SUBJECT: Ph.D. Proposal Presentation
BY: Jung Yun Lee
TIME: Monday, April 15, 2019, 11:30 a.m.
PLACE: MRDC Building, 4211
TITLE: Electrohydrodynamics of electrosprayed charged droplets in a vorticial flow
COMMITTEE: Dr. Andrei Fedorov, Chair (ME)
Dr. Peter Kottke (ME)
Dr. Matt Torres (Biology)
Dr. Devash Ranjan (ME)
Dr. Mostafa Ghiaasiaan (ME)


Electrospray ionization has become a popular method to produce ultra-small charged liquid droplets. The coupling of electrospray ionization to mass spectrometry (ESI-MS) has enabled determination of the composition of complex biological samples with applications including biomarker discovery and disease diagnosis. Improvement in ESI-MS sensitivity can be achieved via effective desolvation of electrosprayed charged droplets and more efficient transport of dry analyte ions into the mass analyzer. Based on a novel implementation of swirling flow, an ESI-MS interface is under development in which a vorticial gas flow is utilized to advantageously alter the spatial size-distribution of droplets. Numerical and experimental studies using a prototype vorticial interface indicate that large droplets are displaced to the periphery of the electrospray plume under the influence of the outward inertia of the vortex flow, resulting in reduction in chemical noise with improvement in sensitivity.
The objective of the proposed research is to increase the understanding the behavior of electrosprayed charged droplets via theoretical and experimental studies focused on (1) the effects of a vorticial flow on the spatial size-distribution, (2) the effects of interaction between a vorticial flow and suction flow on charged droplet transmission. Multiphysics modeling will consider vorticial flow hydrodynamics in the presence of active suction, applied external electric fields, and inter-droplet electrostatic interactions (space charge) to study their impact and ability to control charged droplets of differing size and charge. Experimental flow visualization and ion current measurements will be used to provide basic insight into the phenomena and validation of model predictions. The successful implementation of the proposed studies will provide valuable input and insights into the vorticial ESI-MS interface design and operation.