Term
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Definition
| any device that converts one form of energy into another |
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Term
| Types of transducers (general) |
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Definition
electric motor (electric to kinetic)
light bulb (electric to heat and light)
muscle ( chemical to kinetic)
loudspeaker (electric to acoustic) |
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Term
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Definition
| a property of certain materials to create a voltage when pressure is applied or when the material is mechanically deformed |
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Term
Piezoelectric materials
aka ferroelectric material
Natural |
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Definition
| quartz, Rochelle salts, tourmaline |
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Term
Piezoelectric materials
aka ferroelectric material
Man Made (synthetic) |
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Definition
| barium titanate, lead metaniobate, lead titanate, LEAD ZIRCONATE TITANATE (PZT) |
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Term
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Definition
| ceramic, active element, or crystal |
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Term
| Curie Temperature or Curie Point |
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Definition
| if PZT is heated above this temperature (approx 360 degrees centigrade or 680 degrees Fahrenheit it loses its piezoelectricity.....the PZT is depolarized. |
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Term
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Definition
| the complete destruction of all living microorganisms by means of exposure to heat, chemical agents or radiation |
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Term
| Heat sterilization does this to the crystal |
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Definition
| depolarizes it...........BAD |
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Term
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Definition
| the application of a chemical agent to reduce or eliminate infectious organisms on an object, such as a transducer. |
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Term
| Transducers should be disinfected using germicides such as |
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Definition
CIDEX which is a trademark for gluteraldehyde.
Never alcohol |
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Term
| The active element of a transducer is |
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Definition
the crystal aka ceramic, PZT
It is 1/2 the wavelength thick |
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Term
| The transducer case does what? |
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Definition
| protects the internal components from damage and insulates the patient from electrical shock. |
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Term
| What is the purpose of the wire? |
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Definition
Electrical contact
excites the crystal producing sound (going out)
deforms the crystal producing a voltage (coming back) |
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Term
| What does the matching layer do? |
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Definition
it is an impedance between the skin and the active element to increase the percentage of transmitted US
IT INCREASES THE EFFICIENCY OF SOUND TRANSMISSION |
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Term
| How thick is the matching layer? |
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Definition
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Term
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Definition
| the range of frequencies between the highest and lowest frequency emitted from the transducer |
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Term
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Definition
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Term
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Definition
| bandwidth = maximum frequency-minimum frequency |
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Term
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Definition
| unit-less....represents the extent of damping |
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Term
| The Q-factor of imaging transducers is |
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Definition
| approximated by the number of cycles in the pulse usually 2-4 |
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Term
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Definition
| QF= resonant frequency(MHz)/bandwidth (MHz) |
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Term
| What determines the resonant frequency of a transducer? For continuous wave... |
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Definition
| The sound waves frequency equals the frequency of the voltage applied to the PZT. |
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Term
| What determines the resonant frequency of a transducer? For pulsed transducers..the main or center frequency of the transducer is determined by |
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Definition
| the thickness and the propagation speed of the piezoelectric material. |
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Term
| The propagation speed for PZT is |
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Definition
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Term
Pulsed transducers
Equation |
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Definition
| frequency (MHz)=materials propagation speed(mm/us)/2x thickness(mm) |
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Term
| When the PZT crystal is half as thick the sounds frequency is |
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Definition
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Term
| The thickness of the PZT crystal equals 1/2 of the |
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Definition
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Term
| The thickness of the matching layer is |
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Definition
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