Characterization of the geometry of negative dielectrophoresis traps for particle immobilization in digital...

This paper studies the effect of dielectrophoresis on particle manipulation and immobilization in digital microfluidic (DMF) devices. The dimensions of negative dielectrophoresis (nDEP) traps in the form of circular and square shapes are characterized using numerical and experimental approaches. These efforts will result in defining lifting and trapping zones, the ratio of which is shown to remain constant for trap sizes larger than 40 μm. As a result, a limiting constant K based on the ratio of the particle diameter to the trap size is introduced to identify the status of particle trapping prior to running numerical models or experiments. The results show that K must be less than 0.63 for trapping the particles on the nDEP traps. This study will also result in optimizing the trap size for single particle immobilization which is important for cell printing and growth applications.