Shining light on optofluidics

Optofluidics is a research field that bridges “optics” and “microfluidics”. Recently it has been gaining momentum because of unique capabilities that were demonstrated by optofluidic systems. Dr. Anna Pyayt’s lab from the University of South Florida previously showed a variety of applications including trapping and projection of live cells, sorting of micro-scale particles and 3D assembly of silver nanowires. This technology has tremendous advantages over other traditional micro-trapping technologies including optical tweezers. Pyayt’s Lab demonstrated capturing live worms with a such low laser power that they have not experienced any stress, while in contrast, powers required from optical tweezers would immediately kill a worm. Recent publication by Hao Wang, Joseph Tarriela, Priyanka Shiveshwarkar and led by Professor Anna Pyayt, designed a novel approach to demonstrate three different regimes of optofluidic manipulation. The original research work is currently published in the journal Applied Optics. Dr. Pyayt has been invited with two keynote talks on this topic, since this innovative study is a breakthrough in the field of optofluidics. It theoretically predicts and experimentally demonstrates several new ways to create miniature light-controlled currents that can be used for complex micro-manipulation. One of the key innovations was their design of a bi-metallic substrate that allowed efficient localized light absorption and generation of the micro-currents with completely different characteristics.

The authors reported promising results from the regimes of optofluidic manipulation; for instance, three sets of simulations and corresponding optofluidic experiments were presented by using COMSOL Multiphysics. To be specific, the team noted that for the first regime, local fluid heating was used to create a microcurrent with a symmetric toroid shape capturing particles in the center, while as for the second regime, the microcurrent shifted and tilted because external fluid flow was introduced into the microfluidic channel. Lastly, for the third regime, the whole microfluidic channel was tilted, and the resulting microcurrent projected particles in a fan-like fashion.

In summary, the study presented a novel approach that was developed with the aim of revealing the three different regimes of optofluidics. These three regimes are responsible for the production of different microflow patterns and corresponding particles manipulation trajectories. Based on their approach, their results are vital for better comprehension of design principles for practical applications needing particle manipulation. In a statement to Advances in Engineering, Professor Anna Pyayt, the lead and corresponding author mentioned that their optofluidic systems integrated with microfluidics can be used on-chip manipulation of cells, bacteria and nanoparticles. She further added that their techniques can be used for rapid diagnosis of bacterial infections and blood analysis in future.