The skin is exposed to various mechanical stresses such as stretching and sliding due to body movements and contact in daily life. Nonetheless, the skin can not only withstand these stresses but can also maintain its shape and function. The skin biomechanical properties (SBP) are related to its functional homeostasis. Collagen fibers, the main component of the skin, are related to viscoelasticity, and elastin is related to elasticity.

SBP of the trunk, especially those of the skin around the spine, are thought to be affected by daily posture and repetitive movements. The spine flexes frequently in daily life due to the structural and kinematic characteristics of the human body and the effects of gravity, and therefore the skin of the dorsal trunk is stretched relatively frequently. Although mechanical stimulation of the skin in daily life is thought to affect SBP, there have been no studies showing the relationship between SBP and body movement. In this study, seventeen healthy adult males participated. We divided the trunk into upper, middle, and lower trunk sections and determined the correlation coefficients between SBP measurement sites and the angle of the facet joints in static standing (SS) and the amount of facet joint motion during maximum forward bending (MFB) and maximum backward bending (MBB). Skin elasticity and viscoelasticity were evaluated using Cutometer^Ⓡ. Spinal kinematics measurements were performed on Spinal Mouse^Ⓡ. The results show significant correlations between C7 SBP and T2–3 kinematic parameters (p < 0.05) and between T7 SBP and T9–10 amount of motion during MBB (p < 0.05). In addition, significant correlations are observed between dynamic parameters among various SBP parameters (p < 0.05). These findings indicate a relationship between SBP around the spine of the trunk and the kinematics of the spine in the sagittal plane.

Formulation of κ-Carrageenan/polyvinyl alcohol (PVA) based and optimization of electrospinning parameters for producing electrospun nanofibre were investigated. Two types of PVA polymers; fully hydrolyzed (FH) and partially hydrolyzed (PH), were used as crosslink agents or co-polymer with the ratio of κ-Carrageenan to PVA was 70:30. Nanofibers with κ-Carrageenan/PVA FH blend produced a uniform and smooth nanofiber at 12 w/v % of PVA FH concentration. Both types of PVA promoted the hydrophilicity of the nanofiber with a slight absorption rate for κ-Carrageenan/PVA PH nanofiber. The formulation of 1 w/v % κ-Carrageenan and 12 w/v % PVA FH was used to optimize the electrospinning parameters by varying voltage, distance and flowrate using response surface methodology (RSM). The optimum electrospinning parameters for voltage, distance and flowrate for the respective formulation were 15.07 kV, 12.40 cm, and 0.435 ml/h, respectively.