The fabrication of complex self-propelling particles is an emerging and fascinating topic, yet few concrete applications exist to date. We will report the progress in addressing the challenges of designing complex programmable particles, and identifying areas of their practical use. First we will discuss how external uniform AC electrical fields can be used as means of providing energy, propelling and controlling the motion of miniature semiconductor diodes. These particles move by particle-localized AC and DC electrohydrodynamic propulsion and could be steered by controlling the symmetry of the AC field. In the second part of the talk we will present a new class of gel-based self-propelling particles moving by Marangoni effect in a programmed oscillatory mode. These gel boats floating on the water surface are driven by a hydrogel reservoir releasing an ethanol flux that is periodically disrupted by the bulk flows around the particles. The pulse interval and the distance propelled in a pulse by these gel floaters were interpreted based on the rate of ethanol mass-transfer. This allowed us to design particles that 'dance' in repeatable periodic sequences of forward/backward, or rotary steps, and travel in complex pre-programmed trajectories on the liquid surface. We will also present new types of self-propelling floaters driven by surfactant release that have been functionalized for applications such as mixers and cargo microcarriers, and may serve as a new platform for environmental remediation.

Principles and engineering of steerable, programmed, and cargo-carrying self-propelling particles

245th National Meeting (2013)

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