(6d) Joule Heating Effects On Fluid and Particle Transport In Insulator-Based Dielectrophoresis Devices

Insulator-based dielectrophoresis (iDEP) is an emerging technology that has been widely used to manipulate particles in microfluidic devices. However, due to the locally amplified electric field around the in-channel insulator, Joule heating often becomes an unavoidable issue that may disturb the electroosmotic flow and affect the particle motion. This work presents a combined experimental and numerical study of Joule heating effects on fluid and particle transport in a typical iDEP device, e.g., a constriction microchannel, under DC-biased AC voltages. It is observed that depending on the magnitude of the DC voltage, a pair of counter-rotating fluid circulations can occur at either the downstream end alone or each end of the channel constriction. These circulations are found to affect the dielectrophoretic deflection of particles and thus mitigate the particle focusing and trapping performances in iDEP devices.