Optically induced microfluidic reconfiguration

Reconfigurable systems, like the field-programmable gate array in electronics, have numerous advantages including cost, adaptability, robustness, and security. Despite this, few other chip-based technologies have developed equivalently ubiquitous reconfiguration methods. As a first step to applying this paradigm to channel-based microfluidics, we present here a rapid optofluidic technique to create, move, and remove arbitrary solid regions in a microfluidic flow simply by illumination with an optical pattern. While other techniques have shown the ability to manipulate individual particles using spatial light modulation, we demonstrate here the ability to create reconfigurable flow pathways and build morphable channel structures. These structures can be modified on the order of seconds using a combined photothermal and thermo-rheological effect. In addition to characterizing the effect, we also apply this technique to create dynamic traps for biomolecules, and demonstrate trapping of λ-DNA molecules and nanoparticles, with a 25 fold suppression of diffusion.