Folding-paper-based preconcentrator for low dispersion of preconcentration plug

Abstract

Ion concentration polarization (ICP) has been widely studied for collecting target analytes as it is a powerful preconcentrator method employed for charged molecules. Although the method is quite robust, simple, cheap, and yields a high preconcentration factor, a major hurdle to be addressed is extracting the preconcentrated samples without dispersing the plug. This study investigates a 3D folding-paper-based ICP preconcentrator for preconcentrated plug extraction without the dispersion effect. The ICP preconcentrator is printed on a cellulose paper with pre-patterned hydrophobic wax. To extract and isolate the preconcentration plug with minimal dispersion, a 3D pop-up structure is fabricated via water drain, and a preconcentration factor of 300-fold for 10 min is achieved. By optimizing factors such as the electric field, water drain, and sample volume, the technique was enhanced by facilitating sample preconcentration and isolation, thereby providing the possibility for extensive applications in analytical devices such as lateral flow assays and FTA R cards.

Recent advances in paper‐based preconcentrators by utilizing ion concentration polarization

“…Schematic diagram of 3D ICP paper‐based preconcentrator. (A) 3D origami ICP preconcentrators; reprinted from [89] (Creative Common CC BY). (B and C) 3D origami ICP preconcentration and separation chip; (B) is reprinted from [91], with permission from ACS Publications; (C) is reprinted from [92], with permission from the Royal Society of Chemistry.…”

“…At present, researchers have studied the 3D structure of ICP paper-based preconcentrator. These preconcentrators are based on simple folding, and the addition of an ion-selective membrane can result in preconcentration plugs with a small dispersion [89,90]. However, these studies only focused on obtaining high PF without considering the separation of preconcentration molecules from other substances in the micro-sample.…”

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

“…To minimize this effect, Lee et al. designed a pop‐up μPAD that enable disconnecting the concentrated plug once the maximum enrichment was reached . Orange G dye in 1 mM NaCl was enriched by 300‐fold within 10 min using 100 V. The device design also included a wide outlet reservoir that is 9 mm in diameter to ensure continuous flow through the concentration time.…”

Digital microfluidics-like manipulation of electrokinetically preconcentrated bioparticle plugs in continuous-flow

“…One approach to achieve direct control over the length of the depletion layer, which in turn controls the location of the preconcentrated plug, uses either embedded electrodes or heaters for local stirring of the fluid, which respectively induce alternating-current-electro-osmosis (ACEO) 25 or electro-thermal (ET) flow. 26 Another approach to control the location of a single preconcentrated plug is to use two ion-permselective membranes 27–29 or nanochannels 30 in series. It has been shown that in the intermediate region between the two membranes, the enriched layer prevents propagation of the depletion layer and its corresponding developed preconcentrated molecule plug.…”

“…It has been shown that in the intermediate region between the two membranes, the enriched layer prevents propagation of the depletion layer and its corresponding developed preconcentrated molecule plug. 27–30 While being able to control the location of a preconcentrated biomolecule plug, these approaches are limited to a single plug from a single source ( i.e. inlet) within a straight microchannel.…”