Evaluating distribution and variation of strains near eyes in blinking using digital image correlation

Abstract

Many women use cosmetics on a daily basis for a long time from morning till night, and feel changes in physical properties of the skin and the state of the cosmetic coating as tightness, dryness and so on. Therefore, a method for objectively measuring the physical properties of cosmetic coating on facial skin is demanded. Many cosmetic coatings are designed to be flexible from the viewpoint of feeling of use and exist as thin coatings on the skin surface. Therefore, the contact type measurement may not be able to acquire the state of the coated skin and noncontact measurement is preferable. In past studies on skin, various techniques for evaluating skin deformation have been introduced. Noncontact and noninvasive methods for measuring physical properties of the skin include the use of images and ultrasonics. Ultrasonic micro-elastograph was used for evaluating the elastic properties inside the skin. 1-4 On the other hand, digital image correlation is widely used for studying mechanical deformation of solids and structures. 5-9 This method is one of noncontact and noninvasive optical methods for measuring surface