Institute for Mechanical Systems, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland.
Department of Surgery, University Children's Hospital Zurich, Zurich, Switzerland.
PLoS One. 2018 Aug 8;13(8):e0201440. doi: 10.1371/journal.pone.0201440. eCollection 2018.
Suction experiments have been extensively applied for skin characterization. In these tests the deformation behavior of superficial tissue layers determines the elevation of the skin surface observed when a predefined negative (suction) pressure history is applied. The ability of such measurements to differentiate between skin conditions is limited by the variability of the elevation response observed in repeated experiments. The scatter was shown to be associated with the force exerted by the observer when holding the instrument against the skin. We have developed a novel suction device and a measurement procedure aiming at a tighter control of mechanical boundary conditions during the experiments. The new device weighs only 3.5 g and thus allows to minimize the force applied on the skin during the test. In this way, it is possible to reliably characterize the mechanical response of skin, also in case of low values of suction pressure and deformation. The influence of the contact force is analyzed through experiments on skin and synthetic materials, and rationalized based on corresponding finite element calculations. A comparative study, involving measurements on four body locations in two subjects by three observers, showed the good performance of the new procedure, specific advantages, and limitations with respect to the Cutometer®, i.e. the suction device most widely applied for skin characterization. As a byproduct of the present investigation, a correction procedure is proposed for the Cutometer measurements, which allows to partially compensate for the influence of the contact force. The characteristics of the new suction method are discussed in view of future applications for diagnostic purposes.
吸咐实验已广泛应用于皮肤特征化研究。在这些测试中，当施加预定的负压（吸咐）压力历史时，浅层组织层的变形行为决定了观察到的皮肤表面的升高。这种测量方法区分皮肤状况的能力受到重复实验中观察到的升高响应的可变性限制。已经表明，分散性与在皮肤表面使用仪器时，观察者施加的力有关。我们开发了一种新型的吸咐设备和一种测量程序，旨在更严格地控制实验期间的机械边界条件。新设备仅重 3.5 克，因此可以在测试过程中最小化施加在皮肤上的力。这样，就可以可靠地描述皮肤的机械响应，即使在吸咐压力和变形较低的情况下也是如此。通过对皮肤和合成材料的实验，分析了接触力的影响，并基于相应的有限元计算进行了合理化处理。一项涉及两名受试者四个身体部位的由三名观察者进行的比较研究表明，新程序具有良好的性能、特定的优势和相对于 Cutometer（即最广泛用于皮肤特征化的吸咐设备）的局限性。作为本研究的副产品，提出了一种 Cutometer 测量的校正程序，该程序可以部分补偿接触力的影响。鉴于未来用于诊断目的的应用，讨论了新的吸咐方法的特点。
