Strategies for Steering Self-Propelled Active Particles

The advent of autonomous self-propulsion has directed research towards using active particles for a variety of functions such as sensing and environmental remediation. While much progress has been made in the last decade on various mechanisms to synthesize active particles, the ability to steer self-propelled colloidal devices has so far been limited. A critical barrier in increasing the impact of such particles is in directing their motion against the Brownian rotation, which randomizes particle orientations. Current strategies for directing self-propelled particles either lack autonomy or only constrain along one-dimension. Here we will discuss two strategies of steering catalytic particles namely their interactions with boundaries and the use of external fields. We will discuss how geometric constraints can be utilized to steer these active colloids along arbitrary trajectories. We will also demonstrate how the behavior of the particles can be programmed based on real-time image analysis and steering with external fields. These strategies can be used to render active particles ‘intelligent’ which will have a major impact on their application in robotics, engineering, biology, and medicine.