Transdermal drug delivery using low-frequency sonophoresis: COMSOL simulation of piezoelectric array transducers

This study explores the design and simulation of specialized sonophoretic transducers aimed at enhancing the transdermal delivery of large drugs. We examine different elements of the transducer's design, such as the choice of materials, its dimensions, and the matching of acoustic impedance. We selected PZT-4, from the lead zirconate titanate (PZT) group, as the main material due to its excellent piezoelectric features and durability. We also use polymer matrices to make the transducer less rigid. The simulation outcomes, using COMSOL Multiphysics, cover five different transducer array sizes (8x5, 10x6, 12x8, 14x9, and 16x10) within the frequency range of 20-40 kHz. We measure the acoustic pressure at a depth of 0.1 mm under the skin, which is key for successful drug delivery through the skin. Our results show how increasing the size of the array affects the transducer's efficiency. We confirm our simulation results by comparing them with a previously published ANSYS simulation and finding good alignment. This comparison adds reliability to our methods and outcomes. The study also proposes creating a small, wrist-mounted device for drug delivery that could be combined with drug patches, making it user-friendly. Moreover, we stress the need to follow Mechanical Index (MI) guidelines to avoid damaging the skin. Overall, our findings highlight the importance of the array size in the performance of the transducer and confirm the validity of our simulation approach, paving the way for innovative solutions in drug delivery that could have wide applications in healthcare.