Modeling Capillary Behavior in Finger-Device Interfaces

Understanding tribology in finger-device interfaces is crucial for the field of haptics, which finds widespread application in consumer electronics, virtual reality and Internet of Things. Many experimental and theoretical analyses have been carried out to characterize the friction force and its relationship with other factors including topography, deformation, adhesion and electro-adhesion. While it has been stated in previous studies that capillary can potentially affect friction force, there have been limited reports on quantifying or modeling of the capillary in the finger-device interface, partially due to the complicated geometry of the contact interface. In this paper, a multi-physics model of the finger-device interface is built, incorporating both mechanical deformation and capillary formation and
distribution due to sweating. The simulation result demonstrates how water redistributes in the contact interface after sweat secretion and furthermore, explains why different surfaces feel differently when touched by fingers.