Propulsion of diodes in aqueous suspension under alternating-current or light stimulation
Year: 2025
Type: article
Abstract: Micro- or nano-diodes suspended in water can propel controllably under alternating-current fields or light without the need for fuels such as hydrogen peroxide or urea. This makes them promising candidates for miniature motors in biomedical and other applications. However, the mechanisms underlying their propulsion remain unclear. This study investigates the propulsion of diodes floating in an aqueous solution at the millimeter scale, which facilitates observation of motion, allowing direct correlation with electrical measurements of device properties. We find that the diode’s propulsion is driven by forward current under an alternating-current field and by photocurrent under illumination. The velocity of propulsion scales linearly with the net current, with the rectified or photogenerated current creating an imbalance of ions at the ends of the diodes. This, in turn, generates an electric field that induces electrophoretic flow around the diode and propels the diode. Additionally, we assess the velocity of diodes intentionally damaged by high reverse bias and find that it decreases significantly because of the reduced difference between forward and reverse currents. These results suggest potential uses of diode propulsion for characterizing and separating bottom-up-grown nano-/micro- diodes based on their reverse-saturation current, as well as nanomotors formed from multiple-junction nanowire diodes that can self-propel in water under light.
Source: Journal of Applied Physics
DOI: 10.1063/5.0285306
Language: English
Topic: Micro and Nano Robotics
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,500
Funder: National Science Foundation
OpenAlex ID: W4416169793