Micromachined piezoelectric microphones with in-plane directivity

Spatial Coherence between Microphones with Arbitrary First-order Directivity in Reverberant Acoustic Fields

The theoretical expressions for the spatial correlation and spatial coherence between signals representing the pressure and the components of the particle velocity vector in a reverberant acoustic field are established in the literature and have also been corroborated with measurements [F. Jacobsen, J. Acoust. Soc. Am., 108(1), 2000]. In the present paper, expressions are derived from theory fo...

Aluminum Nitride Piezoelectric Micromachined Ultrasound Transducer Arrays

Air-coupled piezoelectric micromachined ultrasound transducer arrays, operating at ~190 kHz, have been fabricated utilizing an aluminum nitride piezoelectric layer. Improved fabrication processes have reduced the frequency variation seen in our previous work with single transducers resulting in arrays of transducers with resonant frequencies (fn) that match within the fractional half-power band...

Development of piezoelectric micromachined ultrasonic transducers

Piezoelectric micromachined ultrasonic transducers (pMUTs) are an example of the application of MEMS technology to ultrasound generation and detection, which is expected to offer many advantages over conventional transducers. In this work, we investigate pMUTs through novel design and fabrication methods. A finite element (FE) model, with original tools to measure device performance, was develo...

Micromachined piezoelectric ultrasonic transducer with ultra-wide frequency bandwidth

In-plane Band Gaps in a Periodic Plate with Piezoelectric Patches

A plate periodically bonded with piezoelectric patches on its surfaces is considered. The differential quadrature element method is used to solve the wave motion equation for the two-dimensional periodic structure. The method is very simple and easy to implement. Based on the method, band structures for in-plane wave propagating in the periodic piezoelectric plate are studied, from which the fr...