Medical Ultrasonics Laboratory (MEDUSA), Department of Neuroscience and Biomedical Engineering, Aalto University, Rakentajanaukio 2, Espoo, 02150, Finland.
J Acoust Soc Am. 2023 Nov 1;154(5):3388-3396. doi: 10.1121/10.0022326.
Annually, more than 16 × 109 medical needles are consumed worldwide. However, the functions of the medical needle are still limited mainly to cutting and delivering material to or from a target site. Ultrasound combined with a hypodermic needle could add value to many medical applications, for example, by reducing the penetration force needed during the intervention, adding precision by limiting the needle deflection upon insertion into soft tissues, and even improving tissue collection in fine-needle biopsy applications. In this study, we develop a waveguide construct able to operate a longitudinal-flexural conversion of a wave when transmitted from a Langevin transducer to a conventional medical needle, while maintaining high electric-to-acoustic power efficiency. The optimization of the waveguide structure was realized in silico using the finite element method followed by prototyping the construct and characterizing it experimentally. The experiments conducted at low electrical power consumption (under 5 W) show a 30 kHz flexural needle tip displacement up to 200 μm and 73% electric-to-acoustic power efficiency. This, associated with a small sized transducer, could facilitate the design of ultrasonic medical needles, enabling portability, batterization, and improved electrical safety, for applications such as biopsy, drug and gene delivery, and minimally invasive interventions.
每年，全球有超过 160 亿支医用针被消耗。然而，医用针的功能仍然主要局限于切割和将物质输送到或来自目标部位。将超声波与皮下注射针结合使用可以为许多医疗应用增加价值，例如，通过减少介入过程中所需的穿透力，通过限制插入软组织时的针偏转来提高精度，甚至改善细针活检应用中的组织采集。在这项研究中，我们开发了一种波导结构，当从兰格文换能器传输到常规医用针时，能够实现波的纵向-弯曲转换，同时保持高的电能-声能功率效率。使用有限元法对波导结构进行了计算机模拟优化，然后对该结构进行了原型制作并进行了实验表征。在低电功率消耗（低于 5W）下进行的实验显示，弯曲针尖的位移高达 200μm，电能-声能功率效率为 73%。这与小尺寸的换能器结合使用，可以为超声医疗针的设计提供便利，实现便携性、电池化和提高电安全性，适用于活检、药物和基因输送以及微创手术介入等应用。
