  Passive droplet transport mechanisms, in which continuous external energy
input is not required for motion, have received significant attention in recent
years. Experimental studies of such mechanisms often ignore, or use careful
treatments to minimize, contact angle hysteresis, which can impede droplet
motion, or even arrest it completely. Here, we consider the effect of contact
angle hysteresis on bendotaxis, a mechanism in which droplets spontaneously
deform an elastic channel via capillary pressure and thereby move. Here, we
seek to understand when contact angle hysteresis prevents bendotaxis. We
supplement a previous mathematical model of the dynamics of bendotaxis with a
simple model of contact angle hysteresis, and show that this model predicts
droplet trapping when hysteresis is sufficiently strong. By identifying the
equilibrium configurations adopted by these trapped droplets and assessing
their linear stability, we uncover a sensitive dependence of bendotaxis on
contact angle hysteresis and develop criteria to describe when droplets will be
trapped.
