Faradaic Ion Concentration Polarization on a Paper Fluidic Platform

Abstract

We describe the design and characteristics of a paper-based analytical device for analyte concentration enrichment. The device, called a hybrid paper-based analytical device (hyPAD), uses faradaic electrochemistry to create an ion depletion zone (IDZ), and hence a local electric field, within a nitrocellulose flow channel. Charged analytes are concentrated near the IDZ when their electrophoretic and electroosmotic velocities balance. This process is called faradaic ion concentration polarization. The hyPAD is simple to construct and uses only low-cost materials. The hyPAD can be tuned for optimal performance by adjusting the applied voltage or changing the electrode design. Moreover, the throughput of hyPAD is 2 orders of magnitude higher than that of conventional, micron-scale microfluidic devices. The hyPAD is able to concentrate a range of analytes, including small molecules, DNA, proteins, and nanoparticles, in the range of 200−500-fold within 5 min.

Recent Advancements in Bipolar Electrochemical Methods of Analysis

“…46 Enrichment of small molecules, proteins, and nucleic acids by electrokinetic focusing has also been accomplished by bipolar electrochemistry in an ePAD. 86 This approach leads to greater sensitivity during fluorescence or colorimetric readout and holds the potential for integration with amperometric detection.…”

Alleviating concentration polarization: a micro three-electrode interdigitated glucose sensor based on nanoporous gold from a mild process

“…34,36,[39][40][41] Designing the layout of each electrode on the circuit board can surely enhance the performance of the whole device. 42,43 Combining the interdigitated structure with the above high-performance materials can obviously elevate the nal performance of the glucose sensors.…”

Recent advances in enhancing the sensitivity of electrophoresis and electrochromatography in capillaries and microchips (2016–2018)

“…Faradaic ICP relies on bipolar electrodes to create ICP without the need to incorporate a NMI. Li et al [138] demonstrated the enrichment of small molecules, DNA, protein, and nanoparticles with enrichment factors ranging from 200-to 500-fold within 5 min. The analytes were dissolved in 100 mM Tris-HClO 4 buffer (pH 8.1).…”

“…Li et al. demonstrated the enrichment of small molecules, DNA, protein, and nanoparticles with enrichment factors ranging from 200‐ to 500‐fold within 5 min. The analytes were dissolved in 100 mM Tris‐HClO 4 buffer (pH 8.1).…”