In yet another family of potential applications, diodes would be embedded in microscopic gears, wheels, propellers, and the like, wherein they would be positioned and oriented so that upon application of AC electric fields, the resulting electro-osmotic flows would produce torques that would cause these objects to rotate. The feasibility of this concept was demonstrated in an experiment on a macroscopic (≈1.8-cm-diameter) rotor with diodes mounted on its periphery.

In a variation on the basic theme of these and other potential applications, diode propulsion units would be made to emit or respond to light. (In experiments, light-emitting diodes suspended in the water in the presence of a suitably strong AC electric field both propelled themselves electro-osmotically and emitted light.) In another variation, regulation of speed would be achieved through exploitation of electrical characteristics of diodes or of microcircuitry integrated with diodes: For example, in an experiment on Zener diodes, the electro-osmotic speed remained approximately constant when the magnitude of the AC field was increased beyond a point corresponding to the Zener voltage.

This work was done by Orlin D. Velev of North Carolina State University for the Air Force Research Laboratory. For more information, download the Technical Support Package (free white paper) at www.defensetechbriefs.com/tsp under the Electronics/Computers category. AFRL- 0020

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