Disclosure of Invention
The invention aims to provide a magnetic sensor based on surface acoustic wave and magnetic torque effects and a preparation method thereof, so as to solve the problems.
In order to achieve the purpose, the invention adopts the following technical scheme:
a magnetic sensor based on surface acoustic wave and magnetic torque effects comprises a fixed base, a surface acoustic wave generating structure, a cantilever beam structure and a magnet; one end of the cantilever beam structure is arranged at the top of the fixed base, and the magnet is arranged at the other end of the cantilever beam structure; the surface acoustic wave generating structure is arranged on the surface of the cantilever beam structure;
the surface acoustic wave generating structure comprises interdigital electrodes and piezoelectric materials; the piezoelectric material is arranged on the surface of the cantilever beam structure, and the plurality of interdigital electrodes are arranged on the piezoelectric material.
Furthermore, the piezoelectric material is piezoelectric single crystal or piezoelectric film, and the piezoelectric material is LiNbO3、LiTaO3(iii), ST-quar, PZT, ZnO or AlN.
Further, the surface acoustic wave generating structure is a single port or delay line structure.
Furthermore, the interdigital electrode consists of an electrode film and an adhesion layer, wherein the electrode film is positioned on the adhesion layer; the electrode thin film is one of Au, Al, Pt or Cu; the adhesion layer is one of Ta or Cr.
Further, the material of the cantilever beam is one of copper foil or stainless steel foil.
Further, the number of magnets is composed of a plurality of blocks; the magnets are stacked in parallel or on the upper and lower surfaces of the cantilever beam; the magnet is one of a ferrite magnet, a rubidium-iron-boron magnet, an alnico magnet, a samarium-cobalt magnet, or a metal alloy magnet.
Further, a preparation method of a magnetic sensor based on surface acoustic wave and magnetic torque effects comprises the following steps:
1) pretreatment of the piezoelectric single crystal or piezoelectric thin film substrate: sequentially cleaning with ethanol and acetone, and oven drying;
2) defining an interdigital electrode pattern: and spin-coating photoresist on the piezoelectric material, exposing, depositing an electrode adhesion layer and an electrode layer, and finally peeling to obtain an interdigital electrode pattern.
3) And bonding the surface acoustic wave generating structure on the cantilever beam structure, and curing.
4) The magnet is placed at the free end of the cantilever beam.
Compared with the prior art, the invention has the following technical effects:
the surface acoustic wave magnetic sensor of the invention amplifies the influence of a magnetic field on the center frequency of the surface acoustic wave by introducing the torque effect, and effectively improves the sensitivity of the surface acoustic wave magnetic sensor. The new surface acoustic wave magnetic sensor not only improves the sensitivity of the magnetic sensor by nearly ten times, but also does not need an additional direct current bias magnetic field, thereby simplifying the structure of the sensor and reducing the loss.
Detailed Description
The invention is further described below with reference to the accompanying drawings:
referring to fig. 1, the surface acoustic wave magnetic sensor of the present invention includes a substrate 1, and a cantilever beam 2 fixed on the substrate 1; the surface acoustic wave generating device 3 is bonded on the cantilever beam 2; the surface acoustic wave generating device 3 is composed of a piezoelectric material 4 and interdigital electrodes 5. A magnet 6 is placed at the free end of the cantilever beam 2.
The base body 1 is a fixed base of the cantilever beam 2.
The cantilever beam 2 is a copper foil or a stainless steel foil, but is not limited thereto.
The surface acoustic wave generating device 3 is one of a single port, a delay line, and the like.
The piezoelectric material is composed of piezoelectric single crystal or piezoelectric film, and the piezoelectric material is LiNbO3,LiTaO3ST-quar, PZT, ZnO, AlN, etc.
The interdigital electrode material consists of an electrode film and an adhesion layer.
The electrode thin film is made of one of Au, Al, Pt, Cu and the like.
The adhesion layer of the electrode material is made of one of Ta, Cr, and the like.
The number of magnets is made up of a plurality of pieces.
The magnets are stacked in parallel or up and down.
The magnet is one of ferrite magnet, rubidium iron boron magnet, alnico magnet, samarium cobalt magnet metal alloy magnet, etc.
According to the magnetic sensor based on the surface acoustic wave and the torque effect, the torque effect is introduced, so that the changes of the Young modulus and the sound velocity of the piezoelectric material under the action of a magnetic field are amplified, the movement of the central frequency of the surface acoustic wave is enlarged, and finally the sensitivity is increased.
The invention relates to a preparation process of a magnetic sensor based on surface acoustic wave and torque effect, which comprises the following steps:
1) cleaning a piezoelectric single crystal or piezoelectric thin film substrate: respectively cleaning with ethanol and acetone, and oven drying;
2) defining an interdigital electrode pattern: and spin-coating photoresist on the piezoelectric material, exposing, depositing an electrode adhesion layer and an electrode layer, and finally peeling to obtain an interdigital electrode pattern. The present embodiment selects a single port surface acoustic wave device, but is not limited thereto.
3) And bonding the surface acoustic wave generating structure on the cantilever beam structure, and curing.
4) The magnet is placed at the free end of the cantilever beam. In this embodiment, two magnets are selected and stacked one above the other, but not limited thereto.
Example 1
Referring to fig. 1, a magnetic sensor based on surface acoustic wave and magnetic torque effect and a method for manufacturing the same includes a substrate 1, and a cantilever beam 2 fixed on the substrate 1; the surface acoustic wave generating device 3 is bonded on the cantilever beam 2; the surface acoustic wave generating device 3 is composed of a piezoelectric material 4 and interdigital electrodes 5. A magnet 6 is placed at the free end of the cantilever beam 2.
The base body 1 is a fixed base of the
cantilever beam 2. The
cantilever 2 is a copper foil. The surface acoustic wave generating device 3 is a single port. The piezoelectric material being a piezoelectric single crystal
InterdigitalThe electrode is composed of an electrode film Cu and an adhesive layer Ta, the thickness of the Cu film is 100nm, and the thickness of the Ta film is 5 nm. The magnet material is rubidium iron boron, the number of the magnet material is two, and the magnet material is stacked by adopting an upper structure and a lower structure.
According to the magnetic sensor based on the surface acoustic wave and the torque effect, the cantilever beam with the magnet is bent under an external magnetic field by introducing the torque effect, and the deformation is transmitted to the piezoelectric layer in the surface acoustic wave structure, so that the Young modulus of the piezoelectric material is changed finally. According to the formula
Where f is the center frequency of the SAW device, v is the acoustic velocity, E is the effective piezoelectric modulus, p is the interdigital electrode aperture, and ρ is the effective density. f is proportional to E and p generally does not change, so the torque effect amplifies the shift in center frequency caused by the magnetic field, thereby increasing sensitivity.
The invention relates to a preparation process of a magnetic sensor based on surface acoustic wave and torque effect, which comprises the following steps:
1) cleaning of the piezoelectric single crystal: respectively cleaning with ethanol and acetone, and oven drying;
2) defining an interdigital electrode pattern: and spin-coating photoresist on the piezoelectric material, exposing, depositing an electrode adhesion layer and an electrode layer, and finally peeling to obtain an interdigital electrode pattern.
3) And bonding the surface acoustic wave generating structure on the cantilever beam structure, and curing for 24 hours.
4) Two magnets are taken and stacked up and down at the free end of the cantilever beam
Example 2
A magnetic sensor based on surface acoustic wave and magnetic torque effect and its preparation method, including the matrix 1, fix the cantilever beam 2 on matrix 1; the surface acoustic wave generating device 3 is bonded on the cantilever beam 2; the surface acoustic wave generating device 3 is composed of a piezoelectric material 4 and interdigital electrodes 5. A magnet 6 is placed at the free end of the cantilever beam 2.
The base body 1 is a fixed base of the cantilever beam 2. The cantilever beam 2 is a stainless steel foil. The surface acoustic wave generating device 3 is a delay line structure. The piezoelectric material is a piezoelectric film ZnO with the thickness of 5 μm. The interdigital electrode consists of an electrode film Al and an adhesive layer Ta, wherein the thickness of the Al film is 100nm, and the thickness of the Ta film is 5 nm. The magnet material is rubidium, iron and boron, the number of the magnet material is two, and the magnet material is stacked in a parallel structure.
The invention relates to a preparation process of a magnetic sensor based on surface acoustic wave and torque effect, which comprises the following steps:
1) cleaning of the piezoelectric film substrate: respectively cleaning with ethanol and acetone, and oven drying;
2) depositing a ZnO film by magnetron sputtering with the power of 100W and the pressure of 1Pa for 2 hours.
2) Defining an interdigital electrode pattern: and spin-coating photoresist on the piezoelectric material, exposing, depositing an electrode adhesion layer and an electrode layer, and finally peeling to obtain an interdigital electrode pattern. The present embodiment selects a single port surface acoustic wave device, but is not limited thereto.
3) And bonding the surface acoustic wave generating structure on the cantilever beam structure, and curing for 24 hours.
4) Two magnets are taken and stacked in parallel at the free end of the cantilever beam.