Development and evaluation of ultrasound-facilitated drug delivery device

Abstract

We developed a new ultrasound-facilitated delivery (UFD) device with a drug infusion sapphire needle enabling real-time magnetic resonance imaging (MRI) observation and an ultrasound piezoelectric transducer (drive frequency: 260 kHz) with an effective structure for increasing drug diffusion. The sapphire needle (outside diameter: 0.6 mm, inside diameter: 0.3 mm, length: 150 mm) was grown by a micro-pulling-down method. The transducer is composed of two-stacked layers of lead zirconate titanate (PZT) on a brass base. The sound pressure distribution of the developed UFD device in water was measured with a miniature probe hydrophone, showing good agreement with the value simulated by the finite element method (FEM) analysis. The developed UFD device demonstrated high efficiency and reliability of drug diffusion, exhibiting an 8.5% increase in the volume of drug diffusion with 80% higher reproducibility and 66% lower driving voltage than the previous device. Consequently, the operating temperature of the new UFD device was decreased from 60 °C to room temperature.