Research

Along the evolutionary path from single cells to multicellular organisms with a central nervous system, there are species of intermediate complexity that possess many autonomous cells programmed to respond to environmental stimuli. One of the more striking responses is phototaxis[1], in which motile organisms adjust their locomotory path according to the incident light in a finely controlled manner, either towards or against the light source (positive or negative phototaxis). Inspired by them we developed an inanimate/chemical system in which an organic droplet is self-propelled in response to a photo-stimulus. The centimetre-scale directional movement of the organic droplet on the aqueous solution is powered by the combination of photo-induced pH change and surface tension effects.