Even the smallest mechanical pumps have limitations, from the micro-fabrication techniques required to make them to the fact that there are limits on their size. A laser-driven photoacoustic microfluidic pump was developed that is capable of moving fluids in any direction without moving parts or electrical contacts. The pump uses a plasmonic quartz plate implanted with gold atoms to move liquids with a laser that generates an ultrasonic wave.
A quartz substrate was fabricated and implanted with ten-thousand-trillion gold atoms per square centimeter; researchers tested to see if a laser pulse could generate an ultrasonic wave capable of creating a liquid stream. The quartz plate — about the size of a fingernail — was implanted with gold nanoparticles; when a pulsed laser hits the plate, the gold nanoparticles generate an ultrasonic wave, which then drives the fluid via acoustic streaming.
The work could have practical implications from biomedical devices and drug delivery, to microfluidic and optofluidic research. The nanoparticles offer an almost limitless number of targets for the laser, which can be aimed far more precisely than a mechanical micropump.