The Development of Polymeric Devices as Dielectrophoretic Separators and Concentrators
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The Development of
Polymeric Devices as Dielectrophoretic Separators and Concentrators
Blake A. Simmons, Gregory J. McGraw, Rafael V. Davalos, Gregory J. Fiechtner, Yolanda Fintschenko, and Eric B. Cummings Abstract Efficient and reliable particle separators and concentrators are needed to support a wide range of analytical functions including pathogen detection, sample preparation, high-throughput particle sorting, and biomedical diagnostics. The advent of lab-on-a-chip devices based on the phenomenon of dielectrophoresis offers advantages that can meet several of the challenges associated with cell sorting and detection. The majority of the devices presented in the scientific literature have used glass-based devices for these applications, but there has been recent activity that indicates that polymer-based devices can operate as effectively as their glass progenitors. Processing and operational advantages motivate the transition from glass and silicon to polymer microdevices: mechanical robustness, economy of scale, ease of thermoforming and mass manufacturing, and the availability of numerous innate chemical polymer compositions for tailoring performance. We present here a summary of the developments toward, and results obtained from, these polymeric dielectrophoretic devices in the selective trapping, concentration, and gated release of a range of biological organisms and particles. Keywords: biomedical, dielectrophoresis, fluidics, microscale, polymer.
Introduction Efficient cellular and subcellular particle separation and sorting is an important field of science and technology development for numerous lab-on-a-chip and biomedical applications. For example, recent national and global events have drawn attention to the need for rapid and accurate monitoring of water distribution networks for safety and quality. To detect pathogens at low concentrations in raw water or other liquid samples, it is vital to develop selective techniques that collect, concentrate, and deliver such particles for further testing and identification. Similar operational requirements are present in
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the biomedical and analytical chemistry fields, where the delivery of a concentrated and purified sample is of paramount importance to eliminate the contribution of background interference and thereby minimize errors. Dielectrophoresis (DEP) is the motion of particles driven by conduction effects in a nonuniform electric field.1 It has been shown that DEP can be used to transport suspended particles using either oscillating (ac) or steady (dc) electric fields.2 This phenomenon is attractive for differentiating biological particles (e.g., cells, spores, viruses, DNA), because it can collect spe-
cific types of particles rapidly and reversibly based on their size, shape, and intrinsic properties such as conductivity and polarizability. Many device architectures and configurations have been developed to sort a wide range of biological particles by DEP. Early DEP experiments, carried out by Pohl et al., utilized pin–plate and pin–pin el
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