Bioinspired artificial fingertips that exhibit friction reduction when subjected to transverse ultrasonic vibrations

This paper presents the design of a bioinspired artificial fingertip that resembles the mechanical behavior of a human fingertip under conditions of both static deformation and high frequency excitation. The artificial fingertip is constructed around a deformable spherical membrane filled with a cellulose sponge, itself connected to a rigid structure that acts as a bone. Force-deformation characteristics and response to a transient mechanical perturbation are both shown to be in good qualitative agreement with those of a real finger. More importantly, the fingertip exhibits friction reduction when interacting with TPads (variable friction tactile displays based on transverse ultrasonic vibrations). Comparison with artificial fingertips that do not exhibit friction reduction suggests that mechanical damping characteristics play a key role in the amount of friction reduction achieved.