Dual‐Laser Optical Tweezers for Photothermal Analysis of Hybrid Microgels

Dual‐laser optical tweezers unlock real‐time, single‐particle resolution of light‐driven actuation. Direct visualization and precise quantification of size changes under varying laser intensity provide new insights, overcoming limitations of conventional microscale actuator analysis. Abstract Soft actuators that respond to external stimuli play a fundamental role in microscale robotics, active matter, and bio‐inspired systems. Among these actuators, photo‐thermal hybrid microgels (HMGs) containing plasmonic nanoparticles enable rapid, spatially controlled actuation via localized heating. Understanding their dynamic behavior at the single‐particle level is crucial for optimizing performance. However, traditional bulk characterization methods such as dynamic light scattering (DLS) provide only ensemble‐averaged data, thereby limiting analytical insights. Here, a dual‐laser optical tweezers approach is introduced for real‐time, single‐particle analysis of HMGs under controlled light exposure. Combining direct imaging and mean‐squared displacement (MSD) analysis, our method quantifies the precise laser power required for actuation and accurately tracks the particle size. The results are benchmarked against dual‐laser DLS, demonstrating comparable precision while offering the unique advantage of single‐actuator resolution. Thus, this method provides a robust platform for precise optimization of programmable actuators with applications in soft robotics, microswimmers, and biomedical devices. Dual-laser optical tweezers unlock real-time, single-particle resolution of light-driven actuation. Direct visualization and precise quantification of size changes under varying laser intensity provide new insights, overcoming limitations of conventional microscale actuator analysis. Abstract Soft actuators that respond to external stimuli play a fundamental role in microscale robotics, active matter, and bio-inspired systems. Among these actuators, photo-thermal hybrid microgels (HMGs) containing plasmonic nanoparticles enable rapid, spatially controlled actuation via localized heating. Understanding their dynamic behavior at the single-particle level is crucial for optimizing performance. However, traditional bulk characterization methods such as dynamic light scattering (DLS) provide only ensemble-averaged data, thereby limiting analytical insights. Here, a dual-laser optical tweezers approach is introduced for real-time, single-particle analysis of HMGs under controlled light exposure. Combining direct imaging and mean-squared displacement (MSD) analysis, our method quantifies the precise laser power required for actuation and accurately tracks the particle size. The results are benchmarked against dual-laser DLS, demonstrating comparable precision while offering the unique advantage of single-actuator resolution. Thus, this method provides a robust platform for precise optimization of programmable actuators with applications in soft robotics, microswimmers, and biomedical devices. Advanced Science, EarlyView.