Dual-frequency integrated ultrasonic transducer based on piezoelectric composite film

Abstract

The invention discloses a dual-frequency integrated ultrasonic transducer based on a piezoelectric composite film. The basic structure is a multi-layer structure of a 0-0-3 type piezoelectric composite film (a high-frequency piezoelectric composite film), an AlN piezoelectric film (an ultrahigh-frequency piezoelectric film) and three layers of electrodes. The structure comprises a metal upper electrode layer, the 0-0-3 type piezoelectric composite film, a middle metal electrode layer, an AlN piezoelectric film layer, a lower electrode layer and the like from top to bottom. The frequency range of the 0-0-3 type piezoelectric composite film layer ultrasonic transducer is dozens of MHz to hundreds of MHz, and the frequency range of the AlN layer ultrasonic transducer is GHz so that through the design of the dual-frequency integrated ultrasonic transducer, the frequency and resolution use requirements of different scenes can be met by switching different transducer layers, therefore, the frequency application range of the ultrasonic transducer is widened, and the transducer has multiple purposes.

Description

technical field [0001] The invention belongs to the field of micro-electromechanical technology, in particular to a dual-frequency integrated ultrasonic transducer based on a piezoelectric composite film. Background technique [0002] Polymer / piezoelectric ceramic composite is a composite functional material containing both polymer and piezoelectric ceramics. This composite material not only has the characteristics of low acoustic impedance and high acceptance coefficient of polymer, but also has the high-voltage strain constant d of piezoelectric ceramics. 33 , High electromechanical coupling coefficient characteristics. However, the current research on composite piezoelectric materials shows that the performance of composite piezoelectric materials prepared by simply mixing polymers and piezoelectric ceramic materials is not good. This is because most of the PVDF-based polymer in this type of composite piezoelectric material is composed of α phase without piezoelectric p...

AI Technical Summary

Problems solved by technology

However, the current research on composite piezoelectric materials shows that the performance of composite piezoelectric materials prepared by simply mixing polymers and piezoelectric ceramic materials is not good.

This is because most of the PVDF-based polymer in this type of composite piezoelectric material is composed of α phase without piezoelectric properties, and the proportion of β phase with piezoelectric properties is too small, thus limiting the piezoelectricity of composite materials to a certain extent. electrical properties

In addition, composite piezoelectric materials prepared by simply mixing polymers and piezoelectric ceramics are prone to insufficient polarization of composite materials due to the difference in polarization voltage between polymers and ceramics.

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