Phototunable Hopping of Microparticles Enables Surface-Selective Continuous Separation via Microfluidics

Abstract

High surface area materials are central to next-generation technologies, yet their purification remains limited by lab-scale methods. We present a continuous-flow technique that separates microparticles by surface area and porosity. The method relies on light-responsive surfactants that generate surface-localized photochemical activity under illumination, scaling with particle surface area. Particles with sufficient activity undergo light-induced "hopping" into an overlying channel, enabling deflection across streamlines and obstacles. Non-porous particles remain confined, while porous particles are diverted to secondary outlets. We demonstrate control of hopping efficiency through illumination parameters, establishing a scalable platform for high-throughput, surface-sensitive purification.