Biophys J, January 2001, p. 531-541, Vol. 80, No. 1

Holding Forces of Single-Particle Dielectrophoretic Traps

Joel Voldman,^* Rebecca A. Braff,^* Mehmet Toner, Martha L. Gray,^* and Martin A. Schmidt^*

 ^*Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and  Harvard Medical School, Cambridge, Massachusetts 02138 USA

We present experimental results and modeling on the efficacy of dielectrophoresis-based single-particle traps. Dielectrophoretic forces, caused by the interaction of nonuniform electric fields with objects, have been used to make planar quadrupole traps that can trap single beads. A simple experimental protocol was then used to measure how well the traps could hold beads against destabilizing fluid flows. These were compared with predictions from modeling and found to be in close agreement, allowing the determination of sub-piconewton forces. This not only validates our ability to model dielectrophoretic forces in these traps but also gives insight into the physical behavior of particles in dielectrophoresis-based traps. Anomalous frequency effects, not explainable by dielectrophoretic forces alone, were also encountered and attributed to electrohydrodynamic flows. Such knowledge can now be used to design traps for cell-based applications.

Biophys J, January 2001, p. 531-541, Vol. 80, No. 1
© 2001 by the Biophysical Society   0006-3495/01/01/531/11  $2.00

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