Background: Nowadays, nail care products are extremely important both in medical and cosmetic fields. Actually, there are only a very few "in vivo" methods to evaluate the safety and the efficacy of nail products.
Methods: The new apparatus, based on a recently patented technology, is developed for the "in vivo" evaluation of nails in terms of thickness, structural firmness, flattening, and bending properties. The device analyzes nails by an "in vivo" non-invasive methodology in a timely way and with high accuracy. The assessment of the resistance to compression measures the cohesion of the nail matrix (nail firmness), while the evaluation of the resistance to transversal deformation detects the elasticity of the nail plate. Furthermore, the apparatus is able to assess the nail thickness and the flexibility of their distal edge.
Results: The instrument provides nail thickness and several parameters reflecting mechanical properties of nail plate: Viscoelasticity expressed as viscoelasticity index (VI), structural strength/ firmness expressed as Firmness Index (FI), and viscoelasticity of the distal edge expressed as Bending Index (BI).
Conclusions: The instruments described in this work represent an innovative apparatus for the safety and efficacy evaluation of nail products in several fields: cosmetics, pharmaceuticals, and medical devices.
Keywords: evaluation of nail alteration; indentometer; nail biomechanical properties; nail characterization; nail elasticity; nail firmness; nails thickness.
© 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.