By using the principles behind phononic crystals, a periodic array of circular holes made along the polarization thickness direction of piezoceramic resonators are used to stop the planar resonances around the thickness mode band. In this way, a piezoceramic resonator adequate for operation in the thickness mode with an in phase vibration surface is obtained, independently of its lateral shape. Laser vibrometry, electric impedance tests and finite element models are used to corroborate the performances of different resonators made with this procedure. This method can be useful in power ultrasonic devices, physiotherapy and other external medical power ultrasound applications where piston-like vibration in a narrow band is required.
Acknowledgements
J.L.A. wishes to thank Dirección General Asuntos del Personal Académico, Universidad Nacional Autónoma de México and CONACYT for financial support through grants IN106115 and 179619, respectively. R.Q.T. thanks DGAPA-UNAM for financial support through grant IN111614. J.L.D.J. wishes to thank Cátedras CONACYT in CFATA, F.M.E wishes to thank to CICYT DPI2013-46915-C2-1-R support. Finally, F.M.E. and J.L.A. thank the Scientific Cooperation Program UNAM-CSIC.
