Directing Particle Assembly with Light and Sound

It is well known that focussed beams of light or sound can be used to trap individual particles (i.e. optical or acoustic tweezers). Less well known is that light and sound can also be used to create forces between multiple particles via "binding" effects. In principle, these binding effects could be used to program the assembly of colloidal structures, but there are significant practical barriers to doing so. I will discuss our experimental, theoretical, and numerical efforts aimed at better understanding optical and acoustic binding effects, as well as the challenges which remain.