Elouneg A, Chambert J, Lejeune A, Lucot Q, Jacquet E, Bordas S P A
Université de Franche-Comté, CNRS, institut FEMTO-ST, F-25000 Besançon, France; Institute of Computational Engineering and Sciences, Department of Engineering, Université du Luxembourg, Esch-sur-Alzette, Luxembourg.
Université de Franche-Comté, CNRS, institut FEMTO-ST, F-25000 Besançon, France.
J Mech Behav Biomed Mater. 2023 May;141:105779. doi: 10.1016/j.jmbbm.2023.105779. Epub 2023 Mar 15.
Human skin is a soft tissue behaving as an anisotropic material. The anisotropy emerges from the alignment of collagen fibers in the dermis, which causes the skin to exhibit greater stiffness in a certain direction, known as Langer's line. The importance of determining this anisotropy axis lies in assisting surgeons in making incisions that do not produce undesirable scars. In this paper, we introduce an open-source numerical framework, MARSAC (Multi-Axial Ring Suction for Anisotropy Characterization: https://github.com/aflahelouneg/MARSAC), adapted to a commercial device CutiScan CS 100® that applies a suction load on an annular section, causing a multi-axial stretch in the central zone, where in-plane displacements are captured by a camera. The presented framework receives inputs from a video file and converts them into displacement fields through Digital Image Correlation (DIC) technique. From the latter and based on an analytical model, the method assesses the anisotropic material parameters of human skin: Langer's line ϕ, and the elastic moduli E and E along the principal axes, providing that the Poisson's ratio is fixed. The pipeline was applied to a public data repository, https://search-data.ubfc.fr/femto/FR-18008901306731-2021-08-25_In-vivo-skin-anisotropy-dataset-for-a-young-man.html, containing 30 test series performed on a forearm of a Caucasian subject. As a result, the identified parameter averages, ϕˆ=40.9±8.2 and the anisotropy ratio Eˆ/Eˆ=3.14±1.60, were in accordance with the literature. The intra-subject analysis showed a reliable assessment of ϕ and E. As skin anisotropy varies from site to site and from subject to subject, the novelty of the method consists in (i) an optimal utilization of CutiScan CS 100® probe to measure the Langer's line accurately and rapidly on small areas with a minimum diameter of 14mm, (ii) validation of an analytical model based on deformation ellipticity.
人体皮肤是一种表现为各向异性材料的软组织。这种各向异性源于真皮中胶原纤维的排列，这使得皮肤在特定方向（即朗格线）上表现出更大的硬度。确定该各向异性轴的重要性在于帮助外科医生进行不会产生不良疤痕的切口。在本文中，我们介绍了一个开源数值框架MARSAC（用于各向异性表征的多轴环形抽吸：https://github.com/aflahelouneg/MARSAC），它适用于商业设备CutiScan CS 100®，该设备在环形区域施加抽吸负载，在中心区域引起多轴拉伸，其中平面内位移由相机捕获。所提出的框架从视频文件接收输入，并通过数字图像相关（DIC）技术将其转换为位移场。基于后者并基于一个分析模型，该方法评估人体皮肤的各向异性材料参数：朗格线ϕ，以及沿主轴的弹性模量E和E，前提是泊松比是固定的。该流程应用于一个公共数据存储库，https://search-data.ubfc.fr/femto/FR-18008901306731-2021-08-25_In-vivo-skin-anisotropy-dataset-for-a-young-man.html，其中包含对一名白种人受试者前臂进行的30个测试系列。结果，所确定的参数平均值ϕˆ=40.9±8.2以及各向异性比率Eˆ/Eˆ=3.14±1.60与文献一致。受试者内分析显示对ϕ和E的评估可靠。由于皮肤各向异性因部位和个体而异，该方法的新颖之处在于：（i）最佳利用CutiScan CS 100®探头在最小直径为14mm的小区域准确快速地测量朗格线，（ii）基于变形椭圆率对一个分析模型进行验证。
