Surface Mechanics of Biological Tissues Using Low Frequency Rayleigh Waves Detected by Laser Speckle

摘要

An acousto-optical method for the determination of the mechanical loss factor (tan δ) in biological tissues is presented. Measurements of the loss factor were made on a polyvinyl chloride (PVC) phantom, elastin derived from a bovine nuchal ligament, and porcine skin. The acousto-optical values of the loss factor were compared with those measured with a more conventional mechanical testing system. The values for the mechanical loss factor for PVC and nuchal elastin as calculated from the acousto-optical method agreed with those determined using the mechanical testing system. However, there was a significant difference between the two methods for the porcine skin. We hypothesize that the acousto-optical method measures only the stratum corneum of the skin (i.e. surface characteristics) while the mechanical method evaluates the bulk properties of the skin. The rigid, keratinous fibers of the stratum corneum are believed to be responsible for the lower loss factor measured with the acousto-optical method.