Piezoelectric material is the core of the transducer(2)

(2) The theory of mechanical acoustic properties of l-3 type piezoelectric resonance sensor is established by w.A smith et al.The model is simulated and the electromechanical coincidence coefficient of the thickness vibration of the piezoelectric composite material is obtained.The effects of speed, dielectric constant, and acoustic impedance. The results show that when the l-3 type piezoelectric composite piezoelectric.When the volume fraction of the phase material changes from 30% to 80%, the electromechanical coefficient of the composite material is almost 1.5 times of piezoelectric ceramics ; dielectric constant with volume fraction of piezoelectric ceramic phase is increasing and substantially increasing linearly; and the speed of sound l- 3 type piezoelectric composite varies with the volume of the piezoelectric phase.The number is increasing, and the growth trend can be three segments, wherein the piezoelectric phase volume fraction is less than 30%,As the volume fraction of the piezoelectric phase material increases, the speed of sound increases faster, when the volume fraction of the Piezoelectric ceramic materials is between 30% and 80%.When the speed is between the speed of sound increases linearly. When the volume fraction exceeds 80%, the growth trend increases again.

(3) Through the Devaney-Levinc theoretical model, it has been studied from theoretical simulation and experimental verification.Acoustic matching material RTV6 smart silicone rubber is adoped with different volume fraction of alumina particles for its sound velocity, The influence and change of characteristics such as attenuation and acoustic impedance provide reference for the development of high frequency focused ultrasonic transducers.

 (4) Preparation of point focusing and line focusing in the focusing high-frequency ultrasonic transducer,The heart frequency is around 50 MHz, and its time domain waveform and sound field characteristics of piezo rings components are tested and analyzed. both focused ultrasound transducers have better focusing characteristics (focus depth <l0mm) and spaceResolution (both horizontal and vertical resolutions are less than 200um). For current medical ultrasound in interventional diagnosis,Superficial tissue fine structure resolution, small animal experiments and applications in photoacoustic imaging have important reference value.

Medical ultrasound imaging is one of the most common imaging diagnostic methods in the clinical practice, with non-invasive and superior point.Piezoelectric transducer animation is widely used in the field of disease diagnosis and other fields. However, since the attenuation of the ultrasonic wave is proportional to its frequency,The frequency of this conventional ultrasonic transducer is generally below 10 MHz, and the application is generally in the vitro diagnostics.Ultrasound transducers, such as those used for abdominal diagnosis and cardiac diagnosis, range is in the frequency from 3 MHz to 10 MHz. However,With the development of mechanical manufacturing technology, high-performance piezoelectric materials and various intracavity interventional diagnostic methods. Making ultrasonic transducers are also getting more and more frequent.

 The application fields of high frequency piezoelectric acceleration transducer mainly include cardiovascular, such as intervention Intravascular ultrasound (IVUS), the frequency of the transducer can reach 20MHz to 60MHZ, the resolution can reach several tens of micrometers, and the coronary artery can be examined in real time.Better distinguish the fine structure of the vessel wall and detect vascular plaque for coronary atherosclerosis.The diagnosis of cardiovascular diseases such as atherosclerotic plaques and stenosis has important value and significance. For example, Visual SonicS of Canada introduced the experiment for small animals as early as around 2002.An ultrasound imager with a resolution is less than 100um. for example, for dermatology in 1986.Diagnosed 20MHZ high-frequency ultrasound probe in 1996 is applied to dermatology. 50 MHz high frequency Piezo bimorph actuator with various layer thicknesses and lesions Ophthalmology Super Life, 2006 Southern California, USA Professor KK Shung University.A 30MHz and 35MHz high-frequency focusing linear array ultrasonic transducer for ophthalmologic diagnosis was developed for the diagnosis of ophthalmic diseases such as glaucoma, ocular trauma, and corneal disease. As can be seen,High-frequency focused ultrasound transducers can further improve imaging resolution.The rate has a broad application prospect in distinguishing the fine structure of the tissue.