Magnetorheological liquid metal pressure sensing device and method of manufacturing

Abstract

The application discloses a magneto-rheological liquid metal pressure sensor device and a manufacturing method thereof, and belongs to the technical field of pressure sensor devices.The sensor device comprises a first magnetic field excitation device, a flexible pressure sensing body and a second magnetic field excitation device which are overlapped from top to bottom in sequence, and an external current regulator and a resistance data acquisition instrument, the first magnetic field excitation device and the second magnetic field excitation device form a Helmholtz coil, and a glass fiber reinforced polyformal is selected as a shell base material, the flexible pressure sensing body internally comprises a double-wire planar spiral micro flow channel which is communicated, and the micro flow channel is filled with a magneto-rheological liquid metal.The pressure sensor device has the advantages of simple manufacturing method and stable material performance.The application overcomes the defects of fixed detection limit and sensitivity of the existing pressure sensor, improves the adjustable controllability of the sensor device, and realizes intelligent detection of pressure.

Description

TECHNICAL FIELD

[0001] The present application relates to a pressure sensing device, in particular to an intelligent detection limit and sensitivity adjustable magneto-rheological liquid metal pressure sensing device and a manufacturing method thereof. BACKGROUND

[0002] Pressure sensors have a wide range of applications in industrial production and scientific research testing fields. 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 adopts an elastic material as a surface covering to form a liquid metal pressure sensor; CN 115507216A discloses a magnetic fluid pressure control valve and a regulating method, which adopts a magneto-rheological liquid as an adjusting matrix to steplessly regulate the resistance gap cross-section area, thereby changing the pressure of the valve device. However, the pressure sensors made of liquid metal have the following problems:

[0003] 1. The pressure detection range is fixed, and the upper and lower limits of pressure detection are not adjustable, which cannot simultaneously consider the lower detection limit and the higher detection limit, and the range is small;

[0004] 2. The pressure detection sensitivity is low, and it cannot be applied to different pressure detection scenes;

[0005] 3. The pressure sensing body has poor durability, and the arrangement of micro-channels and the position of wiring ports are unreasonable, resulting in local stress concentration and uneven stress;

[0006] 4. It cannot intelligently control the current and magnetic field strength according to the measured pressure change, and cannot realize intelligent detection of pressure;

[0007] 5. The magneto-rheological liquid used in the valve device has poor electrical conductivity, and has a large magnetic resistance effect, which cannot obtain regular resistance value changes. The so-called magnetic resistance effect refers to the phenomenon that the resistance value of some metals or semiconductors changes with the change of the applied magnetic field. In the existing non-conductive magneto-rheological liquid or weakly conductive magneto-rheological liquid (including the magneto-rheological liquid disclosed in CN 115507216A), the carbonyl iron particles are arranged loosely without a magnetic field to the directional arrangement when magnetized, which will cause a large change in resistance value. SUMMARY

[0008] In view of the problems existing in the prior art, the technical problem to be solved by the present application is to provide a magneto-rheological liquid metal pressure sensing device, which can improve the upper and lower limits of pressure sensor detection, sensitivity and range, increase the application range of the sensor, improve the controllability and durability during use, and realize intelligent detection of pressure. The present application also provides a manufacturing method of the magneto-rheological liquid metal pressure sensing device.

[0009] To solve the above technical problems, the technical scheme of the present application is:

[0010] The present application provides a magneto-rheological liquid metal pressure sensing device, which comprises a first magnetic field excitation device, a flexible pressure sensing body and a second magnetic field excitation device overlapped in sequence from top to bottom, the outer connecting power supply circuit of the first magnetic field excitation device and the second magnetic field excitation device is connected with a current regulator, the leading 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.

[0011] Preferably, a double-wire plane spiral micro-flow channel is arranged in the flexible pressure sensing body, and the micro-flow channel is filled with the magneto-rheological liquid metal.

[0012] The present application provides a preparation method of the magneto-rheological liquid metal pressure sensing device, which comprises the following steps:

[0013] Step 1: using a photoetching technology to manufacture an injection mold of the magnetic field excitation device and a flexible pressure sensing body mold containing a double-wire plane spiral micro-flow channel;

[0014] Step 2: selecting a glass fiber reinforced polyformaldehyde, and using an injection molding process to manufacture a circular pie-shaped magnetic field excitation device disc coated with a copper coil, the upper and lower discs of the magnetic field excitation device are completely consistent in specifications, and are connected with a current regulator on an external circuit;

[0015] Step 3: mixing silicone rubber with a curing agent, stirring uniformly, placing the liquid PDMS into a degassing machine for more than 30 minutes to remove internal bubbles, then pouring the PDMS into the flexible pressure sensing body mold containing the double-wire plane spiral micro-flow channel, placing it into a temperature box to keep the temperature at 60-80 DEG C, and curing for more than 50 minutes, then taking out the first layer after the PDMS solidifies, and using the same method to manufacture a second layer;

[0016] Step 4: bonding the two PDMS layers manufactured in step 3, that is, bonding the two layers to form an integral body containing a micro-flow channel;

[0017] Step 5: mixing liquid metal with carbonyl iron particles, stirring uniformly to obtain a magneto-rheological liquid metal, placing the magneto-rheological liquid metal into a degassing machine for more than 30 minutes to remove internal bubbles, then using a punch to punch a pre-set through hole, then using a syringe to inject the magneto-rheological liquid metal, and using glue to seal the through hole to obtain a flexible pressure sensing body, and connecting the leading detection end of the flexible pressure sensing body with a resistance data acquisition instrument;

[0018] Step 6, the flexible pressure sensor center filled with magnetorheological liquid metal is placed between the upper and lower plates of the magnetic field excitation device, and the resistance data acquisition instrument is connected with the current regulator.

[0019] The basic working principle of the magnetorheological liquid metal pressure sensing device of the application is as follows:

[0020] By using the magnetorheological effect and the variable stiffness principle of the magnetorheological elastomer, a high permeability and non-soluble medium is added to the liquid metal to form a magnetorheological liquid metal. A uniform magnetic field is generated in space by using a Helmholtz coil as a magnetic field excitation device, 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 the liquid metal quickly solidifies and loses its flowability, which further causes the stiffness of the flexible pressure sensor containing the magnetorheological liquid metal to change. The stiffness change in the above process is a transient process and can be completed within milliseconds, and it is also reversible. After the external magnetic field is removed, the magnetorheological liquid metal regains its flowability. In addition, the resistance data acquisition instrument is connected with the current regulator, and the real-time resistance data is transmitted to the current regulator. The set resistance threshold value is used as the current control signal. When the resistance threshold value is reached, the current regulator automatically controls the current, so as to realize the intelligent adjustment of the upper and lower limits of the pressure detection, and obtain the detected pressure data from the output signal of the resistance data acquisition instrument.

[0021] The technical effect of the application is that the upper and lower limits and sensitivity of the pressure detection can be adjusted and controlled. The resistance data acquisition instrument can feed back the resistance signal in real time, and the current regulator can control the current size of the magnetic field excitation device, so as to realize the intelligent detection of the pressure. BRIEF DESCRIPTION OF DRAWINGS

[0022] The drawings of the application are as follows:

[0023] Figure 1 The drawings of the application are as follows:

[0024] Figure 2 The drawings of the application are as follows:

[0025] Figure 3 The drawings of the application are as follows:

[0026] Figure 4 The drawings of the application are as follows:

[0027] Figure 5 The drawings of the application are as follows:

[0028] In the figure, 1. First magnetic field excitation device; 2. Flexible pressure sensor; 3. Second magnetic field excitation device; 4. Current regulator; 5. Resistance data acquisition instrument; 6. Non-magnetic rigid shell; 7. Helmholtz coil; 8. Double-line planar spiral; 9. Magnetorheological liquid metal; 10. Carbonyl iron particles. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0030] To clearly describe the invention, this patent application uses the directional terms "upper" and "lower" for distinction. The terms "upper" and "lower" are determined based on the arrangement of the above figures. When the actual use direction of the invention changes, the terminology of the orientation will change accordingly, and this should not be regarded as a limitation on the scope of patent protection.

[0031] like Figure 1 As shown, the present invention includes a first magnetic field excitation device 1, a flexible pressure sensor 2, and a second magnetic field excitation device 3, which are stacked sequentially from top to bottom. A current regulator 4 is connected to the external power supply lines of the first and second magnetic field excitation devices 1 and 3. A resistance data acquisition instrument 5 is connected to the detection end of the flexible pressure sensor 2. The output signal terminal of the resistance data acquisition instrument 5 is connected to the control signal input terminal of the current regulator. The current regulator receives the control signal and adjusts the current of the magnetic field excitation device according to a pre-set resistance threshold, thereby controlling the intensity of the excitation magnetic field generated by the magnetic field excitation device. This achieves intelligent pressure detection and adjustable upper and lower limits and sensitivity of the flexible pressure sensor.

[0032] like Figure 2 As shown, the first magnetic field excitation device 1 and the second magnetic field excitation device 3 are identical in specifications, forming a Helmholtz coil 7, which is encased in a non-magnetic rigid shell 6. The non-magnetic rigid shell 6 is made of glass fiber reinforced polyoxymethylene, and a uniform magnetic field is generated using the Helmholtz coil.

[0033] like Figure 3 As shown, the flexible pressure sensor 2 has microchannels engraved inside, and the microchannels are interconnected double-line planar spirals 8. The interior of the microchannels is filled with magnetorheological liquid metal 9. The flexible pressure sensor 2 is made of polydimethylsiloxane (PDMS).

[0034] The magnetorheological liquid metal 9 is a mixture of gallium-indium alloy liquid metal and carbonyl iron particles 10. Depending on the application requirements, the carbonyl iron particles 10 and the gallium-indium alloy liquid metal are mixed at a mass ratio of 0.1 to 1:2.

[0035] The signal fed back by the resistance data acquisition instrument regulates the current regulator, controls the current flowing through the Helmholtz coil, and further controls the strength of the excitation magnetic field, adjusts the pressure detection range and detection sensitivity of the sensing device. The detection end of the flexible pressure sensor 2 is connected to the resistance data acquisition instrument. The resistance change of the magnetorheological liquid metal in the double-wire plane spiral micro-channel is detected, and the real-time feedback control signal is fed back to the current regulator. The control signal here is the resistance signal. The resistance data acquisition instrument is separately connected to alternating current, 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 flowing through the excitation magnetic field are transmitted to the computer processing module to obtain the pressure acting on the flexible pressure sensor.

[0036] The working principle of the present application is:

[0037] Magnetorheological effect: the magnetorheological liquid metal is EGaIn liquid metal mixed with a certain proportion of carbonyl iron particles. The carbonyl iron particles 10 are uniformly and randomly dispersed in the gallium-based liquid metal. The difference in magnetic permeability between the liquid metal matrix and the carbonyl iron particles is the fundamental reason for the magnetorheological effect of the present application.

[0038] As shown in Figure 4 The carbonyl iron particles 10 have the characteristic of magnetic field polarization. Under the action of the external magnetic field, the originally loose arrangement of the carbonyl iron particles in the liquid state will form a chain structure along the magnetic field direction, resulting in regular directional arrangement, and thus the rigidity of the flexible pressure sensor 2 as a whole changes. Since the carbonyl iron particles are soft magnetic materials without solidification remanence, and have high saturation magnetization, when the external magnetic field is removed, the magnetorheological liquid metal quickly recovers under the action of the external elastomer, which is the basis for the repeated operation of the present application.

[0039] In addition, the liquid metal can be regarded as a mixture of positive ion fluid and free electron gas, and has high conductivity. The liquid metal has a dirty nature, that is, the liquid metal leaves a trace on the path it flows through. The trace is continuous and continuous, and the main component is an ultra-thin layer of liquid metal and its oxide. Even if the double-wire plane spiral micro-channel inside the flexible pressure sensor is compressed to be flat, the complete electrically conductive path can be ensured, so that the pressure sensor has strong electrically conductive stability. In addition, the electrical conductivity of the liquid metal in the magnetorheological liquid metal is much stronger than that of the carbonyl iron particles, and the liquid metal plays a major role in electrical conductivity. Therefore, the movement of the carbonyl iron particles does not affect the electrical conductivity of the overall electrically conductive path, overcoming the magnetic resistance effect of the existing magnetorheological liquid and the instability of the electrical conductivity of the magnetic flow liquid, ensuring that the resistance value of the magnetorheological liquid only changes with the geometry of the micro-channel according to the resistance law, and a function formula can be established between the pressure borne by the flexible pressure sensor and the change of the resistance of the liquid metal.

[0040] The magnetization of carbonyl iron particles in a uniform electromagnetic field can be derived according to the Langevin classical paramagnetism theory, in which 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 acting on the carbonyl iron particles cannot be specifically calculated, it can be replaced by a random force according to the random potential introduced by the Langevin equation, and thus the magnetization of the carbonyl iron particles under the action of the electromagnetic field can be derived. The derivation process is as follows:

[0041] First, the number of carbonyl iron particles in the magnetorheological liquid metal is derived. The number of carbonyl iron particles contained in the magnetorheological liquid metal is controlled by two factors: the volume fraction of carbonyl iron particles contained in the liquid metal, and the particle size of the carbonyl iron particles. The carbonyl iron particles used in the present application are uniformly produced and customized, and the particle size is the same. Therefore, the number of carbonyl iron particles contained in the magnetorheological liquid metal is:

[0042]

[0043] In formula (1), Φ v is the volume fraction of carbonyl iron particles in the magnetorheological liquid metal; d is the particle size of the carbonyl iron particles.

[0044] The magnetic moment of a single carbonyl iron particle is:

[0045]

[0046] In formula (2), M S is the saturation magnetization of the carbonyl iron particles.

[0047] The expression of the introduced Langevin function is:

[0048]

[0049] In formula (3), coth is the hyperbolic cosecant 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 the magnetic field strength and the magnetic field temperature, and the characteristics of the carbonyl iron particles themselves include the vacuum permeability and the magnetic moment. Therefore, the parameter of the Langevin function can be expressed as:

[0050]

[0051] In formula (4), μ0 is the vacuum permeability of the 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; and T is the absolute temperature.

[0052] According to Langevin theory, the relationship of magnetization of the magnetorheological liquid metal after introducing random potential is:

[0053] M = nmL (a) (5)

[0054] The overall magnetization of the carbonyl iron particle in the magnetorheological liquid metal is calculated by formula (5):

[0055]

[0056] The formula of the magnetization of the magnetorheological liquid metal is obtained by formula (6):

[0057]

[0058] In formula (7), n is the number of carbonyl iron particles;

[0059] m is the magnetic moment of a single carbonyl iron particle;

[0060] Φ v is the volume fraction of the carbonyl iron particle in the magnetorheological liquid metal;

[0061] d is the particle size of the carbonyl iron particle;

[0062] M S is the saturation magnetization of the carbonyl iron particle;

[0063] a is the parameter of the Langevin function;

[0064] μ0 is the vacuum permeability of the carbonyl iron particle;

[0065] H is the applied magnetic field strength;

[0066] K is the Boltzmann constant;

[0067] T is the absolute temperature.

[0068] The magnetic field excitation device in the magnetorheological liquid metal flexible pressure sensing device is a fiberglass reinforced polyformaldehyde coated Helmholtz coil. The fiberglass reinforced polyformaldehyde, also known as race steel, has the advantages of high strength, non-magnetic, heat and acid resistance, and good stability. Within the range of the flexible pressure sensing body pressure range, it can be regarded as a rigid body without deformation. The Helmholtz coil can generate a uniform magnetic field in space, thereby ensuring that the carbonyl iron particles in the magnetorheological liquid metal in the microchannel of the flexible pressure sensing body are uniformly magnetized.

[0069] As Figure 1As shown, the flexible pressure sensor 2 is connected to 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 a current regulator. The current regulator receives a control signal, which is a resistance signal. According to the calibration experiment of the flexible pressure sensor, different resistance threshold values are set. After the current regulator stores the resistance threshold values, the current of the magnetic field excitation device is adjusted to a predetermined size according to the pre-set threshold value, so as to control the excitation magnetic field strength generated by the magnetic field excitation device. This is the intelligent control process of the pressure sensor device.

[0070] The resistance change of the magnetorheological liquid metal in the micro-channel of the pressure sensor can be measured by a resistance data acquisition instrument. The resistance data acquisition instrument can be a high-precision LCR tester (HG2810). The current regulator can be a controllable silicon adjustable DC power controller produced by Shanghai Nenggong.

[0071] As shown in Figure 4 , applying different sizes of direct current to the magnetic field excitation device will cause the carbonyl iron particles in the micro-channel of the pressure sensor to have different magnetization strengths, and then affect the overall stiffness of the pressure sensor. When the magnetic field excitation device is not powered, the stiffness of the pressure sensor is the smallest, the sensitivity of the sensor device is the highest, and the sensor device can detect small pressure, but the upper limit of the pressure monitoring is low. When the magnetic field excitation device is powered, the stiffness of the pressure sensor increases, the detection lower limit of the sensor device gradually increases, and the pressure detection upper limit also gradually increases, which can meet the demand of detecting larger pressure. This is the basic principle of the adjustable detection limit and sensitivity of the pressure sensor device.

[0072] As shown in Figure 4 , after the magnetic field excitation device is adjusted to a predetermined size of external current, the magnetic field excitation device generates a uniformly distributed magnetic field, and the carbonyl iron particles in the micro-channel of the pressure sensor are uniformly magnetized. When subjected to external pressure, the micro-channel in the pressure sensor will be compressed and deformed, thereby affecting the resistance value of the micro-channel in the pressure sensor. There is a functional relationship between the external pressure and the resistance value of the pressure sensor. The size of the external pressure can be represented by measuring the resistance change. This is the basic principle of the pressure sensor device for detecting pressure.

[0073] As shown in Figure 5 , as shown in Figure 5 (a) is the filling diameter d of the magnetorheological liquid metal in the micro-channel when no pressure is applied in the present embodiment. Figure 5(b) When the embodiment is under pressure, the flexible pressure sensor 2 is deformed, and the filling diameter of the magnetic rheological liquid metal in the micro-channel is d'; according to the principle of the pressure sensing device, the change of the diameter of the micro-channel in the pressure sensor will inevitably cause the change of the resistance value of the magnetic rheological liquid metal in the connected double-wire planar spiral coil; therefore, the change value of the resistance value of the magnetic rheological liquid metal in the connected double-wire planar spiral coil can reflect the size of the pressure P.

[0074] By adjusting the access current size of the magnetic field excitation device, magnetic fields of different strengths can be generated, and the magnetic fields of different strengths will affect the magnetization intensity of the carbonyl iron particles in the pressure sensor, and the deformation rigidity of the pressure sensor is different when the magnetization intensity is different; the size of the resistance change, the external current change and the pressure can be measured, and theoretically, the pressure detection limit can be continuously adjusted without limit, but in actual use, in order to simplify the experiment calibration times, different pressure detection gears can be set, for example, high, medium and low gears are set to detect three types of pressure respectively. Determining different external currents is to select different detection gears, and this work can be completed by the resistance data acquisition instrument and the current regulator working together. The resistance data acquisition instrument feeds back the real-time resistance value data to the current regulator, and the gear is automatically adjusted when the set resistance threshold is reached. According to the last stable resistance value output by the resistance data acquisition instrument, the pressure applied to the flexible pressure sensor is determined, and the electric signal measured by the resistance is converted into a pressure value.

[0075] The manufacturing method of the pressure sensing device provided by the application comprises the following steps:

[0076] Step 1: using photolithography technology to manufacture an injection mold of the magnetic field excitation device and a flexible pressure sensor mold containing a double-wire planar spiral micro-channel;

[0077] Step 2: selecting glass fiber reinforced polyformaldehyde to manufacture a circular pie-shaped magnetic field excitation device disc coated with a copper coil by using an injection molding process, and the upper and lower discs of the magnetic field excitation device are completely consistent in specifications and are connected with a current regulator on an external circuit.

[0078] Step 3: according to the requirement of the hardness of PDMS when in use, mixing organic silicone rubber and curing agent at a mass ratio of 10:1-1.2, stirring uniformly, placing the liquid PDMS into a debubbling machine for more than 30 minutes to remove the internal bubbles; then pouring the PDMS into the flexible pressure sensor mold containing the double-wire planar spiral micro-channel, placing it into a temperature box to keep the temperature at 60-80 DEG C, and curing for more than 50 minutes; after the PDMS solidifies, taking out the sheet layer 1 from the mold, and manufacturing the sheet layer 2 in the same way.

[0079] Step 4: bonding the two sheet layers of PDMS manufactured in step 3; the bonding is to stick the two layers manufactured above to one piece to form an integral whole containing a micro-channel inside.

[0080] Step 5, after mixing the liquid metal with the carbonyl iron particles, stirring evenly, get the magneto rheological liquid metal, the magneto rheological liquid metal is put into the defoaming machine for more than 30 minutes, remove the internal bubble, again using puncher in the pre-set hole for punching, then using the syringe to inject the magneto rheological liquid metal, using glue for sealing, get the flexible pressure sensor, the leading detection end of the flexible pressure sensor is connected with the resistance data acquisition instrument;

[0081] Step 6, the flexible pressure sensor injected with the magneto rheological liquid metal is placed in the middle of the upper and lower discs of the magnetic field excitation device, and the resistance data acquisition instrument is connected with the current regulator.

[0082] In actual use, the flexible pressure sensor and the upper and lower discs of the magnetic field excitation device are placed in the center of the stack in alignment, without bonding, so that the flexible pressure sensor can fully deform under stress, thereby improving the sensitivity of pressure detection.

[0083] The magnetic field excitation device is connected with the current regulator to control the size of the input current, the detection end of the flexible pressure sensor is connected with the resistance data acquisition instrument, and the resistance data acquisition instrument feeds back the control signal to the current regulator in real time. The flexible pressure sensor device with adjustable pressure detection limit and sensitivity is calibrated, and finally the current value output by the current regulator and the final stable resistance signal obtained by the resistance data acquisition instrument are transmitted to the calculation processing module, so that the external pressure can be measured by measuring the final stable resistance value of the magneto rheological liquid metal.

Claims

1. A magneto-rheological liquid metal pressure sensing device, characterized by: It comprises first magnetic field excitation device (1), flexible pressure sensor (2) and second magnetic field excitation device (3) which are overlapped from top to bottom, the current regulator (4) is connected to the external power supply circuit of the first magnetic field excitation device (1) and the second magnetic field excitation device (3), the detection end of the flexible pressure sensor (2) is connected to the 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 (4); The magnetorheological liquid metal (9) is a mixture of gallium-indium alloy liquid metal and carbonyl iron particles (10); The first magnetic field excitation device (1) and the second magnetic field excitation device (3) are of the same specification and constitute a Helmholtz coil (7), and the Helmholtz coil is covered by a non-magnetic rigid shell (6); The flexible pressure sensor (2) is internally engraved with a micro channel, which is a double-line plane spiral (8) in communication, and the micro channel is filled with magnetorheological liquid metal (9).

2. The magneto-rheological liquid metal pressure sensing device of claim 1, wherein: The carbonyl iron particles (10) and gallium-indium alloy liquid metal are mixed in a mass ratio of 0.1-1:

2.

3. The magneto-rheological liquid metal pressure sensing device of claim 1 or 2, wherein: The non-magnetic rigid shell (6) is made of glass fiber reinforced polyformaldehyde, and the flexible pressure sensor (2) is made of PDMS.

4. A method of manufacturing a magneto rheological liquid metal pressure sensing device, characterized by, It comprises the following steps: Step 1, using photolithography technology to make injection mold of first magnetic field excitation device and second magnetic field excitation device and flexible pressure sensor mold containing double-line plane spiral micro channel; Step 2, using glass fiber reinforced polyformaldehyde to make non-magnetic rigid shell, using injection molding process to make circular pie-shaped first magnetic field excitation device and second magnetic field excitation device covering Helmholtz coil, the two magnetic field excitation devices are completely consistent in specification, and the magnetic field excitation device is connected to the current regulator on the external power supply circuit; Step 3, after mixing organic silicone rubber and curing agent in proportion, stirring uniformly, placing liquid PDMS into a degassing machine for more than 30 minutes to remove internal bubbles, then pouring it into the flexible pressure sensor mold containing double-line plane spiral micro channel, placing it into a temperature box to keep 60-80℃, curing for more than 50 minutes, taking out the first layer after PDMS solidification, and making the second layer in the same way; Step 4, bonding the two PDMS layers made in step 3; the bonding is to stick the two PDMS layers made in step 3 together to form a whole containing micro channel inside; Step 5, after mixing liquid metal and carbonyl iron particles, stirring uniformly, obtaining magnetorheological liquid metal, placing the magnetorheological liquid metal into a degassing machine for more than 30 minutes to remove internal bubbles, then using a punch to punch a pre-set through hole on the bonded PDMS, then using a syringe to inject the magnetorheological liquid metal into the micro channel, and using glue to seal the through hole, obtaining the flexible pressure sensor, and connecting the detection end of the flexible pressure sensor to the resistance data acquisition instrument; Step 6, placing the flexible pressure sensor filled with magnetorheological liquid metal between the first magnetic field excitation device and the second magnetic field excitation device in the center; The resistance data acquisition instrument is connected to the current regulator.

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