A compact sampling tool mechanism that can operate at various temperatures, and transport and sieve particle sizes of powdered cuttings and soil grains with no moving parts, has been created using traveling surface acoustic waves (SAWs) that are emitted by an inter-digital transducer (IDT). The generated waves are driven at about 10 MHz, and it causes powder to move towards the IDT at high speed with different speeds for different sizes of particles, which enables these particles to be sieved.
This design is based on the use of SAWs and their propelling effect on powder particles and fluids along the path of the waves. Generally, SAWs are elastic waves propagating in a shallow layer of about one wavelength beneath the surface of a solid substrate. To generate SAWs, a piezoelectric plate is used that is made of LiNbO3 crystal cut along the x-axis with rotation of 127.8º along the y-axis. On this plate are printed pairs of fingerlike electrodes in the form of a grating that are activated by subjecting the gap between the electrodes to electric field. This configuration of a surface wave transmitter is called IDT. The IDT that was used consists of 20 pairs of fingers with 0.4-mm spacing, a total length of 12.5 mm. The surface wave is produced by the nature of piezoelectric material to contract or expand when subjected to an electric field.
Driving the IDT to generate wave at high amplitudes provides an actuation mechanism where the surface particles move elliptically, pulling powder particles on the surface toward the wavesource and pushing liquids in the opposite direction. This behavior allows the innovation to separate large particles and fluids that are mixed. Fluids are removed at speed (7.5 to 15 cm/s), enabling this innovation of acting as a bladeless wiper for raindrops. For the windshield design, the electrodes could be made transparent so that they do not disturb the driver or pilot.
Multiple IDTs can be synchronized to transport water or powder over larger distances. To demonstrate the transporting action, a video camera was used to record the movement. The speed of particles was measured from the video images.
This work was done by Yoseph Bar-Cohen, Xiaoqi Bao, Stewart Sherrit, Mircea Badescu, and Shyh-shiuh Lih of Caltech for NASA’s Jet Propulsion Laboratory. NPO-46252
This Brief includes a Technical Support Package (TSP).
High-Speed Transport of Fluid Drops and Solid Particles via Surface Acoustic Waves
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Overview
The document discusses a novel technology developed by the California Institute of Technology and NASA's Jet Propulsion Laboratory (JPL) for the high-speed transport of fluid drops and solid particles using surface acoustic waves (SAW). This innovative mechanism operates without any physically moving parts, significantly enhancing reliability and reducing the risk of mechanical failure.
The core of the invention involves the use of an Inter-Digital Transducer (IDT) that generates surface acoustic waves at approximately 10 MHz. These waves facilitate the movement of powder particles towards the IDT at varying speeds, depending on the size of the particles, effectively allowing for sieving. The technology also enables the transport of fluid drops, which can flow in the opposite direction to the powder, providing a unique capability to separate fluids from solid particles.
Key features of the invention include:
- A high-speed transport mechanism for solid fragments and powders without moving parts.
- A sieving mechanism for powdered samples, also without moving parts.
- The ability to transport fluid drops at high speeds.
- The operation of the mechanism across various temperatures, making it suitable for extreme environments, such as those found on other planets.
- A bladeless wiper function that can remove water from surfaces, which could be particularly useful in applications like windshield designs.
The document emphasizes the relevance of this technology for future NASA missions, particularly those involving in-situ exploration. As these missions require the analysis of samples for life biomarkers and geological content, the ability to control the flow of powders and fluids is critical. The compact nature of this mechanism allows for reduced system mass, power, and volume, which is essential for space applications.
Moreover, the technology's reliance on piezoelectric actuators enables it to function effectively in extreme temperatures, from the cold of Europa and Titan to the heat of Venus. This adaptability enhances the sample handling capabilities necessary for future exploratory missions, increasing the likelihood of success and enabling the development of micro-fluidic networks.
In summary, the document outlines a significant advancement in fluid and particle transport technology that holds promise for various scientific and commercial applications, particularly in the context of space exploration.
