Engineering

Reverberation

Materials science

Impedance matching

Ultrasonic sensor

Distortion (music)

Amplifier

Acoustics

Acoustic wave

Acoustic impedance

Electrical impedance

Transducer

Physics

Piezoelectricity

CMOS

Optoelectronics

Electrical engineering

Sensors

The coupling of waves between the piezoelectric generators, detectors, and propagating media is challenging due to mismatch in the acoustic properties. The mismatch leads to the reverberation of waves within the transducer, heating, low signal-to-noise ratio, and signal distortion. Acoustic impedance matching increases the coupling largely. This article presents standard methods to match the acoustic impedance of the piezoelectric sensors, actuators, and transducers with the surrounding wave propagation media. Acoustic matching methods utilizing active and passive materials have been discussed. Special materials such as nanocomposites, metamaterials, and metasurfaces as emerging materials have been presented. Emphasis is placed throughout the article to differentiate the difference between electric and acoustic impedance matching and the relation between the two. Comparison of various techniques is made with the discussion on capabilities, advantages, and disadvantages. Acoustic impedance matching for specific and uncommon applications has also been covered.

A Review of Acoustic Impedance Matching Techniques for Piezoelectric Sensors and Transducers