PhD Student, Durham University, 2011-present
Optical deformation of microemulsion droplets and nanothreads
My work involves extending the applications of the famous optical trapping technique to induce flow and distortion of dielectric liquids. Indeed, microscopic droplets of immiscible fluids can be manipulated in form as well as position. The deformation is weak even for an intense laser focus, so for an appreciable effect the surface tension, which restores a minimal spherical surface, must first be reduced by many orders of magnitude. Addition of surfactants allows this to occur under specific conditions of ionic strength and temperature. In this narrow regime of ultralow interfacial tension, 100000-fold less than that of pure water and oil, the optically-controlled droplet shapes can be polymerised to aspherical solid particles. Novel effects also occur, particularly the formation of nanoscopic tubules between droplets formed by splitting a larger parent. Furthermore, control over these networks of threads could open a route to unprecedented flow chemistry on the femtolitre scale and below.