Enabling Light-Driven Microfluidics with Laser Streaming

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Microfluidics deals with flow of small volumes of fluids in a network of tiny channels. Microfluidic devices have the potential to transform several fields including medicine and healthcare, from drug delivery to cancer treatment. Similar to the piping system in your house, the function of a microfluidic device relies on pumps and valves. Because of their small dimensions, such components are complex and costly to fabricate. This is considered a bottle-neck to the wide-spread use of microfluidics. As a novel solution, light-driven microfluidics uses light to drive and control the flow. At present, the light-based methods only work with special types of fluids that do not even include water. This project will create a new approach, called laser streaming, to make the light-driving method in microfluidics possible for all types of fluids. Through this project, training opportunities will be offered to students, from K-12 to graduate levels, to prepare them for future STEM careers. The goal of this project is to lay the scientific and technological foundation for laser streaming by elucidating the underlying physics, addressing the tunability of light-matter interactions, and demonstrating its efficacy for microfluidic operations. This project will focus on four specific aims: (i) Experimentally validating the hypothesis that laser streaming is the synergy of laser-induced photoacoustics and Eckart-type acoustic streaming with resort to particle image velocimetry and acoustic measurements, (ii) Numerically modeling the multi-physical processes involving photothermal, thermoelastic and acoustic streaming interactions, (iii) Developing optical methods to modulate light-to-sound energy conversion and optimize the controllability of laser streaming flow by using laser-induced grating techniques, and (iv) Experimentally showcasing the efficacy of laser streaming in microfluidic pumping, mixing and valving operations. On the practical aspect, this work will unleash light-driven microfluidics from its fundamental constraints for practical applications in a myriad of industries. On the intellectual aspect, this project will set the cornerstone for a new discipline called opto-acoustofluidics, which may go beyond conventional optofluidics and acoustofluidics to foster various new opportunities in science and engineering.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.