Our fingertips are remarkable sensory organs that let us interact safely with our environment. Tactile sensors embedded below the skin surface encode the deformation of the surrounding tissues into neural signals. These signals travel to the brain to allow dexterous object manipulation. Capturing subsurface strains in the fingertip is therefore key to understanding touch. Such strains, however, are difficult to probe in vivo at the depth where the tactile sensors are located.
The numerical model of fingertip deformation developed in this thesis accounts for the contrasted mechanical responses of cutaneous and subcutaneous tissues. The anisotropy induced by collagen fiber networks had not been considered in previous fingertip models, despite substantial histological and experimental evidence. Both features were described within an anisotropic hyperelastic framework. The 2D simulations were run under generalized plane-strain or axisymmetric conditions, depending on the targeted experimental observations.
The model was assessed against experimental measurements of fingertip contact at two length scales. At the macroscale, collagen anisotropy improves the reproduction of the contact area, the pulp expansion, and the surface deflection profile. At the microscale, anisotropy and tissue heterogeneity influence the development of the surface strains. Optical coherence tomography images capturing the deformation of the outermost skin layer show that the model also yields a realistic prediction of the skin thickness evolution during contact. The results identify the collagen fiber networks as structural components that shape the mechanical response of the fingertip
Membres du jury :
- Prof. Laurent DELANNAY (UCLouvain)(Promoteur)
- Prof. Benoit DELHAYE (UCLouvain)(Co-Promoteur)
- Prof. Hadrien RATTEZ (UCLouvain) (Président)
- Prof. Philippe LEFÈVRE (UCLouvain) (Secrétaire)
- Prof. Cédric LAURENT (Université de Lorraine, France)
- Prof. Hannes SAAL (University of Sheffield, United-Kingdom)
Soutenance publique également accessible par visio-conférence via le lien (TEAMS) : https://teams.microsoft.com/meet/390266644685261?p=NMwUPQGJEC62oJ9pno
