Generation of ultrasound using scanning near-field optical microscope

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K18822
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Research Field: Mechanics of materials, Production engineering, Design engineering, and related fields
• Research Institution: Tokyo Denki University (2019); Nagaoka University of Technology (2017-2018)
• Principal Investigator: Matsuya Iwao 東京電機大学, 理工学部, 准教授 (00514465)
• Co-Investigator(Kenkyū-buntansha): 石橋 隆幸 長岡技術科学大学, 工学研究科, 教授 (20272635)
• Project Period (FY): 2017-06-30 – 2020-03-31
• Keywords: レーザ超音波 / 近接場光顕微鏡 / 超音波

Outline of Final Research Achievements

In this work, a new method for generating ultrasonic waves utilizing evanescent light during the total internal reflection at the surface of a half ball lens is presented. A waveguide with a sharp wedge is employed as a specimen to launch a wedge wave and the edge tip of the waveguide ridge is attached to the lens to create a contact point between them. A low-power pulsed Nd:YAG laser is irradiated into the lens to form the evanescent light. The effect of water confinement in a point-contact configuration is investigated for the ability of generating wedge waves by comparing in an open system. The amplitude of the first mode 1 wedge wave produced by the evanescent light is enhanced more than eight times due to the water confinement. The similar relationship between the direct ablation and the confined ablation for the direct laser irradiation is demonstrated.

Free Research Field

計測工学、機械要素

Academic Significance and Societal Importance of the Research Achievements

これまでの取り組みによって、エバネッセント光によるくさび波の励起に成功しており、基本的な光学系の構築ができている。これを利用して、近接場光やエバネッセント光を利用した新たなドラッグデリバリができる可能性がある。特に今回、水で閉じた系にすることによって、水なしの開放系と比較して8倍以上の強度の超音波が励起できた。その時の衝撃圧力を駆動力として、微小物質（核酸医薬を想定）の拡散を増強させられる可能性があることを見出した。本課題で確認した閉じ込め効果による超音波の増大を利用して、エバネッセント光の衝撃圧力で経皮的に薬剤を導入する事も視野に入る。