Steering artificial nanoscale swimmers using teardrop shaped posts*

Microorganisms use various strategies to bias their swimming to achieve long-time directed motion against a flow, against gravity, or up a chemical gradient. To make use of artificial swimmers for transporting cargo, to separate swimming particles from diffusing ones, or to concentrate a solution of motile particles, ways of steering such swimmers are required. We make use of the attraction of artificial bi-metallic swimmers to vertical walls to direct their long-time motion. We will describe how these swimmers are attracted to the surface of teardrop-shaped posts and leave preferentially at regions of higher curvature. We use this understanding to interpret their behavior when interacting with arrays of teardrop-shaped posts.