Transducers Flashcards
What is so special about Piezoelectric material?
It’s material the converts sound to electricity and vice versa.
What to words are commonly used to describe this material?
Piezoelectric or ferroelectric.
What are element piezoelectric elementsmade from?
Lead Zirconate Titanate or simply PZT. These crystals are not found in nature.
What are some synonyms for PZT?
Ceramic. Active element. Crystal.
What special process is utilized in creating PZT crystals?
They are heated up to Curie temperature ( about 365 C), then a current is applied to align the magnetic domains to polarize the PZT element then let it cool down.
Why should you not autoclave an ultrasound transducer?
Getting it to about Curie temperature again destroys its piezoelectric properties. And it can destroy the bonding elements within the transducer.
What are the three primary internal elements of an ultrasound transducer?
Piece electric Crystal, damping material, and matching layers on the face.
Why are matching layers on the face of the transducer so critical?
Ultrasound reflections are created by high acoustic impedance. Matching layers step down the impedance between the transducer crystal and the patient’s skin. Ultrasound gel is utilized to further couple the device to the patient without creating a huge reflection.
How thick is the matching layer?
One quarter wavelength of the operating frequency.
What does the backing material provide?
The backing material provides damping which substantially reduces Crystal ringing. This aids in creating a very short pulse. Has short pulse is good for better axial resolution.
Ultimately the backing material provides better resolution.
What are two drawbacks of using a backing material?
Decreased sensitivity and a broader bandwidth which reduces the quality factor.
