Direct measurement of the dielectrophoresis forces acting on micro-objects using optical tweezers and a simple microfluidic chip

In Soo Park, Se Hee Park, Dae Sung Yoon, Sang Woo Lee and Beop-Min Kim

We constructed a reliable frequency-dependent dielectrophoretic (DEP) force measurement system based on optical tweezers and a microfluidic chip. Using this system, we directly measured the frequency-dependent DEP forces acting on polystyrene beads while varying various parameters, which were all verified by theoretical simulations. We also investigated the DEP characteristics of non-functionalized and carboxyl-functionalized polystyrene beads in solutions with different conductivities by associating the measured crossover frequencies with a theoretical DEP model. This system can be used as a quantifying tool for surface conductance assays by characterizing the DEP forces acting on micro-objects in various experimental conditions.

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