Piezoelectric micromachined ultrasonic transducers based on PZT thin films.
This paper describes fabrication and characterization results of piezoelectric micromachined ultrasonic transducers (pMUTs) based on 2-microm-thick Pb(Zr0.53Ti0.47O3) (PZT) thin films. The applied structures are circular plates held at four bridges, thus partially unclamped. A simple analytical model for the fully clamped structure is used as a reference to optimize design parameters such as thickness relations and electrodes, and to provide approximate predictions for coupling coefficients related to previously determined thin film properties. The best coupling coefficient was achieved with a 270-microm plate and amounted to kappa2 = 5.3%. This value compares well with the calculated value based on measured small signal dielectric (epsilon = 1050) and piezoelectric (e3l,f = 15 Cm(-2)) properties of the PZT thin film at 100 kV/cm dc bias. The resonances show relatively large Q-factors, which can be partially explained by the small diameters as compared to the sound wavelength in air and in the test liquid (Fluorinert 77). A transmit-receive experiment with two quasi-identical pMUTs was performed showing significant signal transmission up to a distance of 20 cm in air and 2 cm in the test liquid.
Muralt
Paul
P
Ceramics Laboratory, Swiss Federal Institute of Technology EPFL, CH-1015 Lausanne, Switzerland. paul.muralt@epfl.ch
Ledermann
Nicolas
N
Baborowski
Jacek
J
Barzegar
Abdolghaffar
A
Gentil
Sandrine
S
Belgacem
Brahim
B
Petitgrand
Sylvain
S
Bosseboeuf
Alain
A
Setter
Nava
N
D003198:Computer Simulation; D017076:Computer-Aided Design; D025802:Electric Capacitance; D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods; D004582:Electronics, Medical; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007854:Lead / Q000737:chemistry* / Q000528:radiation effects; D016014:Linear Models; D008567:Membranes, Artificial; D008839:Microelectrodes; D008904:Miniaturization; D014025:Titanium / Q000737:chemistry* / Q000528:radiation effects; D014159:Transducers; D014463:Ultrasonography / Q000295:instrumentation* / Q000379:methods; D015040:Zirconium / Q000737:chemistry* / Q000528:radiation effects
D008567:Membranes, Artificial; C065536:lead titanate zirconate; D007854:Lead; D015040:Zirconium; D014025:Titanium