New ‘whipping jet’ sprayer controls how aerosols move

Aerosols are tiny particles that can have a significant impact on Earth’s climate and human health.

For example, these microdroplets can reflect incoming sunlight back to outer space, helping to cool a warming planet. Or they can be used to administer drugs to the lungs, especially to treat respiratory ailments.

Thus, the ability to more precisely control how aerosols move is critically important to pharmaceutical sciences and climate research. Aerosol science is also a key aspect of many industries, from automobiles to food processing.  

Now, scientists have published a study describing a breakthrough device — a new whipping jet aerosol sprayer — that is relatively inexpensive to build and operate.

“We have created a unique, steady-state, gas-focused whipping jet that does not use electricity,” says lead author Sankar Raju Narayanasamy, a researcher at Lawrence Livermore National Laboratory, and an affiliate researcher at Berkeley Lab and SLAC National Accelerator Laboratory.

“This development is a significant feat that can have a wide range of applications,” says Narayanasamy, who conducted the research as a BioXFEL scholar, a U.S. National Science Foundation-funded research consortium led by UB, Hauptman-Woodward Medical Research Institute (HWI) and partner institutions.

Martin Trebbin, SUNY Empire Innovation assistant professor of chemistry, UB College of Arts and Sciences, is a co-corresponding author of the study.

He says that “fine monodisperse aerosols with controlled sizes are useful in sample environment instrumentation, such as in mass spectrometry, X-ray free-electron lasers (XFELs) and cryo-electron microscopy, which are used to study bio-macromolecules for structural analysis and drug discovery.”

Trebbin, who calls the research an “important achievement in fluid dynamics and microfluidics,” is a core faculty member of the UB RENEW Institute, and also holds an appointment at the BioXFEL Science and Technology Center.

The technology is described in a study titled, “A sui generis whipping instability-based self-sequencing multi-monodisperse 2D Sprays from an anisotropic microfluidic liquid jet device,” which was published Jan. 11 in the Cell Press journal Cell Reports Physical Science.

The study marks a third-generation advancement in liquid jet technology. First came cylindrical liquid jets in 1998; flat liquid sheet jets followed in 2018.

The new whipping jet is the first of its kind because it produces homogeneous droplets in a two-dimensional profile, says co-corresponding author Hoi-Ying N. Holman, director of the Berkeley Synchrotron Infrared Structural Biology imaging program at Lawrence Berkeley National Laboratory.

In the past 20 years, scientists have tried many ways, such as piezoelectric actuation or local heating, to precisely control the movement of aerosols. Use of those techniques, however, is limited because they tend to alter the specimens that scientists are using the aerosols to study. This is especially true with biological samples.

In the study, researchers discuss the important role that analytical fluid dynamics — a branch of fluid mechanics that uses numerical analysis and data structures to analyze and solve problems involving fluid flows — played in their work.

This includes explaining the “jet diameter, whipping regime and spreading angle” of the devices, says Ramakrishna Vasireddi, co-first author and a research scientist at SOLEIL, the French synchrotron facility in Paris.

He adds: “The phenomenon is further characterized experimentally by measuring the angle with respect to the flow rate, the distances between droplets, the droplet shapes and the reproducibility of these parameters.”

In the study, the team also explains how to build such devices, which are relatively inexpensive.

This work was supported by the Cluster of Excellence “The Hamburg Center for Ultrafast Imaging - Structure, Dynamics and Control of Matter at the Atomic Scale” of the Deutsche Forschungsgemeinschaft (DFG). The work was conducted through the Berkeley Synchrotron Infrared Structural Biology (BSISB) Imaging program, which is supported by the U.S. Department of Energy. It was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory.