Re-use of this resource is governed by a Creative Commons Attribution-
Noncommercial-Share Alike 2.0 Licence UK: England & Wales
https://creativecommons.org/licenses/by-nc-sa/2.0/uk/
creative commons DoITPoMS logo
Piezoelectrics are found in medicine, where they are used in two ways:
+ - + - ] ] ]
An alternating field of a high frequency is applied to the piezoelectric, so that its shape changing forms waves in the ultrasound range.
Waves in the ultrasound range.
] ] ] ] ] ]
These ultrasound waves if pointed at a kidney stone can 'shake' it apart. This is a good non-invasive technique.
Ultrasound waves can reflect from tissue boundaries. The reflected waves can be observed in order to produce an image of internal body tissues, such as a fetus.
+ - + - ] ] ]
The piezoelectric changes shape as an applied field is reversed. It varies with the frequency of the electric field, producing waves in the ultrasound range.
+ -
The waves are directed onto the fetus, usually via a handheld device.
) (
Perhaps a more relevant example of ultrasound is its use in crack detection. The principles are the same.
The ultrasound is again produced by a piezoelectric, and the waves reflect from both sides of possible cracks in order to detect it.
The image is picked up by the piezoelectric, and gives an image of the crack.
Start of crack
End of crack