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Multiplexed electrospray is a promising aerosol generation technique to produce high throughput quasi-monodisperse droplets in the nanometer and micron size range. Here we report the design, fabrication, analysis, and performance of a linear electrospray (LINES) system. The fabrication of the nozzle array is based on a precision computer numerical control (CNC) micromachining platform with 1-micron resolution. This rapid prototyping approach offers the flexibility of creating devices from a wide range of materials including metals and polymers with packing densities on par with silicon microfabrication at 20 sources/cm for LINES devices and 460 sources/cm 2 for the two-dimensional array. The LINES device uses a slot extractor design to simplify alignment and enhance operation robustness. We also used dummy nozzles (posts without fluidic channels) to offset edge effect on electric field and improved droplet size uniformity. We derived the approximate spray expansion model from charge conservation and Gauss' law. We applied the line-of-charge approximation to establish scaling laws for prescribing operating conditions. The devices show excellent droplet size uniformity from source to source, with relative standard deviation (RSD) of primary droplets <3%.

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We report a scalable approach to generate strictly monodisperse microdroplets by introducing transverse periodic perturbations on microliquid jets. The fringe field of a thin capacitor, driven by sinusoidal signals, induces periodic electrohydrodynamic (EHD) stress and "chops" the liquid jet at precise and adjustable intervals. When the driving signal is near the 50% of the Rayleigh frequency, liquid jets exhibit highly ordered breakup. We have shown that for the same jet diameter, the monodispersed droplet diameter can be changed by a factor of 1.75, corresponding to more than five times in change of droplet volume. Further, we demonstrate the scale-up of this approach by chopping multiple jets using a single set of EHD exciters.