EWOD-driven stirring in lab-on-a-chips: Dependence on the electrodes' geometry

Rachid Malk (1) , Johannes Theisen (1) , Yves Fouillet (2) , Laurent Davoust (3)

1 LEGI - Laboratoire des Écoulements Géophysiques et Industriels [Grenoble]
2 CEA-LETI - Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information
3 SIMaP - Science et Ingénierie des Matériaux et Procédés

Electrowetting on dielectrics (EWOD) with coplanar electrodes is increasingly used in microsystems. This paper enlightens the physical mechanisms of stirring flows in sessile droplets actuated by oscillating EWOD with potential applications to biochemical reaction enhancement or cells handling. Depending on electrodes design (circular vs. square electrodes), EWOD-induced convective flow can be observed to switch from toroidal to quadripolar flows. Due to the coplanar geometry of the electrodes, a model can be proposed which helps to interpret EWOD-induced flow as a result of capillary streaming. Numerical calculations are compared with imaging of drops and demonstrate clearly the essential role of oscillating EWOD as a Bow actuator.

Mots clés: Digital microfluidics; Stirring; Flow-focusing; Electrowetting

Domaines: Matériaux

Rachid Malk, Johannes Theisen, Yves Fouillet, Laurent Davoust. EWOD-driven stirring in lab-on-a-chips: Dependence on the electrodes' geometry. Microelectronic Engineering, 2012, 97, pp.306-310. ⟨10.1016/j.mee.2012.04.009⟩. ⟨hal-00781317⟩