A quantitative comparison of devices for in vivo biomechanical characterization of human skin

Abstract

Non-invasive skin characterization devices are emerging as a valuable tool in clinical skin research. In recent years, the range of available experimental techniques and methods used to determine the biomechanical properties of skin has increased considerably. Although a substantial amount of work has been devoted to assessing the working principle of macroscopic skin characterization devices individually, a rationalization and comparison between them is still lacking. This motivated the present study, which aimed to characterize and compare three commonly used working principles: suction, dynamic shear loading, and indentation. A synthetic model system with tunable mechanical properties was used to assess the three devices, and the results rationalized based on corresponding finite element models. In vivo measurements were performed on healthy volunteers to investigate the capability of differentiating the biomechanical properties of skin at different body locations, and to assess the intra- and inter-rater reliability of each device. The present comparative analysis indicates that the analyzed functional principles perceive the stiffness of human skin differently, with relevant implications for the interpretation of the respective measurement results.

Correlation analysis between texture features and elasticity of skin hyperspectral images in the near‐infrared band

“…The characteristics and types of materials that make up each layer are different. 4 , 5 In addition, the skin has mechanical properties that are affected by deformability, such as anisotropy and viscoelasticity. The skin affected by physical and chemical deformation from the outside and inside becomes dry, wrinkles deepen, and elasticity decreases owing to a decrease in moisture, the phenomenon appears.…”

Assessment of Intraday Variations in Skin Indentation Resistance

“…One method to obtain this information is to measure the force required to indent the skin to a specified indentation depth. This process measures the tissue’s resistance to indentation or its compressibility [ 12 - 14 ]. Various devices have been developed and used to measure elastic or viscoelastic skin properties with varying degrees of complexity [ 15 - 18 ].…”

“…However, from the point of view of clinical utility, it is important to have an uncomplicated yet accurate assessment method. One such method is provided by a handheld device that employs a 2.5 mm diameter indentor that upon contact with the skin penetrates 1.3 mm and automatically records the force required for this indentation [ 12 - 14 ]. From a fundamental analytical point of view, the relationship between indentation force (FORCE) and indentation depth (d) for soft tissues with an overall soft tissue thickness H can be expressed as \begin{document}\text{FORCE} = \delta \times E \times D \times \left( \frac{K}{1 - v^2} \right)\end{document} in which E is the effective elastic modulus of the tissue, D the indentor diameter, v the Poisson’s ratio for the tissue and a factor K, that depends on the ratio of both δ/H and D/H.…”