Design, fabrication and characterization of piezoelectric micro-cantilever operated in liquid environment for ultrasound energy source applications

This paper presents a resonant-driving piezoelectric micro-cantilever for application to the ultrasound source, which can provide sufficient ultrasound energy in liquid environment by actuating maximally at the cantilever’s resonant frequency. The compact-sized micro-cantilevers were firstly designed to be operated in deionized water solution in this paper with consideration of its further application to intravascular catheter-delivered transducer-tipped ultrasound thrombolysis devices as the ultrasound energy source. The micro-cantilever models, which have the target resonant frequencies of ~40 kHz in DI water, were designed on the basis of numerical calculations, finite element method analysis and pre-experiment results based on the measured resonant frequencies in air, and fully fabricated by micromachining technologies. The resonant frequencies in DI water for each cantilever model were measured to be 10.94, 23.14, 33.1, and 44.02 kHz which are matched excellently with the targeted frequencies of 10, 20, 30 and 40 kHz, respectively. In addition, we could experimentally observe that red blood cells aggregated locally in 5% diluted blood solution were rapidly disaggregated within a few seconds by sufficient ultrasound energy generated by resonant-actuations of the proposed micro-cantilever.