Autochemotactic droplet swimmers shape their environment

Self-propelled agents require fuel to move, which they commonly take up from their surroundings, for example swimmers in a solution of fuel or nutrient. If the fuel depletion equilibrates slower than the timescale on which the swimmers move, this can cause measurable chemorepulsive effects: swimmers avoid areas of depleted fuel, leading to interparticle signaling and the emergence of complex collective phenomena.

We demonstrate such effects in an experimental model system of self-propelling droplet swimmers shedding persistent chemorepulsive trails: the interaction with self-generated chemical fields aids the droplets to navigate microfluidic structures, explore self-avoiding walks and even causes chemorepulsive arrest in dense systems.