Physical Review E
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.
Original Publication Citation
Dey, M., Bandyopadhyay, D., Sharma, A., Qian, S., & Joo, S. W. (2012). Electric-field-induced interfacial instabilities of a soft elastic membrane confined between viscous layers. Physical Review E, 86(4), 041602. doi:10.1103/PhysRevE.86.041602
Dey, Mohar; Bandyopadhyay, Dipankar; Sharma, Ashutosh; Qian, Shizhi; and Joo, Sang Woo, "Electric-Field-Induced Interfacial Instabilities of a soft Elastic Membrane Confined Between Viscous Layers" (2012). Mechanical & Aerospace Engineering Faculty Publications. 26.