Quantifying Photochemical Propulsion in Light-Powered Janus Micromotors

Janus particles reveal transient propulsion forces with a median of 4.5-6.2 pN lasting on average 21-41 ms and reaching up to 20 pN under optical confinement. Simulations incorporating these transient forces reproduce the observed trajectories, confirming their role in driving active motion. Functionalization with long DNA polymers further enhances directional motion by reducing rotational diffusion. These results establish a single-particle framework for quantifying active forces in photocatalytic Janus particles and offer design principles for light-powered micromotors.