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Electrospray involves breaking the meniscus of a charged liquid formed at the end of a capillary tube into fine droplets using an electric field. Multiplexed electrospray is arraying tubes to increase the overall flow rate without affecting the size of the ejected droplets. In order to maximize the flow rate and miniaturize the entire system, microelectromechanical systems (MEMS) fabrication techniques can be used to create densely packed nozzles and integrate them with the other components.
Further reduction in the size of the multiplexed electrospray is currently restricted by the required manual assembly of the components. Current alignment accuracy is limited to 50 microns and prevents the assembly of smaller than conventional electrospray components. Because droplet characteristics are not affected by the changes in nozzle dimensions, improved fabrication and assembly methods could shrink the nozzle size and increase the nozzle density. Increased nozzle density would permit further increases in device flow rate capability while maintaining sub-10 μm droplet diameters.
Army researchers have made strides in size reduction through a process to assemble an integrated multiplexed electrospray atomizer with superior alignment accuracy thereby making possible more compact devices with higher flow rates and lower operating voltage. Key to this technology is a ring extractor formed by MEMs fabrication. This component is voltage activated and pulls droplets from a nozzle. A spacer provides electrical standoff and isolates differential potentials. Unlike a conventional integrated multiplexed electrospray atomizer this process affords a degree of alignment previously unattainable.
Through the manufacture of multiplexed electrospray components and in particular a ring extractor with greater accuracy and techniques facilitating alignment with a bond aligner, concentric alignment tolerances of 10 microns or less are obtained between a nozzle central axis and a ring extractor hole. The enhanced tolerances greatly improve the performance of the device. Alignment tolerances of less than 5 microns and even less than 1 micron are routinely obtained by this process.
- Smaller component sizes
- Higher flow rates
- Businesses can commercialize this technology via an express license from the Army