Pyroelectric sensor and preparation method thereof

Abstract

The invention provides a pyroelectric sensor and a preparation method thereof. A novel needle type structure of the pyroelectric sensor comprises a tubular shell, a fixed tube, an extension tube, an insulating layer, a detection probe and a sound absorption material. The preparation method comprises the following steps: uniformly stirring a main agent and a curing agent of polyurethane according to a mass ratio of 3: 1, preparing a polyurethane solution, glass beads K1 and boron carbide according to a weight ratio of 10: 1: 1, curing at room temperature, connecting the upper and lower surfaces of a PMN-PT relaxation ferroelectric single crystal material with a copper pipe by using conductive silver adhesives, and then assembling with a bullet structure; when the solution prepared by K1 is in a semi-solidified state, the solution covers the front surface of the PMN-PT relaxation ferroelectric single crystal, and the pyroelectric sensor is obtained through curing, the preparation method is simple in process and good in pyroelectric signal, and can be used in the field of acoustic power measurement.

Description

Technical Field

[0001] The present invention relates to the technical field of sensors, and in particular to a pyroelectric sensor and a preparation method thereof. Background Art

[0002] Pyroelectric sensors are based on the pyroelectric effect, that is, when the temperature of a pyroelectric material changes, its polarization state changes accordingly, generating an electric charge on the surface of the material. This effect was first discovered more than 2,000 years ago, but it was not scientifically defined until the 1820s. In recent years, with the development of materials science and microelectronics technology, pyroelectric sensors have been widely used in many fields such as infrared detection, temperature measurement, and ultrasonic sensing. The traditional hydrophone scanning sound field method has a long operation time and cumbersome steps; the radiation force balance measures sound power, and has strict requirements on the placement distance and angle of the transducer and the radiation target when used, and the instrument cost is also relatively high. Therefore, pyroelectric sensors have great potential in the field of sound power measurement.

[0003] The pyroelectric coefficient and dielectric constant are two important parameters of pyroelectric sensors. The pyroelectric sensor absorbs sound through its backing material and converts it into heat. The heat is transferred to the sensitive element to complete the energy conversion of sound, heat and electricity. The pyroelectric coefficient directly corresponds to the sensitivity performance of the sensor.

[0004] At present, pyroelectric materials are mainly divided into three types: single crystal materials, ceramic materials, and high molecular polymer materials. Among them, single crystal materials have a small dielectric constant and a large pyroelectric coefficient. At the same time, single crystal materials have good frequency response and high sensitivity. It is the best choice for the sensitive element of pyroelectric sensors. However, the acoustic impedance of single crystal materials is high, and the traditional pyroelectric structure cannot meet the requirements of sound passing through single crystal materials as sensitive elements to reach the backing sound absorbing material. Summary of the invention

[0005] In view of this, the present invention provides a pyroelectric sensor and a preparation method thereof. The method is simple and the prepared pyroelectric sensor has high sensitivity.

[0006] In order to solve the above technical problems, the present invention provides a pyroelectric sensor and a preparation method thereof, comprising a tubular shell, the tubular shell serving as the positive and negative outputs of the pyroelectric sensor circuit; a fixed tube is arranged inside the tubular shell to facilitate the assembly of the shell and the bullet head structure; an extension tube is sleeved inside the fixed tube; an insulating layer is arranged between the inner wall of the fixed tube and the outer arc surface of the extension tube to isolate the positive and negative outputs of the circuit and ensure the normal operation of the circuit; a glue layer is arranged between the outer arc surface of the fixed tube and the inner wall of the tubular shell to reinforce the tubular shell and the bullet head structure while increasing the water tightness of the pyroelectric sensor; a detection probe is arranged at the end of the extension tube through conductive silver glue, the probe outputs a pyroelectric signal, and a composite sound absorbing material is arranged on the detection probe, the composite sound absorbing material receives sound, converts it into heat, and conducts it to the detection probe;

[0007] The composite sound-absorbing material is composed of polyurethane, glass microspheres and boron carbide; that is, polyurethane is used as the main material, glass microsphere K1 material is added to improve the sound absorption coefficient, and boron carbide material is added to improve the thermal conductivity. The final composite material has strong sound absorption and high thermal conductivity.

[0008] The tubular shell, the fixed tube and the extension tube are all made of copper; that is, the outer copper tube is used as the negative electrode of the pyroelectric sensor circuit and is connected to the upper surface of the PMN-PT relaxor ferroelectric single crystal; the inner copper tube is used as the positive electrode of the pyroelectric sensor circuit and is connected to the lower surface of the PMN-PT relaxor ferroelectric single crystal;

[0009] The insulation layer is made of heat shrink tubing material; the inner and outer copper tubes are insulated, i.e. the positive and negative electrodes, to prevent the pyroelectric sensor circuit from short-circuiting and failing;

[0010] The glue coating layer adopts epoxy resin adhesive material; that is, the water tightness is increased when the outer copper tube and the bullet head structure are assembled;

[0011] The detection probe uses PMN-PT relaxor ferroelectric single crystal material; that is, single crystal material with high pyroelectric coefficient as a sensitive element, which effectively improves the sensitivity of the pyroelectric sensor;

[0012] The outer arc surface of one end of the tubular housing is provided with a thread, which matches the BNC connector and is convenient for assembly with the coaxial cable.

[0013] The main agent and curing agent of the polyurethane are mixed in a mass ratio of 3:1 and stirred evenly. The glass beads and boron carbide powder are added to the solution in a weight ratio of polyurethane solution: glass beads K1: boron carbide = 10:1:1 and stirred evenly.

[0014] Pour 15 ml of the mixture into a paper cup and solidify at room temperature;

[0015] The upper and lower surfaces of the PMN-PT relaxor ferroelectric single crystal material with a diameter of 2 mm were connected to the copper tube using conductive silver glue, and then assembled with the bullet head structure;

[0016] When the solution prepared by K1 is in a semi-solidified state, it is applied to the front surface of the PMN-PT relaxor ferroelectric single crystal and waited for solidification.

[0017] In summary, compared with the prior art, the present application has at least one of the following beneficial technical effects:

[0018] 1. Polyurethane, glass microbeads K1 and boron carbide are used to prepare composite sound-absorbing materials. Glass microbeads increase the sound absorption coefficient, and boron carbide powder increases the thermal conductivity. The prepared composite sound-absorbing material has strong sound absorption and high thermal conductivity, which effectively improves the sensitivity of the pyroelectric sensor.

[0019] 2. The needle-type structure in front of the sound-absorbing material solves the disadvantage of high acoustic impedance of PMN-PT relaxor ferroelectric single crystal material and effectively utilizes the advantage of high pyroelectric coefficient of PMN-PT relaxor ferroelectric single crystal material. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of a pyroelectric sensor and a preparation method thereof according to the present invention;

[0021] Figure 2 It is a structural schematic diagram of a cross-sectional view of a tubular housing of the present invention;

[0022] Figure 3 For the present invention Figure 2 A structural diagram of the enlarged view at A in FIG.

[0023] Figure 4 It is a structural schematic diagram of the process of the method for preparing a pyroelectric sensor of the present invention.

[0024] Description of reference numerals:

[0025] 100, tubular shell; 101, extension tube; 102, composite sound absorbing material; 103, detection probe; 104, external thread; 105, insulation layer; 106, fixing tube; 107, rubber coating layer; DETAILED DESCRIPTION

[0026] To make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the following will be combined with the appended drawings of the embodiments of the present invention. Figure 1-4 , the technical scheme of the embodiment of the present invention is clearly and completely described. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0027] like Figure 1-4As shown: This embodiment provides a pyroelectric sensor and a preparation method thereof, comprising a tubular shell 100, the tubular shell 100 serving as the positive and negative outputs of the pyroelectric sensor circuit; a fixing tube 106 is arranged inside the tubular shell 100 to facilitate assembly of the shell and the bullet head structure; an extension tube 101 is sleeved inside the fixing tube 106; an insulating layer 105 is arranged between the inner wall of the fixing tube 106 and the outer arc surface of the extension tube 101 to isolate the positive and negative outputs of the circuit and ensure the normal operation of the circuit; a glue layer 107 is arranged between the outer arc surface of the fixing tube 106 and the inner wall of the tubular shell 100 to reinforce the tubular shell 100 and the bullet head structure while increasing the water tightness of the pyroelectric sensor; a detection probe 103 is arranged at the end of the extension tube 101 through conductive silver glue, the probe outputs a pyroelectric signal, and a composite sound absorbing material 102 is arranged on the detection probe 103, the composite sound absorbing material 102 receives sound, converts it into heat, and conducts it to the detection probe 103. Compared with traditional pyroelectric sensors, this new needle-type sensor structure is simple to manufacture and has higher sensor sensitivity. The sound-absorbing material is changed from the traditional post-placement design to a pre-placement design of the sensitive element, which solves the disadvantage of high acoustic impedance of PMN-PT relaxor ferroelectric single crystal material and effectively utilizes the advantage of high pyroelectric coefficient of PMN-PT relaxor ferroelectric single crystal material.

[0028] Composite sound absorbing material 102 such as Figure 3 As shown,

[0029] The composite sound absorbing material 102 is composed of polyurethane, glass microspheres and boron carbide. The polyurethane is used as the main material, the glass microsphere K1 material is added to improve the sound absorption coefficient, and the boron carbide material is added to improve the thermal conductivity. The composite material has the performance of strong sound absorption and high thermal conductivity.

[0030] The tubular housing 100 is Figure 2 As shown,

[0031] The tubular housing 100, the fixing tube 106 and the extension tube 101 are all made of copper. The outer copper tube is used as the negative electrode of the pyroelectric sensor circuit and is connected to the upper surface of the PMN-PT relaxor ferroelectric single crystal. The inner copper tube is used as the positive electrode of the pyroelectric sensor circuit and is connected to the lower surface of the PMN-PT relaxor ferroelectric single crystal.

[0032] The insulating layer 105 is as follows Figure 3 As shown,

[0033] The insulating layer 105 is made of heat shrink tubing material, which insulates the inner and outer copper tubes, i.e. the positive and negative electrodes, to prevent the pyroelectric sensor circuit from short-circuiting and failing;

[0034] The adhesive layer 107 is as follows Figure 3 As shown,

[0035] The adhesive layer 107 is made of epoxy resin adhesive material, which increases water tightness when the outer copper tube is assembled with the bullet head structure;

[0036] The detection probe 103 is as follows Figure 1 As shown,

[0037] The detection probe 103 uses PMN-PT relaxor ferroelectric single crystal, a single crystal material with a high pyroelectric coefficient as a sensitive element, which effectively improves the sensitivity of the pyroelectric sensor;

[0038] The tubular housing 100 is Figure 1 As shown,

[0039] An outer arc surface at one end of the tubular housing 100 is provided with an external thread 104, which matches the BNC connector and is convenient for assembly with a coaxial cable.

[0040] like Figure 4 As shown, the pyroelectric sensor and the preparation method thereof provided by the present invention include the following steps:

[0041] The main agent and curing agent of the polyurethane are mixed in a mass ratio of 3:1 and stirred evenly. The glass beads and boron carbide powder are added to the solution in a weight ratio of polyurethane solution: glass beads K1: boron carbide = 10:1:1 and stirred evenly.

[0042] Pour 15 ml of the mixture into a paper cup and solidify at room temperature;

[0043] The upper and lower surfaces of the PMN-PT relaxor ferroelectric single crystal material with a diameter of 2 mm were connected to the copper tube using conductive silver glue, and then assembled with the bullet head structure;

[0044] When the solution prepared by K1 is in a semi-solidified state, it is applied to the front surface of the PMN-PT relaxor ferroelectric single crystal and waited for solidification.

[0045] In order to further illustrate the present invention, a pyroelectric sensor and a preparation method thereof provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the scope of protection of the present invention;

[0046] Example 1

[0047] Figure 4 As shown in S1;

[0048] The main agent and curing agent of the polyurethane are mixed in a mass ratio of 3:1 and stirred evenly. The glass beads and boron carbide powder are added to the solution in a weight ratio of polyurethane solution: glass beads K1: boron carbide = 10:1:1 and stirred evenly.

[0049] Pour 15 ml of the mixture into a paper cup and solidify at room temperature;

[0050] Figure 4 As shown in S2;

[0051] The upper and lower surfaces of the PMN-PT relaxor ferroelectric single crystal material with a diameter of 2 mm were connected to the copper tube using conductive silver glue, and then assembled with the bullet head structure;

[0052] Figure 4 As shown in S3;

[0053] When the solution prepared by K1 is in a semi-solidified state, it is coated on the front surface of the PMN-PT relaxor ferroelectric single crystal and waited for solidification to obtain a pyroelectric sensor;

[0054] The pyroelectric sensor is connected to the sound power test system, and the focusing transducer operating frequency is set to 7MHz and the power is set to 20W. The pyroelectric sensor is measured. The original signal output by the pyroelectric sensor on the oscilloscope contains piezoelectric signals and pyroelectric signals. The low-pass filter is processed to remove the high-frequency piezoelectric signal to obtain the pyroelectric signal. The corresponding pyroelectric signal can be obtained by changing the working power of the transducer. The data analysis shows that it has high linearity. The pyroelectric sensor prepared in this embodiment has high sensitivity, and the sound power measurement is realized based on this.

[0055] Example 2

[0056] Figure 4 As shown in S1;

[0057] The main agent of polyurethane and the curing agent are mixed in a mass ratio of 3:1 and stirred evenly. The glass beads and boron carbide powder are added to the solution in a weight ratio of polyurethane solution: glass beads K1: boron carbide = 10:2:1 and stirred evenly.

[0058] Pour 15 ml of the mixture into a paper cup and solidify at room temperature;

[0059] Figure 4 As shown in S2;

[0060] The upper and lower surfaces of the PMN-PT relaxor ferroelectric single crystal material with a diameter of 2 mm were connected to the copper tube using conductive silver glue, and then assembled with the bullet head structure;

[0061] Figure 4 As shown in S3;

[0062] When the solution prepared by K1 is in a semi-solidified state, it is coated on the front surface of the PMN-PT relaxor ferroelectric single crystal and waited for solidification to obtain a pyroelectric sensor;

[0063] The pyroelectric sensor was connected to the acoustic power test system, the operating frequency of the focused transducer was set to 7 MHz and the power was set to 20 W, and the pyroelectric sensor was measured. S1 can be obtained. Composite materials with different ratios will change the final performance of the pyroelectric sensor.

[0064] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0065] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A pyroelectric sensor, characterized in that: The invention comprises a tubular shell (100), wherein a fixed tube (106) is arranged inside the tubular shell (100), an extension tube (101) is sleeved inside the fixed tube (106), an insulating layer (105) is arranged between the inner wall of the fixed tube (106) and the outer arc surface of the extension tube (101), a glue coating layer (107) is arranged between the outer arc surface of the fixed tube (106) and the inner wall of the tubular shell (100), and a detection probe (103) is arranged at the end of the extension tube (101) through conductive silver glue, and a composite sound absorbing material (102) is arranged on the detection probe (103).

2. A pyroelectric sensor according to claim 1, characterized in that: The composite sound absorbing material (102) is composed of polyurethane, glass microspheres and boron carbide.

3. A pyroelectric sensor as claimed in claim 1, characterized in that: The tubular housing (100), the fixing tube (106) and the extension tube (101) are all made of copper.

4. A pyroelectric sensor as claimed in claim 1, characterized in that: The insulating layer (105) is made of heat shrinkable tube material.

5. A pyroelectric sensor as claimed in claim 1, characterized in that: The adhesive coating layer (107) is made of epoxy resin adhesive material.

6. A pyroelectric sensor as claimed in claim 1, characterized in that: The detection probe (103) is made of PMN-PT relaxor ferroelectric single crystal material.

7. A pyroelectric sensor as claimed in claim 1, characterized in that: An external thread (104) is provided on an outer arc surface at one end of the tubular housing (100).

8. A pyroelectric sensor and a method for preparing the same as claimed in claim 1, characterized in that: The following steps are involved: The main agent and curing agent of the polyurethane are mixed in a mass ratio of 3:1 and stirred evenly. The glass beads and boron carbide powder are added to the solution in a weight ratio of polyurethane solution: glass beads K1: boron carbide = 10:1:1 and stirred evenly. Pour 15 ml of the mixture into a paper cup and solidify at room temperature; The upper and lower surfaces of the PMN-PT relaxor ferroelectric single crystal material with a diameter of 2 mm were connected to the copper tube using conductive silver glue, and then assembled with the bullet head structure; When the solution prepared by K1 is in a semi-solidified state, it is applied to the front surface of the PMN-PT relaxor ferroelectric single crystal and waited for solidification.

Images