Technologies for optically controlling friction with plasmon-active photofriction elements

Inventors

BATTEAS, James • GUARINO, Maelani N. N. • Sheldon, Matthew • Hipwell, Mary Cynthia

Assignees

Texas A&M University System

Abstract

Technologies for optically controlling friction include a plasmon-active photofriction element, or a friction pixel. A structure includes a base substrate material, a plasmon-active element coupled to the base substrate material, and a frictional interface material. The frictional interface material is positioned at a surface of the structure and has a phonon mode. The plasmon-active element includes a pattern comprising multiple pattern elements that have a plasmon mode tuned to couple with the phonon mode of the frictional interface material. When illuminated, the plasmon mode of the plasmon-active element is excited. Thus, energy dissipation of a sliding contact across the surface of the structure is changed to generate an active decrease or increase in friction based on light illumination frequency or intensity. The frictional interface material may include silica, and the plasmon-active element may include graphene. Other embodiments are described and claimed.

Core Innovation

The invention relates to a photofriction structure that includes a base substrate material, a plasmon-active element coupled to the base substrate material and including a pattern comprising a plurality of pattern features, and a frictional interface material positioned at a surface of the photofriction structure. The frictional interface material has a first predetermined phonon mode, and the pattern of the plasmon-active element has a first predetermined plasmon mode tuned to couple with the first predetermined phonon mode of the frictional interface material.

The disclosed concept uses tuned plasmon-phonon coupling so that optical excitation at a predetermined frequency excites the plasmon mode and thereby reversibly decreases or increases friction. Selective illumination is used to optically control friction by exciting the plasmon-active element, with the frictional interface responding through the coupled phonon mode. The partial content describes selective illumination at predetermined frequencies to achieve reversible friction changes, with the friction returning when illumination is removed.

Example implementations in the partial content include photofriction structure material stacks such as PFPA self-assembled monolayers with a patterned silane layer and graphene, as well as glass with gold nanorods. The partial content also describes tunable geometric parameters of the pattern features, including pitch distance and feature dimensions, and reports calculated absorbance and AFM results showing friction decrease at a resonant frequency and recovery when illumination is removed. The partial content further describes integration into touch devices including haptic or sliding touch interfaces such as touch screens, touch pads, smartphones, and other computing devices.

Claims Coverage

The patent includes two independent claims: one directed to a photofriction structure and one directed to a method for an active photofriction interaction. Across these independent claims, the main inventive features are plasmon-active patterned coupling to a frictional phonon mode and selective optical excitation at a predetermined frequency via an optically coupled light source.

Overall, the independent claims require a patterned plasmon-active element whose plasmon mode is tuned to couple to a phonon mode of a frictional interface material, with an active control step achieved by selectively illuminating at a predetermined frequency using a light source optically coupled to the plasmon-active element.

Stated Advantages

Documented Applications