An accelerometer probe based on double-layer split ring frequency screening effect

Abstract

The invention discloses an acceleration sensor probe based on the frequency screening effect of a double-layer open ring, comprising: a cantilever beam, a base structure, an upper open ring, a lower open ring, a signal receiving port and a support structure; the support structure is fixedly arranged on the upper surface of the base structure, the cantilever beam is arranged on the support structure, the upper open ring is arranged on the lower surface of the cantilever beam, and the lower open ring is arranged on the upper surface of the base structure; in the case of transmission, a through hole is opened on the surface of the base structure for signal transmission, and the signal receiving port is in or under the through hole for receiving signals; in the case of reflection, no through hole is opened on the surface of the base structure, and the cantilever beam is deformed under acceleration, resulting in a change in the distance between the upper open ring and the lower open ring. The advantages of the invention are: utilizing the frequency screening properties of the cantilever beam structure and the sub-wavelength size open ring, and realizing the measurement of acceleration through the frequency shift caused by the change in the relative distance of the open ring, with high measurement accuracy.

Description

Technical Field

[0001] The invention relates to the technical field of optical measurement, and in particular to an acceleration sensor probe based on a double-layer open ring frequency screening effect. Background Art

[0002] Accelerometers are widely used in defense, industry and other fields. As the requirements for instrument safety and measurement sensitivity in engineering environments increase, vibration sensors or accelerometers are increasingly used, and the requirements for the sensitivity, volume, and weight of accelerometers are also increasing. Therefore, what kind of structure should be used to meet the sensitivity measurement requirements of the sensor so that it can meet the requirements of engineering environment monitoring has become a recent research hotspot.

[0003] At present, the mainstream acceleration sensors used at home and abroad are mainly piezoelectric, piezoresistive, piezoelectric, capacitive and servo. In essence, sensors change the impedance of the device through external pressure changes and measure acceleration through changes in current and voltage. However, for precision instruments and vibrations with very small frequencies, various existing acceleration sensors are not able to perform well. At present, in the process of measuring acceleration sensors under microscopic research, there are problems such as large device size, inconvenient measurement and insufficient measurement accuracy. Acceleration sensors based on optical measurement, such as optical fiber, can further improve measurement accuracy, but their volume is related to measurement accuracy and is difficult to further reduce.

[0004] Among them, piezoelectric sensors have low accuracy; piezoresistive sensors are easily affected by temperature and other factors, and need to be equipped with temperature control equipment; capacitive sensors have nonlinear output, and miniaturization is bound to affect their accuracy; servo sensors are limited by principles and their volume cannot be reduced to the microscopic level.

[0005] In addition, the acceleration sensor can also be obtained by measuring the change of the structure position through optical methods. A typical example is the fiber optic acceleration sensor based on the fiber Bragg grating. The tension of the grating structure changes during acceleration, and the acceleration value is obtained by measuring and demodulating the frequency shift caused by the micro-change in the spectrum. However, the sensitivity of this sensor is related to the length of the optical fiber, etc., and the volume is relatively large.

[0006] The most promising acceleration sensor in terms of volume control is the MEMS-based microsystem, but its measurement method is also based on changes in current and other factors caused by pressure changes, and the measurement accuracy is difficult to further improve. Summary of the invention

[0007] In view of the defects of the prior art, the present invention provides an acceleration sensor probe based on the frequency screening effect of a double-layer open ring.

[0008] In order to achieve the above invention object, the technical solution adopted by the present invention is as follows:

[0009] An acceleration sensor probe based on a double-layer open ring frequency screening effect comprises: a cantilever beam 1, a base structure 2, an upper open ring 3, a lower open ring 4, a signal receiving port 5 and a supporting structure 6;

[0010] The base structure 2 is used to support and protect the acceleration sensor probe as a whole;

[0011] The side surface of the base structure 2 is in a "concave" shape, a support structure 6 is fixedly arranged on the upper surface of the base structure 2, the side surface of the support structure 6 is close to the inner wall of the base structure 2, a cantilever beam 1 is arranged on the support structure 6, and the length of the cantilever beam 1 is longer than the length of the support structure 6; the connecting end of the cantilever beam 1 and the support structure 6 is connected to or not connected to the inner wall of the base structure 2, and the other end of the cantilever beam 1 is not connected to the inner wall of the base structure 2;

[0012] An upper layer opening ring 3 is fixedly arranged on the lower surface of the cantilever beam 1, and a lower layer opening ring 4 is fixedly arranged on the upper surface of the base structure 2.

[0013] In the case of transmission, a through hole is opened on the surface of the base structure 2 for a signal transmission channel, and the signal receiving port 5 is in or under the through hole for receiving a signal;

[0014] In the case of reflection, the surface of the base structure 2 does not need to have a through hole, and the signal receiving port 5 is set close to the light source;

[0015] The cantilever beam 1 is made of a material with a high transmittance in the corresponding waveband; the cantilever beam 1 is deformed by force under acceleration, causing the distance between the upper open ring 3 and the lower open ring 4 to change;

[0016] The centers of the upper open ring 3, the lower open ring 4 and the signal receiving port 5 are in a straight line;

[0017] The inner and outer diameters of the upper open ring 3 and the lower open ring 4 are both smaller than the wavelength. The shapes of the upper open ring 3 and the lower open ring 4 are circular rings or square rings and deformed structures based thereon. A gap is opened in a certain part of the ring. The upper open ring 3 and the lower open ring 4 use semiconductor or dielectric materials.

[0018] Furthermore, the inner and outer ring diameters, radii and materials of the upper open ring 3 and the lower open ring 4 can be modified as needed, thereby changing the absorption peak or reflection peak to the required band; changes in the distance between the upper open ring 3 and the lower open ring 4, changes in the size of the structural material and the relative position of the notch can all help achieve changes in sensitivity and working band.

[0019] Furthermore, in the transmission state, the through holes on the surface of the base structure 2 are filled with a material having a higher transmittance in the corresponding wavelength band.

[0020] Furthermore, the through-hole filling material of the base structure 2 and the cantilever beam 1 are made of silicon material or titanium dioxide.

[0021] Furthermore, the material of the upper open ring 3 and the lower open ring 4 is metal or semiconductor material.

[0022] Furthermore, the resonant frequencies of the upper open ring 3 and the lower open ring 4 are calculated as follows:

[0023]

[0024] Where C is the capacitance per unit length between the inner and outer rings, r0 is the radius of the inner ring, and L is the total inductance of the open resonant ring.

[0025] Furthermore, the thickness of the upper open ring 3 and the lower open ring 4 is controlled at nanometer level, greater than 5 nm.

[0026] Preferably, the structures of the upper open ring 3 and the lower open ring 4 are composed of an inner ring 7 and an outer ring 8, the inner ring 7 and the outer ring 8 are concentric, the diameter of the inner ring 7 is smaller than the diameter of the outer ring 8, and a certain part of the inner ring 7 and the outer ring 8 is opened with a gap.

[0027] Compared with the prior art, the advantages of the present invention are:

[0028] By utilizing the cantilever beam structure and the frequency screening properties of the sub-wavelength size split ring, the acceleration can be measured through the frequency shift caused by the relative distance change of the split ring, with high measurement accuracy. The size can be reduced to the micron level. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the structure of an acceleration sensor probe according to a first embodiment of the present invention;

[0030] Figure 2 1 is a three-view diagram of an acceleration sensor probe according to a first embodiment of the present invention, wherein a is a main view, b is a left view, and c is a top view;

[0031] Figure 3 3 views of an upper layer opening ring and a lower layer opening ring of a first embodiment of the present invention, a is a main view, b is a left view, and c is a top view;

[0032] Figure 4 It is a schematic diagram of the structure of the upper layer open ring and the lower layer open ring of the second embodiment of the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and examples.

[0034] Embodiment 1

[0035] like Figure 1 and 2 As shown, an acceleration sensor probe based on a double-layer open ring frequency screening effect comprises: a cantilever beam 1, a base structure 2, an upper open ring 3, a lower open ring 4, a signal receiving port 5 and a supporting structure 6;

[0036] The base structure 2 is used to support and protect the acceleration sensor probe as a whole;

[0037] The side of the base structure 2 is in a "concave" shape, and a fixed support structure 6 is provided on the upper surface of the base structure 2. The side of the support structure 6 is close to the inner wall of the base structure 2. A cantilever beam 1 is provided on the support structure 6. The length of the cantilever beam 1 is longer than the length of the support structure 6, and the width is smaller than the width of the support structure 6. The connecting end of the cantilever beam 1 and the support structure 6 is connected to or not connected to the inner wall of the base structure 2, and the other end of the cantilever beam 1 is not connected to the inner wall of the base structure 2.

[0038] An upper layer open ring 3 is fixedly arranged on the lower surface of the cantilever beam 1, a lower layer open ring 4 is fixedly arranged on the upper surface of the base structure 2, a through hole is opened on the surface of the base structure 2 for signal transmission, and the signal receiving port 5 is in or under the through hole for receiving signals;

[0039] The centers of the upper open ring 3 , the lower open ring 4 and the signal receiving port 5 are on a straight line.

[0040] like Figure 3 As shown, the inner and outer diameters of the upper open ring 3 and the lower open ring 4 are both smaller than the wavelength. The upper open ring 3 and the lower open ring 4 are in the shape of a ring with a gap in a certain part of the ring. The upper open ring 3 is made of metal material. When the incident light irradiates the surface of the upper open ring 3, the surface plasmons are excited to cause the electric potential to change. The free electrons in the material form an oscillating structure, which in turn acts on the incident light, resulting in a frequency screening effect.

[0041] The inner and outer, upper and lower radii of the upper open ring 3 and the lower open ring 4 can be modified as needed to change the absorption peak or reflection peak to the desired band. Changes in the distance between the upper open ring 3 and the lower open ring 4, changes in the size of the structural material, and the relative position of the opening can all help achieve changes in sensitivity and working band.

[0042] Under acceleration, the cantilever beam 1 is deformed by force, resulting in a change in the distance between the upper open ring 3 and the lower open ring 4 .

[0043] The acceleration sensor probe is combined with a wide-spectrum light source and a spectrometer to realize acceleration measurement using transmitted light. The through holes on the surface of the base structure 2 are filled with materials with high transmittance in the corresponding band, and the cantilever beam 1 also uses materials with high transmittance in the corresponding band: for example, common infrared detectors use silicon materials, and the visible light band uses titanium dioxide. The incident light is scanned from the upper opening ring 3 through the optical fiber port or through spatial light from the top of the cantilever beam 1, and is received by the signal receiving port 5 after passing through the lower opening ring 4, and its spectrum is measured by the spectrometer. In the process of passing through the upper opening ring 3 and the lower opening ring 4, the light interacts with the sub-wavelength size structure in a complex manner, thereby obtaining typical absorption peaks and transmission peaks.

[0044] The upper open ring 3 and the lower open ring are made of metal or semiconductor material. When the size is smaller than the incident wavelength, they have a better frequency screening effect. When the size is comparable to the wavelength, the frequency screening function can also be achieved.

[0045] The resonant frequencies of the upper open ring 3 and the lower open ring 4 can be derived using a quasi-static method:

[0046]

[0047] Where C is the capacitance per unit length between the inner and outer rings, r0 is the radius of the inner ring, and L is the total inductance of the open resonant ring. Combined with the size of the open ring that can achieve the frequency screening result, it can be inferred that the vibration of the structure within the operating frequency of 1Hz-200Hz can still achieve a good detection effect.

[0048] The upper open ring 3 and the lower open ring 4 increase the contact area with the incident light through periodic distribution, reducing the impact of background noise. Periodic distribution increases the contact area with the incident light

[0049] The typical structure size is in the nanometer range, and the spectral signal is weak and difficult to measure; the size of the open ring is in the nanometer range, but the structure is distributed periodically, so the structure size can be increased according to the actual beam size.

[0050] Refer to the micrometer-sized spot, but only the nanometer-diameter portion of it is modulated;

[0051] Therefore, a periodic arrangement is used to increase the structural size to the millimeter level to enhance the signal; the period size will also affect the spectral distribution;

[0052] The thickness of a single element of the open ring is controlled at the nanometer level (considering the quality of metal evaporation, it is generally greater than 5nm and can reach the micrometer level at most), which can achieve the frequency screening effect of the incident light, and its absorption peak or reflection peak is sensitive to the distance between the double-layer open rings.

[0053] The sizes of the upper open ring 3 and the lower open ring 4 are as follows:

[0054] The inner diameter is 30nm, the outer diameter is 50nm, the opening height is 10nm, the thickness is 10 nanometers, and the material is gold. When it is prepared on a typical glass surface with dimensions of 2000um in length, 200um in width and 1mm in thickness, assuming the spectrometer accuracy is 1pm, the measurement accuracy is 0.00045g (higher than conventional accelerometers ~1mg and lower than fiber optic accelerometers).

[0055] Reducing the structure size, shortening the cantilever beam length, using softer materials (higher elastic modulus), higher precision spectrometers, multi-ring structures, etc. will further improve the measurement accuracy, and vice versa.

[0056] Embodiment 2:

[0057] like Figure 4 As shown, the structures of the upper open ring 3 and the lower open ring 4 are composed of an inner ring 7 and an outer ring 8, the inner ring 7 and the outer ring 8 are concentric, the diameter of the inner ring 7 is smaller than the diameter of the outer ring 8, and some parts of the inner ring 7 and the outer ring 8 are opened with a gap.

[0058] Embodiment three:

[0059] The shape of the upper layer open ring 3 and the lower layer open ring 4 may also be square.

[0060] Embodiment 4:

[0061] The aforementioned structure places the signal receiving port 5 under the lower open ring, and realizes light field detection through material settings. The structure can also complete spectral measurement through reflection length, placing the light source and the detector in the same position, or introducing and leading out through optical fiber and other devices. The sensitivity of the structure is still affected by the material and size of the structure, but the reflection field helps to further compress the thickness of the structure. The light source and the detector are located on the same side of the probe, because both have a certain volume and the thickness they occupy overlaps. If it is a transmission structure, space needs to be opened up above and below the probe respectively, so the volume of the reflection structure will be further reduced relative to the transmission structure. Regardless of which structure is used, the position of the characteristic peak in its spectrum is affected by the size of the structure.

[0062] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the implementation methods of the present invention, and should be understood that the protection scope of the present invention is not limited to such special statements and embodiments. Those skilled in the art can make various other specific variations and combinations that do not deviate from the essence of the present invention based on the technical revelations disclosed by the present invention, and these variations and combinations are still within the protection scope of the present invention.

Claims

1. An acceleration sensor probe based on a double-layer open ring frequency screening effect, characterized in that: include: A cantilever beam (1), a base structure (2), an upper open ring (3), a lower open ring (4), a signal receiving port (5) and a supporting structure (6); The base structure (2) is used to support and protect the acceleration sensor probe as a whole; The side surface of the base structure (2) is in a "concave" shape; a support structure (6) is fixedly arranged on the upper surface of the base structure (2); the side surface of the support structure (6) is close to the inner wall of the base structure (2); a cantilever beam (1) is arranged on the support structure (6); the length of the cantilever beam (1) is longer than the length of the support structure (6); the connecting end of the cantilever beam (1) and the support structure (6) is connected to or not connected to the inner wall of the base structure (2); the other end of the cantilever beam (1) is not connected to the inner wall of the base structure (2); An upper layer opening ring (3) is fixedly arranged on the lower surface of the cantilever beam (1), and a lower layer opening ring (4) is fixedly arranged on the upper surface of the base structure (2). In the case of transmission, a through hole is opened on the surface of the base structure (2) for a signal transmission channel, and the signal receiving port (5) is in or under the through hole for receiving a signal; In the case of reflection, the surface of the base structure (2) does not need to be provided with a through hole, and the signal receiving port (5) is arranged at a position close to the light source; The cantilever beam (1) is made of a material with a high transmittance in the corresponding waveband; the cantilever beam (1) is deformed under acceleration, causing the distance between the upper open ring (3) and the lower open ring (4) to change; The centers of the upper open ring (3), the lower open ring (4) and the signal receiving port (5) are on a straight line; The inner and outer diameters of the upper open ring (3) and the lower open ring (4) are both smaller than the wavelength; the shapes of the upper open ring (3) and the lower open ring (4) are circular rings or square rings or deformation structures based thereon; a gap is opened in a certain part of the ring; and the upper open ring (3) and the lower open ring (4) use semiconductor or dielectric materials.

2. The acceleration sensor probe based on the double-layer open ring frequency screening effect according to claim 1, characterized in that: The inner and outer ring diameters, radii and materials of the upper open ring (3) and the lower open ring (4) can be modified as required, thereby changing the absorption peak or reflection peak to a desired band; changes in the distance between the upper open ring (3) and the lower open ring (4), changes in the size of the structural material and the relative position of the notch can all help achieve changes in sensitivity and working band.

3. The acceleration sensor probe based on the double-layer open ring frequency screening effect according to claim 1, characterized in that: In the transmission case, the through holes on the surface of the base structure (2) are filled with a material having a high transmittance in the corresponding wavelength band.

4. The acceleration sensor probe based on the double-layer open ring frequency screening effect according to claim 3 is characterized in that: The materials used for the through-hole filling material of the base structure (2) and the cantilever beam (1) are silicon material or titanium dioxide.

5. The acceleration sensor probe based on the double-layer open ring frequency screening effect according to claim 1, characterized in that: The materials of the upper layer open ring (3) and the lower layer open ring (4) are metal or semiconductor materials.

6. The acceleration sensor probe based on the double-layer open ring frequency screening effect according to claim 5, characterized in that: The resonant frequencies of the upper open ring (3) and the lower open ring (4) are calculated using the following formula: Where C is the capacitance per unit length between the inner and outer rings, r0 is the radius of the inner ring, and L is the total inductance of the open resonant ring.

7. The acceleration sensor probe based on the double-layer open ring frequency screening effect according to claim 1, characterized in that: The thickness of the upper open ring (3) and the lower open ring (4) is controlled at the nanometer level and is greater than 5 nm.

8. The acceleration sensor probe based on the double-layer open ring frequency screening effect according to claim 1, characterized in that: The structures of the upper layer open ring (3) and the lower layer open ring (4) are composed of an inner ring (7) and an outer ring (8), the inner ring (7) and the outer ring (8) are concentric, the diameter of the inner ring (7) is smaller than the diameter of the outer ring (8), and a gap is opened in a certain part of the inner ring (7) and the outer ring (8).

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