The Piezoelectric Crystal Ultrasound Uses to See Through Stuff

There are piezoelectric crystal ultrasound employs to detect matter through matter, probing only with sound. Ultrasound waves, also known as ultrasonic waves, are simply sound waves read by a special type of microphone, usually around 1.8-5 MHz (acoustic frequency). This is 1.8-5 million cycles per second.

Just like sound, ultrasound travels through matter and bounces off dense matter. These reflections are also ultrasound, just traveling toward instead of away from the detector. The detector reads back relative density based on the strength of the reflected ultrasound signals. The piezoelectric crystal ultrasound uses is in the detection of the reflected ultrasound waves.

Ultrasound is Acoustic waves, not Electromagnetic

Acoustic waves are longitudinal pressure waves detected by the ears, as opposed to light detected by the eyes (which are electromagnetic, transverse waves). This means ultrasound waves wiggle back and forth along the same line they travel on, just like regular sound. But ultrasound is a higher frequency, with a shorter wavelength than ordinary sound, and thus higher energy, wave than sound. Our ears cannot hear it, ultrasound is “above” sound.

Even though we cannot hear ultrasound frequencies with our ears, the waveforms can excite molecules in a crystal lattice.

How Does the Crystal Read Ultrasound

The crystal is chosen to vibrate with the ultrasound and produce a corresponding electric field that can be read out with wires. This is the property of piezoelectricity.

When the molecules in the crystal lattice absorb the energy of the ultrasound wave, they move. In a crystal lattice the molecules are constrained in certain crystal planes. Absorbing the ultrasound offsets the crystal planes, thus changing the crystal’s conductivity. Since the crystals used in ultrasound have selective conductivity, the on/off electric signals will read out and can be correlated in a computer to describe the signal as desired. Read more about how the piezoelectric effect works.

What Type of Piezoelectric Crystal Ultrasound Uses

Piezoelectric Crystals in Ultrasound Use Echo Location

The piezoelectric transducer reads the sound like a microphone. “Transducer” is basically a transLATOR of signals from one form to another.

The crystals used in ultrasound transducers must be very fine tuned to the task. Only certain kinds of piezoelectric crystals can be used, and they must be trimmed to exact geometrical measurements. The crystals must often be polarized in a strong electric field as well. Then they are typically formed in a grid called a phase array, which you could think of as like pixels on a screen. Each crystal in the grid can read back an electrical signal of a certain strength. Stronger reflected ultrasound wave would mean denser media detected and thus a more contrasted pixel on the readout screen. Less dense media, such as amnionic fluid, would read beck as a less contrasted, lighter pixel on the readout. This is how the piezoelectric crystal ultrasound detector makes a picture!

The ultimate transfer of electric signals into the reflectance values involves computer operations known as convolutions. Convolutions done in a computer are basically just wave math to determine how the detected waves might have superimposed on each other. The ultrasound may have some effects in the tissues, as research goes on to see if the bubbles and deformations can be used to assemble nanomaterials.

Piezoelectric crystal ultrasound devices are just one piece of technology piezoelectric crystals are used in, click here to read 11 more examples.