In vivo measurement of skin surface strain and sub-surface layer deformation induced by natural tissue stretching

Abstract

Stratum corneum and epidermal layers change in terms of thickness and roughness with gender, age and anatomical site. Knowledge of the mechanical and tribological properties of skin associated with these structural changes are needed to aid in the design of exoskeletons, prostheses, orthotics, body mounted sensors used for kinematics measurements and in optimum use of wearable on-body devices. In this case study, optical coherence tomography (OCT) and digital image correlation (DIC) were combined to determine skin surface strain and sub-surface deformation behaviour of the volar forearm due to natural tissue stretching. The thickness of the epidermis together with geometry changes of the dermal-epidermal junction boundary were calculated during change in the arm angle, from flexion (90°) to full extension (180°). This posture change caused an increase in skin surface Lagrange strain, typically by 25% which induced considerable morphological changes in the upper skin layers evidenced by reduction of epidermal layer thickness (20%), flattening of the dermal-epidermal junction undulation (45-50% reduction of flatness being expressed as Ra and Rz roughness profile height change) and reduction of skin surface roughness Ra and Rz (40-50%). The newly developed method, DIC combined with OCT imaging, is a powerful, fast and non-invasive methodology to study structural skin changes in real time and the tissue response provoked by mechanical loading or stretching.

Guidelines for designing a realistic peripheral venous catheter insertion simulator: A literature review

“…In vivo measurements of the thickness of the dermis and hypodermis have also been conducted on the volar forearm using ultrasound images [23][24][25][26] . More recently, the in vivo epidermal thickness was measured by Maiti et al 27 using optical coherence tomography (OCT). In the same study, a literature review of the epidermal thickness obtained using various techniques was also reported.…”

“…In addition to the friction coefficient, the touch properties of materials are also characterized by roughness parameters. Maiti et al 27 performed measurements on one human subject to assess human skin roughness parameters (Ra, arithmetic mean roughness and Rz, mean depth roughness), and the values were compared to the literature. The measurements were obtained using OCT at different forearm angles (90° flexion and 180° full extension 27 prompted us to perform a literature review to identify results for Ra and Rz in extended arms.…”

An injectable meta-biomaterial

“…2b, absent in non-frictional control provided in Supplementary 5). But the yield strain was substantially below the 50% typically required for a soft tissue filler 8 to withstand physiological movement 32 . On the other hand, bulk crosslinking ( Fig.…”

Carbon Nanofiber versus Graphene‐Based Stretchable Capacitive Touch Sensors for Artificial Electronic Skin

“…After each stretch–release cycles, heat gun annealing (≈180 °C for 1 min) was performed as schematically shown in Figure 2c (Step C). The rationale behind the 20% stretch–release cycle measurements was the fact that human skin on the joints (elbows, knees, fingers) experience such levels of strain under motion 58. In Figure 2c, the dimensionless ratio I 0 / I i between the initial current and the current during each cycle (steps from A to C), is represented with a columnar graph.…”

“…Biomechanics of human motion indicates that human skin can elongate between 20 and 40% at the joints 58. Our capacitive device, however, was tested up to 100% elongation that may be more realistic for mechanics of extreme soft robotics motion.…”