title: Electric-field-induced interfacial instabilities of a soft elastic membrane confined between viscous layers.
abstract: We explore the electric-field-induced interfacial instabilities of a trilayer composed of a thin elastic film confined between two viscous layers. A linear stability analysis (LSA) is performed to uncover the growth rate and length scale of the different unstable modes. Application of a normal external electric field on such a configuration can deform the two coupled elastic-viscous interfaces either by an in-phase bending or an antiphase squeezing mode. The bending mode has a long-wave nature, and is present even at a vanishingly small destabilizing field. In contrast, the squeezing mode has finite wave-number characteristics and originates only beyond a threshold strength of the electric field. This is in contrast to the instabilities of the viscous films with multiple interfaces where both modes are found to possess long-wave characteristics. The elastic film is unstable by bending mode when the stabilizing forces due to the in-plane curvature and the elastic stiffness are strong and the destabilizing electric field is relatively weak. In comparison, as the electric field increases, a subdominant squeezing mode can also appear beyond a threshold destabilizing field. A dominant squeezing mode is observed when the destabilizing field is significantly strong and the elastic films are relatively softer with lower elastic modulus. In the absence of liquid layers, a free elastic film is also found to be unstable by long-wave bending and finite wave-number squeezing modes. The LSA asymptotically recovers the results obtained by the previous formulations where the membrane bending elasticity is approximately incorporated as a correction term in the normal stress boundary condition. Interestingly, the presence of a very weak stabilizing influence due to a smaller interfacial tension at the elastic-viscous interfaces opens up the possibility of fabricating submicron patterns exploiting the instabilities of a trilayer.
authors.affiliation: School of Mechanical Engineering, Yeungnam University, Gyeongsan 712-749, South Korea.
authors.forename: Mohar
authors.initials: M
authors.lastname: Dey
authors.forename: Dipankar
authors.initials: D
authors.lastname: Bandyopadhyay
authors.forename: Ashutosh
authors.initials: A
authors.lastname: Sharma
authors.forename: Shizhi
authors.initials: S
authors.lastname: Qian
authors.forename: Sang Woo
authors.initials: SW
authors.lastname: Joo
mesh_terms: D000465:Algorithms; D001696:Biomechanical Phenomena; D001703:Biophysics / Q000379:methods*; D003198:Computer Simulation; D016503:Drug Delivery Systems; D004548:Elasticity; D004560:Electricity; D004563:Electrochemistry / Q000379:methods; D057446:Hydrodynamics; D016014:Linear Models; D008564:Membrane Potentials; D008566:Membranes / Q000737:chemistry*; D044085:Microfluidics / Q000379:methods; D011108:Polymers / Q000737:chemistry; D011312:Pressure; D055672:Static Electricity; D013314:Stress, Mechanical; D013499:Surface Properties; D014783:Viscosity
chemical_list: D011108:Polymers