Miniature electroactive-polymer rakes (MEARs) are undergoing development for eventual use as simple, lightweight, inexpensive low-power-consumption devices that would remove soil, dust, and/or other loose particulate matter from the surfaces of solid objects. In the original intended application, MEARs is being sought for use, in exploration of remote planets, to expose surfaces of rocks for examination by video cameras and/or other optoelectronic instruments. MEARs could also be used in similar remote-control geological exploration on Earth.

Figure 1. A Miniature Electroactive Polymer Rake contains actuator fingers that bend when voltage is applied. Overlapping sine-shaped wires on the tips enhance the raking action. Ground wires (not shown) at the tips prevent the accumulation of static electric charges.

Unlike the tines in an ordinary rake, the tines in a MEAR are actuator fingers that bend under electrical control. Each finger consists mostly of a sandwichlike composite of (1) an inner layer comprising an ion-exchange-polymer membrane between (2) two outer polymeric layers that contain or are coated with gold or platinum and that serve as electrodes. The amount and direction of bending depends on the magnitude and polarity of the potential (typically of the order of several volts) applied between the electrodes. An alternating potential can be applied to obtain a repetitive raking or sweeping action. As described thus far, the MEAR fingers are nearly identical to the bending actuators described in "Robot Hands With Electroactive-Polymer Fingers" (NPO-20103), NASA Tech Briefs, Vol. 22, No. 10 (October 1998), page 78 and "Wipers Based on Electroactive Polymeric Actuators" (NPO-20371), NASA Tech Briefs, Vol. 23, No. 2 (February 1999), page 7b.

Figure 1 is a drawing of a typical MEAR. To enhance the raking action, wires made from aromatic polyamid fibers and bent into sine curves are attached to the tips of the actuator fingers. To prevent the potential accumulation of static electric charges from the rubbing of the fingers and/or sine-shaped wires on other objects, copper ground wires are added to the tips.

Figure 2. A Window Wiper containing one or more electroactive-polymer actuators and high-voltage circuitry would remove charged particles and dust.

Figure 2 schematically depicts a variant of the basic MEAR concept for removing dust from a glass window. In this case, the window would be wiped by either a MEAR with metal-coated fingers or else by a metal-coated electroactive-polymer wiper like those described in the noted previous article about wipers. To remove charged particles and dust from the window, a large positive or negative dc potential difference would be applied between the window frame and the MEAR fingers or wiper. From time to time, the polarity of the applied dc potential would be switched.

This work was done by Yoseph Bar-Cohen and Sean Leary of Caltech for NASA's Jet Propulsion Laboratory.

NPO-20613

Topics:
Emissions Exhaust emissions Exteriors Motion Control Particulate matter (PM) Sensors and actuators Soils Test equipment and instrumentation Windows and windshields
This Brief includes a Technical Support Package (TSP).
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Miniature Electroactive-Polymer Rakes

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Overview

The document is a technical support package prepared by the Jet Propulsion Laboratory (JPL) under the sponsorship of the National Aeronautics and Space Administration (NASA). It focuses on the development of Miniature Electroactive-Polymer Rakes (MEARs), a novel technology designed for applications in space exploration and geological studies.

The report highlights the innovative nature of MEARs, which utilize electroactive polymers to create actuators that can bend and move in response to electrical signals. This capability allows the rakes to effectively remove soil, dust, and other loose materials from surfaces, making them particularly useful for planetary exploration where traditional methods may be impractical. The lightweight and low-power characteristics of MEARs enhance their suitability for deployment in remote and challenging environments.

The document includes information about the inventors, Sean Leary and Yoseph Bar-Cohen, and outlines the technical aspects of the MEARs, including their design and operational principles. It emphasizes the potential applications of this technology not only in space missions but also in terrestrial geological studies, where efficient surface cleaning and material collection are essential.

Additionally, the report contains disclaimers regarding the use of trade names and manufacturers' names, clarifying that their mention does not imply endorsement by the U.S. Government or JPL. It also states that the work was conducted under a contract with NASA, ensuring that the research aligns with the agency's goals and standards.

Overall, the document serves as a comprehensive overview of the MEAR technology, detailing its development, functionality, and potential impact on both space exploration and Earth-based applications. It underscores the importance of innovative technologies in advancing our understanding of planetary surfaces and enhancing the efficiency of scientific investigations. The report is a testament to the ongoing efforts of NASA and JPL in pushing the boundaries of technology to facilitate exploration and research in diverse environments.