Time periodic electroosmosis of linear viscoelastic liquids over patterned charged surfaces in microfluidic channels

• Time periodic electroosmotic flow of Maxwell fluid over patterned charged surfaces.
• Frequency induced phenomenon of roll breakup.
• Quantified mixing analysis using a box counting efficiency.

In the present study, we aim to highlight the interactions between fluid rheology and interfacial electrokinetic phenomenon pertaining to time periodic electroosmotic flows of viscoelastic fluids, obeying linearized Maxwell model, over charge-modulated substrates. We successfully demonstrate that by altering the forcing frequency, fluid rheology, and charge-patterning characteristics, one may obtain drastically altered flow fields and hence mixing characteristics. Accordingly, we suggest that one may explore the paradigm of enhanced microfluidic mixing by exploiting the fluid rheology, supplementing the traditionally used methods such as topographical and geometrical modifications.