A continuous-flow droplet-based concentrator using ion concentration polarization†
We propose a method to continuously generate droplets with programmable concentration using the ion concentration polarization (ICP) phenomenon. The concentration of a sample in continuously formed droplets can be tuned with a combination of flow rate and applied voltage. The nanoporous junction needed for ICP was fabricated by embedding a Nafion membrane inside a PDMS mixture and then self-sealed by curing it. Compared to other methods previously reported in the literature, our fabrication method has the advantages of simplicity, reliability, repeatability and low-cost. Sample droplets with up to 100-fold concentration were generated continuously with our device.