How cosmetic tightening products modulate the biomechanics and morphology of human skin.

The active and passive mechanical behavior of a cosmetic tightening product for skin anti-aging is investigated based on a wide range of in vivo and in vitro measurements. The experimental data are used to inform a numerical model of the attained cosmetic effect, which is then implemented in a commercial finite-element framework and used to analyze the mechanisms that regulate the biomechanical interaction between the native tissue and the tightening film. Such a film reduces wrinkles and enhances skin consistency by increasing its stiffness by 48-107% and reducing inelastic, non-recoverable deformations (-47%). The substrate deformability influences both the extent of tightening and the reduction of wrinkle amplitude. The present findings allow, for the first time, to rationalize the mechanisms of action of cosmetic products with a tightening action and provide quantitative evidence for further optimization of this fascinating class of biomaterials.

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Copyright © 2020. Published by Elsevier Ltd.

Déclaration de conflit d'intérêts

Declaration of Competing Interest This work was conducted in the framework of a collaboration between ETH Zurich and L’Oréal Research & Innovation, which involved funding from L’Oréal Research & Innovation. The analyzed cosmetic product is developed by L’Oréal Research & Innovation and was provided to ETH Zurich as part of this scientific collaboration. Some of the authors are currently employed by L’Oréal Research & Innovation.