MEMS ultrasonic positioning sensor with Helmholtz resonant cavity

Abstract

The invention discloses an MEMS ultrasonic positioning sensor. The MEMS ultrasonic positioning sensor comprises an upper layer substrate (3), a Helmholtz resonant cavity (2) formed in the upper layersubstrate (3), a piezoelectric ultrasonic emission unit (9) located on the upper layer substrate (3), an ultrasonic receiving unit (1) located at the bottom of the Helmholtz resonant cavity (2), wherein at least one through hole communicating with the Helmholtz resonant cavity (2) is formed in the piezoelectric ultrasonic emission unit (9), the resonant frequency of the Helmholtz resonant cavity (2) is the same as that of the piezoelectric ultrasonic emission unit (9), and the resonant frequency of the ultrasonic receiving unit (1) is greater than or equal to that of the piezoelectric ultrasonic emission unit (9). The MEMS ultrasonic positioning sensor can improve the energy conversion efficiency of the sensor and avoid crosstalk of the sensor.

Description

technical field [0001] The disclosure belongs to the technical field of ultrasonic transducers, and relates to a MEMS ultrasonic positioning sensor with a Helmholtz resonant cavity. Background technique [0002] Position sensors can be broadly classified into three categories. (1) Fine position sensing types that work over short distances, such as eddy current, magnetoresistive, and Hall effect sensors. The advantages of this type of sensor are high sensitivity and strong anti-interference ability, but it is not suitable for long-distance measurement. (2) Optical time-of-flight and optical coherent position sensors, such as laser interferometry, engineering triangulation, etc. The advantage is high precision, and the disadvantage is that such devices are usually complex in structure and need to be equipped with multiple optical components. (3) Acoustic or ultrasonic position sensors. One such sensor is the piezoacoustic resonator (PSRC) position sensor, which features a ...

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Problems solved by technology

Its advantage is high resolution, but the measurement distance is short. In addition, when the device size is small, the resonant frequency of the Helmholtz resonator cavity and the resonant frequency of the piezoelectric stack layer are difficult to match, so the size of this type of sensor is usually large , and the resonant frequency is low when working, resulting in poor resolution at close range

At the same time, in order to achieve the best receiving effect, the resonant frequencies of the receiving sensor, transmitting transducer, and Helmholtz resonator are usually set to be the same, but at this time, crosstalk will occur when sending and receiving sound waves

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