Context:Based on the recent discovery elsewhere that when thin films of hafnium oxide (HfO2) are crystallized under certain mechanical constraints they become piezoelectric, this project seeks to answer the question whether bulk materials can be prepared with the same or similar piezoelectric crystal
Mason, Piezoelectric Crystal
and Their Application to Ultrasonics, Van Nostrand, New York, NY, USA, 1950.
The sensor itself is approximately 3 millimeters long and is powered by a piezoelectric crystal
. The crystal converts ultrasound vibrations into electricity, which gives the device the juice it needs.
"The big advance is phased arrays where an array of piezoelectric crystal
is fired in phase to create a beam that can be steered through the test piece.
Series accelerometers incorporate the use of Meggitt's proprietary piezoelectric crystal
technology, operating in annular shear mode.
Here's how an accelerometer works: Accelerometers contain a piezoelectric crystal
element, which is bonded to a mass.
Unlike Aoyagi's previous attempts to mimic a mosquito's bite, each of these parts is driven by tiny motors based on lead zirconium titanate (PZT) - a piezoelectric crystal
that expands very slightly when you apply an alternating voltage.
(10) If an alternating voltage at an ultrasonic frequency is applied across a piezoelectric crystal
, it will result in an oscillating shape change of the crystal at the frequency applied.
A voltage placed across an unstressed piezoelectric crystal
causes the crystal to deform.
As the fluid strikes a bluff body, imparting alternating vortices downstream of the bluff, it creates a vibration on a sensor body containing a piezoelectric crystal
. The frequency of the sensor is proportional to the velocity of the fluid and is amplified and converted to a 4 to 20 mA output signal.
Those oscillations, in turn, stress the piezoelectric crystal
and produce the voltage.
Just as increasing the mass hanging from a spring will change the resonant frequency of the spring, the added mass of molecules on the QCM affects the resonant frequency of the piezoelectric crystal
. This frequency can be easily measured electronically, providing a measurement of the amount of analyte in the sample.