Microchannels with Self-Pumping Walls.
When asymmetric Janus micromotors are immobilized on a surface, they act as chemically powered micropumps, turning chemical energy from the fluid into a bulk flow. However, such pumps have previously produced only localized recirculating flows, which cannot be used to pump fluid in one direction. Here, we demonstrate that an array of three-dimensional, photochemically active Au/TiO2 Janus pillars can pump water. Upon UV illumination, a water-splitting reaction rapidly creates a directional bulk flow above the active surface. By lining a 2D microchannel with such active surfaces, various flow profiles are created within the channels. Analytical and numerical models of a channel with active surfaces predict flow profiles that agree very well with the experimental results. The light-driven active surfaces provide a way to wirelessly pump fluids at small scales and could be used for real-time, localized flow control in complex microfluidic networks.
['Yu|Tingting|T|', 'Athanassiadis|Athanasios G|AG|http://orcid.org/0000-0002-2015-829X', 'Popescu|Mihail N|MN|http://orcid.org/0000-0002-1102-7538', 'Chikkadi|Vijayakumar|V|', 'Güth|Achim|A|', 'Singh|Dhruv P|DP|', 'Qiu|Tian|T|', 'Fischer|Peer|P|http://orcid.org/0000-0002-8600-5958']
active surfaces microfluidics Janus structured surfaces chemical micropump photocatalysts