A VAPOR BASED MICROFLUIDIC SAMPLE CONCENTRATOR

We report a PDMS microfluidic sample concentrator based on active evaporation through temperature gradient mediated mass transfer. The configuration design consists of multiple passes on the channel side walls interfacing to the ambient environment. With a thermal gradient, liquid in the channel can evaporate through the passes, and therefore resulting in a more concentrated fluid flow without breaking the liquid/vapor interface due to the hydrophobic nature of PDMS material. Experiments are performed using a dye and fluorescein to monitor the concentration change. With ease of fabrication, such system can be monolithically integrated to existing microfluidic devices for sample preparation.