Abstract

Ultra-high Sample Concentration by Ion Concentration Polarization on a Paper Based Converging Microfluidic Analytical Device Laminated by Paraffin

Adhikarige Taniya Kaushalya Perera, , Nanyang Technological University

Microfluidic paper based analytical devices (µPAD) are an inexpensive and expedient solution for a wide range of point of care analyses. Implementation of ion concentration polarization (ICP) on µPAD provides a promising pre-concentration platform to achieve lower limit-of-detection (LOD) on µPAD. Here, we present a µPAD, implementing ICP using a nanoporous Nafion® membrane. Devices with two geometrical configurations, a straight channel converging at the middle and a device with an input channel connecting to three absorption channels, all converging at the junction, are fabricated. An off-the-shelf Nafion® membrane is attached to the absorption channels of the device encased by heating with paraffin films at both sides to suppress the electroosmotic flow. Under an applied DC electric field, fluorescein sodium salt gets pre-concentrated by ICP enabling a concentration factor more than 250 folds within minutes. We also report a novel fabrication method providing convenient regulation of channel thickness by heating time and lowering the fabrication cost to 0.3 USD per device. This device would serve as a simple pre-concentration platform for medical diagnostics and environmental monitoring of tracer pollutants in aqueous eco-systems.