We are investigating the properties of plasmonic nanoparticles and nanostructures as energy absorbers to induce photo-thermal changes in fluidic systems.  The energy supplied by absorption of light in these structures can be used to power fluid transport, evaporation, calorimetry, and other fundamental process in lab on a chip systems for biology and chemistry applications. In addition these techniques may also allow for ‘all- optical’ functionality of optofluidic systems, in which liquids are used to control optical functionality of the systems, and optical beams are simultaneously used to control the position and properties of liquids.

We have examined the use of nanosecond pulsed holographic recording, to get time resolved measurements of heat transport in suspensions of silver nanoparticles.  This technique allows us to measure the heating of liquids both on the nanosecond and nanometer scales.  In addition, we have demonstrated microfluidic channels with incorporated arrays of gold nanoparticles that can be excited via continuous wave laser light to control the properties of the leading edge of a fluid filling the channel.  By scanning the laser spot, we can ‘drag’ the fluid to a desired location, induce formation of bubbles, and control evaporation rates.  We are focused on developing these techniques as a flexible means of optical control.