  One objective of active matter science is to unveil principles by which
chaotic microscale dynamics could be transformed into useful work. A nematic
liquid crystal environment offers a number of possibilities, one of which is a
directional motion of an active droplet filled with an aqueous dispersion of
swimming bacteria. In this work, using the responsiveness of the nematic to the
electric field and light, we demonstrate how to control the direction and speed
of active droplets. The dielectric response of nematic to the electric field
causes two effects: (i) reorientation of the overall director, and (ii)
changing the symmetry of the director configuration around the droplet. The
first effect redirects the propulsion direction while the second one changes
the speed. A laser beam pointed to the vicinity of the droplet can trigger the
desired director symmetry around the droplet, by switching between dipolar and
quadrupolar configurations, thus affecting the motility and polarity of
propulsion. The dynamic tuning of the direction and speed of active droplets
represents a step forward in the development of controllable microswimmers.

Soft Condensed Matter