  Active particles disturb the fluid around them as force dipoles, or
stresslets, which govern their collective dynamics. Unlike swimming speeds, the
stresslets of active particles are rarely determined due to the lack of a
suitable theoretical framework for arbitrary geometry. We propose a general
method, based on the reciprocal theorem of Stokes flows, to compute stresslets
as integrals of the velocities on the particle's surface, which we illustrate
for spheroidal chemically-active particles. Our method will allow tuning the
stresslet of artificial swimmers and tailoring their collective motion in
complex environments.
