Gas Dynamic Virtual Nozzle for Generation of Microscopic Droplet Streams

TL;DR

This paper introduces a gas dynamic virtual nozzle that produces microscopic droplet streams without clogging, suitable for biological and analytical applications, by compressing a liquid jet with a co-flowing gas.

Contribution

It presents a novel, clog-resistant droplet source based on gas-dynamic forces, offering a miniature, reliable alternative to traditional nozzles.

Findings

Generates monodisperse, single-file droplet streams

Device is miniature, robust, and clog-resistant

Suitable for biological sample delivery into vacuum

Abstract

As shown by Ganan-Calvo and co-workers, a free liquid jet can be compressed in iameter through gas-dynamic forces exerted by a co-flowing gas, obviating the need for a solid nozzle to form a microscopic liquid jet and thereby alleviating the clogging problems that plague conventional droplet sources of small diameter. We describe in this paper a novel form of droplet beam source based on this principle. The source is miniature, robust, dependable, easily fabricated, and eminently suitable for delivery of microscopic liquid droplets, including hydrated biological samples, into vacuum for analysis using vacuum instrumentation. Monodisperse, single file droplet streams are generated by triggering the device with a piezoelectric actuator. The device is essentially immune to clogging.