Tactile sensor and manufacturing method thereof

Abstract

The invention discloses a tactile sensor and a manufacturing method thereof, the tactile sensor comprises a coil unit and a magnetic column unit, and the coil unit is provided with a plurality of coils; the magnetic column unit is provided with a plurality of magnetic columns, the magnetic columns are obliquely arranged in the same direction, the lower ends of the magnetic columns are fixedly connected with the upper surface of the coil unit, and induced electromotive force can be generated in the coil when the magnetic columns are bent. The manufacturing method comprises the following steps: S1, respectively preparing the coil unit and the magnetic column unit; and S2, adhering and fixing the magnetic column unit on the upper surface of the coil unit. Compared with the prior art, the tactile sensor provided by the invention is provided with the obliquely arranged magnetic column, in the bending process of the oblique magnetic column, the spatial distribution of a magnetic field is changed, the magnetic flux passing through the coil is changed, the sensor generates a changed induced electromotive force, and the magnetic column is bent upwards or downwards to deflect, so that the tactile sensor is formed. Therefore, two distinguishable signals can be generated, and high sensitivity and low detection limit are achieved.

Description

Technical Field

[0001] The present invention relates to the field of sensor technology, and in particular to a tactile sensor and a manufacturing method thereof. Background Art

[0002] With the rapid development of artificial intelligence technology, robots and wearable products related to it have entered the era of "human-computer interaction". Electronic skin, as a tactile sensor, is an important tool for robots to contact the outside world. Tactile sensors not only need to achieve highly sensitive object load detection, but also need to be able to transmit human information.

[0003] However, most single sensors can only generate one signal, which cannot meet the needs of human-computer interaction. Sensor arrays can generate different signals, but multiple devices will face problems such as signal crosstalk, power consumption and increased volume. Therefore, developing a sensor unit that outputs multiple signals from a single sensor, realizing massive information communication between human-computer interface devices, and simplifying the entire system are of great significance for efficient and convenient human-computer interface systems.

[0004] Currently, single tactile sensors that can generate distinguishable signals can be divided into piezoresistive, piezoelectric, capacitive, and frictional types according to the sensing mechanism. However, both piezoresistive and capacitive sensors require external power supply, which makes the sensor equipment large and cannot be efficiently integrated. In contrast, friction and piezoelectric sensors are self-powered, but friction sensors are greatly affected by the external environment, resulting in unstable output. In addition, piezoelectric sensors are mostly toxic materials containing lead, which is not suitable for use in tactile sensors. Summary of the invention

[0005] The purpose of the present invention is to overcome the above technical deficiencies, to provide a tactile sensor and a method for manufacturing the same, and to solve the technical problems in the prior art that various sensors either cannot generate distinguishable signals or are not suitable as tactile sensors.

[0006] In order to achieve the above technical objectives, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a tactile sensor, comprising: a coil unit, the coil unit having a plurality of coils; a magnetic column unit, the magnetic column unit having a plurality of magnetic columns, the magnetic columns being arranged obliquely in the same direction, the lower ends of the magnetic columns being fixedly connected to the upper surface of the coil unit, and when the magnetic columns are bent, an induced electromotive force will be generated in the coil.

[0007] In some embodiments, the plurality of magnetic pillars are arranged in a matrix.

[0008] In some embodiments, the magnetic column unit further includes a base, the lower end of the magnetic column is fixedly connected to the base, and the base is fixedly connected to the upper surface of the coil unit.

[0009] In some embodiments, the magnetic column has an inclination angle of 30°-40°.

[0010] In some embodiments, the coil unit has two coils, which are arranged in a spiral and have opposite rotation directions.

[0011] In some embodiments, the coil unit includes a base layer, a polyimide packaging layer, a first coil, an insulating layer, a second coil and a polymer stress layer stacked in sequence from bottom to top, and the magnetic column unit is fixedly connected to the polymer stress layer.

[0012] In some embodiments, the base and the base layer are both made of silicone.

[0013] In a second aspect, the present invention further provides a method for manufacturing a tactile sensor, comprising the following steps: S1, prepare the coil unit and the magnetic column unit respectively; S2. Adhere and fix the magnetic column unit to the upper surface of the coil unit.

[0014] In some embodiments, the method of preparing the magnetic column unit is: S111, preparing a plurality of magnetic columns; S112, placing the magnetic column in a magnetic column unit mold, adding silicone into the magnetic column unit mold, and forming a base of the magnetic column unit after the silicone is cured; S113, magnetizing the magnetic column so that the angle between the magnetic pole direction of the magnetic column and its axis is 15°-55°.

[0015] In some embodiments, the method for making a magnetic column is: pouring NdFeB magnetic powder and silica gel into a beaker, stirring at a speed of 500 rpm / min for 3 minutes to obtain a mixture of NdFeB magnetic powder and silica gel, and then injecting the mixture into a magnetic column mold and curing it at room temperature for 4 hours.

[0016] Compared with the prior art, the tactile sensor provided by the present invention has obliquely arranged magnetic columns. During the bending process of the inclined magnetic columns, the spatial distribution of the magnetic field will change, the magnetic flux passing through the coil will change, and the sensor will generate a changing induced electromotive force. By bending and deflecting the magnetic columns upward or downward, two distinguishable signals can be generated. The tactile sensor not only has high sensitivity and low detection limit, but also can be miniaturized because no external power supply is required, and is widely used in various tactile detection and non-contact applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of the structure of a tactile sensor provided by an embodiment of the present invention; Figure 2 An exploded diagram of a tactile sensor provided by an embodiment of the present invention; Figure 3The schematic diagram of the induced electromotive force generated when the magnetic column is bent; Figure 4 A flow chart of a method for manufacturing a tactile sensor provided by an embodiment of the present invention; Figure 5 for Figure 4 Flowchart for manufacturing a single coil. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0019] In order to solve the technical problems in the prior art that various sensors either cannot generate distinguishable signals or are not suitable as tactile sensors, the present invention provides a tactile sensor that can generate two distinguishable signals by bending and deflecting a magnetic column upward or downward. It not only has high sensitivity and a low detection limit, but also can be miniaturized because it does not require external power supply, and is widely used in various tactile detection and non-contact applications.

[0020] It should be noted that the tactile sensor described in the present invention is used for but not limited to tactile sensors, and can also be applied to other types of sensors. For the convenience of explanation, in the present invention, only the tactile sensor is used as an example for explanation, and the principles applied to other types of sensors are substantially the same as those applied to the tactile sensor, and are not described one by one here.

[0021] See also Figure 1 and Figure 2 , Figure 1 A schematic diagram of the structure of a tactile sensor provided by an embodiment of the present invention; Figure 2 An exploded diagram of a tactile sensor provided by an embodiment of the present invention.

[0022] The tactile sensor includes: a magnetic column unit 1 and a coil unit 2. The magnetic column unit 1 has a plurality of magnetic columns 11, which are arranged tilted in the same direction, and the lower ends of the magnetic columns 11 are fixedly connected to the upper surface of the coil unit 2. The coil unit 2 has a plurality of coils. When the magnetic column is bent, an induced electromotive force is generated in the coil.

[0023] like Figure 3 As shown, the magnetic column 11 is arranged obliquely and can be bent and deflected in two directions, upward or downward, under the action of external force. When the magnetic column 11 bends downward and approaches the coil, the magnetic flux passing through the coil will increase, and an upward waveform will be generated first; after the external force disappears, the magnetic column 11 deflects upward and returns to its original state, and the magnetic column moves away from the coil, generating a downward waveform, that is, (+ / -). When the magnetic column 11 bends upward, the opposite waveform is generated, that is, (- / +).

[0024] Through the above principle, the tactile sensor can generate at least two signals, overcoming the defect that the existing sensor has a single output and cannot meet the needs of human-computer interaction. The sensor is triggered by the bending of the magnetic column 11, has excellent performance of high sensitivity and wide range, is insensitive to environmental factors, and has a simple structure and is easy to prepare.

[0025] In some embodiments, the plurality of magnetic columns 11 are arranged in a matrix with an inclination angle of 30°-40°.

[0026] In this embodiment, the magnetic pillars 11 are arranged in a 4×4 array, the diameter of the magnetic pillars 11 is 1 mm, the length is 3 mm, the inclination angle is 35°, and the magnetic pillar gap is 1 mm.

[0027] Regarding the selection of the inclination angle of the magnetic column 11, when the inclination angle of the magnetic column 11 is small, it is too close to the coil, and the change in magnetic flux is too small, resulting in the sensor output being too small, or even undetectable. At the same time, it will cause the magnetic column 11 to compress and overlap. When the inclination angle of the magnetic column 11 is too large, the magnetic column 11 is too far away from the coil, and the angle at which the magnetic column 11 bends upward is too small, and the opposite signal output is also too small or even undetectable. Therefore, combined with the structural parameters of the magnetic column 11 and the output parameters of the sensor, under the existing device parameters, when the inclination angle of the magnetic column 11 is 35°, the two distinguishable signals generated by the bidirectional bending of the sensor are the best.

[0028] In some embodiments, the magnetic column unit 1 further includes a base 12 , the lower end of the magnetic column 11 is fixedly connected to the base 12 , and the base 12 is fixedly connected to the upper surface of the coil unit 2 .

[0029] In this embodiment, the base 12 is made of silicone material and is used to connect and fix the magnetic columns 11 together.

[0030] In some embodiments, the coil unit 2 has two coils, which are arranged in a spiral shape and have opposite rotation directions. Providing multiple coils can enhance the electrical signal generated by the tactile sensor.

[0031] In some embodiments, the coil unit 2 includes a base layer 21, a polyimide encapsulation layer 22, a first coil 23, an insulating layer 24, a second coil 25, and a polymer stress layer 26, which are stacked and fixedly connected from bottom to top. The polymer stress layer 26 is fixedly connected to the magnetic column unit 1, i.e., the base 12. The connection method is generally fixed by adhesive. The base layer 21 is also made of silicone material, and the first coil 23 and the second coil 25 are both MEMS micro-nano coils.

[0032] See also Figure 4 , Figure 4 This is a flow chart of a method for manufacturing a tactile sensor provided by an embodiment of the present invention.

[0033] A method for manufacturing a tactile sensor comprises the following steps: S1. Prepare the magnetic column unit 1 and the coil unit 2 respectively.

[0034] S2, gluing and fixing the magnetic column unit 1 on the upper surface of the coil unit 2.

[0035] In some embodiments, the method for preparing the magnetic column unit 1 is: S111, preparing a plurality of magnetic columns 11.

[0036] S112 , placing the magnetic column 11 in a magnetic column unit mold, adding silicone into the magnetic column unit mold, and forming a base 12 of the magnetic column unit after the silicone is cured, while fixing each magnetic column 11 .

[0037] S113, magnetizing the magnetic column 11 so that the angle between the magnetic pole direction of the magnetic column 11 and its axis is 15°-55°.

[0038] In some embodiments, the method for making the magnetic column 11 is as follows: pour NdFeB magnetic powder and silica gel into a beaker, stir at a speed of 500 rpm / min for 3 minutes to obtain a mixture of NdFeB magnetic powder and silica gel, and then inject the mixture into the magnetic column mold and cure it at room temperature for 4 hours. The silica gel can be Ecoflex silica gel, which is a degradable plastic launched by BASF of Germany in 1998. It has excellent properties of good elasticity, waterproofness, and tensile strength, and can be decomposed into environmentally friendly components. It is widely used in many fields, such as food packaging, agricultural films, medical devices, toys, etc. In the field of bioelectronics, Ecoflex is widely used in the packaging layer of multi-channel wearable devices due to its low modulus and large tensile properties.

[0039] In some embodiments, the coil unit 2 is prepared by: S121 , preparing a base layer 21 and cleaning the base layer 21 with deionized water and nitrogen. In a specific embodiment, the base layer 21 is a rectangular sheet structure.

[0040] S122. At room temperature (20°C) in the process room, a polyimide encapsulation layer 22 is pasted on the upper surface of the base layer 21 in step S121. The base layer 21 after pasting the polyimide encapsulation layer 22 is used as the base for making the coil unit 2. The base layer 21 provides a flat surface for the subsequent process. The polyimide encapsulation layer 22 uses polyurethane glue. The base layer 21 is placed on the workbench of the film laminating machine. The base layer 21 is heated to 80°C by the heating function of the film laminating machine to remove water vapor to prevent the bottom of the polyimide encapsulation layer 22 from bubbling when the polyimide encapsulation layer 22 is subsequently pasted, which affects the subsequent process operation. At the same time, the vacuum valve of the film laminating machine workbench is opened to vacuumize and adsorb the base layer 21 to the workbench of the film laminating machine to prevent the base layer 21 from moving during the process of pasting the polyimide encapsulation layer 22. This ensures that there is no bubbling and the surface is flat during the process of pasting the polyimide encapsulation layer 22, and then the polyimide encapsulation layer 22 is pasted on the base layer 21. Then, the surface of the polyimide encapsulation layer 22 is cleaned with deionized water and nitrogen.

[0041] S123. Before making a single-layer MEMS coil, first sputter an adhesion layer and a seed layer on the surface of the polyimide packaging layer 22, and the thickness ratio of the adhesion layer and the seed layer is 1:5 or 1:10. The adhesion layer and the seed layer as a whole serve as a conductive layer to prepare for subsequent electroplating work. The adhesion layer and the conductive layer can be a chromium layer and a copper layer, a chromium layer and a gold layer, or a titanium layer and a copper layer, respectively. In a specific embodiment, the thickness of the sputtered chromium layer is 20nm, and the thickness of the copper layer is 100nm. A single-layer MEMS micro-nano coil is made on the polyimide packaging layer 22 on top of the base layer 21 to form a first coil 23. Then, a photosensitive polyimide film is spin-coated, and through holes corresponding to the two electrodes of the MEMS micro-nano coil are photoetched on the photosensitive polyimide film.

[0042] See also Figure 5 ,The sub-steps of making a single-layer MEMS micro-nano coil are: S31, place the base layer 21 with the conductive layer on the workbench of the glue spreader, spin-coat the photoresist of model AZ4620, spread the glue at 1000r / min, and pre-bake it at 100℃ for 150s. After an interval of 50min, spread the glue for the second time again. At this time, the thickness of the photoresist will reach about 15um, and the pre-bake will be carried out at 100℃ for 150s. Put it to room temperature, use the photolithography machine of model EVG610 to set the relevant parameters for photolithography operation, the thickness of the base layer 21 and the attachments thereon is 620um, of which the photoresist is 15um thick. Perform photolithography exposure and patterning processing, and then use the developer of model AZ400K to process it in a 1:3 configuration, and the development time is about 55s. Use a plasma stripper to remove the residual photoresist, and set the parameters of the plasma stripper to O2-300W-2min. Finally, harden the film on a high-temperature baking table at 120℃ for 15min, and the first layer of coil template is prepared.

[0043] S32, the first layer of coil template is processed through electroplating process to complete the processing of the first coil 23, the specific operation is: use a dust-free stick to dip in acetone solution to wipe ten electrode interfaces uniformly in the circumference of the base layer 21, connect the power clamp at a relative set of electrode interfaces to electroplate the first layer of coil template, the power clamp is a DC power clamp or an AC power clamp. After a certain period of time, switch to the next set of relative electrode interfaces, so that the thickness of the entire electroplating layer will be consistent. Specifically according to the electroplating area and the concentration of the electroplating solution, the current intensity is calculated to be 0.1A, and each electrode is electroplated for 1min, 10min, and the ten electrode interfaces are connected in turn until the first coil 23 with a thickness of 10um is prepared.

[0044] S124, repeat step S123 until the total number of coil layers meets the design requirements. In this embodiment, a double-layer coil is provided, namely a first coil 23 and a second coil 25. A photosensitive polyimide film is provided between the multiple layers of coils as an insulating layer 24.

[0045] S125, spin-coat a photosensitive polyimide film as a polymer stress layer 26 on the top layer for encapsulation, adjust the thickness of the polymer stress layer 26 to control its stress, and then perform a pre-baking treatment on the photosensitive polyimide film at 120°C, and use an EVG610 photolithography machine to set relevant parameters. In this embodiment, the double-layer coil is set to have an overall thickness of 620um, a photosensitive polyimide film thickness of 15um, and is subjected to photolithography exposure and patterning, and then developed with a diluted AZ400K developer for about 100s, and photolithography holes corresponding to the two electrodes of the MEMS micro-nano coil are formed on the polymer stress layer 26; the metal electrodes of the coil are exposed, and finally the photosensitive polyimide film is cured for subsequent connection and conduction.

[0046] Finally, in step S2 , a silicone film adhesive 27 is applied to the surface of the polymer stress layer 26 , and then the base 12 is adhered and fixed to the upper surface of the polymer stress layer 26 to obtain the tactile sensor.

[0047] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A tactile sensor, characterized in that: include: A coil unit, wherein the coil unit has a plurality of coils; The magnetic column unit comprises a plurality of magnetic columns, the magnetic columns are arranged obliquely in the same direction, the lower ends of the magnetic columns are fixedly connected to the upper surface of the coil unit, and when the magnetic columns are bent, an induced electromotive force is generated in the coil.

2. The tactile sensor according to claim 1, characterized in that: The plurality of magnetic columns are arranged in a matrix.

3. The tactile sensor according to claim 1, characterized in that: The magnetic column unit further includes a base, the lower end of the magnetic column is fixedly connected to the base, and the base is fixedly connected to the upper surface of the coil unit.

4. The tactile sensor according to claim 1, characterized in that: The inclination angle of the magnetic column is 30°-40°.

5. The tactile sensor according to claim 3, characterized in that: The coil unit has two coils, which are arranged in a spiral and have opposite rotation directions.

6. The tactile sensor according to claim 5, characterized in that: The coil unit comprises a base layer, a polyimide packaging layer, a first coil, an insulating layer, a second coil and a polymer stress layer which are stacked in sequence from bottom to top, and the magnetic column unit is fixedly connected to the polymer stress layer.

7. The tactile sensor according to claim 6, characterized in that: The base and the base layer are both made of silicone.

8. A method for manufacturing a tactile sensor according to any one of claims 1 to 7, characterized in that: The steps include: S1. Prepare the coil unit and the magnetic column unit respectively; S2. Adhere and fix the magnetic column unit to the upper surface of the coil unit.

9. The method for manufacturing a tactile sensor according to claim 8, characterized in that: The method for preparing the magnetic column unit is: S111, preparing a plurality of magnetic pillars; S112, placing the magnetic column in a magnetic column unit mold, adding silicone into the magnetic column unit mold, and forming a base of the magnetic column unit after the silicone is cured; S113, magnetizing the magnetic column so that the angle between the magnetic pole direction of the magnetic column and its axis is 15°-55°.

10. The method for manufacturing a tactile sensor according to claim 9, characterized in that: The method for making the magnetic column is as follows: pouring NdFeB magnetic powder and silica gel into a beaker, stirring at a speed of 500 rpm / min for 3 minutes to obtain a mixture of NdFeB magnetic powder and silica gel, and then injecting the mixture into a magnetic column mold and curing it at room temperature for 4 hours.

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