Instrument for microscopical observation of the biophysical effects of ultrasound

Abstract

In this instrument, a quartz driver, thickness resonant at 1 MHz, and a thin cover were concentrically mounted on the stage of a microscope. Electroding was omitted over a central area to allow transmitted-light observation of the test space between them. The acoustic field generated in the cylindrical test volume was approximately by a standing-wave solution to the linearized wave equation. The boundary values were zero pressure at the radial boundary and interferometrically determined values of the acoustic displacement at the driver and cover. The truncated-series solution was successfully used to explain the radiation-force-induced migration of small polystyrene spheres suspended in the water-filled test space. In addition, the determined pressure distribution substantially agreed with independent measurements obtained by interferometrically detecting (via the acousto-optical interaction) the pressure oscillations, averaged over height.