Contactless handling of biological nanoparticles by dielectrophoretic forces - Tools and results

Investigation of individual or small numbers of biological micron- and sub-micron-sized biological particles such as bacteria or viruses requires means for separation, accumulation, trapping and analysis. This may be achieved employing dielectrophoresis (DEP) in microfluidic systems [1-13]. Since DEP relies on polarization effects, smaller particles require higher electric field strength and accordingly smaller electrode spacing in fluidic microsystems. A newly developed microsystem contains different dielectrophoretic function blocks, which may be applied in a versatile, flexible fashion to a wide variety of tasks. A dedicated manufacturing technology yields precise bonding [14] and small electrode spacing results in extremely high field strengths and superior dielectrophoretic performance. Among the functions integrated are: separators, band-pass filters for flexible fractionation of particulate samples, funnel-structures and field-cages for particle alignment, accumu lation and trapping, pDEP structures for field-driven adsorption of particles and molecules onto electrode surfaces. The micro-systems are transparent, exhibit virtually no fluorescence and are reusable [15], [13].