Frequency-Response Models for Electroosmotic Actuators

Electroosmosis is a low-cost actuation methodology for micro- and nanofluidic systems including lab-on-chip technologies. Potential applications include transport and analysis of DNA, RNA, proteins, vaccines, antibiotics, and a range of other molecules at the micro- and nanoscales. Fields of application range from microbiology, biochemistry, and medicine to genetics. This paper develops new control-oriented frequency-response models for thin rectangular channels that, for example, relate applied voltage to flow rate. These are 2D models, which can be approximated with simple first-order responses whose bandwidth can be expressed in terms of the fundamental actuator parameters of solution density and viscosity and channel height. The DC response is characterized largely by channel height, viscosity, permittivity, and the zeta-potential (ζ-potential), which is the electrical potential in the solution at the channel walls.