A MEMS optical acceleration sensor based on oil-sealed over-damping technology

Abstract

The present disclosure relates to a MEMS optical acceleration sensor based on oil-sealed over-damping technology. The MEMS optical acceleration sensor based on oil-sealed over-damping technology comprises a chip, the bottom of the chip is provided with an oil inlet opening, the oil inlet opening is arranged to communicate with the FP cavity of the chip; a chip cover is arranged to cover the outer surface of the chip, a first cavity is arranged between the outer surface of the chip and the inner surface of the chip cover; a sensor shell is arranged to cover the outer surface of the chip cover, a second cavity is arranged between the outer surface of the chip cover and the inner surface of the sensor shell, wherein the first cavity is filled with damping oil. Some technical solutions of the present disclosure aim to effectively suppress impact oscillation, provide stable damping characteristics, and have a high-reliability acceleration sensor with the advantages of optical measurement by arranging a double-cavity structure.

Description

Technical Field

[0001] This application relates to the field of fiber optic sensing technology, and in particular to a MEMS optical accelerometer based on oil-sealed overdamping technology. Background Technology

[0002] Accelerometers are key components in inertial navigation, automotive electronics, industrial control, structural health monitoring, and consumer electronics. Traditional MEMS accelerometers are mainly based on capacitive or piezoresistive principles. While the technology is mature, it also has some inherent drawbacks, such as susceptibility to electromagnetic interference, high temperature sensitivity requiring complex temperature compensation circuits, a trade-off between dynamic range and resolution, and the potential for sensor structural damage or signal saturation when measuring severe impacts (high g-values). Furthermore, it struggles to simultaneously measure weak signals at high resolution. Optical accelerometers sense acceleration by detecting changes in light signals, offering advantages such as natural resistance to electromagnetic interference and high sensitivity. However, existing optical accelerometers also face the challenge of damping control. When subjected to impacts and vibrations, the sensitive mass may oscillate significantly, leading to signal distortion or even mechanical damage.

[0003] Therefore, existing technologies still need to be improved and enhanced.

[0004] It should be noted that the above introduction to the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of this application and facilitating understanding by those skilled in the art. It should not be assumed that these technical solutions are known to those skilled in the art simply because they have been described in the background section of this application. Utility Model Content

[0005] To address one or more of the aforementioned technical problems, there is an urgent need for a highly reliable accelerometer that can effectively suppress shock oscillations, provide stable damping characteristics, and also possess the advantages of optical measurement. This disclosure provides a MEMS optical accelerometer based on oil-sealed overdamping technology, which aims to achieve an overdamped state by combining an optically sensitive structure with high-viscosity damping oil encapsulation, thereby significantly improving the sensor's shock resistance, stability, and measurement bandwidth.

[0006] In a first aspect of this disclosure, a MEMS optical accelerometer based on oil-sealed overdamping technology is proposed. The sensor includes: a chip, the bottom of which has an oil inlet opening configured to communicate with a FP cavity of the chip; a chip housing, configured to cover the outer surface of the chip, with a first cavity provided between the outer surface of the chip and the inner surface of the chip housing; and a sensor housing, configured to cover the outer surface of the chip housing, with a second cavity provided between the outer surface of the chip housing and the inner surface of the sensor housing, wherein the first cavity is filled with damping oil.

[0007] Furthermore, in some embodiments, the sensor further includes a base disposed at the bottom of the sensor, and the bottom of the chip is fixed to the top of the base.

[0008] Furthermore, in some embodiments, the bottom of the chip cover is fixed to the top of the base, and the gap between the bottom of the chip cover and the top of the base is sealed by welding.

[0009] Furthermore, in some embodiments, the bottom of the sensor housing is fixed to the top of the base, and the gap between the bottom of the sensor housing and the top of the base is sealed by welding.

[0010] Furthermore, in some embodiments, the outer surface of the side wall of the base is provided with an oil filling port, which is configured to communicate with the first cavity via an oil filling path.

[0011] Furthermore, in some embodiments, the top of the base is provided with a cross-shaped groove, and the oil filling port is configured to communicate with the bottom of the cross-shaped groove via an oil filling path.

[0012] Furthermore, in some embodiments, a secondary sealing port is provided on the outer surface of the side wall of the sensor housing, and the secondary sealing port is configured to communicate with the outer surface of the side wall of the sensor housing and the second cavity.

[0013] Furthermore, in some embodiments, the aforementioned secondary sealing port is disposed on the outer surface of the top of the aforementioned sensor housing.

[0014] Furthermore, in some embodiments, the second cavity is filled with a filling medium.

[0015] Furthermore, in some embodiments, the aforementioned oil filling port and / or the aforementioned secondary sealing port are configured as circular stepped holes or threaded holes.

[0016] The beneficial effects of this disclosure are as follows: In some embodiments, by providing a first cavity between the outer surface of the chip and the inner surface of the chip housing, and providing a second cavity between the outer surface of the chip housing and the inner surface of the sensor housing, and filling the first cavity with damping oil, this dual-cavity structure design combines the optical sensing structure with high-viscosity damping oil encapsulation, achieving an overdamped state, thereby significantly improving the sensor's shock resistance, stability, and measurement bandwidth; furthermore, due to the sealing and strengthening effect of the second cavity on the oil-filled first cavity and the promoting effect on structural stability, the sensor of this disclosure has a longer service life. Attached Figure Description

[0017] The above and other features, advantages and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description, wherein: Figure 1 A half-sectional schematic diagram of a MEMS optical accelerometer based on oil-sealed overdamped technology according to an embodiment of the present disclosure is shown. Figure 2 This illustration shows another perspective schematic diagram of a MEMS optical accelerometer based on oil-sealed overdamping technology according to an embodiment of the present disclosure; Figure 3 It shows Figure 2 Cross-sectional view at CC; Figure 4 A schematic diagram of a base according to an embodiment of the present disclosure is shown; Figure 5 A schematic cross-sectional view of a base according to an embodiment of the present disclosure is shown; Figure 6 A schematic diagram of a base according to an embodiment of the present disclosure is shown from another perspective; Figure 7 A schematic diagram of the overall structure of a MEMS optical accelerometer based on oil-sealed overdamping technology according to an embodiment of the present disclosure is shown. Figure 8 A schematic diagram of a chip structure according to an embodiment of the present disclosure is shown; and In the various figures, the same or corresponding reference numerals indicate the same or corresponding parts, including: sensor 100, chip 10, substrate 11, glass 12, optical fiber 13, oil inlet 14, first cavity 15, chip outer cover 20, second cavity 25, sensor housing 30, secondary sealing port 35, base 40, oil filling port 45, and oil filling path 46. Detailed Implementation

[0018] Embodiments of this disclosure will now be described in more detail with reference to the accompanying drawings. While some embodiments of this disclosure are shown in the drawings, it should be understood that this disclosure can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this disclosure. It should be understood that the accompanying drawings and embodiments of this disclosure are for illustrative purposes only and are not intended to limit the scope of protection of this disclosure.

[0019] In the description of embodiments of this disclosure, the term "comprising" and similar terms should be understood as open-ended inclusion, i.e., "including but not limited to". The term "based on" should be understood as "at least partially based on". The term "one embodiment" or "the embodiment" should be understood as "at least one embodiment". The terms "first", "second", etc., may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0020] Generally, MEMS optical accelerometers achieve an overdamped state by combining an optically sensitive structure with high-viscosity damping oil encapsulation, thereby significantly improving the sensor's shock resistance, stability, and measurement bandwidth. It should be noted that the composition of the high-viscosity damping oil is not the focus of this disclosure; rather, it emphasizes designing advantageous structures to obtain novel MEMS optical accelerometers based on oil-sealed overdamping technology. A more detailed description follows with reference to the accompanying drawings.

[0021] Figure 1 A half-sectional schematic diagram of a MEMS optical accelerometer based on oil-sealed overdamping technology according to an embodiment of the present disclosure is shown. In this example embodiment, a MEMS optical accelerometer 100 based on oil-sealed overdamping technology is shown. The sensor 100 includes, from the inside out, a chip 10, a chip housing 20, and a sensor shell 30 as shown in the figure. The bottom of the chip 10 is provided with an oil inlet (not shown), which can be configured to communicate with the FP cavity (not shown) of the chip 10. Further, the chip housing 20 is configured to cover the outer surface of the chip 10, and the cavity formed between the outer surface of the chip 10 and the inner surface of the chip housing 20 is a first cavity 15. Further still, the sensor shell 30 is configured to cover the outer surface of the chip housing 20, and the cavity between the outer surface of the chip housing 20 and the inner surface of the sensor shell 30 forms a second cavity 25. It should also be noted that the base 40 is located near the bottom of the sensor 100, meaning that the base 40 can be set at the bottom of the sensor 100. Obviously, the bottom of the chip 10 is fixed to the top of the base 40 near the center of the top of the base 40.

[0022] To more clearly illustrate the relationship between the components of the sensor 100, please refer to... Figure 2 and Figure 3 ,in Figure 3 It shows along Figure 2 A schematic diagram of the sensor along the CC section. In the illustrated embodiment, the first cavity 15 and the oil-filling path 46 connected to the first cavity 15 have been darkened to more clearly show the first cavity 15 and the chambers connected to the first cavity 15. The second cavity 25 has also been darkened, and it is not connected to the first cavity 15. It should be understood that in this illustrated embodiment, only the outer contour shape of the chip 10 is shown, and its internal structure and its FP cavity are not shown. It is only necessary to note that the bottom of the chip 10 is provided with an oil inlet (not shown), and the oil inlet (not shown) can be configured to communicate with the FP cavity (not shown) of the chip 10, so as to combine the optical sensitive structure with high viscosity damping oil encapsulation to achieve an overdamped state, thereby significantly improving the sensor's shock resistance, stability and measurement bandwidth.

[0023] Still refer to Figure 3 In some implementations, the bottom of the chip cover 20 is fixed to the top of the base 40, and the gap between the bottom of the chip cover 20 and the top of the base 40 is sealed by welding. Further, as shown in the figure, the top of the base 40 has a step for reinforcing the sealing effect, which forms an annular protrusion on the top of the base 40, such as... Figure 4 As shown. Furthermore, still referring to... Figure 3 In some implementations, the bottom of the sensor housing 30 is fixed to the top of the base 40, and the gap between the bottom of the sensor housing 30 and the top of the base 40 is sealed by welding.

[0024] Furthermore, referring to Figure 4 , Figure 5 and Figure 6 In some embodiments, the outer surface of the sidewall of the base 40 is provided with an oil filling port 45, which is configured to communicate with the first cavity 15 via an oil filling path 46. Further, in some embodiments, the top of the base 40 is provided with a cross-shaped groove, and the oil filling port 45 is configured to communicate with the bottom of the cross-shaped groove via an oil filling path 46.

[0025] Furthermore, referring to Figure 7In some embodiments, a secondary sealing port 35 is provided on the outer surface of the side wall of the sensor housing 30, and the secondary sealing port 35 is configured to communicate with the outer surface of the side wall of the sensor housing 30 and a second cavity (not shown). Preferably, the secondary sealing port 35 is provided on the outer surface of the top of the sensor housing 30 as shown in the figure. It should also be understood that the first cavity may be filled with damping oil, while the second cavity is filled with a filling medium; for the so-called filling medium, in noise-proof applications, a medium for absorbing noise may be filled, in leak-proof applications, a filling medium for preventing damping oil leakage may be filled, or a corresponding filling medium may be filled in special scenarios, but the composition of the filling medium itself is not the inventive point of this disclosure. Further, in some embodiments, the oil filling port 45 and / or the secondary sealing port 35 are configured as circular stepped holes or threaded holes to facilitate the design as a sealing element or an interface for easy connection with other injection devices or vacuum injection devices.

[0026] It should also be understood that, in some embodiments, see Figure 7 The MEMS optical accelerometer 100 based on oil-sealed overdamping technology comprises an externally visible sensor housing 30, a plug 50, and an optical fiber 60 (e.g., which may include an LC, FC, or E2000 connector). Further, see... Figure 1 and Figure 3 The chip 10 is fixed to the base 40 by adhesive bonding; the chip cover 20 is laser welded to the base 40 to form the first cavity 15; and the sensor housing 30 is laser welded to the base 40 to form the second cavity 25; the plug 50 is fixed to the sensor housing 30 by threads; and the optical cable 60 (e.g., may include LC, FC or E2000 connectors) can be fixed to the plug 50 by adhesive bonding and riveting.

[0027] It should be noted that, Figure 1 and Figure 3 In the example embodiment, the sensor 100 is configured as a dual-cavity structure, wherein the first cavity 15 is used to fill oil, and the second cavity 25 is used for secondary sealing (it should be understood that the laser welding connection described above forms the first seal). Since the first cavity 15 has a welded seal, there is a risk of leakage. Therefore, the second cavity 25 is designed to be filled with glue or oil to form a double-layer filling, thereby solving the problem of oil leakage of the sensor 100.

[0028] Alternatively, in some embodiments, the sensor's dual-cavity structure can be used for another application: vacuum encapsulation to form a double-layered vacuum cavity, thereby blocking sound and preventing noise from affecting the chip, thus improving the sensor's signal-to-noise ratio. This is generally used in scenarios with high environmental noise and weak main signals.

[0029] Further, see Figure 3and Figure 5 In some embodiments, the base 40 has a threaded mounting hole 47 at its bottom. Alternatively, the sensor 100 can be mounted by thread or by adhesive. In other embodiments, the oil filling path 46 adopts an L-shaped design, which avoids the threaded mounting hole 47 at the center of the base 40, making the sensor 100 smaller in size, more concentrated in its packaging, and increasing the resonant frequency of the sensor 100 structure itself.

[0030] Further, see Figure 3 and Figure 5 and Figure 7 The oil filling port 45 on the base 40 is designed as a circular stepped hole or a threaded hole for sealing: it should be understood that the circular stepped hole can be sealed by external filling with solder and then by resistance welding or electron beam welding; while the threaded hole can be hard sealed by filling with steel balls and using a set screw.

[0031] Further, see Figure 7 In some embodiments, the secondary sealing port 35 on the base 40 is designed as a circular stepped hole, which can be sealed by external filling with solder and then by resistance welding or electron beam welding, or by adhesive sealing.

[0032] For illustrative purposes, in Figure 8 The diagram shows a schematic of a chip 10. In this illustrated embodiment, the chip 10 consists of a substrate 11, glass 12, and optical fiber 13. An oil inlet 14 is provided at the bottom of the substrate 11, and the surface of the substrate 11 facing downwards is bonded to a base 40. For example, damping oil can be introduced through an oil channel on the base 40 (e.g., Figure 4 and Figure 6 After the cross-shaped groove structure in the middle is filled, it enters the first cavity, and the damping oil entering the first cavity can enter the interior of the chip 10 through this oil inlet 14 and fill the optical interference cavity inside the chip 10. When the first cavity is filled with oil, the entire chip is simultaneously immersed in the oil.

[0033] It should also be noted that in some implementations, see Figures 1 to 8When the sensor 100 is in use, the second cavity 25 is first filled and sealed with a filling medium, such as glue or silicone grease. When damping oil is filled into the sensor 100, only the first cavity 15 is filled and operates. The damping oil enters the first cavity 15 inside the sensor 100 through the oil filling port 45. Furthermore, because the second cavity 25 is already sealed during oil filling, the first cavity 15 is not affected during oil filling. It will only expel the gas in the first cavity 15 by drawing negative pressure, and the oil will be filled into the first cavity 15. Furthermore, in some embodiments, the potential problem of oil leakage from the weld between the first cavity 15 and the second cavity 25 is solved by secondary sealing of the weld by the filling medium in the second cavity 25.

[0034] It should also be understood that, see Figures 1 to 8 The sensor 100, after being filled with damping oil in the first cavity 15, possesses excellent shock and vibration resistance. In particular, this overdamped design prevents the mass block from oscillating after impact or high-speed vibration, allowing it to quickly and smoothly return to its equilibrium position, greatly minimizing the risk of signal distortion and structural damage due to resonance. Furthermore, it exhibits a wide bandwidth response. Specifically, the frequency response curve of the overdamped system is relatively steep, decaying rapidly at low frequencies, making it usable only from DC to several Hz. It has no resonance peaks and exhibits a flat phase and amplitude response within a specific operating bandwidth, making it ideal for measuring low-frequency vibration signals. Moreover, it also boasts high stability and reliability. Specifically, the oil seal effectively isolates it from environmental factors (such as humidity and dust), and the damping coefficient of the liquid is much more stable than that of the gas, less affected by changes in external pressure, ensuring the long-term stability of the sensor's performance. Furthermore, it also has natural resistance to electromagnetic interference because it adopts optical sensing principles, which avoids the problem of electrical sensors being susceptible to electromagnetic interference from the sensing mechanism, making it suitable for harsh environments such as strong electromagnetic fields.

[0035] Balancing high range and high resolution: Overdamped characteristics allow for the design of softer cantilever beams to improve sensitivity to weak accelerations, while damping oil can suppress excessive displacement under large impacts, thus ensuring high range without sacrificing resolution.

[0036] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

[0037] The above description is merely an optional embodiment of this disclosure and is not intended to limit this disclosure. Various modifications and variations can be made to this disclosure by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A MEMS optical accelerometer based on oil-sealed overdamped technology, characterized in that, include: The chip has an oil inlet at its bottom, which is configured to communicate with the FP cavity of the chip. A chip cover is configured to cover the outer surface of the chip, and a first cavity is provided between the outer surface of the chip and the inner surface of the chip cover; The sensor housing is configured to cover the outer surface of the chip cover, and a second cavity is provided between the outer surface of the chip cover and the inner surface of the sensor housing, the first cavity being filled with damping oil.

2. The sensor according to claim 1, characterized in that, Also includes: A base is disposed at the bottom of the sensor, and the bottom of the chip is fixed to the top of the base.

3. The sensor according to claim 2, characterized in that, The bottom of the chip cover is fixed to the top of the base, and the gap between the bottom of the chip cover and the top of the base is sealed by welding.

4. The sensor according to claim 3, characterized in that, The bottom of the sensor housing is fixed to the top of the base, and the gap between the bottom of the sensor housing and the top of the base is sealed by welding.

5. The sensor according to claim 2, characterized in that, The outer surface of the side wall of the base is provided with an oil filling port, which is configured to communicate with the first cavity via an oil filling path.

6. The sensor according to claim 5, characterized in that, The top of the base is provided with a cross-shaped groove, and the oil filling port is configured to communicate with the bottom of the cross-shaped groove via an oil filling path.

7. The sensor according to claim 5, characterized in that, The outer surface of the side wall of the sensor housing is provided with a secondary sealing port, which is configured to connect the outer surface of the side wall of the sensor housing with the second cavity.

8. The sensor according to claim 7, characterized in that, The secondary sealing port is located on the outer surface of the top of the sensor housing.

9. The sensor according to claim 1, characterized in that, The second cavity is filled with a filling medium.

10. The sensor according to claim 7, characterized in that, The oil filling port and / or the secondary sealing port are configured as circular stepped holes or threaded holes.

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