer is arranged on the lower side of the flexible supporting body, and the Hall magnetic sensor is arranged on the hard isolation layer. According to the flexible pressure sensor based on the magnetic field and the preparation method and the detection method of the flexible pressure sensor, the problem that an existing flexible pressure sensor based on the magnetic field does not have high sensitivity and wide range at the same time can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible electronic devices, and more specifically, to a flexible pressure sensor based on a magnetic field and a preparation method and a detection method thereof. Background Art

[0002] With the rise of the Internet and the development of wearable technology, people have invested more and more energy in the research and development of artificial intelligence and artificial devices. People also have a strong vision for the prospects of flexible electronics and human-computer interaction. More and more electronic devices allow people to use contact and pressing as input signals to meet people's increasingly rich life and production needs. This working principle can be simply abstracted as giving instructions to human-machine devices, processing data and finally outputting them.

[0003] People's understanding of the trigger mechanism of contact and pressure was initially inspired by human skin or animal fur. Therefore, electronic skin that can recognize pressure or touch like skin came into being, for example, flexible pressure sensor devices based on magnetic fields.

[0004] As a very important type of electronic device for information collection, flexible pressure sensors based on magnetic fields can convert external pressure stimulation into electrical signals such as resistance, capacitance, and current that can be observed in real time. They play an important role in the fields of electronic skin, intelligent robots, human-machine interfaces, medical diagnosis, and sports behavior monitoring, and have become one of the main research hotspots in the field of flexible electronics. At present, the existing flexible tactile sensors include various principles such as piezoelectric, piezoresistive, capacitive, optical, and triboelectric. Most of these flexible tactile sensors have great advantages in high-precision perception and high-speed response. However, with the continuous improvement of the performance of flexible sensors, the complexity of their internal circuits continues to increase, which greatly increases the difficulty of manufacturing sensors. Moreover, the built-in circuits of this flexible pressure sensor based on magnetic fields are prone to damage in frequent mechanical contact, making it difficult to ensure the stability of operation.

[0005] Flexible pressure sensors based on magnetic fields have the advantages of simple structure, high physical robustness, low cost and wireless penetration. They can avoid frequent friction of connecting wires and the risk of circuit damage; but in terms of sensitivity, they need to be improved.

[0006] In the prior art, there are mainly two types of magnetic field-based flexible pressure sensors. One is to increase the magnetic field strength by embedding hard permanent magnets, but this type of solution will reduce the flexibility of the sensor, making it easy to be damaged when a large external impact is applied. The other is to use flexible magnetic materials. However, the magnetic field generated by flexible magnetic materials is weak and the sensing distance is short. Moreover, these two types of magnetic field-based flexible pressure sensors do not fully utilize the advantages of wireless penetration of magnetic fields.

[0007] It can be seen that the existing technology mainly improves the magnetic field-based flexible pressure sensor by selecting a suitable hard permanent magnet or using a magnetic film (a flexible magnetic material) and an elastic structure; however, after the improvement, there is still the problem that sensitivity and wide range cannot be achieved at the same time. Based on this technical problem, there is an urgent need for a magnetic field-based flexible pressure sensor that can achieve both high sensitivity and wide range. Summary of the invention

[0008] In view of the above problems, an object of the present invention is to provide a flexible pressure sensor based on a magnetic field and a preparation method and a detection method thereof, so as to solve the problem that the existing flexible pressure sensors based on a magnetic field do not have both high sensitivity and wide range at the same time.

[0009] The magnetic field-based flexible pressure sensor provided by the present invention comprises a gradient magnetic elastomer, a flexible support, a hard isolation layer and a Hall magnetic sensor; wherein,

[0010] The gradient magnetic elastomer is arranged on the upper side of the flexible support body, the hard isolation layer is arranged on the lower side of the flexible support body, and the Hall magnetic sensor is arranged on the lower side of the hard isolation layer.

[0011] In addition, a preferred solution is that the gradient magnetic elastomer includes at least two layers of uniform magnetic elastomer stacked one above the other; wherein,

[0012] Each uniform magnetic elastomer is made of a flexible elastic resin and magnetic particles; and,

[0013] The content of magnetic particles in each homogeneous magnetic elastomer is different.

[0014] In addition, a preferred solution is that when two layers of the uniform magnetic elastomer in the gradient magnetic elastomer are arranged, the uniform magnetic elastomer in the upper layer is made of a flexible elastic resin with a mass fraction of 60% and a magnetic particles with a mass fraction of 40%, and the uniform magnetic elastomer in the lower layer is made of a flexible elastic resin with a mass fraction of 90% and a magnetic particles with a mass fraction of 10%.

[0015] In addition, a preferred solution is that the magnetic particles include at least one of neodymium iron boron, samarium iron nitrogen, samarium cobalt, ferrite nanoparticles and micron particles.

[0016] In addition, a preferred solution is that the flexible support body is a soft elastic resin piece; and\or,

[0017] The hard isolation layer is a hard photocurable component.

[0018] In addition, a preferred solution is that the thickness of the flexible support body is between 0.1 mm and 6 mm; and\or,

[0019] The thickness of each uniform magnetic elastomer is between 600 μm and 1000 μm; and\or,

[0020] The thickness of the hard isolation member is 0.1 mm to 1 mm.

[0021] In addition, a preferred solution is that the flexible support body is a body-centered cubic lattice structure support body.

[0022] In addition, a preferred solution is that the Hall magnetic sensor is electrically connected to an external single chip computer.

[0023] On the other hand, the present invention also provides a method for preparing the aforementioned flexible pressure sensor based on magnetic field, comprising:

[0024] Use 3D printing equipment to print each uniform magnetic elastomer, flexible support body and hard isolation layer respectively;

[0025] Connecting each uniform magnetic elastic body, the flexible support body and the hard isolation layer from top to bottom;

[0026] The Hall magnetic sensor is fixed on the hard isolation layer.

[0027] On the other hand, the present invention also provides a detection method of the flexible pressure sensor based on magnetic field as described above, comprising:

[0028] When external pressure acts on the gradient content magnetic elastomer, the gradient content magnetic elastomer is deformed and drives the flexible support body to deform, so that the distance between the gradient content magnetic elastomer and the Hall magnetic sensor is reduced;

[0029] The distance between the gradient content magnetic elastic body and the Hall magnetic sensor is reduced, and the gradient content magnetic elastic body is deformed, resulting in a change in the external detected magnetic field of the Hall magnetic field, thereby causing a change in the identification magnetic field of the Hall sensor;

[0030] The single chip microcomputer detects the change of the identification magnetic field of the Hall magnetic sensor to realize the detection of external pressure.

[0031] Compared with the prior art, the flexible pressure sensor based on magnetic field and the preparation method and detection method thereof according to the present invention have the following beneficial effects:

[0032] The flexible pressure sensor based on magnetic field provided by the present invention designs a common uniform magnetic elastomer into a gradient content magnetic elastomer with different magnetic powder contents in each layer, making full use of the magnetic field changes caused by displacement and the magnetic field changes caused by stress, so that the flexible pressure sensor based on magnetic field has both high sensitivity and wide range. In addition, the flexible pressure sensor based on magnetic field provided by the present invention replaces the uniform magnetic elastomer with a gradient content magnetic elastomer. In addition to the magnetic field changes caused by the change in the distance between the gradient content magnetic elastomer and the Hall magnetic sensor, other magnetic field change factors are added, namely, the magnetic field changes caused by the deformation of the gradient content magnetic elastomer itself; the magnetic field changes caused by these two magnetic field change factors are superimposed, which can improve the output response to external pressure, thereby achieving the technical effect of improving the sensitivity of the pressure sensor based on magnetic field.

[0033] In order to achieve the above and related purposes, one or more aspects of the present invention include features that will be described in detail later and are particularly pointed out in the claims. The following description and the accompanying drawings describe some exemplary aspects of the present invention in detail. However, these aspects indicate only some of the various ways in which the principles of the present invention can be used. In addition, the present invention is intended to include all of these aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] By referring to the following description and claims in conjunction with the accompanying drawings, and with a more comprehensive understanding of the present invention, other objects and results of the present invention will become more apparent and easier to understand. In the accompanying drawings:

[0035] Figure 1 A schematic diagram of the structure of a flexible pressure sensor based on a magnetic field is prepared according to an embodiment of the present invention;

[0036] Figure 2 4 is a comparison chart of the sensitivities of four samples according to an embodiment of the present invention.

[0037] The same reference numerals throughout the drawings indicate similar or corresponding features or functions. DETAILED DESCRIPTION

[0038] In the following description, for the purpose of illustration, in order to provide a comprehensive understanding of one or more embodiments, many specific details are set forth. However, it is apparent that these embodiments may also be implemented without these specific details. In other examples, for ease of describing one or more embodiments, known structures and devices are shown in the form of block diagrams.

[0039] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0040] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present application description and examples are exemplary only.

[0041] Figure 1 The structure of the flexible pressure sensor based on magnetic field is shown in Example 1 of the present invention. Figure 1 As shown, the magnetic field-based flexible pressure sensor provided by the present invention includes a gradient magnetic elastomer composed of a plurality of uniform magnetic elastomers with different magnetic particle contents (mainly referring to the mass fraction of magnetic particles) stacked on top of each other, a flexible support body, a hard isolation layer and a Hall magnetic sensor; wherein the gradient magnetic elastomer is arranged in the uppermost layer and attached to the upper side of the flexible support body; the flexible support body is in the middle layer; the hard isolation layer is arranged in the lowermost layer and attached to the lower side of the flexible support body; and the Hall magnetic sensor is arranged on the hard isolation layer.

[0042] Specifically, for the gradient magnetic elastomer, the gradient magnetic elastomer needs to include multiple layers (at least two layers) of uniform magnetic elastomer stacked up and down; wherein, in order to ensure that the uniform magnetic elastomer has the required magnetism and elasticity, each uniform magnetic elastomer needs to be made of a combination of a soft elastic resin (providing elasticity) and magnetic particles (providing magnetism); and the content of magnetic particles in each uniform magnetic elastomer is different.

[0043] It should be noted that the simplest and most effective structure for the gradient magnetic elastomer is a double-layer structure. When the uniform magnetic elastomer in the gradient magnetic elastomer is a double-layer structure, in order to further improve the sensitivity of the manufactured flexible pressure sensor based on the magnetic field, based on experimental data, the uniform magnetic elastomer in the upper layer is preferably made of a flexible elastic resin with a mass fraction of 60% and a magnetic particles with a mass fraction of 40%, and the uniform magnetic elastomer in the lower layer is preferably made of a flexible elastic resin with a mass fraction of 90% and a magnetic particles with a mass fraction of 10%; and the thickness of each uniform magnetic elastomer is preferably set between 600μm and 1000μm.

[0044] In addition, for the selection of magnetic particles, it is necessary to select materials with strong magnetism. For example, one or more materials selected from neodymium iron boron, samarium iron nitrogen, samarium cobalt, ferrite nano and micron particles can be selected as magnetic particles to make uniform magnetic elastomers.

[0045] In addition, for the flexible support, the flexible support is preferably configured as a body-centered cubic lattice structure support (such as Figure 1 As shown), the flexible support body includes an upper surface and a lower surface, and the gradient magnetic elastomer is arranged on the upper surface thereof; in the actual production process, the flexible support body can use a flexible elastic resin part printed by a 3D printing device, and the height (i.e., thickness) of the flexible support body is usually set between 0.1mm and 6mm. For the hard isolation layer, it includes an upper surface and a lower surface, and its upper surface is arranged on the lower surface of the flexible support body. The Hall magnetic sensor is placed on the lower surface of the hard isolation layer. In the actual production process, the hard isolation layer can use a hard light-cured part printed by a 3D printing device, and the thickness of the hard isolation part is preferably set to 0.1mm to 1mm.

[0046] It should be noted that in order to realize the detection of external pressure by the magnetic field-based flexible pressure sensor provided by the present invention, the Hall magnetic sensor needs to be electrically connected to an external single-chip microcomputer, and the single-chip microcomputer detects the changes in the identification magnetic field of the Hall magnetic sensor to realize the detection of external pressure.

[0047] To explain in detail the preparation process of the flexible pressure sensor based on the magnetic field provided in this embodiment, the preparation method of the flexible pressure sensor based on the magnetic field provided in this embodiment is further explained below. The preparation method includes:

[0048] First, a 3D printing device is used to continuously print at least two uniform upper and lower magnetic elastomers with different gradient contents, as well as a flexible support body and a hard isolation layer;

[0049] Then, each uniform magnetic elastic body, the flexible support body and the hard isolation layer are connected from top to bottom;

[0050] Finally, the Hall magnetic sensor is fixed on the hard isolation layer using a flexible elastic resin and connected to the single-chip microcomputer, thereby completing the preparation and connection of the entire magnetic field-based flexible pressure sensor.

[0051] It should be noted that the technical implementation means included in the present invention are mainly reflected in the design and preparation process of gradient content magnetic elastomer. The gradient content magnetic elastomer is prepared by photocuring 3D printing, which can accurately control the thickness of different content layers and achieve efficient combination between different layers. The detailed process of preparation and combination of the gradient content magnetic elastomer, flexible support body and hard isolation layer included in the above-mentioned flexible pressure sensor is as follows:

[0052] Preparation of magnetic photocurable resins with different contents: Put the flexible resin (A30 resin) and magnetic powder in a certain mass ratio in the same plastic bottle, then ultrasonically disperse the aggregated magnetic particles in an ultrasonic crusher for 10 minutes, and then stir and vacuum in a vacuum homogenizer to remove bubbles for 250 seconds to make the magnetic particles and resin uniformly and completely dispersed. This method can be used to prepare magnetic photocurable resins with different mass ratios.

[0053] Preparation of gradient content magnetic elastomer: First, pour the prepared 40% magnetic photocurable resin into the material box of the 3D printer, set the printing layer thickness to 25um, the running speed to 1-4mm / s, and the exposure power to 25mW / cm 2 , set the exposure time to 7s, stop printing after printing 40% of the 1mm magnetic elastomer; wipe off the remaining resin on the surface of the printed 40% magnetic elastomer, replace the material box, introduce 10% of the magnetic photocurable resin into the material box, and continue to print 10% of the magnetic elastomer on the 40% of the 1mm magnetic elastomer. Set the printing layer thickness to 25um, the running speed to 1-4mm / s, and the exposure power to 15mW / cm 2 , set the exposure time to 3s, and stop after printing 1mm10% of the magnetic elastomer. The upper and lower layers of the prepared magnetic elastomer have different magnetic powder contents. Erase the resin on the surface of the gradient content magnetic elastomer, and continue to replace the material box, pour in the soft elastic resin (A30 resin), continue to set the printing layer thickness to 25um, the running speed to 1-4mm / s, and the exposure power to 12mW / cm 2 , set the exposure time to 1s for printing, print a 3mm flexible support, stop after printing 3mm, wipe off the resin on the surface of the flexible support, and continue to replace the material box, import hard light-curing resin, continue to set the printing layer thickness to 25um, the running speed to 1-4mm / s, and the exposure power to 18mW / cm 2 , set the exposure time to 2s to print the hard isolation layer.

[0054] Finally, the printed complete component is placed in isopropyl alcohol for ultrasonic treatment for 1-3 minutes, and finally cured with a UV lamp for 2-5 minutes. The Hall sensor and the complete component are combined with light-curing resin to form a complete flexible pressure sensor.

[0055] Furthermore, four samples (such as Figure 2 The main difference is the gradient content magnetic elastomer (gradient magnetic elastomer composed of 1mm-40% and 1mm-10%) and the ordinary uniform magnetic elastomer (2mm-40%, 2mm-10% and 2mm-25%). Figure 2It can be seen that the magnetic field-based flexible pressure sensor with gradient content provided by the present invention exhibits the greatest sensitivity (slope size).

[0056] In addition, in order to explain in detail the working principle of the flexible pressure sensor based on the magnetic field provided in this embodiment, the detection method of the flexible pressure sensor based on the magnetic field provided in this embodiment is further described below. The detection method includes:

[0057] When external pressure acts on the gradient content magnetic elastomer, the gradient content magnetic elastomer is deformed and drives the flexible support body to deform, so that the distance between the gradient content magnetic elastomer and the Hall magnetic sensor is reduced;

[0058] The distance between the gradient content magnetic elastic body and the Hall magnetic sensor is reduced, and the gradient content magnetic elastic body is deformed, resulting in a change in the external detected magnetic field of the Hall magnetic field, thereby causing a change in the identification magnetic field of the Hall sensor;

[0059] The single chip microcomputer detects the change of the identification magnetic field of the Hall magnetic sensor to detect the external pressure.

[0060] It can be seen from the above specific embodiments that the flexible pressure sensor based on magnetic field and the preparation method and detection method thereof provided by the present invention have at least the following advantages:

[0061] 1. Through continuous 3D printing, the thickness of the upper and lower parts (or multiple parts) of the gradient content magnetic elastomer and the uniformity of the magnetic powder content can be accurately controlled, which can not only realize the combination of the gradient content magnetic elastomer, the flexible support body and the hard isolation layer, but also ensure the stability of the overall flexible pressure sensor;

[0062] 2. By replacing the uniform magnetic elastomer with a gradient content magnetic elastomer, in addition to the magnetic field change caused by the change in the distance between the gradient content magnetic elastomer and the Hall magnetic sensor, the magnetic field change factor is also increased, that is, the magnetic field change caused by the deformation of the gradient content magnetic elastomer itself. The magnetic field changes caused by the two factors are superimposed, which improves the output response to pressure, thereby achieving the technical effect of improving the sensitivity of the pressure sensor;

[0063] 3. When the pressure causes the distance between the gradient content magnetic elastomer and the Hall magnetic sensor to reach a limit and no longer change, the deformation of the gradient content magnetic elastomer caused by continuing to increase the pressure can still cause the magnetic field to change, thereby achieving the effect of increasing the range of the flexible pressure sensor;

[0064] 4. This flexible sensor has the characteristics of high sensitivity, high range, and batch preparation, and is suitable for a wide range of scenarios.

[0065] As above Figure 1 and Figure 2 The flexible pressure sensor based on magnetic field and its preparation method and detection method according to the present invention are described by way of example. However, those skilled in the art should understand that various improvements can be made to the flexible pressure sensor based on magnetic field and its preparation method and detection method proposed by the present invention without departing from the content of the present invention. Therefore, the protection scope of the present invention should be determined by the content of the attached claims.

Claims

1. A flexible pressure sensor based on magnetic field, characterized in that: It includes a gradient magnetic elastomer, a flexible support, a hard isolation layer and a Hall magnetic sensor; wherein, The gradient magnetic elastomer is arranged on the upper side of the flexible support body, the hard isolation layer is arranged on the lower side of the flexible support body, and the Hall magnetic sensor is arranged on the hard isolation layer.

2. The flexible pressure sensor based on magnetic field as claimed in claim 1, characterized in that: The gradient magnetic elastomer comprises at least two layers of uniform magnetic elastomer stacked one above the other; wherein, Each uniform magnetic elastomer is made of a soft elastic resin and magnetic particles; and, The content of magnetic particles in each homogeneous magnetic elastomer is different.

3. The flexible pressure sensor based on magnetic field as claimed in claim 2, characterized in that: When the uniform magnetic elastomer in the gradient magnetic elastomer is provided with two layers, the uniform magnetic elastomer in the upper layer is made of a flexible elastic resin with a mass fraction of 60% and a magnetic particle with a mass fraction of 40%, and the uniform magnetic elastomer in the lower layer is made of a flexible elastic resin with a mass fraction of 90% and a magnetic particle with a mass fraction of 10%.

4. The flexible pressure sensor based on magnetic field as claimed in claim 2, characterized in that: The magnetic particles include at least one of neodymium iron boron, samarium iron nitrogen, samarium cobalt, ferrite nanoparticles and micron particles.

5. The flexible pressure sensor based on magnetic field as claimed in claim 2, characterized in that: The flexible support body is a flexible elastic resin piece; and\or, The hard isolation layer is a hard photocurable component.

6. The flexible pressure sensor based on magnetic field as claimed in claim 5, characterized in that: The thickness of the flexible support is between 0.1 mm and 6 mm; and\or, The thickness of each uniform magnetic elastomer is between 100 μm and 1000 μm; and\or, The thickness of the hard isolation piece is between 0.1 mm and 1 mm.

7. The flexible pressure sensor based on magnetic field as claimed in claim 1, characterized in that: The flexible support body is a body-centered cubic lattice structure support body.

8. The flexible pressure sensor based on magnetic field according to any one of claims 1 to 7, characterized in that: The Hall magnetic sensor is electrically connected to an external single chip computer.

9. A method for preparing a flexible pressure sensor based on a magnetic field as claimed in any one of claims 1 to 8, characterized in that: include: Use 3D printing equipment to print each uniform magnetic elastomer, flexible support body and hard isolation layer respectively; Connecting each uniform magnetic elastic body, the flexible support body and the hard isolation layer from top to bottom; The Hall magnetic sensor is fixed on the hard isolation layer.

10. A detection method of a flexible pressure sensor based on a magnetic field as claimed in any one of claims 1 to 8, characterized in that: include: When external pressure acts on the gradient content magnetic elastomer, the gradient content magnetic elastomer is deformed and drives the flexible support body to deform, so that the distance between the gradient content magnetic elastomer and the Hall magnetic sensor is reduced; The distance between the gradient content magnetic elastic body and the Hall magnetic sensor is reduced, and the gradient content magnetic elastic body is deformed, resulting in a change in the external detected magnetic field of the Hall magnetic field, thereby causing a change in the identification magnetic field of the Hall sensor; The single chip microcomputer detects the change of the identification magnetic field of the Hall magnetic sensor to realize the detection of external pressure.

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