title: A new ac electrospray mechanism by Maxwell-Wagner polarization and capillary resonance.
abstract: We report a new high-frequency (>10 kHz) ac electrospray that is capable of generating micron-sized electroneutral drops. Unlike its dc counterpart, the drops are not ejected continuously from a sharp Taylor cone but intermittently from a resonating meniscus at the orifice. We attribute the resonant frequency to the capillary-inertia vibration time of the meniscus and the drop ejection to the Maxwell-Wagner electric stress at the drop tip, which is observed to reverse its direction across a crossover frequency. Above this frequency, the oppositely directed Maxwell-Wagner force causes the liquid to recede up the microneedle as an apparent electrowetting effect.
authors.affiliation: Center for Microfluidics and Medical Diagnostics, Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, USA.
authors.forename: Leslie Y
authors.initials: LY
authors.lastname: Yeo
authors.forename: Dmitri
authors.initials: D
authors.lastname: Lastochkin
authors.forename: Shau-Chun
authors.initials: SC
authors.lastname: Wang
authors.forename: Hsueh-Chia
authors.initials: HC
authors.lastname: Chang