Authors: T.T. Kanagasabapathi, C.J. Backhouse and K.V.I.S. Kaler
Affilation: University of Calgary, Canada
Pages: 81 - 84
Keywords: dielectrophoresis, pdms, microfluidics, continuous fractionation, microfabrication
Dielectrophoresis (DEP)  The behavior of polarized, neutral particles to the non-uniform electric field has been successfully applied for the levitation and subsequent isolation of biological cells and other micron-sized inorganic particles [2, 3]. This technique has been proven to be reliable and sensitive for noninvasive manipulation of micro and nanoscale particles [4, 5]. The aim of this work is to miniaturize the previously demonstrated work on levitation of microscopic particle under laminar flow conditions to a microchannel assembly made of inexpensive Poly(dimethylsiloxane) elastomer as shown in figure 2 and 3. In this paper, the continuous fractionation of microparticles on the PDMS microfluidic channel is presented. The design, development and fabrication of this microfluidic assembly [6, 7, 8] with an in-built interdigitated microelectrode array is described in detail as shown in figure 1. Preliminary results obtained using microscopic sized (5micrometer) Polystyrene beads prove the levitation phenomena in PDMS microchannel [figure-4]. The polystyrene beads are shown levitated, under negative DEP conditions, above the chamber floor. These levitated beads appear blurred in fig. 4 and they are found to form a pearl-chain. These suspended beads are then separated by fluid flow resulting in a continuous fractionation of the sample. The application of this low-cost, non-invasive technique for isolating a mixture of cancerous cells will be presented. Further integration of this technology with on-chip imaging and control unit will provide a microsystem capable of quantitative and sensitive analysis of the DEP signatures of various cancerous cells.
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