Combining Thermo-plasmonics with Microfluidics for Biological Applications

Abstract

In this project we, for the first time, integrated microfluidics with thermo-plasmonics. While microfluidics is a popular platform allowing experiments with small volumes of fluid, thermo-plasmonics can be used for powerful particle manipulation including capturing, mixing, filtering and projection. Combined, these two techniques give us an opportunity to work with numerous complex fluids containing particles, cells, and micro-beads. Here we designed, developed and tested several devices demonstrating various aspects of this exciting hybrid technology. This required use of soft lithography, metal deposition, 3D printing, oxygen plasma treatment and several other surface modification techniques. Additional challenges were in the fabrication of a multi-layer chip with several types of surfaces binding at several interfaces. The detailed design optimization was conducted, and many characteristics of the microfluidic channel were varied. After that, optimal flow patterns were determined using high-quality syringe pumps. An experiment with the simultaneous flow of two colored solutions through the same microfluidic chip demonstrated controlled laminar flow with minimal mixing. Next, thermo-plasmonic experiments were conducted in optimized micro-fluidic channels. Efficient capturing of microbeads were demonstrated using low power green laser with a wavelength 532 nm. In future, these experiments have many important applications including separation of bacteria from blood on a microfluidic chip. This might help with treatment of sepsis, analysis of blood pathogens and better prescription of antibiotics