Medical and biological applications of Langevin-type ultrasonic transducers: A narrative review

Power ultrasound is increasingly important in healthcare applications involving non-ionizing radiation. The evolution of piezoelectric-based transducers has enabled the expansion and cost reduction of high-power ultrasonic systems. Among these, Langevin-type transducers are prominent due to their low cost, versatility, and ability to generate high acoustic intensity, which significantly affects the propagation medium. Structurally simple, these devices consist of two metal masses compressing piezoelectric ceramics, secured by a tensioning bolt. For applications demanding high acoustic pressure, mechanical amplifiers can be coupled to intensify ultrasound output. Langevin transducers find extensive use in medical and biological fields. In medicine, they are applied in surgical tools, targeted drug delivery, and cellular stimulation, offering advantages such as cutting precision and tissue selectivity. In biology, they support enzyme activation, microbial control in food, and environmentally friendly biofuel production. Their capacity to enhance biological responses while minimizing invasiveness makes them valuable in both research and clinical contexts. This review explores the main applications of Langevin transducers in biomedical and biotechnological areas. It highlights their functional advantages, operational challenges, and future prospects. By consolidating current knowledge, this paper aims to clarify their role and potential in advancing health-related technologies and sustainable biotechnological solutions.