  We study the detention statistics of self-propelling droplet microswimmers
attaching to microfluidic pillars. These droplets show negative autochemotaxis:
they shed a persistent repulsive trail of spent fuel that biases them to detach
from pillars of a certain size after orbiting them just once. We have designed
a microfluidic assay recording swimmers in pillar arrays of varying diameter,
derived detention statistics via digital image analysis and interpreted these
statistics via the Langevin dynamics of an active Brownian particle (ABP)
model. By comparing data from orbits with and without residual chemical field,
we can independently estimate quantities like hydrodynamic and chemorepulsive
torques, chemical coupling constants and diffusion coefficients, as well as
their dependence on boundary conditions like wall curvature.
