The evolution of skin’s biomechanical and optical properties as a function of aging and/or photoaging is one of the main targets of cosmetic and dermatological research. Many noninvasive devices to measure skin’s biomechanical properties have been developed using alternative methods such as stretching, torsion, indentation and suction. Measurements of skin deformation after suction or torsion are the most widely used techniques in cosmetic research.
The skin’s optical properties play an important role as well, and devices measuring these characteristics assess reflected light after illumination of the skin surface. Different noninvasive methods have been proposed for evaluating skin complexion in vivo. These include quantitative measurements of skin color, using colorimetry—i.e., L*a*b* and Individual Typological Angle (ITA°); or of the intensity of specular reflection and the back-scattering of light from the skin. The purpose of this study was to demonstrate the evolution of the measured parameters with aging, and to find the correlation between measured mechanical and optical properties of the skin.
Test population and body sites: A total of 113 female volunteers ages 18–76 participated in the study. All participants were Caucasian, with no apparent signs of skin disease. The volunteers applied no cosmetic products for 24 hr before measurements were taken. Measurements were conducted on two different anatomical regions: the inner forearms and/or the face, i.e., the forehead, temples or cheeks.
Biomechanics: The biomechanical properties of the skin were measured using commercially available standard devices as well as an internally developed device, referred to as a corneovacumeter. The corneovacumeter measures capacitance between skin and a conductive plate, whereby capacitance is proportional to skin deformation. With this type of device, 12 simultaneous suctions are realized and the result provided is the mean of the measurements. While such suction-based devices measure vertical skin deformation after suction, torque-based devices measure deformation after torsion. For the present study, both standard and surface methods were used for calculating biomechanical skin parameters.