Alippi A, Bettucci A, Biagioni A, D'Orazio A, Germano M, Passeri D
Dipartimento di Scienze di Base e Applicate per l'Ingegneria, Sapienza, Università di Roma, Via A. Scarpa 16, 00161 Roma, Italy.
Rev Sci Instrum. 2010 Oct;81(10):104903. doi: 10.1063/1.3480545.
Photoacoustics has emerged as a tool for the study of liquid gel suspension behavior and has been recently employed in a number of new biomedical applications. In this paper, a photoacoustic sensor is presented which was designed and realized for analyzing photothermal signals from solutions filled with microbubbles, commonly used as ultrasound contrast agents in echographic imaging techniques. It is a closed cell device, where photothermal volume variation of an aqueous solution produces the periodic deflection of a thin membrane closing the cell at the end of a short pipe. The cell then acts as a Helmholtz resonator, where the displacement of the membrane is measured through a laser probe interferometer, whereas photoacoustic signal is generated by a laser chopped light beam impinging onto the solution through a glass window. Particularly, the microbubble shell has been modeled through an effective surface tension parameter, which has been then evaluated from experimental data through the shift of the resonance frequencies of the photoacoustic sensor. This shift of the resonance frequencies of the photoacoustic sensor caused by microbubble solutions is high enough for making such a cell a reliable tool for testing ultrasound contrast agent, particularly for bubble shell characterization.
光声技术已成为研究液体凝胶悬浮行为的一种工具，最近已被应用于许多新的生物医学领域。本文介绍了一种光声传感器，该传感器是为分析充满微泡的溶液中的光热信号而设计和实现的，微泡通常用作超声成像技术中的超声造影剂。它是一种封闭细胞装置，水溶液的光热体积变化会使短管末端封闭细胞的薄膜产生周期性偏转。该细胞随后充当亥姆霍兹共振器，通过激光探针干涉仪测量薄膜的位移，而光声信号则由通过玻璃窗照射到溶液上的激光斩波光产生。特别是，微泡壳已通过有效表面张力参数进行建模，然后通过光声传感器共振频率的偏移从实验数据中进行评估。由微泡溶液引起的光声传感器共振频率的这种偏移足够大，使得这种细胞成为测试超声造影剂的可靠工具，特别是用于气泡壳表征。
