Sound field particle vibration velocity sensitive structure and making method

Abstract

The invention relates to a sound field particle vibration velocity sensitive structure and a making method. A bridge hole is formed on a silicon substrate, two sides of the bridge hole are provided with electrodes respectively, and thin wires are arranged between the electrodes at two sides. The sound field particle vibration velocity sensitive structure is characterized in that multiple thin wires are arranged; in correspondence to each thin wire, one electrode is arranged correspondingly at two sides of the bridge hole respectively; the outermost thin wire in the multiple thin wires is an electrically heating thin wire, and the rest are sensitive thin wires; and the sound field particle vibration velocity sensitive structure is a unilateral non-equidistant bridge-type thin wire sensitivestructure. By adopting the unilateral non-equidistant bridge-type thin wire sensitive structure, the finite-length boundary heat conduction effects of a sensitive unit can be effectively suppressed,the response characteristics of the sensor in a low frequency band are improved, and the response sensitivity of the sensitive structure to the low-frequency sound field particle vibration velocity isenhanced.

Description

technical field [0001] The invention relates to a 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 field in spac...

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Problems solved by technology

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