Microscale Ion-Driven Air Flow Over a Flat Plate

Abstract

A microscale air pump concept that uses ionized air molecules under the influence of an electric field is studied. The method employed is an extension of the corona wind concept and is referred to here as microscale ion-driven air flow. The two major differences are that the ions are created in a distinct generation region, and are then put in motion by a traveling electric field in the pumping region. The ions create bulk motion of the air because of ion drag. One application of this technology involves generation of air flow through microchannels or other micro-featured surfaces to create compact, high flux heat sinks for electronics cooling. This work focuses on the ion pumping aspect of the technology. A device was constructed and tested with an array of micro-fabricated electrodes that generate strong electric fields in the air. The electrode potentials were cycled to impart a unidirectional force to the ions over meso-scale distances. The microscale ion-driven air flow concept was demonstrated by electrical means, through the measurement of the ion current produced. A set of designed experiments were conducted that showed the electrode potential to be the most significant factor for sustaining an ion current. A two-dimensional numerical model of the ion motion has been developed and validated against the experimental results. The model describes the time-dependent ion flow induced over an array of evenly spaced microscale electrodes that are used to generate a translating electric field.