  Dielectric environment engineering is an efficient and general approach to
manipulating polaritons. Liquids serving as surrounding media of polaritons
have been used to shift polariton dispersions and tailor polariton wavefronts.
However, those liquid-based methods have so far been limited to their static
states, not fully unleashing the promises offered by the mobility of liquids.
Here, we propose a microfluidic strategy for polariton manipulation by merging
polaritonics with microfluidics. The diffusion of fluids causes gradient
refractive indices over microchannels, which breaks the symmetry of polariton
dispersions and realizes the non-reciprocal dragging of polaritons. Based on
polariton microfluidics, we also design a set of on-chip polaritonic elements
to actively shape polaritons, including planar lenses, off-axis lenses, Janus
lenses, bends, and splitters. Our strategy expands the toolkit for the
manipulation of polaritons at the subwavelength scale and possesses potential
in the fields of polariton biochemistry and molecular sensing.
