Biology subjects

Doumont, D.

Publications and source records attributed to Doumont, D..

3 recordsLinked to original sources

bioRxiv2026

Whole-fingertip 3D Skin Surface Deformation under Tangential Loading

AO_SCPLOWBSTRACTC_SCPLOWDuring tactile interaction, skin deformation drives the widespread activation of tactile afferents distributed across the fingertip. Yet the full spatial extent and evolution of these deformations remain largely unquantified. Using high-resolution 3D imaging, we reconstructed the complete volar surface of the fingertip under progressive tangential loadings typical of object manipulation. We show that much of the deformation occurs in the out-of-contact regions, accounting for approximately 70% of the total deformation energy. This deformation consistently initiates in the peripheral zones and smoothly propagates inward as partial slip develops. Tangential loading also induces pronounced directional asymmetries and local curvature changes, reflecting both surface and bulk tissue deformation. Furthermore, we observe localized strain patterns consistent with skin wrinkling across all participants, with individual variations in intensity and location driven by distinct frictional and biomechanical properties. This dataset provides a strong foundation for developing highly accurate biomechanical models and for linking fingertip mechanics to tactile neural encoding.

neuroscience↗

bioRxiv2026

Collagen Shapes Fingertip Surface Strains during Normal Loading

When making contact, fingertip mechanoreceptors respond to the skin deformation, and provide essential information for tactile perception and object manipulation. Since subsurface measurements remain challenging, strains close to the receptors are commonly estimated using numerical models. Here, we present a biomechanical finite element model simulating fingertip normal loading against a flat plate. Several model variants are designed to isolate the role of tissue heterogeneity and collagen-induced anisotropy. Their predictions are compared to experimental data of fingertip surface strains obtained with 3-D stereo imaging. By varying the stiffness contrast and fiber orientation, we demonstrate that incorporating collagen anisotropy is required to reproduce strain localization at the contact edge while maintaining realistic global shape changes. In particular, fibers aligned parallel to the skin surface induce local skin thickening and a pronounced radial expansion beneath the contact edge, affecting mechanoreceptors. This observation suggests a collagen-mediated contribution to the deep transmission of mechanical stimuli. These results highlight collagen architecture as a key determinant of fingertip mechanics and underscore its importance for accurate modeling of tactile interactions.

bioengineering↗

bioRxiv2025

3-D Reconstruction of Fingertip Deformation during Contact Initiation

Dexterous manipulations rely on tactile feedback from the fingertips, which provides crucial information about contact events, object geometry, interaction forces, friction, and more. Accurately measuring skin deformations during tactile interactions can shed light on the mechanics behind such feedback. To address this, we developed a novel setup using 3-D digital image correlation (DIC) to both reconstruct the bulk deformation and local surface skin deformation of the fingertip under natural loading conditions. Here, we studied the local spatiotemporal evolution of the skin surface during contact initiation. We showed that, as soon as contact occurs, the skin surface deforms very rapidly and exhibits high compliance at low forces (<0.05 N). As loading and thus the contact area increases, a localized deformation front forms just ahead of the moving contact boundary. Consequently, substantial deformation extending beyond the contact interface was observed, with maximal amplitudes ranging from 5% to 10% at 5 N, close to the border of the contact. Furthermore, we found that friction influences the partial slip caused by these deformations during contact initiation, as previously suggested. Our setup provides a powerful tool to get new insights into the mechanics of touch and opens avenues for a deeper understanding of tactile afferent encoding.

neuroscience↗