Self-regulating photochemical Rayleigh-Bénard convection using a highly-absorbing organic photoswitch

Serena Seshadri, Luke F. Gockowski, Jaejun Lee, Miranda Sroda, Matthew E. Helgeson, Javier Read de Alaniz, and Megan T. Valentine. Nature Communications 11:2599 (2020).

Abstract

We identify unique features of a highly-absorbing negatively photochromic molecular switch, donor acceptor Stenhouse adduct (DASA), that enable its use for self-regulating light-activated control of fluid flow. Leveraging features of DASA’s chemical properties and solvent-dependent reaction kinetics, we demonstrate its use for photo-controlled Rayleigh-Bénard convection to generate dynamic, self-regulating flows with unparalleled fluid velocities (~mm s−1) simply by illuminating the fluid with visible light. The exceptional absorbance of DASAs in solution, uniquely controllable reaction kinetics and resulting spatially-confined photothermal flows demonstrate the ways in which photoswitches present exciting opportunities for their use in optofluidics applications requiring tunable flow behavior.