(102c) Precision Formation and Stabilization of Photopolymerizable Microbeads for Enhanced Fluorescence-Based Thermometry in Microfluidics

This work develops a photocurable resin co-flow microfluidic system for the precision formation of multifunctional double emulsion droplets. Utilizing a PDMS-glass chip fabricated through 3D printed molds, we generate droplets containing a photocurable, biocompatible resin. This resin, a blend of polyethylene glycol diacrylate (PEGDA) and ethylene glycol polyether acrylate (EGPEA), allows for the in-situ solidification of droplets under UV illumination, thereby stabilizing their size and shape. The polymer composition of EGPEA and PEGDA was meticulously controlled, to modulate crosslinking kinetics. This enabled the successful encapsulation of Rhodamine B within the resin droplets to leverage its temperature-dependent quantum yield for non-contact thermometry applications. The emission peaks of Rhodamine B at 570nm, upon excitation at 546nm, remain distinct from the UV curing wavelength of the resin, ensuring the stability of the thermal reporting mechanism.

Through comprehensive experimental and numerical analyses, including constructing resin droplet flow regime maps and leveraging CFD simulations, the work offers novel insights into the physics of resin droplet generation. These insights encompass the effects of surface wettability, flow rates, and capillary numbers on droplet formation dynamics and stability within high-viscosity photopolymer systems. The research addresses critical gaps in current methodologies by presenting a scalable, efficient strategy for generating monodisperse, functionalized photocurable microbeads. Such advancements promise significant impacts on fields ranging from biosensing to precision medicine, highlighting the potential of microfluidics in revolutionizing microscale analysis and synthesis platforms.