Reconfiguring hydrodynamic flow fields of active particles by light

While natural microorganisms can switch between pusher and puller swimming modes to adapt to their environment, synthetic active particles are typically constrained to a fixed hydrodynamic propulsion mode defined during fabrication. We demonstrate a self-thermophoretic active particle capable of reconfiguring its flow field on demand using inhomogeneous light patterns created by a spatial light modulator. These illumination patterns generate surface temperature fields that induce thermo-osmotic flows, controlling both particle propulsion and hydrodynamic interactions. Using gold nanoparticles as tracers, we characterize the particle's hydrodynamic flow field. This dynamic reconfigurability opens new possibilities for investigating and controlling particle interactions and collective behavior.