There is a need for effective sample handling tools to deliver and sort particles for analytical instruments that are planned for use in future NASA missions. Specifically, a need exists for a compact mechanism that allows transporting and sieving particle sizes of powdered cuttings and soil grains that may be acquired by sampling tools such as a robotic scoop or drill. The required tool needs to be low mass and compact to operate from such platforms as a lander or rover. This technology also would be applicable to sample handling when transporting samples to analyzers and sorting particles by size.

A Schematic View of the System using a rotary motor and a slide with asymmetric grooves.
A metal bar or plate with a linear array of asymmetric grooves has been designed to be shaken at low frequency by a voice coil, or linear actuator, mechanism which induces the particles to jump from one groove to the next. Larger particles with diameters greater than the groove depth were shown to move quicker, while particles with a diameter that is less than the groove depth were found to move slower, thus creating a sorting by size. Using this asymmetry in particle motion with particle size, it is shown that both the movement of unconsolidated particles along the slide provided both transportation and sorting mechanisms.

The initial motion of the plate was created by a rotary motor linked to create symmetric vibrations. The figure shows a graphic illustration of this system. The rotary motion can be used to sample unconsolidated material from a platform. A rotary motor causes linear oscillatory motion in the rod through a linkage, and causes particles in the grooves to move to higher-level grooves by being thrown from a lower groove. The linear actuation also could be developed with a voice coil actuator or any other linear motor. The use of asymmetric teeth increases the likelihood of a forward transfer of particles, and in each jump, the particles climb the toothlike steps. Introducing elliptical oscillations increases the efficiency of transfer by giving the sample movement vector normal to the slide axis.

An option to this design includes sieves to allow gauging of particle dimension. A distribution of particles is transported to the end of the groove rod. When particles enter a sieve with smaller holes, the excitation shakes them through the sieve. The excitation frequency is then increased, and the differentiated sample is then moved to the next larger size sieve where the process is repeated until all particles are sieved.

This work was done by Stewart Sherrit, James S. Scott, Yoseph Bar-Cohen, Mircea Badescu, and Xiaoqi Bao of Caltech for NASA’s Jet Propulsion Laboratory. For more information, download the Technical Support Package (free white paper) at www.techbriefs.com/tsp under the Mechanics/Machinery category. NPO-46334

Topics:
Emissions Exhaust emissions Mechanical Components Mechanics Metal finishing Metallurgy Particulate matter (PM) Plating Soils
This Brief includes a Technical Support Package (TSP).
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Mechanism for Particle Transport and Size Sorting via Low-Frequency Vibrations

(reference NPO-46334) is currently available for download from the TSP library.

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NASA Tech Briefs Magazine

This article first appeared in the August, 2010 issue of NASA Tech Briefs Magazine (Vol. 34 No. 8).

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Overview

The document outlines a novel mechanism developed by NASA's Jet Propulsion Laboratory for particle transport and size sorting using low-frequency vibrations. This technology is particularly relevant for future NASA missions that require in-situ exploration and analysis of soil and regolith samples to detect biomarkers and geological content.

The core innovation involves a flat plate or rod equipped with a linear array of asymmetric grooves. When subjected to low-frequency vibrations (around 4 Hz), this mechanism facilitates the movement and sorting of particles based on their size. Larger particles, which exceed the groove depth, move more quickly, while smaller particles travel slower, leading to effective size segregation. The system can also employ a rod with asymmetric grooves that contacts the subsurface at an angle and operates at a higher frequency (approximately 10 Hz) for sampling purposes.

The document emphasizes the importance of this technology in addressing the challenges of sample handling in future space missions. As missions increasingly require the analysis of powdered cuttings and soil grains, a compact and lightweight mechanism that can operate from landers or rovers is essential. The proposed solution not only transports particles but also sorts them, enhancing the efficiency of sample delivery to analytical instruments.

Illustrations in the document depict the system's design, including a schematic of the rotary motor setup and the grooved surface. Demonstrations of the sorting capability show how particles are arranged in a spectral shape, with larger particles positioned further left than smaller ones after a brief shaking period.

Overall, this invention represents a significant advancement in the field of particle manipulation, offering a practical solution for the effective handling of unconsolidated materials in extraterrestrial environments. The technology's potential applications extend beyond space exploration, suggesting broader implications for various scientific and commercial fields that require precise particle sorting and transport. The document serves as a technical support package, providing insights into the development and application of this innovative mechanism, which is poised to play a crucial role in future NASA missions.