Low-Frequency Ultrasound in Medicine: An In Vivo Evaluation

Ultrasound energy at frequencies lower than 200 kHz has recently been used in the medical field to improve transdermal drug transport and to achieve a more suitable therapeutic approach. Low-frequency ultrasound energy was shown to be more effective than high-frequency ultrasound energy, so low-frequency ultrasound is attracting its share of attention in the medical field. In this paper, we take into consideration the most promising applications of low-frequency ultrasound with emphasis on transducer technology and measurements. In particular, a piezopolymer transducer is proposed, originally aimed at emulating the biosonar of bats, which has a low acoustic impedance in correspondence to biological tissue. The transducer is light, small, and inexpensive and could be used for medical applications, a possibility of which is a potential device for improving the cutaneous passage of drug compounds.