A low driving power SAW atomizer was developed consisting of a unidirectional interdigital transducer
, a horn, and awaveguide fabricated on a LiNb[O.sub.3] substrate to increase the focus .
The acoustic tweezers are manufactured by fabricating an interdigital transducer
onto a piezoelectric chip surface.
FLOWave uses four interdigital transducers
, which are located on the outside of the measuring tube and therefore have no direct contact with the fluid.
Unlike the piezoelectric IDTs, where a pair of the surface electrodes establish one finger of the transducer, CMUT interdigital transducers
need only one surface electrode, since another one is at the bottom of the device.
Nowadays, Lamb waves can be actively generated and collected with various methods such as ultrasonic probes coupled with angle-adjustable Perspex wedges ; Hertzian contact transducer ; laser-based ultrasonic (LBU) for Lamb wave generation and laser interferometer for their acquisition ; piezoelectric lead zirconate titanate (PZT) elements ; and interdigital transducers
such as polyvinylidene fluoride (PVDF) piezoelectric polymer film .
The interdigital transducers
(IDTs) on the sensor surface allow electrical energy to be transferred to the piezoelectric substrate in the form of mechanical wave energy.
Reasons for apodized and unapodized transducer electrodes, linear and nonlinear finger spacing of interdigital transducers
and the use of window functions for improved band-pass response are explained clearly.