Development of in vivo Skin Viscoelastometer and its Rheological Applications

Abstract

The effect of alkalic salts on the apparent viscosity of soybean protein was investigated using a modified coaxial cylinder viscometer. The apparent viscosity increased with a rise and with a fall in temperature in ascending order of Hofmeister's series.
A technique of measuring the dynamic viscoelasticity of human skin in vivo was developed. With it,the mechanical properties of the skin are measured using decade filter and newly developed noise suppression logic. The technique is sensitive enough to detect the difference in visco-elasticity between sites of the body, and the differences before and after application of cosmetics.
We developed a new evaluation system for the quantitative analysis of facial wrinkles. This system enables us to obtain precise three-dimensional information based on the curved shape measurement. Using this system, we can quickly classify the wrinkles at the corner of the eye “crow's feet” into coarse or intermediate wrinkles and fine wrinlde. This system was applied for the quantitative analysis of wrinkles in association with aging in 275 skin surface negative replicas of the“crow's feet”site in Japanese females ranging in age from 20 and 80 years. Data clearly revealed that the wrinkles could be extracted from the other three-dimensional data. In addition, it was confirmed that most of the coarse or intermediate wrinkle parameters gradually increased with age, while the fine wrinkle parameters increased up to the middle age and decreased thereafter. These results suggest that the formation of coarse or intermediate wrinkles must be caused by different mechanisms than that of fine wrinkles.