Phononic Crystals Applied to Localised Surface Haptics.

ABSTRACT

Metamaterials are solid lattices with periodicities commensurate with desired wavelengths. Their geometric features can endow the bulk material with unusual properties, such as inter alia, negative indices of refraction or unique absorbing qualities. Mesoscale metamaterials and phononic crystals can be designed to cause the occurence of band gaps in the ultrasonic domain. These localised phenomena induce fixed boundary conditions that correspond to acoustic mirrors which, in turn, can be used to establish waveguides in thin plates. Ultrasonic lubrication has been successfully applied to create haptic interfaces that operate by modulating the apparent friction of a surface. In this article, we demonstrate that phononic crystals can be designed to localise the modulation of friction in specific portions of the surface of a thin plate, opening novel possibilities for the design of surface haptic interfaces.