Absorption force that rules them all: chemical control over optical trapping

Controlling the self-organization of colloidal nano- and micro-scale objects into intricate or periodic structures is a current challenge, hampering the development of novel functional materials. Traditional physicochemical strategies lack the necessary spatiotemporal precision for effective control at the microscale. Optical absorption forces offer a promising solution, providing high spatial and temporal resolution and enabling the reconfigurability of assembled structures. This force can be amplified and controlled through chemical stimuli, such as pH changes, allowing for precise modulation of particle interactions and assembly morphology. The study introduces pH-responsive particles that exhibit reversible optical transitions, paving the way for the development of adaptive materials that respond to chemical changes in their environment.