Active transport and concentration of analytes in microfluidic paper based analytical devices using ion concentration polarization

Abstract

Microfluidic paper-based analytical devices (µPADs) have a high potential for miniaturizing complex testing functions, since they are inexpensive, disposable, and portable. Paper has the advantage over traditional fluid channel systems in that it houses capillary-driven flow, which requires no external pumps or equipment. However, these paper-based devices have one disadvantage in that they do not enable further flow of fluids after becoming fully wet. In this work, active transport and concentration of analytes in fully wet paper-based assays is demonstrated by leveraging ion concentration polarization (ICP). The efficacy of ICP-inducing µPADs is demonstrated through transporting and concentrating dye, fluorescein and immunoglobulins. The application of actively concentrating immunoglobulins - antibodies with sample concentrations that are typically below traditional limits of detection - is a novel application of ICP and can be used to create universally accessible allergy tests.