A nanostructured surface increases friction exponentially at the solid-gas interface

Abstract

According to Stokes' law, a moving solid surface experiences dissipation that is linearly related to its velocity and the viscosity of the medium. This linear dependence on viscosity forms the basis for many characterization techniques for liquids. Unlike viscosities of different liquids, viscosities of gases vary only in a narrow range which limits their use as an effective characterization parameter using moving structures. Here we report experimental results of dissipation showing exponential dependence on viscosity for oscillating surfaces modified with nanostructures. The surface nanostructures alter solid-gas interplay greatly, amplifying the dissipation response exponentially for even minute variations in viscosity. Nanostructured resonator thus allows discrimination of otherwise narrow range of gaseous viscosity making it an ideal detection parameter for analysis. We attribute the observed exponential enhancement to the stochastic nature of interactions of many coupled nanostructures with the gas media.