Fig. 1: Current limitations and a new approach for open-channel electrofluidics.
From: Open-channel microfluidics via resonant wireless power transfer
a Schematic of common fluidic microsystems, comparing operating voltage and characteristic fluidic dimensions. This work offers digital fluidic actuation with micron-scale channel confinement and user-friendly, open-drop loading for either ionic or dielectric solutions. b Schematic of an open-micro-electrofluidic (OMEF) channel that travels a distance, dz, with a circular-sector cross section of radius R and sector angle α. Two electrodes comprise the legs of the sector separated by a gap, g, beneath a passivation layer with thickness t, dielectric permittivity εt, and contact angle θ0. The liquid channel has a dielectric permittivity of εL, surrounded by an environment with a permittivity of ε0 and surface tension, γ. c Theoretical threshold voltage necessary to pull a channel of deionized (DI) water using coplanar electrodes (α = π) for various g values as a function of R. Literature values are plotted and in good agreement with our work38,39,43. A few of our results using a nonplanar geometry are plotted for comparison. d Reducing α simultaneously reduces the surface-energy cost to extrude OMEF channels (black curve) until spontaneous capillary action occurs and it also confines E-fields more efficiently within the channel volume (red curve, normalized to the coplanar geometry with the same radius). The inset shows simulation of the E-field distribution for a nanogap-stacked electrode whose sidewall forms the OMEF circular-sector channel. Symbols match the definitions of Fig. 1b. Source data are provided as a Source Data file for Fig. 1c, d.
