(84a) Polymer Based Microfluidic Reactor for Liquid-Liquid Extraction Applications

Liquid-liquid extraction (LLX), which involves reactions occurring at the aqueous-organic interface in a two-phase system, finds application in diverse fields, ranging from purification and isolation of biomolecules to organic synthesis.  Conventional techniques for LLX suffer from several limitations, including inefficient handling of small volumes, long extraction times due to long diffusion lengths, and long times required to form stable interfaces.  In this context, working at the micro-scale enables effective handling of small volumes, short extraction times, and rapid formation of stable interfaces.  We report on solvent-resistant polymer-based microfluidic reactors for LLX applications.  These microreactors provide quantitative information on the extraction process compared to conventional techniques, due to the superior control over the spatial and temporal properties of the interface.

Microfluidic systems for LLX extractions involving droplets have been reported previously, where the droplet of one phase is encapsulated in the other phase.  However, these systems are not suitable for applications where off-chip analysis or post processing of the solutions is required, as the separation of phases is challenging.  In contrast, micro-reactors that enable co-flow of the aqueous and organic phases allow for more convenient phase separation.  Microreactors based on hard materials (glass and silicon) have been developed for co-flowing aqueous-organic streams; however, these reactors require complex fabrication that is time and cost intensive.  We have developed polymer based solvent resistant microreactors fabricated via a simple and inexpensive procedure.  We systematically optimized several factors affecting the interface stability, including geometry of the micro-channel, surface functionalization, and the flow rates of the two immiscible streams.

In this work, we report the design, fabrication, and application of thiolene (NOA 81) and perfluoropolyether (SIFEL) based micro-reactors for liquid-liquid extraction applications, including purification of cyclotron-produced radioisotopes that are of interest in medical imaging, and studying distribution of pharmaceuticals between two phases to evaluate molecule’s uptake in the human body.