CN116380305A - Magnetorheological liquid metal pressure sensing device and manufacturing method thereof - Google Patents

Abstract

The invention discloses a magnetorheological liquid metal pressure sensing device and a manufacturing method thereof, wherein the sensing device comprises a first magnetic field excitation device, a flexible pressure inductor, a second magnetic field excitation device, an external current regulator and a resistance data acquisition instrument, wherein the first magnetic field excitation device, the flexible pressure inductor, the second magnetic field excitation device, the external current regulator and the resistance data acquisition instrument are sequentially overlapped from top to bottom, a Helmholtz coil is formed by the first magnetic field excitation device and the second magnetic field excitation device, glass fiber reinforced polyoxymethylene is selected as a shell substrate, a communicated double-line planar spiral micro-channel is formed in the flexible pressure inductor, and magnetorheological liquid metal is filled in the micro-channel. The invention overcomes the defects of fixed detection limit and sensitivity of the existing pressure sensor, improves the adjustability and controllability of the sensing device, and can realize intelligent pressure detection.

Description

A magnetorheological liquid metal pressure sensing device and manufacturing method thereof

technical field

The invention relates to a pressure sensing device, in particular to an intelligent magneto-rheological liquid metal pressure sensing device with adjustable detection limit and sensitivity and a manufacturing method of the pressure sensing device.

Background technique

Pressure sensors have a wide range of applications in industrial production and scientific research testing. In addition to traditional rigid pressure sensors, in the prior art, Chinese patent CN 113091988A discloses a flexible pressure sensor based on liquid metal, which uses elastic materials as surface covering A liquid metal pressure sensor composed of objects; CN 115507216A discloses a magnetic fluid pressure control valve and its regulation method, which uses magnetorheological fluid as the regulating substrate, and steplessly regulates the blocking area of the resistance gap to change the pressure of the valve device. But there are problems with these pressure sensors made of liquid metal:

1. The pressure detection range is fixed, the upper and lower limits of pressure detection cannot be adjusted, and the lower detection limit and higher detection upper limit cannot be taken into account at the same time, and the measuring range is small;

2. The sensitivity of pressure detection is low, so it cannot be applied to different pressure detection scenarios;

3. The durability of the pressure sensing body is poor, and the arrangement of the micro-channels and the position of the wiring port are unreasonable, resulting in local stress concentration and uneven force;

4. It is impossible to intelligently regulate the current and magnetic field strength according to the measured pressure change, and it is impossible to realize the intelligent detection of pressure;

5. The magnetorheological fluid used in the valve device has poor conductivity and has a large magnetoresistance effect, so regular resistance value changes cannot be obtained. The so-called magnetoresistance effect refers to the phenomenon that the resistance value of some metals or semiconductors changes with the external magnetic field. In the rheological fluid), carbonyl iron particles are loosely arranged in the absence of a magnetic field to an oriented arrangement when magnetized, and a large change in resistance value will occur.

Contents of the invention

Aiming at the problems existing in the prior art, the technical problem to be solved by the present invention is to provide a magneto-rheological liquid metal pressure sensing device, which can improve the upper and lower detection limits, sensitivity and range of the pressure sensor, increase the applicable range of the sensor, and improve Controllability and durability during use, while realizing intelligent detection of pressure. The invention also provides a manufacturing method of the magnetorheological liquid metal pressure sensing device.

In order to solve the problems of the technologies described above, the technical solution of the present invention is:

A magnetorheological liquid metal pressure sensing device provided by the present invention comprises a first magnetic field excitation device, a flexible pressure sensitive body and a second magnetic field excitation device overlapping sequentially from top to bottom, the first magnetic field excitation device and the second magnetic field excitation device The external power supply line of the excitation device is connected with a current regulator, the detection end of the flexible pressure sensing body is connected with a resistance data acquisition instrument, and the output signal end of the resistance data acquisition instrument is connected with the control signal input end of the current regulator. Transmit real-time resistance data to the current regulator.

Preferably, a connected double-wire planar spiral micro-channel is arranged in the flexible pressure sensing body, and the micro-channel is filled with magnetorheological liquid metal.

A method for preparing a magnetorheological liquid metal pressure sensing device provided by the present invention comprises the following steps:

Step 1, making the injection mold of the magnetic field excitation device and the flexible pressure-sensing body mold containing the double-line planar helical microfluidic channel by photolithography technology;

Step 2. Select glass fiber reinforced polyoxymethylene, and use injection molding technology to make a circular cake-shaped magnetic field excitation device plate coated with copper coils. The specifications of the upper and lower plates of the magnetic field excitation device are completely consistent, and are in phase with the current regulator on the external circuit. catch;

Step 3. After mixing the silicone rubber with the curing agent, stir evenly, put the liquid PDMS in the defoamer for more than 30 minutes, and remove the internal air bubbles; Put the pressure-sensitive body mold into an incubator, keep at 60°C-80°C, and cure for more than 50 minutes. After the PDMS is solidified, take it out of the mold to obtain the first layer, and make the second layer in the same way;

Step 4. Bond the 2 PDMS sheets prepared in step 3; the bonding is to stick the 2 layers made above together to form a whole with a microfluidic channel inside;

Step 5. After mixing liquid metal and carbonyl iron particles, stir evenly to obtain magnetorheological liquid metal. Put the magnetorheological liquid metal in the defoamer for more than 30 minutes to remove internal air bubbles, and then use a puncher to Drill a hole at the preset through hole, then use a syringe to inject magnetorheological liquid metal, and seal it with glue to obtain a flexible pressure sensing body, and connect the lead-out detection end of the flexible pressure sensing body to the resistance data acquisition instrument;

Step 6. The center of the flexible pressure sensing body injected with magnetorheological liquid metal is placed in the middle of the upper and lower plates of the magnetic field excitation device, and the resistance data acquisition instrument is connected with the current regulator.

The basic working principle of the magnetorheological liquid metal pressure sensing device of the present invention:

Utilizing the magnetorheological effect and the variable stiffness principle of magnetorheological elastomers, a high magnetic permeability and insoluble medium is added to the liquid metal to make magnetorheological liquid metal, and the Helmholtz coil is used as the magnetic field excitation device in the liquid metal. A uniform magnetic field is generated in the space, so that the magnetic particles in the magnetorheological liquid metal are magnetized. At this time, the rheological properties of the magnetorheological liquid metal change suddenly, and it solidifies rapidly and loses fluidity. The stiffness of the flexible pressure sensing body changes. The stiffness change in the above process is a transient process, which can be completed within milliseconds and is reversible at the same time. After the external magnetic field is removed, the magnetorheological liquid metal recovers its fluidity. In addition, the resistance data acquisition instrument is connected with the current regulator, and transmits the real-time resistance data to the current regulator. The set resistance threshold is used as the current regulation signal. After the resistance threshold is reached, the current regulator automatically regulates the current, so as to realize the pressure detection. The lower limit is intelligently adjusted, and the detected pressure data is obtained from the output signal of the resistance data acquisition instrument.

The technical effects of the invention are: the upper and lower limits and sensitivity of pressure detection can be adjusted and controlled, the resistance signal is fed back in real time through the resistance data acquisition instrument, and the current regulator is used to regulate the current size connected to the magnetic field excitation device, so as to realize the intelligent detection of pressure.

Description of drawings

The accompanying drawings of the present invention are as follows:

Fig. 1 is a structural representation of the present invention;

Fig. 2 is the structural representation of first, second magnetic field excitation device;

Fig. 3 is a schematic structural diagram of a flexible pressure sensing body;

Fig. 4 is a schematic diagram of the adjustable detection limit and sensitivity of the flexible pressure sensing body;

Fig. 5 is a diagram of deformation of the flexible pressure sensing body under pressure.

In the figure, 1. first magnetic field excitation device; 2. flexible pressure sensing body; 3. second magnetic field excitation device; 4. current regulator; 5. resistance data acquisition instrument; 6. non-magnetic rigid shell; 7. Mholtz coil; 8. Two-wire planar spiral; 9. Magneto-rheological liquid metal; 10. Carbonyl iron particles.

Detailed ways

Below in conjunction with accompanying drawing and embodiment the present invention will be further described:

In order to clearly describe the content of the invention, this patent application uses the orientation words "upper" and "lower" to distinguish them. The "upper" and "lower" are determined according to the layout orientation of the above drawings. The name of its location changes accordingly, which cannot be regarded as a limitation on the scope of patent protection.

As shown in Figure 1, the present invention comprises the first magnetic field excitation device 1, the flexible pressure sensitive body 2 and the second magnetic field excitation device 3 that overlap successively from top to bottom, the first magnetic field excitation device 1 and the second magnetic field excitation device 3 The external power supply line is connected with a current regulator 4, and the detection terminal of the flexible pressure sensing body 2 is connected with a resistance data acquisition instrument 5, and the output signal end of the resistance data acquisition instrument 5 is connected with the control signal input end of the current regulator. The current regulator receives the control signal, adjusts the current of the magnetic field excitation device according to the preset resistance threshold gear, controls the excitation magnetic field strength generated by the magnetic field excitation device, and realizes intelligent pressure detection and the upper and lower detection limits of the flexible pressure sensor and adjustable sensitivity.

As shown in FIG. 2 , the above-mentioned first magnetic field excitation device 1 and the second magnetic field excitation device 3 have the same specifications, and form a Helmholtz coil 7 , which is covered with a non-magnetically conductive rigid casing 6 . The non-magnetic rigid shell 6 is made of glass fiber reinforced polyoxymethylene, and a uniform magnetic field is generated by a Helmholtz coil.

As shown in FIG. 3 , the inside of the flexible pressure sensing body 2 is engraved with a micro-channel, which is a connected double-line planar spiral 8 , and the inside of the micro-channel is filled with magnetorheological liquid metal 9 . The flexible pressure sensing body 2 is made of polydimethylsiloxane (PDMS).

The magnetorheological liquid metal 9 is a mixture of gallium indium alloy liquid metal and carbonyl iron particles 10 . According to usage requirements, the carbonyl iron particles 10 are mixed with the gallium-indium alloy liquid metal at a mass ratio of 0.1-1:2.

Through the signal fed back by the resistance data acquisition instrument, the current regulator is regulated to control the magnitude of the current passed through the Helmholtz coil, thereby controlling the strength of the excitation magnetic field, and adjusting the pressure detection range and detection sensitivity of the sensing device. The flexible pressure sensor 2 The detection end is connected with a resistance data acquisition instrument, which detects the resistance change of the magnetorheological liquid metal in the connected double-wire planar spiral microfluidic channel, and feeds back the control signal to the current regulator in real time. The control signal here is the resistance signal, and the resistance data The acquisition instrument is connected to AC power alone, and does not share the power supply with the magnetic field excitation device and the current regulator. The stable resistance value obtained by the resistance data acquisition instrument and the current value of the excitation magnetic field are transmitted to the computer processing module, and the pressure acting on the flexible pressure is obtained. The pressure on the sensing body.

The working principle of the present invention is:

Magneto-rheological effect: Magneto-rheological liquid metal is EGaIn liquid metal mixed with a certain proportion of carbonyl iron particles, carbonyl iron particles 10 are uniformly and randomly dispersed in gallium-based liquid metal, the difference in magnetic permeability between the liquid metal matrix and carbonyl iron particles It is the root cause of the magneto-rheological effect of the present invention.

As shown in Figure 4, the carbonyl iron particles 10 have the characteristics of magnetic field polarization. Under the action of an external magnetic field, the carbonyl iron particles 10 in the magnetorheological liquid metal will form along the direction of the magnetic field. The chain structure produces a regular directional arrangement, and changes from a fluid state to a quasi-solid state, thereby causing the overall stiffness of the flexible pressure sensing body 2 to change. Since carbonyl iron particles are soft magnetic materials, there is no solidified remanence. And it has high saturation magnetization. When the external magnetic field is removed, the magnetorheological liquid metal recovers rapidly under the action of the external elastic body, which is the basis for the repeated operation of the present invention.

In addition, liquid metal can be regarded as a mixture of positive ion fluid and free electron gas, which has high conductivity, and liquid metal has turbidity. The so-called turbidity means that liquid metal will leave traces on the path it flows through. This trace Continuous and uninterrupted, the main components are ultra-thin layered liquid metal and its oxides. Even if the double-wire planar spiral micro-channel inside the flexible pressure-sensing body is compressed to flat, it can also ensure the integrity of the conductive path, making the pressure-sensing body It has extremely strong conductivity stability. In addition, the conductivity of liquid metal in magnetorheological liquid metal is much stronger than that of carbonyl iron particles. Liquid metal plays a major role in conductivity, so the movement of carbonyl iron particles will not affect the overall conductivity. The conductivity of the path affects the magnetoresistance effect of the existing magnetorheological fluid and the instability of the conductivity of the magnetorheological fluid, ensuring that the resistance value of the magnetorheological fluid only changes with the geometry of the microchannel according to the law of resistance. It is possible to establish the function formula of the change of the pressure of the flexible pressure sensing body and the resistance of the liquid metal.

The magnetization of carbonyl iron particles in a uniform electromagnetic field can be deduced according to Langevin's classical paramagnetic theory. In this theory, the Langevin equation introduces a random potential for the motion of magnetic particles under the action of an electromagnetic field. Although the force of the electromagnetic field on carbonyl iron particles It cannot be calculated specifically, but it can be replaced by a random force according to the random potential introduced by the Langevin equation, from which the magnetization of carbonyl iron particles under the action of an electromagnetic field can be deduced. The derivation process is as follows:

First deduce the number of carbonyl iron particles in the magnetorheological liquid metal, the number of carbonyl iron particles contained in the entire magnetorheological liquid metal is controlled by the following two factors, the volume fraction of carbonyl iron particles contained in the liquid metal, and carbonyl iron The particle diameter of particle, the carbonyl iron particle that adopts in the present invention is custom-made for unified production, and particle particle diameter is identical, so the carbonyl iron particle number contained in the magnetorheological liquid metal is:

In formula (1), Φ _v is the volume fraction of carbonyl iron particles in the magnetorheological liquid metal; d is the particle size of carbonyl iron particles.

The magnetic moment of a single carbonyl iron particle is:

In formula (2), M _S is the saturation magnetization of carbonyl iron particles.

The expression of the introduced langevin function is:

In formula (3), coth is the hyperbolic cotangent in the hyperbolic function, and α is the parameter of the langevin function. The size of this parameter is determined by the external environmental factors and the characteristics of the magnetic particles themselves. The external environmental factors include magnetic field strength and magnetic field temperature , the properties of carbonyl iron particles include vacuum permeability and magnetic moment, so the parameters of the langevin function can be expressed as:

In formula (4), μ ₀ is the vacuum magnetic permeability of carbonyl iron particles; m is the magnetic moment of a single carbonyl iron particle; H is the applied magnetic field strength; K is the Boltzmann constant; T is the absolute temperature.

According to the Langevin theory, the relational expression of magnetization of magnetorheological liquid metal after introducing random potential is:

M=nmL(α) (5)

The overall magnetization of carbonyl iron particles in the magnetorheological liquid metal is calculated by formula (5):

According to formula (6), the magnetization formula of magnetorheological liquid metal is as follows:

In formula (7): n is the number of carbonyl iron particles;

m is the magnetic moment of a single carbonyl iron particle;

Φ _v is the volume fraction of carbonyl iron particles in the magnetorheological liquid metal;

d is the particle diameter of carbonyl iron particle;

M _S is the saturation magnetization of carbonyl iron particles;

α is the parameter of langevin function;

μ ₀ is the vacuum magnetic permeability of carbonyl iron particles;

H is the applied magnetic field strength;

K is the Boltzmann constant;

T is the absolute temperature.

The magnetic field excitation device in the magnetorheological liquid metal flexible pressure sensing device is a glass fiber reinforced polyoxymethylene coated Helmholtz coil. Glass fiber reinforced polyoxymethylene is also called Saigang, which has high strength, non-magnetic conductivity, heat and acid resistance , good stability and other advantages, the flexible pressure sensing body can be regarded as a rigid body without deformation within the pressure range, and the Helmholtz coil can generate a uniform magnetic field in the space, thereby ensuring the magnetorheological flow in the microchannel of the flexible pressure sensing body The carbonyl iron particles in the liquid metal are uniformly magnetized.

As shown in Figure 1, the detection end of the flexible pressure sensing body 2 is connected with a resistance data acquisition instrument 5, and the output signal end of the resistance data acquisition instrument 5 is connected to the control signal input end of the current regulator, and the current regulator receives the control signal. The signal is the resistance signal. Different resistance thresholds are set according to the calibration experiment of the flexible pressure sensing body. After the current regulator stores the resistance threshold, it adjusts the current of the magnetic field excitation device to a predetermined value according to the preset threshold level, and then controls The intensity of the excitation magnetic field generated by the magnetic field excitation device is an intelligent control process that the pressure sensing device can realize.

The resistance change of the magnetorheological liquid metal in the microchannel of the pressure sensing body can be measured by a resistance data acquisition instrument, and the resistance data acquisition instrument can be a high-precision LCR tester (HG2810). The current regulator can choose the thyristor adjustable DC power controller produced by the domestic brand Shanghai Nenggong.

As shown in Figure 4, passing DC currents of different magnitudes to the magnetic field excitation device will cause the carbonyl iron particles in the microchannel of the pressure sensing body to produce different magnetizations, thereby affecting the overall stiffness of the pressure sensing body. When the magnetic field excitation device is not energized, the stiffness of the pressure sensing body is the smallest at this time, and the sensitivity of the sensing device is the highest, and micro pressure can be detected, but the upper limit of pressure monitoring is low at this time; when the magnetic field excitation device is energized, the pressure sensing body As the stiffness increases, the detection lower limit of the sensing device gradually increases, and the pressure detection upper limit also gradually increases, which can meet greater pressure detection requirements. This is the basic principle of the adjustable detection limit and sensitivity of the pressure sensing device.

As shown in Figure 4, after the magnetic field excitation device is adjusted to a predetermined external current, the magnetic field excitation device generates a uniformly distributed magnetic field, and the carbonyl iron particles in the microchannel of the pressure sensing body are uniformly magnetized. When subjected to external pressure, the micro-channel in the pressure-sensing body will be compressed and deformed, which will affect the resistance value of the micro-channel inside the pressure-sensing body. There is a functional relationship between the external pressure and the resistance value of the pressure-sensing body. By measuring the change in resistance Represents the magnitude of external pressure. This is the basic principle behind the pressure sensing device's ability to detect pressure.

As shown in Fig. 5, Fig. 5(a) shows that when no pressure is applied in this embodiment, the filling diameter of the magnetorheological liquid metal in the microchannel is d. Figure 5(b) shows that when the embodiment is under pressure, the flexible pressure sensing body 2 deforms, and the filling diameter of the magnetorheological liquid metal in the micro-channel is d'; the change of the micro-channel diameter in the pressure sensing body, according to the pressure sensor The principle of device detection pressure will inevitably cause the resistance value change of the magnetorheological liquid metal in the connected double-wire planar spiral coil; therefore, the resistance value change value of the magnetorheological liquid metal in the connected double-wire planar spiral coil can reflect the pressure the size of.

Different strengths of magnetic fields can be generated by adjusting the access current of the magnetic field excitation device. The magnetic field with different strengths will affect the magnetization of carbonyl iron particles in the pressure sensing body. The deformation stiffness of the pressure sensing body is different with different magnetization, and the resistance change is measured. , the change of external current, and the magnitude of pressure, in theory, the infinite continuous adjustment of the pressure detection limit can be achieved, but in actual use, in order to simplify the number of experimental calibrations, different pressure detection gears can be set, such as setting high, medium and low three gears, Three types of pressure, large, medium and small, are detected respectively. To determine different external currents is to select different detection gears, and this work can be completed by the cooperation of the resistance data acquisition instrument and the current regulator. The real-time resistance data is fed back to the current regulator through the resistance data acquisition instrument, and the gear is automatically adjusted after reaching the set resistance threshold. According to the final stable resistance value output by the resistance data acquisition instrument, the pressure applied on the flexible pressure sensor is determined, and the electrical signal measured by the resistance is converted into a pressure value.

The manufacturing method of the pressure sensing device provided by the present invention comprises the following steps:

Step 1, making the injection mold of the magnetic field excitation device and the flexible pressure-sensing body mold containing the double-line planar helical microfluidic channel by photolithography technology;

Step 2. Select glass fiber reinforced polyoxymethylene, and use injection molding technology to make a circular cake-shaped magnetic field excitation device plate coated with copper coils. The specifications of the upper and lower plates of the magnetic field excitation device are completely consistent, and are in phase with the current regulator on the external circuit. catch;

Step 3. According to the requirement of PDMS hardness during use, mix the silicone rubber and curing agent in a mass ratio of 10:1~1.2, stir evenly, put the liquid PDMS in the defoamer for more than 30 minutes, and remove the internal air bubbles ; Then pour it into a flexible pressure-sensitive body mold containing a double-line planar spiral microchannel, put it in an incubator, keep it at 60°C-80°C, and maintain it for more than 50 minutes. After the PDMS is solidified, take it out of the mold to obtain Sheet 1, the same method to make sheet 2;

Step 4. Bond the 2 PDMS sheets prepared in step 3; the bonding is to stick the 2 layers made above together to form a whole with a microfluidic channel inside;

Step 5. After mixing liquid metal and carbonyl iron particles, stir evenly to obtain magnetorheological liquid metal. Put the magnetorheological liquid metal in the defoamer for more than 30 minutes to remove internal air bubbles, and then use a puncher to Drill a hole at the preset through hole, then use a syringe to inject magnetorheological liquid metal, and seal it with glue to obtain a flexible pressure sensing body, and connect the lead-out detection end of the flexible pressure sensing body to the resistance data acquisition instrument;

Step 6. Place the center of the flexible pressure sensing body injected with magnetorheological liquid metal in the middle of the upper and lower plates of the magnetic field excitation device, and connect the resistance data acquisition instrument to the current regulator.

In actual use, the flexible pressure sensing body and the upper and lower plates of the magnetic field excitation device can be aligned and placed in the center without bonding, which ensures that the flexible pressure sensing body can be fully deformed after being stressed, thereby improving the sensitivity of pressure detection.

The magnetic field excitation device is connected to the current regulator to control the magnitude of the input current. The detection terminal led by the flexible pressure sensing body is connected to the resistance data acquisition instrument, and the resistance data acquisition instrument feeds back the control signal to the current regulator in real time. Perform a calibration test on the manufactured flexible pressure sensing device with adjustable pressure detection limit and sensitivity, and finally transmit the current value output by the current regulator and the final stable resistance signal obtained by the resistance data acquisition instrument to the calculation and processing module, and then pass Measure the final stable resistance value of the magnetorheological liquid metal, and measure the magnitude of the external pressure.

Claims (7)

1. A magnetorheological liquid metal pressure sensing device is characterized in that: the flexible pressure sensor comprises a first magnetic field excitation device (1), a flexible pressure sensor (2) and a second magnetic field excitation device (3) which are sequentially overlapped from top to bottom, wherein a current regulator (4) is connected on an external power supply line of the first magnetic field excitation device (1) and the second magnetic field excitation device (3), a resistance data acquisition instrument (5) is connected at an extraction detection end of the flexible pressure sensor (2), and an output signal end of the resistance data acquisition instrument (5) is connected with a control signal input end of the current regulator (4).

2. The magnetorheological liquid metal pressure sensing device of claim 1, wherein: the first magnetic field excitation device (1) and the second magnetic field excitation device (3) are identical in specification, a Helmholtz coil (7) is formed, and the coil is wrapped by a non-magnetic conductive rigid shell (6).

3. The magnetorheological liquid metal pressure sensing device of claim 2, wherein: micro-channels are engraved in the flexible pressure sensing body (2), the micro-channels are communicated double-line plane spirals (8), and magnetorheological liquid metal (9) is filled in the micro-channels.

4. The magnetorheological liquid metal pressure sensing device of claim 3, wherein: the magnetorheological liquid metal (9) is a mixed liquid of gallium-indium alloy liquid metal and carbonyl iron particles (10).

5. The magnetorheological liquid metal pressure sensing device of claim 4, wherein: the carbonyl iron particles (10) and gallium indium alloy liquid metal are mixed according to the mass ratio of 0.1-1:2.

6. The magnetorheological liquid metal pressure sensing device according to any one of claims 2 to 5, wherein: the non-magnetic conductive rigid shell (6) is made of glass fiber reinforced polyformaldehyde; the flexible pressure sensor (2) is made of PDMS.

7. The preparation method of the magnetorheological liquid metal pressure sensing device is characterized by comprising the following steps of:

step 1, manufacturing an injection mold of a magnetic field excitation device by using a photoetching technology and a flexible pressure sensor mold comprising a double-line planar spiral micro-channel;

step 2, selecting glass fiber reinforced polyformaldehyde, adopting an injection molding process to manufacture a circular cake-shaped magnetic field excitation device disc coated with a copper coil, wherein each specification of an upper disc and a lower disc of the magnetic field excitation device is completely consistent, and the magnetic field excitation device is connected with a current regulator on an external circuit;

step 3, mixing the organic silicon rubber and the curing agent in proportion, uniformly stirring, and placing the liquid PDMS into a deaerating machine for more than 30 minutes to remove internal bubbles; then pouring the material into a flexible pressure sensor mould containing a double-line plane spiral micro-channel, placing the material into an incubator, maintaining at 60-80 ℃ for more than 50 minutes, taking out the mould after PDMS is solidified to obtain a first sheet, and manufacturing a second sheet by the same method;

step 4, bonding the 2 PDMS sheets manufactured in the step 3; the bonding is to adhere the 2 layers manufactured above to form a whole with micro-channels inside;

step 5, mixing liquid metal with carbonyl iron particles, uniformly stirring to obtain magnetorheological liquid metal, putting the magnetorheological liquid metal into a deaerating machine for more than 30 minutes, removing internal bubbles, punching at a preset through hole by using a puncher, injecting the magnetorheological liquid metal by using an injector, sealing by using glue to obtain a flexible pressure sensor, and connecting an extraction detection end of the flexible pressure sensor with a resistance data acquisition instrument;

and 6, placing the flexible pressure sensor filled with the magnetorheological liquid metal between the upper disc and the lower disc of the magnetic field excitation device by the center of the flexible pressure sensor, and connecting the resistance data acquisition instrument with the current regulator.

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