Thermal motion of an optically trapped nanotool

摘要

By using multiple optical traps suitably sized complex bodies can be bound with respect to their positions and orientations. One recent application of this involves the use of an elongated object, equipped with a probe (a "nanotool"), to measure and apply pico-Newton sized forces to, for example, the surface of a cell. This application has been described as an optical atomic force microscope (AFM). Calculations of the mechanical susceptibility of trapped probes, and their hydrodynamic resistance are presented. These quantities are used to assess the subsequent thermal motion of an optically trapped nanotool in the context of the Orstein-Uhlenbeck process. Implications for the resolution and general behavior of the optical AFM referred to above are discussed.