An Electroosmotically Stirred Continuous Micro Mixer

Abstract

A continuous microfluidic mixer concept is developed by superposition of time-periodic electroosmotic flow on zeta potential patterned surfaces and pressure driven flow. Finite time Lyapunov exponents and filament stretching are utilized to quantify the chaotic strength, and to identify the chaotic and regular zones in the mixer at various operation conditions. Numerical solutions of the species transport equation are performed as a function of the Peclet number (Pe) at fixed kinematic conditions. Mixing efficiency is quantified using mixing index that is based on standard deviation of the scalar species distribution. The mixing length (lm) is characterized as a function of the Peclet number, and lm ∝ ln (Pe) scaling is observed under locally-optimum stirring conditions.