The Patterns of Skin Deformation That Encode Friction

Having a secured grip on an object fundamentally depends on controlling the amount of frictional force. Our sensorimotor system excels at estimating the frictional strength of the contact to anticipate the object’s slippage, which in turn enables our remarkable dexterity. But how the tactile information about the state of friction is encoded within the mechanical deformation of the fingertips? Using a new setup that can image and modify friction in real-time, we show using that the skin undergoes specific patterns of deformation from the moment the skin first enters in contact with a surface all the way to sliding. The presence of these patterns of deformations is confirmed by a parsimonious model of the skin which captures the interplay of the visco-elastic nature of the skin and the frictional boundary layer.<br/>Our finding suggests that the perceptual system uses these patterns of deformation as matched filters to rapidly estimate the frictional state, independently of knowing whether the contact has a large or small amount of friction.