Ion concentration polarization on paper-based microfluidic devices and its application to preconcentrate dilute sample solutions

Abstract

Microfluidic paper-based analytical devices (μPADs) are a promising solution for a wide range of point-of-care applications. The feasibility of inducing ion concentration polarization (ICP) on μPADs has thus far attracted little attention. Accordingly, this study commences by demonstrating the ICP phenomenon in a μPAD with a Nafion ion-selective membrane. We are the first to measure the current-voltage curve on a Nafion-coated μPAD in order to indicate that the ion depletion occurs and the ICP is triggered when the current reaches the limiting current. The ICP effect is then exploited to preconcentrate fluorescein on μPADs incorporating straight and convergent channels. By an optimal geometric design, it is shown that the convergent channel results in a greater preconcentration effect than the straight channel. Specifically, a 20-fold enhancement in the sample concentration is achieved after 130 s given an initial concentration of 10−5 M and an external potential of 50 V. By contrast, the straight channel yields only a 10-fold improvement in the concentration after 180 s. Further, the practical feasibility of the proposed convergent-channel μPAD is demonstrated using fluorescein isothiocyanate labeled bovine serum albumin. The experimental results show that a 15-fold enhancement of the initial sample concentration (10−5 M) is obtained after 120 s given an external potential of 50 V.

Direct DNA Analysis with Paper-Based Ion Concentration Polarization

“…[16][17][18] Recent advances in µPADs position these technologies for broad diagnostic application. [19][20][21][22] Specifically, the integration of nanomaterials into paper potentially offers enhanced detection capabilities. 23 Nanoparticles are the most commonly employed nanomaterial in lateral flow assays and µPADs, and are mainly used as labels for colorimetric detection of DNA and other analytes.…”

Rapid evaporation-driven chemical pre-concentration and separation on paper

“…The most commonly used method is ion concentration polarization (ICP) [20][21][22][23]. This can provide concentration factors of 100-1000 in 2-10 minutes after filling, but require nanoporous membranes, electrodes and relatively high voltages.…”

Paper-based diagnostic devices for clinical paraquat poisoning diagnosis

“…[28][29][30][31][32][33] Moreover, PADs have been conjugated with diverse analytical technologies (e.g., colorimetry, chemiluminescence, electrochemical analysis) to detect a wide range of analytes in humans and in the environment. [34][35][36][37] The strengths of PADs have been exploited as powerful analytical tools for a variety of diagnostic intents including, but not limited to the following: (1) a multiplexed electrochemical platform to detect human immunodeficiency virus (HIV) and hepatitis C virus (HCV) with limits of detection (LODs) for HIV and HCV assays of 300 pg/ml and 750 pg/ml, respectively; and (2) a three-dimensional detection sensor with a linear response for nitrite concentrations of 0-11.5 ppm and oxalate concentrations of 0-1000 mg/100 ml. 38,39 Additionally, paper-based hybrid systems have been presented in response to hard flow control challenges and assay observation that suffers from opaque material properties.…”