  Photonic crystal cavities with bowtie defects that combine ultra-high Q and
ultra-low mode volume are theoretically studied for low-power nanoscale optical
trapping. By harnessing the localized heating of the water layer near the
bowtie region, combined with an applied alternating current electric field,
this system provides long-range electrohydrodynamic transport of particles with
average velocities of 30 $\mathrm{\mu m/s}$ towards the bowtie region on demand
by switching the input wavelength. Once transported to a given bowtie region,
synergistic interaction of optical gradient and attractive negative
thermophoretic forces stably trap a 10 nm quantum dot in a potential well with
a depth of 10 $k_\mathrm{B}T$ using a mW input power.
