Design of insulator-based dielectrophoretic devices: Effect of insulator posts characteristics

Insulator-based dielectrophoresis (iDEP) is a leading technique for the enrichment and manipulation of target bioparticles by exploiting physical and electrical properties of the particles and the suspending medium. Dielectrophoretic forces are produced by employing insulator posts that distort an otherwise uniform electric field. The optimal design for iDEP devices involves a careful balance between electrokinetics (EK) and dielectrophoresis (DEP) in the DEP-active area, where the design of the insulator posts is crucial for their performance. This contribution demonstrates the selection of a geometrical set of parameters that enhances particle capture and enrichment in an iDEP device. Numerical simulations, comprising an average trapping condition (TC) and the average lateral-to-longitudinal force ratio (FR) experienced by particles, were used to determine improved geometrical parameters (e.g., shape, length and width) and arrangement (e.g., lateral and longitudinal spacing) of the insulator posts. Experiments with polystyrene particles demonstrated the enhancement in particle enrichment, validating the employed key output parameters. The fabrication feasibility of the improved devices by a soft-lithographic process was also explored through numerical simulations and experiments. Optimal designs for this study were selected and their capture capacity was examined, demonstrating a decrease up to 84% in the electric potential necessary to generate a clear band of trapped particles. The findings from this study provide a systematic approach toward the design of high performance iDEP devices for their lab-on-a-chip integration.