Mueller Bettina, Elrod Julia, Distler Oliver, Schiestl Clemens, Mazza Edoardo
Institute for Mechanical Systems, ETH Zurich, Leonhardstrasse 21, Zürich 8092, Switzerland.
Department of Surgery, University Children's Hospital Zurich, Steinwiesstrasse 75, Zürich 8032, Switzerland; Children's Research Center (CRC), University Children's Hospital Zurich, Steinwiesstrasse 75, Zürich 8032, Switzerland.
J Biomech Eng. 2021 Feb 1;143(2). doi: 10.1115/1.4047661.
in vivo skin characterization methods were shown to be useful in the detection of microstructural alterations of the dermis due to skin diseases. Specifically, the diagnostic potential of skin suction has been widely explored, yet measurement uncertainties prevented so far its application in clinical assessment. In this work, we analyze specific factors influencing the reliability of suction measurements. We recently proposed a novel suction device, called Nimble, addressing the limitations of existing instruments, and applied it in clinical trials quantifying mechanical differences between healthy skin and scars. Measurements were performed with the commercial device Cutometer and with the new device. A set of new suction measurements was carried out on scar tissue and healthy skin, and FE-based inverse analysis was applied to determine corresponding parameters of a hyperelastic-viscoelastic material model. FE simulations were used to rationalize differences between suction protocols and to analyze specific factors influencing the measurement procedure. Tissue stiffness obtained from Cutometer measurements was significantly higher compared to the one from Nimble measurements, which was shown to be associated with the higher deformation levels in the Cutometer and the nonlinear mechanical response of skin. The effect of the contact force exerted on skin during suction measurements was quantified, along with an analysis of the effectiveness of a corresponding correction procedure. Parametric studies demonstrated the inherently higher sensitivity of displacement- over load-controlled suction measurements, thus rationalizing the superior ability of the Nimble to distinguish between tissues.
体内皮肤表征方法已被证明在检测由于皮肤疾病引起的真皮微观结构改变方面是有用的。具体而言，皮肤抽吸的诊断潜力已得到广泛探索，但测量不确定性迄今为止阻碍了其在临床评估中的应用。在这项工作中，我们分析了影响抽吸测量可靠性的特定因素。我们最近提出了一种名为Nimble的新型抽吸装置，解决了现有仪器的局限性，并将其应用于量化健康皮肤和疤痕之间机械差异的临床试验中。使用商业设备Cutometer和新设备进行测量。对疤痕组织和健康皮肤进行了一组新的抽吸测量，并应用基于有限元的反分析来确定超弹性-粘弹性材料模型的相应参数。有限元模拟用于合理化抽吸方案之间的差异，并分析影响测量过程的特定因素。与Nimble测量结果相比，Cutometer测量获得的组织刚度明显更高，这表明与Cutometer中更高的变形水平和皮肤的非线性力学响应有关。量化了抽吸测量期间施加在皮肤上的接触力的影响，并分析了相应校正程序的有效性。参数研究表明位移控制的抽吸测量固有地具有更高的灵敏度，从而合理化了Nimble区分组织的卓越能力。
