A8.2 - Research on Ferroelectret Based Ultrasound Transducers

Event
SENSOR+TEST Conferences 2011
2011-06-07 - 2011-06-09
Nürnberg
Band
Proceedings SENSOR 2011
Chapter
A8 - Ultrasonic Sensors III
Author(s)
A. Sutor, S. Rupitsch, R. Lerch - Friedrich-Alexander Universität Erlangen-Nürnberg (Germany)
Pages
181 - 186
DOI
10.5162/sensor11/a8.2
ISBN
978-3-9810993-9-3
Price
free

Abstract

An interesting application of ferroelectret materials are electroacoustic transducers. Ferroelectret materials offer both a rather large bandwidth as well as a high piezoelectric strain constant. Due to their cellular structure, the materials are flexible and exhibit an excellent matching to air. Therefore, those polymers are appropriate for both, sound and ultrasound transducer applications. Our research is concentrated on the simulation based design and characterization of ultrasound transducers. In this contribution, we briefly discuss the fabrication process of the material itself and its assets and drawbacks. The advantages certainly are the high piezoelectric strain constant, the acoustic matching, the bandwidth and geometric properties. Temperature behavior and the high driving voltage have to be mentioned as disadvantages. We fabricate and analyze single element and array transducers based on a special ferroelectret material, namely the so-called EMFi (Electro-Mechanical-Film)
material. Furthermore, we analyze the different behavior of single and double layer transducers. To prove the applicability of ferroelectret materials for ultrasound transducers, a special application is presented: a robust sensor array consisting of 16 single elements (4×4). This sensor array has been designed for measuring cavitation effects occurring at extremely high pressure levels in ultrasonic cleaning systems, a task that cannot be fulfilled with common sensors. The sensor array can be placed directly on the specimen's surface and, therefore, does not alter the pressure distribution.

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