Dielectrophoretic Trapping in Paper: Paper-based Electric Field Gradients for High-Throughput Particle Trapping

Abstract

Dielectrophoresis (DEP) is a phenomenon which utilizes a spatially varying electrical field to induce forces on suspended polarizable matter, including particles and cells. Such field non-uniformities are conventionally created using a wide variety of conductive electrode arrays. Alternatively, insulator based dielectrophoresis (iDEP) uses small micron-scale insulating structures to generate high electric field gradient that can used to selectively trap, isolate and concentrate biomolecules such as bacteria, virus, red blood cells, cancer cells etc. Despite significant advances in microfabrication technology, the commercial adoption of iDEP based devices remains elusive. One reason for such low market penetration is a lack of low-cost and scalable fabrication methods to quickly micro-fabricate these insulating structures required for iDEP. We propose here that paper-based devices can offer a low-cost, easy to use alternative to traditional iDEP devices. In this article, we demonstrate for the first time the ability to perform iDEP particle trapping using the naturally occurring insulating porous structures of paper. In particular, we use polymeric laminated nonwoven fiberglass paper channels as a source of insulating structures for iDEP. We apply a flow of polarizable microparticles directly within the nonwoven channel and simultaneously drop a pulsed DC electric field perpendicular to the flow direction. We show the ability to trap particles by DEP using an applied voltage as low as 2V using two different flow mechanisms: constant fluid flow rate using an external pump and passive fluid flow by capillary wicking. Using a combination of micro computed tomography and finite element analysis, we then present a computational model in order to probe the micro-scale DEP force formation dynamics within nonwoven structure. This new iDEP platform enables the development of robust, low-cost, and portable next generation iDEP systems for a wide variety of sample purification and liquid handling applications.