Characterization of organic film with scanning acoustic microscopy

The present article reports a technique to measure velocity of an organic film deposited on a homogeneous substrate, wherein the thickness of the film and the diameter of the measurement area of the specimen are in the order of a few microns. A thinly sliced human kidney was selected as an example of an organic film. The thickness of the specimen was substantially 3 μm. For the substrate, fused quartz was used because its elastic properties are known and stable. The spherical acoustic lens was used to determine the position for measurement. The frequencies at 400 MHz and 600 MHz were used for the measurement and the visualization, respectively. The generation of the Rayleigh waves under the above conditions was simulated by numerical calculations based on the wave propagation theory for layered media.