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A latchable high-pressure thermohydraulic valve actuator
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. (ÅSTC)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology. (ÅSTC)
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
2012 (English)In: Sensors and Actuators A-Physical, ISSN 0924-4247, E-ISSN 1873-3069, Vol. 188, 292-297 p.Article in journal (Refereed) Published
Abstract [en]

This work presents a latchable thermohydraulic microactuator for use in high-pressure valves, e.g. for oceanic sampling in missions of long duration. Mounted on a miniature submersible, it can be used in confined spaces to explore previously unreachable environments. However, the device can be used in any high-pressure application where long duration open and/or closed valve states are required, and power consumption is an issue. The actuator is fabricated using standard batch-processes as photochemical machining, wet etching and photolithography. The actuation and latching mechanisms are both thermohydraulic, using solid-to-liquid phase transition of paraffin for actuation and of a low melting point alloy for latching. Focus of this work is on the endurance of the actuator to facilitate a bistable valve. The actuator managed to keep a deflected position for almost 50 hours to the load equivalent to 1.8 MPa applied pressure, after which the experiment was aborted. No pressure dependence was discovered in the latching losses, i.e. the difference in deflection before and after the actuator is powered off. Furthermore, the effect of intermixing of paraffin and the low melting point alloy was evaluated.

Place, publisher, year, edition, pages
Elsevier, 2012. Vol. 188, 292-297 p.
Keyword [en]
Fluid control, Bistable, Steel, Actuator, Paraffin, Low melting point alloy
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Microsystems Technology
Identifiers
URN: urn:nbn:se:uu:diva-171755DOI: 10.1016/j.sna.2011.11.027ISI: 000312692500039OAI: oai:DiVA.org:uu-171755DiVA: diva2:512251
Conference
The 16th International Conference on Solid-State Sensors, Actuators and Microsystems, 5-9 June, 2011, Beijing, CHINA
Available from: 2012-03-27 Created: 2012-03-27 Last updated: 2017-12-07Bibliographically approved
In thesis
1. Microsystems Technology for Underwater Vehicle Applications
Open this publication in new window or tab >>Microsystems Technology for Underwater Vehicle Applications
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The aim of this thesis work has been to investigate how miniaturization, such as microsystems technology, can potentially increase the scientific throughput in exploration of hard-to-reach underwater environments, such as the subglacial lakes of Antarctica, or other challenging environments, including cave systems and wrecks. A number of instruments and subsystems applicable to miniature submersibles have been developed and studied, and their potential to provide a high functionality density for size-restricted exploration platforms has been assessed.

To provide an onboard camera system with measurement capabilities, simulation and design tools for diffractive optics were developed, and microoptics realized to project reference patterns onto objects to reveal their topography. The influence of murky water on the measurement accuracy was also studied.

For longer-range mapping of the surroundings, and under conditions with even less visibility, the performance of a very small, high-frequency side-scanning sonar was investigated using extensive modeling and physical testing. In particular, the interference on the acoustic beam from tight mounting in a hull was investigated. A range in excess of 30 m and centimeter resolution were obtained.

Besides these systems, which can be used to navigate and map environments, a two-dimensional, thermal sensor for minute flows was developed. Measuring speed and direction of water flows, this sensor can aid in the general classification of the environment and also monitor the submersible’s movement. As the flow of waters in subglacial lakes is estimated to be minute, the detection limit and sensitivity were investigated.

Measurements of water properties are facilitated by the chip-based conductivity, temperature, and depth sensor system developed. Macroscopically, this is an essential oceanographic instrument with which salinity is determined. Contrary to what was expected, MHz frequencies proved to be advantageous for conductivity measurements.

Finally, sampling of water using an acoustically enriching microdevice, and even enabling return of pristine samples via the use of integrated latchable, high-pressure valves, was realized and evaluated. Particularly, investigations of the device’s ability to capture and hold on to microorganisms, were conducted.

Further developed and studied, these devices – as subsystems to miniature submersibles, or as stand-alone instruments – should enable exploration of previously unreachable submerged environments.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2012. 88 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 914
Keyword
Aquatic, Submersible, Underwater, Micro, Miniaturized, Sonar, Sidescan, Topography, Laser, Diffractive, Optics, Sampler, Particle, Microorganism, Acoustic, Enriching, Conductivity, Temperature, Depth, CTD, Flow
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Microsystems Technology
Identifiers
urn:nbn:se:uu:diva-171742 (URN)978-91-554-8323-4 (ISBN)
Public defence
2012-05-11, Polhelmsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Polacksbacken, Uppsala, 10:15 (Swedish)
Opponent
Supervisors
Projects
Deeper Access, Deeper Understanding (DADU)
Available from: 2012-04-20 Created: 2012-03-27 Last updated: 2013-02-20
2. High-Pressure Microfluidics
Open this publication in new window or tab >>High-Pressure Microfluidics
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In this thesis, some fundamentals and possible applications of high-pressure microfluidics have been explored. Furthermore, handling fluids at high pressures has been addressed, specifically by creating and characterizing strong microvalves and pumps.

A variety of microstructuring techniques was used to realize these microfluidic devices, e.g., etching, lithography, and bonding. To be able to handle high pressures, the valves and pumps need to be strong. This necessitates a strong actuator material. In this thesis, the material of choice is paraffin wax.

A new way of latching paraffin-actuated microvalves into either closed or open position has been developed, using the low thermal conductivity of paraffin to create large thermal gradients within a microactuator. This allows for long open and closed times without power consumption.

In addition, three types of paraffin-actuated pumps are presented: A peristaltic high-pressure pump with integrated temperature control, a microdispensing pump with high repeatability, and a pump system with two pumps working with an offset to reduce flow irregularities. Furthermore, the fundamental behavior of paraffin as a microactuator material has been explored by finite element modeling.

One possibility that arises with high-pressure microfluidics, is the utilization of supercritical fluids for different applications. The unique combination of material properties found in supercritical fluids yields them interesting applications in, e.g., extraction and cleaning. In an attempt to understand the microfluidic behavior of supercritical carbon dioxide, the two-phase flow, with liquid water as the second phase, in a microchannel has been studied and mapped with respect to both flow regime and droplet behavior at a bi-furcating outlet.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2013. 53 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1085
Keyword
phase change, actuator, valve, pump, supercritical fluid
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Microsystems Technology
Identifiers
urn:nbn:se:uu:diva-208915 (URN)978-91-554-8773-7 (ISBN)
Public defence
2013-11-29, Polhemsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, 751 21, Uppsala, 09:30 (English)
Opponent
Supervisors
Funder
Swedish Research Council
Available from: 2013-11-07 Created: 2013-10-10 Last updated: 2014-01-23

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Ogden, SamJonsson, JonasThornell, GregerHjort, Klas

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