Electric-Field Induced Movement of MicroDroplets, Models and Design.

Abstract

The objective of this research is to model and design a microfluidic system that uses electrostatic fields to induce movement of discrete droplets of solution. Of particular interest is movement of droplets of H₂O for use in biological testing with lab-on-a-chip and mTAS systems. Using computer modeling, the electric-fields for planar electrode configurations positioned on an insulating substrate are calculated for a hemispherical drop of H₂O on the substrate at various positions. From these electric-fields the force on the drop is calculated. These models show that electrostatic actuation of droplets of H₂O is possible. However, as the complexity of the model increases the properties of the system become less desirable and actuation may not be possible. Using microfabrication techniques, the modeled microfluidic systems have been built for testing using a Kapton substrate with copper electrodes. Hexadecenyltrichlorosilane (HTS), a self-assembled monolayer, and its oxidant have been studied and found capable of providing hydrophobic and hydrophilic surface coatings for the systems.