Fluid Dynamics Seminar

Monday, Oct. 24, 2011, 4:00 PM
Cullimore, Room 611
New Jersey Institute of Technology


Electrospray and Continuous Ink-jet Technologies: Novel Applications and the Electrohydrodynamics of Droplets and Sprays

Paul R. Chiarot


Department of Mechanical Engineering, State University of New York at Binghamton



Electrospray and continuous ink-jet technologies have tremendous potential in a variety of new applications, including: high-throughput MEMS and electronics manufacturing, deposition of specialized coatings, microarray preparation, and portable biosensing. The key to the successful use of electrospray in novel applications is a better understanding of the relationship between operational parameters and performance. For continuous ink-jet (CIJ) systems, reliable manipulation and control of the high velocity jets, including basic on/off control and steering of the liquid droplets, is a priority. Electrohydrodynamics, i.e. the use of electric fields to manipulate and control small fluid volumes, is fundamental to these technologies. In this seminar, a model of an electrified fluid interface and electrospray will be presented. The model accounts for interactions among pressure, surface, and electrostatic forces and is used in process optimization. Novel strategies to steer and control CIJ droplet streams by combining the dielectrophoretic force with droplet rebound from solid substrates will also be presented. A model describing the effect of the dielectrophoretic force on the liquid droplets was developed and efforts to improve droplet steering reveal interesting phenomena on droplet-surface interactions. MEMS fabrication techniques were used to build devices that exploit electrospray and continuous ink-jet technologies, including: microfluidic electrospray emitter chips, miniaturized ion mobility spectrometers, high-density ink-jet nozzles, and specialized substrates for CIJ droplet deflection. Details on the design and performance of these MEMS devices will be presented. Special attention is given to the combination of electrospray with the miniaturized ion mobility spectrometer for biomarker detection. The development of electrospray and continuous ink-jet technologies for use in novel applications incorporates many areas of physics and engineering, including: fluid mechanics, material science, and microfluidics.