In pursuit of propulsion at the nanoscale

This review describes recent developments in self-propelling nano- and micro-scale swimming devices. The ability of these devices to transport nano-scale components in a fluidic environment is demonstrated. Furthermore, the adaptations needed for these devices to meet biological transport challenges such as targeted drug delivery are highlighted. Particular emphasis is placed on describing autonomously powered devices driven by asymmetrical chemical reactions. Methods to control the speed and direction of such swimming devices using external fields are described, and contrasted to recent demonstrations of statistical autonomous migrations and organisations driven by chemical gradients, inter swimmer interactions and external photo-stimulus. Finally the challenges and advantages of converting other nature inspired swimming mechanisms into realistic artificial self-powered devices are considered.