Microfluidic Pumps with Laser Streaming from Tips of Optical Fibers and Sewing Needles

摘要

The discovery of photoacoustic laser streaming has opened up a newavenue to manipulate and drive fluids with light, but the necessity of anin situ “launch pad” has limited its utility in real-world microfluidic applicationsdue to both the size constraint and the complexity of fabrication.Here, it is demonstrated that 1) a versatile microfluidic pump can be materializedby using laser streaming from an optical fiber, and 2) laser streamingcan be generated from a flat metal surface without any fabrication process.In the latter case, by focusing laser on the tip of a sewing needle tip, theneedle can be turned into a micropump with controllable flow direction.Additionally, high-speed imaging of the fluid motion and computationalfluid dynamics simulations to confirm the photoacoustic principle of laserstreaming are employed, and it is revealed that the streaming direction isdetermined by the direction of strongest intensity in the divergent ultrasoundwavefront. Finally, the potential of laser streaming for microfluidicand optofluidic applications is demonstrated by successfully driving fluidinside a capillary tube.