Detecting mechanical properties of the intact skin in-vivo leads to a novel quantitative method to diagnose skin diseases and to monitor skin conditions in clinical settings. Current research and clinical methods that detect skin mechanics have major limitations. The in-vitro experiments are done in non-physiological conditions and in-vivo clinical methods measurer unwanted mechanics of underneath fat and muscle tissues but report the measurement as skin mechanics. An ideal skin mechanics should be captured at skin scale (i.e., micron-scale) and in-vivo. However, extreme challenges of capturing the in-vivo skin mechanics in micron-scale including skin motion due to heart beep, breathing and movement of the subject, has hindered measurement of skin mechanics in-vivo. This study for the first time captures micro-scale mechanics (elasticity and viscoelasticity) of top layers of skin (i.e., the stratum corneum (SC) and stratum granulosum (SG)) in-vivo. In this study, the relevant literature is reviewed and Atomic Force Microscopy (AFM) was used to capture force-indentation curves on the fingertip skin of four human subjects at a high indentation speed of 40 μ m / s . The skin of the same subject were tested in-vitro at 10 different indentation speeds ranging from 0.125 to 40 μ m / s by AFM. This study extracts the in-vivo elasticity of SC and SG by detecting time-dependency of tested tissue using a fractional viscoelastic standard linear model developed for indentation. The in-vivo elasticity of SC and SG were smaller in females and in-vitro elasticity were higher than that of in-vivo results. The results were consistent with previous observations.

中文翻译：

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使用粘弹性模型从原子力显微镜实验中提取微尺度和体内人体皮肤的弹性

在体内检测完整皮肤的机械特性，为诊断皮肤疾病和监测临床环境中的皮肤状况提供了一种新的定量方法。目前检测皮肤力学的研究和临床方法有很大的局限性。体外实验是在非生理条件下进行的，体内临床方法测量脂肪和肌肉组织下不需要的力学，但将测量报告为皮肤力学。理想的皮肤力学应该在皮肤尺度（即微米尺度）和体内捕获。然而，在微米尺度上捕捉体内皮肤力学的极端挑战，包括由于心脏哔哔声、呼吸和受试者运动引起的皮肤运动，阻碍了体内皮肤力学的测量。这项研究首次捕捉了体内皮肤顶层（即角质层 (SC) 和颗粒层 (SG)）的微观力学（弹性和粘弹性）。本研究回顾了相关文献，利用原子力显微镜（AFM）以40μm/s的高压痕速度捕获了四名受试者指尖皮肤上的力-压痕曲线。同一受试者的皮肤通过 AFM 以 0.125 至 40 μm/s 范围内的 10 种不同压痕速度进行体外测试。本研究通过使用为压痕开发的分数粘弹性标准线性模型检测测试组织的时间依赖性，提取 SC 和 SG 的体内弹性。SC和SG的体内弹性在雌性中较小，体外弹性高于体内结果。