A weak magnetic field measuring instrument and a measuring method thereof

Abstract

This invention discloses a weak magnetic field measuring instrument and its measuring method, belonging to the field of weak magnetic field measurement technology. The weak magnetic field measuring instrument includes a mounting platform, on which a thin-film pressure-sensitive sensor and two soft magnets are arranged. The piezoelectric element of the thin-film pressure-sensitive sensor is disposed between the two soft magnets. The signal line of the thin-film pressure-sensitive sensor is electrically connected to an external electrical signal device. A test magnet is disposed between the two soft magnets. The two soft magnets are used to obtain an amplified magnetic field through the demagnetizing effect. Then, the amplified magnetic field is used to apply pressure to the pressure sensor through the soft magnets and the magnet between the soft magnets to output a specific signal. Finally, the magnetic field strength and direction of the external weak magnetic field are obtained using the output signal.

Description

Technical Field

[0001] This invention relates to the field of weak magnetic field measurement technology, and in particular to a weak magnetic field measuring instrument and its measurement method. Background Technology

[0002] Magnetic field measurement is an important technical means in fields such as physics, geophysics, biomedical engineering, and materials science. With the rapid development of science and technology, various magnetic materials and their products are widely used in many fields such as electrical equipment, medical equipment, aerospace, and wireless power transmission.

[0003] Traditional magnetic field measurement techniques include fluxgate magnetometers and magnetoresistive magnetometers. Although these techniques offer high measurement accuracy, they still face challenges when measuring weak magnetic fields, such as interference from environmental noise and issues related to signal processing. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, this invention provides a weak magnetic field measuring instrument and its measuring method, which solves the problem that traditional magnetic field measuring techniques are easily affected by environmental noise interference when measuring weak magnetic fields.

[0005] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0006] A weak magnetic field measuring instrument is provided, comprising an installation platform on which a thin-film pressure-sensitive sensor and two soft magnets are disposed. A test magnet is disposed between the two soft magnets. The piezoelectric element of the thin-film pressure-sensitive sensor is disposed between the test magnet and one of the soft magnets. The signal line of the thin-film pressure-sensitive sensor is electrically connected to an external electrical signal device.

[0007] Furthermore, a glass plate is provided on the upper surface of the installation platform, and two soft magnets are provided on the upper surface of the glass plate; a gap is provided in the middle of the glass plate, and the piezoelectric sheet of the thin-film pressure sensor passes through the gap and is located between the two soft magnets.

[0008] Furthermore, both soft magnets are T-shaped structures, and are arranged symmetrically with respect to the position of the piezoelectric element of the thin-film pressure sensor. The protruding ends of the two soft magnets are located on both sides of the piezoelectric element of the thin-film pressure sensor.

[0009] Furthermore, the external electrical signal device is a multimeter.

[0010] The present invention also provides a measurement method for a weak magnetic field measuring instrument, comprising:

[0011] Step 1: Obtain the curve function of the output resistance of the thin-film piezoresistive sensor versus the strength of the magnetic field to be measured;

[0012] Step 2: Record the initial resistance of the thin-film pressure sensor under no magnetic field conditions;

[0013] Step 3: Place the entire weak magnetic field measuring instrument into the magnetic field to be measured and record the resistance value of the thin-film pressure sensor;

[0014] Step 4: Substitute the resistance value of the thin-film pressure sensor into the curve function of the output resistance of the thin-film pressure sensor and the magnetic field strength to be measured in Step 3 to calculate the magnetic field strength of the magnetic field to be measured.

[0015] Further, in step 1, the method for obtaining the curve function of the output resistance of the thin-film pressure sensor versus the measured magnetic field strength includes:

[0016] Step 1.1: Set the entire weak magnetic field measuring instrument within the Helmholtz coil;

[0017] Step 1.2: Record the initial resistance value of the thin-film pressure sensor;

[0018] Step 1.3: Input a voltage of 0.5V to the Helmholtz coil; wait 20 seconds, then read and record the resistance value of the thin-film pressure sensor and the strength of the magnetic field corresponding to the 0.5V voltage of the Helmholtz coil.

[0019] Step 1.4: Disconnect the voltage input to the Helmholtz coil to bring its magnetic field to zero, and the thin-film pressure sensor will return to its initial resistance value;

[0020] Step 1.5: Repeat steps 1.3 to 1.4, input a voltage of 0.5V to 10V to the Helmholtz coil, and read and record the magnetic field strength of the Helmholtz coil under the voltage of 0.5V to 10V and the resistance value of the magnetic field strength of the thin-film pressure sensor under the voltage of 0.5V to 10V.

[0021] Step 1.6: Input the magnetic field strength of the Helmholtz coil under 0.5V~10V voltage and the resistance value of the magnetic field strength of the thin-film piezoresistive sensor under 0.5V~10V voltage into Matlab software for processing to obtain the curve function of the output resistance of the thin-film piezoresistive sensor versus the magnetic field strength to be measured.

[0022] Furthermore, the expression for the curve function of the output resistance of the thin-film pressure sensor versus the measured magnetic field strength is as follows:

[0023]

[0024] in, The magnetic field strength is the magnetic field to be measured. x This represents the resistance value of the thin-film pressure sensor.

[0025] The beneficial effects of the present invention are as follows: 1. The present invention provides a weak magnetic field measuring instrument and its measuring method, which utilizes two soft magnetic bodies to obtain an amplified magnetic field through the demagnetization effect. Then, the amplified magnetic field is used to apply pressure to a pressure sensor by the soft magnetic bodies and the magnet between the soft magnetic bodies to output a specific signal. Finally, the magnetic field strength and direction of the external weak magnetic field are obtained by using the output signal, which solves the problem that traditional magnetic field measuring technology is easily affected by environmental noise interference when measuring weak magnetic fields.

[0026] 2. The weak magnetic field measuring instrument of the present invention has a simple structure, readily available materials, low manufacturing cost, and high measurement accuracy, and is suitable for measuring weak magnetic fields. Attached Figure Description

[0027] Figure 1 This is a three-dimensional structural diagram of a weak magnetic field measuring instrument.

[0028] Figure 2 This is a schematic diagram of a weak magnetic field measuring instrument.

[0029] Figure 3 This is a graph showing the output voltage of a thin-film pressure sensor versus the magnetic field strength being measured.

[0030] Figure 4 This is a top view schematic diagram of a weak magnetic field measuring instrument.

[0031] The components include: 1. Installation platform; 2. Thin-film pressure sensor; 3. Soft magnet; 4. Signal line; 5. Glass plate; 6. Gap; 7. Test magnet. Detailed Implementation

[0032] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0033] like Figure 1 and Figure 4 As shown, the present invention provides a weak magnetic field measuring instrument, which includes a mounting platform 1.

[0034] The mounting platform 1 is equipped with two soft magnets 3 and a thin-film pressure sensor 2. A test magnet 7 is positioned between the two soft magnets 3. The piezoelectric element of the thin-film pressure sensor 2 is positioned between the test magnet 7 and one of the soft magnets 3. The signal line 4 of the thin-film pressure sensor 2 is electrically connected to an external electrical signal device, specifically a multimeter. To prevent excessive movement of the soft magnets 3 and the test magnet 7 during the setup of the entire weak magnetic field measuring instrument, one of the soft magnets 3 is fixed in place.

[0035] The principle of the entire weak magnetic field measuring instrument is as follows: A test magnet 7 is placed between two soft magnetic bodies 3, and the test magnet 7 is attracted to one of the soft magnetic bodies 3. The piezoelectric element of the thin-film pressure sensor 2 is placed between the test magnet 7 and the soft magnetic body 3. Then, the soft magnetic body 3 without the test magnet 7 is fixed. Since the test magnet 7 magnetizes the two soft magnetic bodies, a demagnetizing field is generated between them. The direction of the demagnetizing field is the same as the direction of the test magnet 7's magnetic field. When the entire weak magnetic field measuring instrument is placed in the weak magnetic field to be measured, the test magnet 7 will not demagnetize because the magnetic field to be measured is relatively weak compared to the test magnet 7. When the direction of the magnetic field to be measured is opposite to the direction of the demagnetizing field, the magnetization of the soft magnetic body 3 is weakened, and the demagnetizing field is also weakened. At this time, because the attractive force between the two soft magnetic bodies 3 is weakened, the pressure applied to the sensor is weakened, thus increasing the resistance. If the direction of the magnetic field to be measured is the same as the direction of the demagnetizing field, the resistance decreases. Finally, the magnetic field strength and direction of the external weak magnetic field are obtained by using the output signal of the thin-film pressure sensor 2.

[0036] Preferably, a glass plate 5 is provided on the upper surface of the mounting platform 1, and two soft magnets 3 are provided on the upper surface of the glass plate 5; a gap 6 is provided in the middle of the glass plate 5, and the piezoelectric sheet of the thin film pressure sensor 2 passes through the gap 6 and is located between the two soft magnets 3.

[0037] Both soft magnets 3 are T-shaped and arranged symmetrically with respect to the piezoelectric element of the thin-film pressure sensor 2. The protruding ends of the two soft magnets 3 are located on both sides of the piezoelectric element of the thin-film pressure sensor 2. The T-shaped structure of the two soft magnets 3 can better concentrate the weak external magnetic field and achieve linear amplification of the magnetic field to be measured.

[0038] like Figure 2As shown, the weak magnetic field measuring instrument of this invention utilizes two soft magnetic bodies 3 to obtain an amplified magnetic field through the demagnetizing effect. The demagnetizing effect refers to the phenomenon that when a magnetic sample of finite size is magnetized by an external magnetic field, the free magnetic poles appearing at its ends will generate a magnetic field opposite to the direction of the magnetization intensity. In this invention, the amplified magnetic field is used to apply pressure to a pressure sensor through the magnet between the soft magnetic bodies 3, thereby outputting a specific signal. Finally, the magnetic field strength and direction of the weak external magnetic field are obtained using the output signal, solving the problem that traditional magnetic field measurement techniques are easily affected by environmental noise when measuring weak magnetic fields.

[0039] The present invention also provides a measurement method for a weak magnetic field measuring instrument, comprising:

[0040] Step 1, as follows Figure 3 As shown, the curve function of output resistance versus magnetic field strength of the thin-film pressure sensor 2 is obtained;

[0041] Step 2: Record the initial resistance of the thin-film pressure sensor 2 under no magnetic field conditions;

[0042] Step 3: Place the entire weak magnetic field measuring instrument into the magnetic field to be measured and record the resistance value of the thin-film pressure sensor 2;

[0043] Step 4: Substitute the resistance value of the thin-film pressure sensor 2 in Step 3 into the curve function of the output resistance of the thin-film pressure sensor 2 and the magnetic field strength to be measured, and calculate the magnetic field strength of the magnetic field to be measured.

[0044] Further, in step 1, the method for obtaining the output resistance-measuring magnetic field strength curve function of the thin-film pressure sensor 2 includes:

[0045] Step 1.1: Set the entire weak magnetic field measuring instrument within the Helmholtz coil;

[0046] Step 1.2: Record the initial resistance value of the thin-film pressure sensor 2;

[0047] Step 1.3: Input a 0.5V voltage to the Helmholtz coil; wait 20 seconds, then read and record the resistance value of the thin-film pressure sensor 2 and the strength of the magnetic field corresponding to the 0.5V voltage of the Helmholtz coil.

[0048] Step 1.4: Disconnect the voltage input to the Helmholtz coil to bring its magnetic field to zero, and the thin-film pressure sensor 2 returns to its initial resistance value;

[0049] Step 1.5: Repeat steps 1.3 to 1.4, input a voltage of 0.5V to 10V to the Helmholtz coil, and read and record the magnetic field strength of the Helmholtz coil under the voltage of 0.5V to 10V and the resistance value of the magnetic field strength of the thin film pressure sensor 2 under the voltage of 0.5V to 10V.

[0050] Step 1.6: Input the magnetic field strength of the Helmholtz coil under 0.5V~10V voltage and the resistance value of the magnetic field strength of the thin-film piezoresistive sensor 2 under 0.5V~10V voltage into Matlab software for processing to obtain the output resistance-measuring magnetic field strength curve function of the thin-film piezoresistive sensor 2.

[0051] Furthermore, the expression for the output resistance-measuring magnetic field strength curve function of the thin-film pressure sensor 2 is as follows:

[0052]

[0053] in, The magnetic field strength is the magnetic field to be measured. x The resistance value is that of the thin-film pressure sensor 2.

Claims

1. A weak magnetic field measuring instrument, characterized in that, The system includes an installation platform on which a thin-film pressure sensor and two soft magnets are installed. A test magnet is installed between the two soft magnets. The test magnet is attracted to one of the soft magnets. The piezoelectric element of the thin-film pressure sensor is installed between the test magnet and one of the soft magnets. The soft magnet that is not attracted to the test magnet is fixed. The test magnet (7) magnetizes the two soft magnets, thereby generating a demagnetizing field between the two soft magnets (3). The signal line of the thin-film pressure sensor is electrically connected to an external electrical signal device. The upper surface of the installation platform is provided with a glass plate, and two soft magnets are provided on the upper surface of the glass plate; a gap is provided in the middle of the glass plate, and the piezoelectric sheet of the thin-film pressure sensor passes through the gap and is located between the two soft magnets. Both of the soft magnets are T-shaped and are arranged symmetrically with respect to the position of the piezoelectric element of the thin-film pressure sensor. The protruding ends of the two soft magnets are located on both sides of the piezoelectric element of the thin-film pressure sensor.

2. The weak magnetic field measuring instrument according to claim 1, characterized in that, The external electrical signal device is a multimeter.

3. A measurement method based on the weak magnetic field measuring instrument according to any one of claims 1 to 2, characterized in that, include: Step 1: Obtain the curve function of the output resistance of the thin-film piezoresistive sensor versus the strength of the magnetic field to be measured; Step 2: Record the initial resistance of the thin-film pressure sensor under no magnetic field conditions; Step 3: Place the entire weak magnetic field measuring instrument into the magnetic field to be measured and record the resistance value of the thin-film pressure sensor; Step 4: Substitute the resistance value of the thin-film pressure sensor into the curve function of the output resistance of the thin-film pressure sensor and the magnetic field strength to be measured in Step 3 to calculate the magnetic field strength of the magnetic field to be measured.

4. The measurement method of the weak magnetic field measuring instrument according to claim 3, characterized in that, In step 1, the method for obtaining the curve function of the output resistance of the thin-film piezoresistive sensor versus the measured magnetic field strength includes: Step 1.1: Set the entire weak magnetic field measuring instrument within the Helmholtz coil; Step 1.2: Record the initial resistance value of the thin-film pressure sensor; Step 1.3: Input a voltage of 0.5V to the Helmholtz coil; wait 20 seconds, then read and record the resistance value of the thin-film pressure sensor and the strength of the magnetic field corresponding to the 0.5V voltage of the Helmholtz coil. Step 1.4: Disconnect the voltage input to the Helmholtz coil to bring its magnetic field to zero, and the pressure sensor will return to its initial resistance value; Step 1.5: Repeat steps 1.3 to 1.4, input a voltage of 0.5V to 10V to the Helmholtz coil, and read and record the magnetic field strength of the Helmholtz coil under the voltage of 0.5V to 10V and the resistance value of the magnetic field strength of the thin-film pressure sensor under the voltage of 0.5V to 10V. Step 1.6: Input the magnetic field strength of the Helmholtz coil under 0.5V~10V voltage and the resistance value of the magnetic field strength of the thin-film piezoresistive sensor under 0.5V~10V voltage into Matlab software for processing to obtain the curve function of the output resistance of the thin-film piezoresistive sensor versus the magnetic field strength to be measured.

5. The measurement method of the weak magnetic field measuring instrument according to claim 4, characterized in that, The expression for the curve function of output resistance versus measured magnetic field strength of a thin-film pressure sensor is: in, The magnetic field strength is the magnetic field to be measured. x This represents the resistance value of the thin-film pressure sensor.

Images