Low-frequency sound field particle velocity sensitive structure and preparation method

Abstract

The invention relates to a low-frequency sound field particle velocity sensitive structure and a preparation method thereof, wherein a bridge hole is formed on a silicon substrate, a first electrode is arranged on one side of the bridge hole, a second electrode and a third electrode are arranged on the other side of the bridge hole, a first thin wire and a second thin wire are arranged above the bridge hole and are arranged in parallel and maintain a fine pitch, sensitive layers of the first thin wire and the second thin wire are sequentially composed of three segments including a first end sensitive layer, a middle sensitive layer and a second end sensitive layer, the length of the middle sensitive layer is greater than that of the first end sensitive layer and the second end sensitive layer, the middle sensitive layer is used for transferring heat, the first end sensitive layer and the second end sensitive layer are used for connecting with the electrode; air gap layers are respectively disposed between the middle sensitive layer and the first end sensitive layer and the second end sensitive layer. The invention can effectively improve the low-frequency response characteristic ofthe low-frequency sound field particle velocity sensitive structure.

Description

technical field [0001] The invention relates to a low-frequency sound field particle vibration velocity sensitive structure and a preparation method. Background technique [0002] In a large number of acoustic measurement applications, because the sound intensity measurement and its spectrum analysis have unique advantages in the study of the characteristics of the noise source, it has become a powerful tool for acoustic research. Usually, the acquisition of sound intensity information requires the measurement of sound pressure and particle velocity in the sound field. [0003] The sensitive structure of the existing particle vibration velocity sensor is to use micro-electromechanical system (MEMS) technology to prepare a sensitive structure composed of several metal platinum resistance wires (thin wires) that are very close to each other on a silicon-based substrate, which can be directly Measure the vibration velocity of medium molecules caused by the propagation of sound...

AI Technical Summary

Problems solved by technology

[0004] The disadvantage of the existing low-frequency sound field particle velocity sensitive structure is that due to the material properties of the above-mentioned sensitive structure of the particle velocity measurement sensor and its topological structure has a finite length boundary heat conduction effect, the heat loss rate from the boundary is higher than that caused by the low-frequency sensor. The heat exchange rate caused by the sound wave makes the response characteristics of the sensor worse in the low frequency band

In the low-frequency band below 100Hz, the sensitivity of the particle velocity measurement sensor is significantly attenuated as the frequency decreases, causing distortion of the acoustic signal in reception and subsequent processing, and a decrease in the signal-to-noise ratio, which makes the lower limit of the effective working frequency of the sensor insufficient.

Since most of the research fields such as noise characteristic analysis and sound source target detection are mainly focused on low-frequency sound waves, this also limits the wide application of this particle velocity measurement sensor.

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