A tympanic membrane bionic microresonator device with a low thermal elastic damping structure

Abstract

The present invention relates to the field of microelectromechanical systems (MEMS), and discloses a tympanic membrane biomimetic microresonator device with a low thermoelastic damping structure, including: a resonator body and a substrate. The four peripheral edges of the resonator body are fixed on the substrate to form a fixed constraint. The resonator body is a tympanic membrane biomimetic structure, which is approximately similar to the human tympanic membrane in shape. The contour curve of the resonator body is obtained by using the first-order Bessel function, and a certain thickness is given, and it is rotated around a fixed axis to form the resonator body. When the resonator body vibrates, it not only generates bending strain, but also tensile strain, and the tensile strain does not generate thermoelastic dissipation, so the structure of the present invention can achieve lower thermoelastic damping.

Description

Technical Field

[0001] The present invention belongs to the field of microelectromechanical systems (MEMS), and relates to a tympanic membrane bionic microresonator device with a low thermoelastic damping structure. Background Art

[0002] The quality factor is an important performance index of a resonator device. For a device encapsulated in a vacuum, thermoelastic damping is one of the important factors affecting the quality factor. Thermoelastic damping is caused by the compression and stretching of a mechanical structure under stress, resulting in a change in volume, heat generation, and dissipation, that is, the vibration energy of the resonator device is dissipated as heat energy. When a microresonator operates in a vacuum and generates high-frequency vibrations, thermoelastic damping is the greatest constraint on its performance and efficiency. In common planar thin-plate microresonators, the main vibration mode is lateral vibration, and thermoelastic damping mainly occurs in the thickness direction with a large degree of bending strain, and the value is relatively large. Therefore, it is necessary to explore a more reasonable structure to reduce the energy loss caused by thermoelastic damping and improve the energy utilization efficiency.

[0003] Bionics is a discipline that uses technologies such as machinery and electronics to imitate the structures and functions of organisms for engineering applications, and is permeated and combined with biology, biophysics, electronics, cybernetics, ergonomics, mathematics, psychology, and automation technology, etc. With the continuous development of bionics, people have begun to use existing technologies to simulate biological structures and functions to solve some engineering problems. With the progress of molecular biology and the development of nanotechnology and MEMS technology, the combination of bionics and MEMS has become feasible. The tympanic membrane is a semi-transparent membrane in the human ear, which has the function of amplifying the received sound waves and has something in common with the function of an MEMS microresonator. In the process of evolution, the tympanic membrane has developed into the existing structure with its advantages. Therefore, designing an MEMS microresonator as a tympanic membrane structure has practical value. Summary of the Invention

[0004] Technical Problem: The present invention provides a tympanic membrane bionic structure microresonator device that can significantly reduce thermoelastic damping.

[0005] Technical Solution: The tympanic membrane bionic microresonator device with a low thermoelastic damping structure of the present invention includes: a resonator body and a substrate. The four peripheral edges of the resonator body are fixed on the substrate to form a fixed constraint. The resonator body is a tympanic membrane bionic structure, and its shape is approximately similar to that of the human tympanic membrane. The contour curve of the resonator body is obtained by using the first-order Bessel function, and a certain thickness is given, and it is rotated around a fixed axis to form the resonator body.

[0006] In the tympanic membrane bionic microresonator device of the present invention, the resonator body operates at its natural frequency to generate high-frequency micro-amplitude vibrations, and the excitation form is electrostatic drive or piezoelectric drive.

[0007] The low-thermal-elastic-damping structure resonator in the present invention is a bionic structure derived from the human eardrum structure. The eardrum structure can be fitted by Bessel functions, and the bionic structure equation of the eardrum is

[0008]

[0009] where a is the radius of the disk, W is the height at a distance r from the origin in the plane, J0(x) and I0(x) are the first-kind Bessel functions of real and imaginary arguments respectively. B = -J0(x) / I0(x), and C is the height coefficient. This bionic eardrum structure operates near its natural frequency, and the thermoelastic damping is significantly less than that of a disk with the same diameter. The physical principle is analyzed as follows.

[0010] When the MEMS resonant device vibrates, the compression and stretching of the structure will cause temperature imbalance, resulting in irreversible heat flow and thermoelastic relaxation, converting mechanical energy into heat energy, forming energy dissipation, that is, thermoelastic damping. Bending strain is the main source of thermoelastic damping.

[0011] The low-thermal-elastic-damping structure resonator of the present invention has a certain curvature in its stationary state. When it is excited by an external force to vibrate, the resonator will not only undergo bending strain but also tensile strain. The bending strain will generate heat transfer in the thickness direction, that is, the normal direction, while the tensile strain itself does not generate heat transfer. Compared with the disk-type microresonator that mainly undergoes transverse vibration and generates bending strain, the bionic eardrum structure microresonator of the present invention has tensile strain that does not generate thermoelastic damping and smaller normal bending strain, so the overall thermoelastic damping is lower.

[0012] Advantages: Compared with the prior art, the present invention has the following advantages:

[0013] For the bionic eardrum structure microresonator of the present invention, when excited by an external force, the maximum amplitude appears at a position biased towards the edge from the midpoint of the radius and appears in a ring form, covering a large range; while for an ordinary disk-type microresonator, the maximum amplitude is at the center of the circle and the range is very small. Therefore, the maximum vibration displacement of the bionic microresonator of the present invention is more easily utilized.

[0014] For the bionic eardrum structure microresonator of the present invention, bending strain and tensile strain will occur during vibration, and the tensile strain does not generate thermoelastic damping. For an ordinary disk-type microresonator, the main form of vibration is transverse vibration, generating bending strain. And bending strain is the main source of thermoelastic damping, so the thermoelastic damping of the bionic eardrum microresonator of the present invention is less than that of a disk microresonator with the same radius. Description of the Drawings

[0015] Figure 1 It is a schematic structural diagram of the present invention

[0016] Figure 2Cross-sectional schematic diagram of the present invention

[0017] Figure 3 External excitation schematic diagram of the present invention

[0018] Figure 4 Schematic diagram of the structure with the change of the height coefficient of the present invention Detailed implementation manners

[0019] The present invention will be further described below in conjunction with examples and the accompanying drawings of the specification.

[0020] As Figure 1 shown, the tympanic membrane bionic micro-resonator device with a low thermoelastic damping structure of the present invention includes a resonator body (1) and a substrate (2). The four peripheral edges of the resonator body (1) are fixed on the substrate (2) to form a fixed constraint. The resonator body (1) is a tympanic membrane bionic structure, which is approximately similar to the human tympanic membrane in shape. The contour curve of the resonator body (1) is obtained by using the first-order Bessel function, and a certain thickness is given, and it is rotated around a fixed axis to form the resonator body (1).

[0021] Based on the size of the MEMS device, the low thermoelastic damping tympanic membrane bionic structure in the present invention is scaled down by a certain multiple with the actual tympanic membrane structure parameters as the reference, and the radius, height, and thickness are kept in proportion. As Figure 3 shown, a normal external excitation close to the first natural frequency is applied at the midpoint of the radius. The resonator body vibrates, and the maximum amplitude appears in the annular region where the midpoint of the radius deviates towards the edge, and the amplitude near the central axis is very small. The bending strain and tensile strain mainly occur in the region with a larger amplitude, and the involved range is limited. When a disk resonator with the same radius vibrates under the same excitation, obvious bending strain occurs from the center to the edge. Therefore, near the natural frequency, the thermoelastic damping of the tympanic membrane bionic structure micro-resonator of the present invention is significantly smaller than that of the disk resonator.

[0022] Under the condition that the constraint remains unchanged, by changing the height coefficient C of the tympanic membrane bionic structure equation, structures with different radian can be obtained. Taking Figure 4 as an example, reducing the height coefficient C reduces the height of the resonator and the curvature, but compared with the disk, it still has certain bionic structure advantages.

Claims

1. A tympanic membrane bionic microresonator device with a low thermal elastic damping structure, characterized in that The device includes a resonator (1) with a low thermoelastic damping structure and a substrate (2). The resonator (1) has a given thickness, and its four peripheral edges are fixed on the substrate (2) to form a fixed constraint. The resonator (1) is a tympanic membrane biomimetic structure, which is approximately similar to the human tympanic membrane in shape. The tympanic membrane structure is fitted by using the first-kind real argument Bessel function J0(x) and the first-kind imaginary argument Bessel function I0(x), and the contour curve equation of the resonator is given as follows: where r is the radial distance from the origin; a is the radius of the resonator; B = -J0(x) / I0(x); C is the height coefficient; The contour curve rotates around a fixed axis to form the resonator (1).

2. The tympanic membrane bionic micro-resonator device with a low thermal elastic damping structure according to claim 1, characterized in that The resonator (1) operates at its natural frequency, generating high-frequency and small-amplitude vibrations, and the excitation form is electrostatic drive or piezoelectric drive.

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