ASA 130th Meeting - St. Louis, MO - 1995 Nov 27 .. Dec 01

3aPAa2. Acoustic detection of inertial microcavitation from ultrasound.

Ronald A. Roy

Appl. Phys. Lab., Univ. of Washington, Seattle, WA 98195

Recent years have witnessed a growing interest in processes governing the nucleation, perpetuation, and physical consequences of inertial microcavitation generated by ultrasound. Fields as diverse as medicine, ultrasonic cleaning, and sonochemistry all rely, in varying degrees, on our ability to either inhibit, promote, or control inertial cavitation activity. Quantitative, spatially resolved assessment of such activity often requires an ability to detect bubbles as small as a micron lasting less than a microsecond. This constitutes a technical challenge that has sought the services of optical, electrical, and acoustical technologies. A review is presented of the state of the art of spatially resolved, acoustic microcavitation detection schemes. This will include descriptions of both passive [Atchley et al., Ultrasonics 26 (1988)] and active [Roy et al., J. Acoust. Soc. Am. 87, 2451 (1990)] systems. Although these systems were designed to detect inertial microcavitation generated by microsecond pulses of Megahertz-frequency ultrasound (similar to that utilized in diagnostic ultrasound), the techniques are quite straightforward and generalizable to any situation where one seeks to detect spatially discrete cavitation activity in a reasonably homogeneous bounded liquid. Issues such as absolute sensitivity and observational invasiveness are discussed. [Work supported by NIH through Grant No. RO1 CA39374.]