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  • 1.
    Berglund, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Miniature Plasma Sources for High-Precision Molecular Spectroscopy in Planetary Exploration2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The prospect of finding life outside Earth has fascinated mankind for ages, and new technology continuously pushes the boundary of how remote and how obscure evidence we can find. Employing smaller, or completely new, types of landers and robots, and equipping them with miniature instruments would indeed revolutionize exploration of other planets and moons.

    In this thesis, microsystems technology is used to create a miniature high-precision isotope-resolving molecular spectrometer utilizing the optogalvanic effect. The heart of the instrument, as well as this thesis, is a microplasma source.

    The plasma source is a split-ring resonator, chosen for its simplicity, pressure range and easily accessible plasma, and modified to fit the challenging application, e.g., by the adding of an additional ground plane for improved electromagnetic shielding, and the integration of microscopic plasma probes to extract the pristine optogalvanic signal.

    Plasma sources of this kind have been manufactured in both printed circuit board and alumina, the latter for its chemical inertness and for compatibility with other devices in a total analysis system. From previous studies, classical optogalvanic spectroscopy (OGS), although being very sensitive, is known to suffer from stability and reproducibility issues. In this thesis several studies were conducted to investigate and improve these shortcomings, and to improve the signal-to-noise ratio. Moreover, extensive work was put into understanding the underlying physics of the technique.

    The plasma sources developed here, are the first ever miniature devices to be used in OGS, and exhibits several benefits compared to traditional solutions. Furthermore, it has been confirmed that OGS scales well with miniaturization. For example, the signal strength does not decrease as the volume is reduced like in regular absorption spectroscopy. Moreover, the stability and reproducibility are greatly increased, in some cases as much as by two orders of magnitude, compared with recent studies made on a classical OGS setup. The signal-to-noise ratio has also been greatly improved, e.g., by enclosing the sample cell and by biasing the plasma. Another benefit of a miniature sample cell is the miniscule amount of sample it requires, which can be important in many applications where only small amounts of sample are available.

    To conclude: With this work, an important step toward a miniature, yet highly performing, instrument for detection of extraterrestrial life, has been taken.

    List of papers
    1. Operation characteristics and optical emission distribution of a miniaturized silicon through-substrate split-ring resonator microplasma source
    Open this publication in new window or tab >>Operation characteristics and optical emission distribution of a miniaturized silicon through-substrate split-ring resonator microplasma source
    2014 (English)In: Journal of microelectromechanical systems, ISSN 1057-7157, E-ISSN 1941-0158, Vol. 23, no 6, p. 1340-1345Article in journal (Refereed) Published
    Abstract [en]

    There are many new microplasma sources being developed for a wide variety of applications, each with different properties tailored to its specific use. Microplasma sources enable portable instruments for, e.g., chemical analysis, sterilization, or activation of substances. A novel microplasma source, based on a microstrip split-ring resonator design with electrodes integrated in its silicon substrate, was designed, manufactured, and evaluated. This device has a plasma discharge gap with a controlled volume and geometry, and offers straightforward integration with other microelectromechancial systems (MEMS) components, e.g., microfluidics. The realized device was resonant at around 2.9 GHz with a quality factor of 18.7. Two different operational modes were observed with the plasma at high pressure being confined in the gap between the electrodes, whereas the plasma at low pressures appeared between the ends of the electrodes on the backside. Measurement of the angular distribution of light emitted from the device with through-substrate electrodes showed narrow emission lobes compared with a reference plasma source with on-substrate electrodes.

    National Category
    Physical Sciences Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-239111 (URN)10.1109/JMEMS.2014.2312849 (DOI)000345851100010 ()
    Available from: 2015-01-05 Created: 2014-12-18 Last updated: 2017-12-05Bibliographically approved
    2. Evaluation of a microplasma source based on a stripline split-ring resonator
    Open this publication in new window or tab >>Evaluation of a microplasma source based on a stripline split-ring resonator
    2013 (English)In: Plasma sources science & technology (Print), ISSN 0963-0252, E-ISSN 1361-6595, Vol. 22, no 5, p. 055017-Article in journal (Refereed) Published
    Abstract [en]

    In this paper, a stripline split-ring resonator microwave-induced plasma source, aimed for integration in complex systems, is presented and compared with a traditional microstrip design. Devices based on the two designs are evaluated using a plasma breakdown test setup for measuring the power required to ignite plasmas at different pressures. Moreover, the radiation efficiency of the devices is investigated with a Wheeler cap, and their electromagnetic compatibility is investigated in a variable electrical environment emulating an application. Finally, the basic properties of the plasma in the two designs are investigated in terms of electron temperature, plasma potential and ion density. The study shows that, with a minor increase in plasma ignition power, the stripline design provides a more isolated and easy-to-integrate alternative to the conventional microstrip design. Moreover, the stripline devices showed a decreased antenna efficiency as compared with their microstrip counterparts, which is beneficial for plasma sources. Furthermore, the investigated stripline devices exhibited virtually no frequency shift in a varying electromagnetic environment, whereas the resonance frequency of their microstrip counterparts shifted up to 17.5%. With regard to the plasma parameters, the different designs showed only minor differences in electron temperature, whereas the ion density was higher with the stripline design.

    Place, publisher, year, edition, pages
    Institute of Physics (IOP), 2013
    Keywords
    Split-ring resonator, Microwave plasma, Microstrip, Stripline, Plasma, Wheeler cap, Langmuir probe
    National Category
    Other Physics Topics Engineering and Technology
    Research subject
    Engineering Science with specialization in Microsystems Technology; Engineering Science with specialization in Microwave Technology
    Identifiers
    urn:nbn:se:uu:diva-206792 (URN)10.1088/0963-0252/22/5/055017 (DOI)000325246400017 ()
    Available from: 2013-09-04 Created: 2013-09-04 Last updated: 2017-12-06Bibliographically approved
    3. Microplasma source for optogalvanic spectroscopy of nanogram samples
    Open this publication in new window or tab >>Microplasma source for optogalvanic spectroscopy of nanogram samples
    2013 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 114, no 3, p. 033302-Article in journal (Refereed) Published
    Abstract [en]

    The demand for analysis of smaller samples in isotopic ratio measurements of rare isotopes is continuously rising with the development of new applications, particularly in biomedicine. Interesting in this aspect are methods based on optogalvanic spectroscopy, which have been reported to facilitate both 13C-to-12C and 14C-to-12C ratio measurements with high sensitivity. These methods also facilitate analysis of very small samples, down to the microgram range, which makes them very competitive to other technologies, e.g., accelerator mass spectroscopy. However, there exists a demand for moving beyond the microgram range, especially from regenerative medicine, where samples consist of, e.g., DNA, and, hence, the total sample amount is extremely small. Making optogalvanic spectroscopy of carbon isotopes applicable to such small samples, requires miniaturization of the key component of the system, namely the plasma source, in which the sample is ionized before analysis. In this paper, a novel design of such a microplasma source based on a stripline split-ring resonator is presented and evaluated in a basic optogalvanic spectrometer. The investigations focus on the capability of the plasma source to measure the optogalvanic signal in general, and the effect of different system and device specific parameters on the amplitude and stability of the optogalvanic signal in particular. Different sources of noise and instabilities are identified, and methods of mitigating these issues are discussed. Finally, the ability of the cell to handle analysis of samples down to the nanogram range is investigated, pinpointing the great prospects of stripline split-ring resonators in optogalvanic spectroscopy.

    Place, publisher, year, edition, pages
    American Institute of Physics (AIP), 2013
    Keywords
    nanostructured materials, optogalvanic spectroscopy, plasma instability, plasma probes, plasma sources, strip line resonators
    National Category
    Other Physics Topics Engineering and Technology
    Research subject
    Engineering Science with specialization in Microsystems Technology; Engineering Science with specialization in Ion Physics; Engineering Science with specialization in Microwave Technology
    Identifiers
    urn:nbn:se:uu:diva-204156 (URN)10.1063/1.4813414 (DOI)000322202700014 ()
    Available from: 2013-07-22 Created: 2013-07-22 Last updated: 2017-12-06Bibliographically approved
    4. Stripline split-ring resonator with integrated optogalvanic sample cell
    Open this publication in new window or tab >>Stripline split-ring resonator with integrated optogalvanic sample cell
    Show others...
    2014 (English)In: Laser Physics Letters, ISSN 1612-2011, Vol. 11, no 4, p. 045701-Article in journal, Letter (Refereed) Published
    Abstract [en]

    Intracavity optogalvanic spectroscopy (ICOGS) has been proposed as a method for unambiguous detection of rare isotopes. Of particular interest is 14C, where detection of extremely low concentrations in the 1:1015 range (14C:12C), is of interest in, e.g., radiocarbon dating and pharmaceutical sciences. However, recent reports show that ICOGS suffers from substantial problems with reproducibility. To qualify ICOGS as an analytical method, more stable and reliable plasma generation and signal detection are needed. In our proposed setup, critical parameters have been improved. We have utilized a stripline split-ring resonator microwave-induced microplasma source to excite and sustain the plasma. Such a microplasma source offers several advantages over conventional ICOGS plasma sources. For example, the stripline split-ring resonator concept employs separated plasma generation and signal detection, which enables sensitive detection at stable plasma conditions. The concept also permits in situ observation of the discharge conditions, which was found to improve reproducibility. Unique to the stripline split-ring resonator microplasma source of in this study, is that the optogalvanic sample cell has been embedded in the device itself. This integration enabled improved temperature control and more stable and accurate signal detection. Significant improvements are demonstrated, including reproducibility, signal-to-noise ratio and precision.

    Place, publisher, year, edition, pages
    Institute of Physics (IOP), 2014
    Keywords
    Optogalvanic spectroscopy, Laser-assisted ratio analyzer, Split-ring resonator, microwave-induced microplasma source
    National Category
    Atom and Molecular Physics and Optics Fusion, Plasma and Space Physics Other Materials Engineering
    Research subject
    Physics; Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-218769 (URN)10.1088/1612-2011/11/4/045701 (DOI)000332768800011 ()
    Funder
    Swedish Research Council, A0442201
    Available from: 2014-02-17 Created: 2014-02-17 Last updated: 2015-05-12Bibliographically approved
    5. Improved optogalvanic detection with voltage biased Langmuir probes
    Open this publication in new window or tab >>Improved optogalvanic detection with voltage biased Langmuir probes
    2014 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 116, no 24, p. 243301-Article in journal (Refereed) Published
    Abstract [en]

    Optogalvanic detectors show great potential for infrared spectroscopy, especially in cavity enhanced techniques where they, in contrast to ordinary absorption detectors, can perform intracavity measurements. This enables them to utilize the signal-to-noise ratio improvement gained from the extended effective path length inside an optical cavity, without losing signal strength due to the limited amount of light exiting through the rear mirror. However, if optogalvanic detectors are to become truly competitive, their intrinsic sensitivity and stability has to be improved. This, in turn, requires a better understanding of the mechanisms behind the generation of the optogalvanic signal. The study presented here focuses on an optogalvanic detector based on a miniaturized stripline split-ring resonator plasma source equipped with Langmuir probes for detecting the optogalvanic signal. In particular, the effect of applying a constant bias voltage to one of the probes is investigated, both with respect to the sensitivity and stability, and to the mechanism behind the generation of the signal. Experiments with different bias voltages at different pressures and gas composition have been conducted. In particular, two different gas compositions (pure CO2 and 0.25% CO2 in 99.75% N-2) at six different pressures (100 Pa to 600 Pa) have been studied. It has been shown that probe biasing effectively improves the performance of the detector, by increasing the amplitude of the signal linearly over one order of magnitude, and the stability by about 40% compared with previous studies. Furthermore, it has been shown that relatively straightforward plasma theory can be applied to interpret the mechanism behind the generation of the signal, although additional mechanisms, such as rovibrational excitation from electron-molecule collisions, become apparent in CO2 plasmas with electron energies in the 1-6 eV range. With the achieved performance improvement and the more solid theoretical framework presented here, stripline split-ring resonator optogalvanic detectors can evolve into a compact, inexpensive, and easy-to-operate alternative for future infrared spectrometers. (C) 2014 AIP Publishing LLC.

    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:uu:diva-242865 (URN)10.1063/1.4904964 (DOI)000347164300003 ()
    Available from: 2015-02-04 Created: 2015-02-02 Last updated: 2017-12-05Bibliographically approved
    6. Evaluation of dielectric properties of HTCC alumina for realization of plasma sources
    Open this publication in new window or tab >>Evaluation of dielectric properties of HTCC alumina for realization of plasma sources
    2015 (English)In: Journal of Electronic Materials, ISSN 0361-5235, E-ISSN 1543-186X, Vol. 44, no 10, p. 3654-3660Article in journal (Refereed) Published
    Abstract [en]

    As the sensitivity of optogalvanic spectroscopy based on prototype microplasma sources increases, contamination from composite materials in the printed circuit board used starts to become a concern. In this paper, a transfer to high-temperature cofired alumina and platinum is made and evaluated. The high-purity alumina provides an inert plasma environment, and allows for temperatures above 1000A degrees C, which is beneficial for future integration of a combustor. To facilitate the design of high-end plasma sources, characterization of the radio frequency (RF) parameters of the materials around 2.6 GHz is carried out. A RF resonator structure was fabricated in both microstrip and stripline configurations. These resonators were geometrically and electrically characterized, and epsilon (r) and tan were calculated using the RF waveguide design tool Wcalc. The resulting epsilon (r) for the microstrip and stripline was found to be 10.68 (+/- 0.12) and 9.65 (+/- 0.14), respectively. The average tan of all devices was found to be 0.0011 (+/- 0.0007). With these parameters, a series of proof-of-concept plasma sources were fabricated and evaluated. Some problems in the fabrication stemmed from the lamination and difficulties with the screen-printing, but a functioning plasma source was demonstrated.

    National Category
    Ceramics Engineering and Technology Physical Sciences
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-251300 (URN)10.1007/s11664-015-3901-7 (DOI)000360672900061 ()
    Funder
    Swedish National Space BoardKnut and Alice Wallenberg Foundation
    Available from: 2015-04-15 Created: 2015-04-15 Last updated: 2017-12-04Bibliographically approved
    7. Manufacturing Miniature Langmuir probes by Fusing Platinum Bond Wires
    Open this publication in new window or tab >>Manufacturing Miniature Langmuir probes by Fusing Platinum Bond Wires
    2015 (English)In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 25, no 10, article id 105012Article in journal (Refereed) Published
    Abstract [en]

    This paper reports on a novel method for manufacturing microscopic Langmuir probes with spherical tips from platinum bond wires for plasma characterization in microplasma sources by fusing. Here, the resulting endpoints, formed by droplets of a fused wire, are intended to act as a spherical Langmuir probe. For studying the fusing behavior, bond wires were wedge-bonded over a 2 mm wide slit, to emulate the final application, and fused at different currents and voltages. For electrical isolation, a set of wires were coated with a 4 µm thick layer of Parylene before they were fused. After fusing, the gap size, as well as the shape and area of the ends of the remaining stubs were measured. The yield of the process was also investigated, and the fusing event was studied using a high-speed camera for analyzing the dynamics of fusing. Four characteristic tip shapes were observed: spherical, semi-spherical, serpentine shaped and folded. The stub length leveled out at ~420µm. The fusing of the coated wires required a higher power for attaining a spherical shape. Finally, a Parylene coated bond wire was integrated into a stripline split-ring resonator (SSRR) microplasma source, and fused to form two Langmuir probes with spherical endpoints. These probes were used for measuring the I-V characteristics of a plasma generated by the SSRR. In a voltage range between -60 V and 60 V, the fused stubs exhibited the expected behavior of spherical Langmuir probes and will be considered for future integration.

    Keywords
    Langmuir probe; bond wire; fusing; microplasma source
    National Category
    Physical Sciences Engineering and Technology
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-251306 (URN)10.1088/0960-1317/25/10/105012 (DOI)000366827400028 ()
    Funder
    Swedish National Space BoardKnut and Alice Wallenberg Foundation
    Available from: 2015-04-15 Created: 2015-04-15 Last updated: 2018-08-03Bibliographically approved
  • 2.
    Berglund, Martin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Khaji, Zahra
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Klintberg, Lena
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Persson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Sturesson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Söderberg Breivik, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Thornell, Greger
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Extreme-temperature lab on a chip for optogalvanic spectroscopy of ultra small samples – key components and a first integration attempt2016In: Journal of Physics: Conference Series, Institute of Physics (IOP), 2016Conference paper (Refereed)
    Abstract [en]

    This is a short summary of the authors’ recent R&D on valves, combustors, plasma sources, and pressure and temperature sensors, realized in high-temperature co-fired ceramics, and an account for the first attempt to monolithically integrate them to form a lab on a chip for sample administration, preparation and analysis, as a stage in optogalvanic spectroscopy.

  • 3.
    Blomqvist, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Construction and evaluation of a magnetoresistive ground penetrating radar system2011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This Master Thesis examines the possibility to apply a magnetometer developed by the Ångstöm space technology center to a small magnetic ground penetrating radar system with dimension in the order of one dm³. The magnetometer is broadband (DC-1GHz) and miniaturized. Loop antennas are used to transmit the signal.

       A series of experiments have been performed in order to characterize the system, mainly examining the ability to determine distance to a target, using continuous sine wave signals and pulse trains. Standing wave patterns are formed between antenna and target and can be used for determining distance in the continuous case. When using a pulse train, the echo from the target could not be resolved using the current experiment set up, distance could therefore not be determined.

  • 4.
    Halvarsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Ett kommunikationssystem för fiberoptisk överföring av bilddata förvärvad av en miniatyriserad undervattensfarkost2011Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report describes the development and implementation of a system for transmitting digital information at high speeds from a miniaturized submersible developed by the Ångström Space Technology Centre at Uppsala University. For instance, the vehicle shall transmit image data – even stream live video - through an optical fibre to a monitor in a ground station. Hence, the system shall be used both to convert the image data to make it transmittable, and to recreate it at the receiver.

    The work includes a pre-study of the programming language and the technology used. A concept for the solution is presented together with main components later broken down into internal functions. Following on this, other components that were necessary for fulfilling the function of the main components were identified. The system was developed with the hardware description language VHDL in order to be implementable and testable on an FPGA platform, but also to be transferable to other devices.

    After the development and implementation on the hardware platform, the system was tested and verified. Analysis showed that some modifications were required to produce the desired results. These modifications implied some deviations from the assignment statement but gave rise to suggestions for further improvement of the concept. All in all, however, the solution was successfully verified since the transmitted data was possible to recreate the original image.

    The report contains drawings of the developed system and the source code it consists of.

  • 5.
    Jonsson, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Microsystems Technology for Underwater Vehicle Applications2012Doctoral 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.

    List of papers
    1. Simulation, manufacturing, and evaluation of a sonar for a miniaturized submersible explorer
    Open this publication in new window or tab >>Simulation, manufacturing, and evaluation of a sonar for a miniaturized submersible explorer
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    2010 (English)In: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, ISSN 0885-3010, E-ISSN 1525-8955, Vol. 57, no 2, p. 490-495Article in journal (Refereed) Published
    Abstract [en]

    Single-beam side-scan sonar elements, to be fitted on a miniaturized submersible, are here simulated, manufactured, and evaluated. Finite element analysis simulations are compared with measurements, and an overall observation is that the agreement between simulations and measurements deviates from the measured values of 1.5 to 2°, for the narrow lobe angle, by less than 10% for most models. An overall finding is that the lobe width along the track direction can be accurately simulated and, hence, the resolution of the sonars can be predicted. This paper presents, to the authors’ knowledge, the world’s smallest side-scan sonars.

    Keywords
    Sonar, beam width, acoustic imaging
    National Category
    Fluid Mechanics and Acoustics
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-121440 (URN)10.1109/TUFFC.2010.1429 (DOI)000274817300023 ()
    Projects
    Deeper Access, Deeper Understanding (DADU)
    Note

    This article is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, this work may not be reposted without the explicit permission of the copyright holder.

    Available from: 2010-03-23 Created: 2010-03-23 Last updated: 2017-12-12Bibliographically approved
    2. Enclosure-Induced Interference Effects in a Miniaturized Sidescan Sonar
    Open this publication in new window or tab >>Enclosure-Induced Interference Effects in a Miniaturized Sidescan Sonar
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    2012 (English)In: IEEE Journal of Oceanic Engineering, ISSN 0364-9059, E-ISSN 1558-1691, Vol. 37, no 2, p. 236-243Article in journal (Refereed) Published
    Abstract [en]

    On, for instance, the miniaturized submersible explorer, Deeper Access, Deeper Understanding (DADU), only 20 cm in length and 5 cm in diameter, the sidescan sonar needs to be tightly mounted in the hull. Finite element analysis (FEA) as well as physical measurements were used to investigate the effects of beam interaction with acoustically nearby rigid boundaries. Computer simulations showed the first major dip in the beam shape to vary in strength, size, and position with the enclosure wall height, from a position of 47° at 0.0-mm wall height to 32° at 3.0-mm wall height. Hydrophonic measurements on the manufactured test device confirmed these values to within 9%, varying between 47° and 29°. In addition, Schlieren imaging was proposed and used as a noninvasive means of qualitative beam shape characterization. A field test was performed with the enclosure height set to 0 and 3 mm. With the latter height, a dark band, corresponding to a sonar sensitivity dip at about 30° in the beam, appeared in the sonar image. It was found that the beam shape is sensitive to small mounting errors, in this case where the wavelength of the sonar is on the same size scale as the enclosure. Furthermore, it was found that FEA models can be used to accurately predict enclosure effects on sonar beam shapes, and Schlieren imaging can be used to visually detect the shape deformations in mounted sonar devices.

    Keywords
    Beam shape, finite element analysis (FEA), miniaturize, Schlieren, sidescan sonar
    National Category
    Fluid Mechanics and Acoustics
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-171730 (URN)10.1109/JOE.2012.2188160 (DOI)000303326500007 ()
    Projects
    Deeper Access, Deeper Understanding (DADU)
    Available from: 2012-03-26 Created: 2012-03-26 Last updated: 2017-12-07Bibliographically approved
    3. A compact system to extract topography information from scenes viewed by a miniaturized submersible explorer
    Open this publication in new window or tab >>A compact system to extract topography information from scenes viewed by a miniaturized submersible explorer
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    2012 (English)In: Sensors and Actuators A-Physical, ISSN 0924-4247, E-ISSN 1873-3069, Vol. 188, no SI, p. 401-410Article in journal, Meeting abstract (Refereed) Published
    Abstract [en]

    In images taken underwater, it is generally difficult to correctly extract distances and geometric informationof objects. Different techniques, collectively referred to as photogrammetry, exist to measurefeatures in images. One of these is to project a reference pattern onto an object in a scene viewed by acamera, and register the distortion of this pattern, to calculate the shape of, and distance to, that object.This method is implemented here on a miniaturized submersible explorer equipped with, among manyother instruments, a camera. Diffractive optical elements (DOEs) have been designed and manufacturedusing microsystems technology, to, together with a laser diode, camera, and in-house developed software,provide a compact system for projecting reference patterns and analyzing their deformations. Thesystem has been characterized by measuring the distances and angles of objects in a water tank, andattempting to reproduce their shapes. The range of operation of the system, verified to be at least onemeter, is limited by the compact mounting in the small submersible and the cameras’ performance.The system was found to work well under turbid conditions as well as in water containing larger particles.Together with a vehicle-mounted camera, the compact and low-power DOE laser projection systemenables topographical measurement.

    Keywords
    Photogrammetry, Diffractive, Laser, Underwater, Images, Miniaturized
    National Category
    Engineering and Technology
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-171732 (URN)10.1016/j.sna.2012.02.034 (DOI)000312692500054 ()
    Conference
    The 16th International Conference on Solid-State Sensors, Actuators and Microsystems, 5-9 June, 2011, Beijing, CHINA
    Projects
    Deeper Access, Deeper Understanding (DADU)
    Available from: 2012-03-26 Created: 2012-03-26 Last updated: 2017-12-07Bibliographically approved
    4. Acoustically enriching, large-depth aquatic sampler
    Open this publication in new window or tab >>Acoustically enriching, large-depth aquatic sampler
    Show others...
    2012 (English)In: Lab on a Chip, ISSN 1473-0197, E-ISSN 1473-0189, Vol. 12, no 9, p. 1619-1628Article in journal (Refereed) Published
    Abstract [en]

    In marine biology, it is useful to collect water samples when exploring the distribution and diversity of microbial communities in underwater environments. In order to provide, e.g., a miniaturized submersible explorer with the capability of collecting microorganisms, a compact sample enrichment system has been developed. The sampler is 30 mm long, 15 mm wide, and just a few millimetres thick. Integrated in a multilayer steel, polyimide and glass construction is a microfluidic channel with piezoelectric transducers, where microorganism and particle samples are collected and enriched, using acoustic radiation forces for gentle and labelless trapping. High-pressure, latchable valves, using paraffin as the actuation material, at each end of the microfluidic channel keep the collected sample pristine. A funnel structure raised above the surface of the device directs water into the microfluidic channel as the vehicle propels itself or when there is a flow across its hull. The valves proved leak proof to a pressure of 2.1 MPa for 19 hours and momentary pressures of 12.5 MPa, corresponding to an ocean depth of more than 1200 metres. By reactivating the latching mechanism, small leakages through the valves could be remedied, which could thus increase the leak-less operational time. Fluorescent particles, 1.9 µm in diameter, were successfully trapped in the microfluidic channel at flow rates up to 15 ml min-1, corresponding to an 18.5 cm s-1 external flow rate of the sampler. In addition, liquid-suspended GFP-marked yeast cells were successfully trapped.

    Keywords
    Acoustic, microorganism, enriching, trap, valve, paraffin, sampler, marine, actuator
    National Category
    Engineering and Technology
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-171734 (URN)10.1039/C2LC00025C (DOI)000302368200009 ()
    Projects
    Deeper Access, Deeper Understanding (DADU)
    Available from: 2012-03-26 Created: 2012-03-26 Last updated: 2017-12-07Bibliographically approved
    5. A latchable high-pressure thermohydraulic valve actuator
    Open this publication in new window or tab >>A latchable high-pressure thermohydraulic valve actuator
    2012 (English)In: Sensors and Actuators A-Physical, ISSN 0924-4247, E-ISSN 1873-3069, Vol. 188, p. 292-297Article 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
    Keywords
    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:nbn:se:uu:diva-171755 (URN)10.1016/j.sna.2011.11.027 (DOI)000312692500039 ()
    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
    6. Two-Dimensional Thermal Velocity Sensor for Submersible navigation and Minute Flow Measurements
    Open this publication in new window or tab >>Two-Dimensional Thermal Velocity Sensor for Submersible navigation and Minute Flow Measurements
    2013 (English)In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 13, no 1, p. 359-370Article in journal (Refereed) Published
    Abstract [en]

    A 2-D thermal velocity microsensor for use as a navigational aid and for flow measurements on a miniaturized submersible is developed in this paper. The sensor with nickel heater and temperature sensors on a Pyrex substrate, designed for mounting on the outside of the submersible hull, is fabricated and tested in an application-like environment and proven to be able to measure water speed from zero to 40 mm/s with a power consumption less than 15 mW and determine the flow direction with an error less than ±8°. Finite Element Analysis is used to investigate design and operation parameters and possible biofouling effects on the sensor signal. The effect on shape and orientation of the sensor's mounting surface is also studied.

    National Category
    Other Materials Engineering
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-171767 (URN)10.1109/JSEN.2012.2216866 (DOI)000313685400028 ()
    Available from: 2012-03-27 Created: 2012-03-27 Last updated: 2017-12-07Bibliographically approved
    7. Towards chip-based salinity measurements for small submersibles and biologgers
    Open this publication in new window or tab >>Towards chip-based salinity measurements for small submersibles and biologgers
    2013 (English)In: International Journal of Oceanography, ISSN 1687-9406, E-ISSN 1687-9414, Vol. 2013, p. 529674-Article in journal (Refereed) Published
    Abstract [en]

    Water’s salinity plays an important role in the environment. It can be determined by measuring conductivity, temperature, anddepth (CTD). The corresponding sensor systems are commonly large and cumbersome. Here, a 7.5 × 3.5mm chip, containingmicrostructured CTD sensor elements, has been developed. On this, 1.5mm2 gold finger electrodes are used to measure theimpedance, and thereby the conductivity of water, in the MHz frequency range. Operation at these frequencies resulted in highersensitivities than those at sub-MHz frequencies. Up to 14 kΩ per parts per thousand salt concentration was obtained repeatedlyfor freshwater concentrations.This was three orders of magnitude higher than that obtained for concentrations in and above thebrackish range. A platinumelectrode is used to determine a set ambient temperature with an accuracy of 0.005∘C.Membranes withNichrome strain gauges responded to a pressure change of 1 bar with a change in resistance of up to 0.21Ω. A linear fit to data over7 bars gave a sensitivity of 0.1185Ω/bar with an R2 of 0.9964. This indicates that the described device can be used in size-limitedapplications, like miniaturized submersibles, or as a bio-logger on marine animals.

    Place, publisher, year, edition, pages
    Hindawi Publishing Corporation, 2013
    Keywords
    Conductivity, Temperature, Depth, CTD, Pressure, Marine, thin film, micro
    National Category
    Engineering and Technology
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-171740 (URN)10.1155/2013/529674 (DOI)
    Projects
    Deeper Access, Deeper Understanding (DADU)
    Funder
    Mistra - The Swedish Foundation for Strategic Environmental Research
    Available from: 2012-03-27 Created: 2012-03-27 Last updated: 2017-12-07Bibliographically approved
  • 6.
    Khaji, Zahra
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Klintberg, Lena
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Barbade, Dhananjay
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Palmer, Kristoffer
    SSC Nanospace.
    Thornell, Greger
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Endurance and Failure of an Alumina-based Monopropellant Microthruster with Integrated Heater, Catalytic Bed and Temperature Sensors2017In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 27, no 5, p. 1-11, article id 055011Article in journal (Refereed)
    Abstract [en]

    Monopropellant ceramic microthrusters with an integrated heater, catalytic bed and two temperature sensors, but of various designs, were manufactured by milling a fluidic channel and chamber, and a nozzle, and screen printing platinum patterns on green tapes of alumina that were stacked and laminated before sintering. In order to increase the surface area of the catalytic bed, the platinum paste was mixed with a sacrificial paste that disappeared during sintering, to leave behind a porous and rough layer. As an early development level in manufacturing robust and high-temperature tolerant microthrusters, the influence of design on the temperature gradients and dry temperature tolerance of the devices was studied. On average, the small reaction chambers showed a more than 1.5 times higher dry temperature tolerance (in centigrade) compared to devices with larger chambers, independent of the heater and device size. However, for a given temperature, big devices consumed on average 2.9 times more power than the small ones. It was also found that over the same area and under the same heating conditions, devices with small chambers were subjected to approximately 40% smaller temperature differences. A pressure test done on two small devices with small chambers revealed that pressures of at least 26.3 bar could be tolerated. Above this pressure, the interfaces failed but the devices were not damaged. To investigate the cooling effect of the micropropellant, the endurance of a full thruster was also studied under wet testing where it was fed with 31 wt.% hydrogen peroxide. The thruster demonstrated complete evaporation and/or full decomposition at a power above 3.7 W for a propellant flow of 50 mu l min(-1). At this power, the catalytic bed locally reached a temperature of 147 degrees C. The component was successfully heated to an operating temperature of 307 degrees C, where it cracked. Under these firing conditions, and assuming complete decomposition, calculations give a thrust and specific impulse of 0.96 mN and 106 s, respectively. In the case of evaporation, the corresponding values are calculated to be 0.84 mN and 92 s.

  • 7.
    Khaji, Zahra
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Klintberg, Lena
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Palmer, Kristoffer
    SSC Nanospace, Uppsala, Sweden.
    Thornell, Greger
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Catalytic Effect of Platinum and Silver in a Hydrogen Peroxide Monopropellant Ceramic MicrothrusterIn: Sensors and Actuators A-Physical, ISSN 0924-4247, E-ISSN 1873-3069, ISSN 0924-4247Article in journal (Refereed)
  • 8.
    Khaji, Zahra
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Klintberg, Lena
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Thornell, Greger
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Manufacturing and characterization of a ceramic single-use microvalve2016In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 26, no 9, article id 095002Article in journal (Refereed)
    Abstract [en]

    We present the manufacturing and characterization of a ceramic single-use microvalve withthe potential to be integrated in lab-on-a-chip devices, and forsee its utilization in space andother demanding applications. A 3 mm diameter membrane was used as the flow barrier, andthe opening mechanism was based on cracking the membrane by inducing thermal stresses onit with fast and localized resistive heating.

    Four manufacturing schemes based on high-temperature co-fired ceramic technology werestudied. Three designs for the integrated heaters and two thicknesses of 40 and 120 μmfor the membranes were considered, and the heat distribution over their membranes, therequired heating energies, their opening mode, and the flows admitted through were compared.Furthermore, the effect of applying +1 and −1 bar pressure difference on the membraneduring cracking was investigated. Thick membranes demonstrated unpromising results forlow-pressure applications since the heating either resulted in microcracks or cracking of thewhole chip. Because of the higher pressure tolerance of the thick membranes, the designwith microcracks can be considered for high-pressure applications where flow is facilitatedanyway. Thin membranes, on the other hand, showed different opening sizes depending onheater design and, consequently, heat distribution over the membranes, from microcracks toholes with sizes of 3–100% of the membrane area. For all the designs, applying +1 bar overpressure contributed to bigger openings, whereas −1 bar pressure difference only did so forone of the designs, resulting in smaller openings for the other two. The energy required forbreaking these membranes was a few hundred mJ with no significant dependence on designand applied pressure. The maximum sustainable pressure of the valve for the current designand thin membranes was 7 bar.

  • 9.
    Khaji, Zahra
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Sturesson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC). Swedish National Defence College.
    Hjort, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Klintberg, Lena
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Thornell, Greger
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Investigation of the storage and release of oxygen in a Cu-Pt element of a high-temperature microcombustor2014In: The 14th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications(PowerMEMS 2014), Institute of Physics (IOP), 2014Conference paper (Refereed)
    Abstract [en]

    A miniature combustor for converting organic samples into CO2 with application in carbon isotopic measurements has been manufactured and evaluated. The combustor was made of High-Temperature Co-fired Ceramic (HTCC) alumina green tapes. The device has a built-in screen printed heater and a temperature sensor made of platinum, co-sintered with the ceramic. A copper oxide oxygen supply was added to the combustor after sintering by in-situ electroplating of copper on the heater pattern followed by thermal oxidation. Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and Thermal Gravimetric Analysis (TGA) were used to study electroplating, oxidation and the oxide reduction processes. The temperature sensor was calibrated by use of a thermocouple. It demonstrates a temperature coefficient resistance of 4.66×10−3/°C between 32 and 660 °C. The heat characterization was done up to 1000 °C by using IR thermography, and the results were compared with the data from the temperature sensor. Combustion of starch confirmed the feasibility of using copper oxide as the source of oxygen of combustion.

  • 10.
    Kratz, Henrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Karlsson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Eriksson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Köhler, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Stenmark, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Thornell, Greger
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Design and Modeling of a thermally regulated communications module for nanospacecraft2006In: Journal of Spacecraft and Rockets, ISSN 0022-4650, E-ISSN 1533-6794, Vol. 43, no 6, p. 1377-1386Article in journal (Refereed)
    Abstract [en]

    A silicon-based integrated communications and thermal management microsystem qualifying for use on Nanospace-1, a modularized microsystem-based advanced integrated nanospacecraft, is presented. The transmitter and receiver share the same module framework with essential differences only in the electronics implementation. A data rate of 1 Mbps for the transmitter and 114 kbps for the receiver is accomplished with a transmitter power for the spacecraft and ground station of 2 and 10 W, respectively. Concurrent triple usage of paraffin as low loss antenna substrate, actuator material, and heat sink is designed and analyzed for the first time. On low-power or short-time high-power dissipation of heat from the electronics, energy is stored as latent heat in this phase-change material acting as a heat sink. Thermal transport through the module is initiated,by actuation of thermal switches when 75% of the paraffin's latent heat is consumed. A static thermal analysis reveals a thermal modulation factor of 5.6 between the on and off states of the thermal switches. The size of the module is 6.6 x 68 x 68 mm, and its weight is 43 g.

  • 11.
    Kratz, Henrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Öjefors, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Signals and Systems Group.
    Stenmark, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Micromachined S-band Patch Antenna with Reduced Dielectric Constant2006In: Sensors and Actuators A-Physical, ISSN 0924-4247, E-ISSN 1873-3069, Vol. 130-131, p. 478-484Article in journal (Refereed)
    Abstract [en]

    A generic dielectric constant reduction method for silicon substrates is presented in detail along with a process description to produce variable dielectric layers for planar antennas. Virtually any dielectric constant below the value for solid silicon 11.9 can be produced down to the limit of structural durability. A first-order volumetric average yields a dielectric constant of 3.8 for the following bonded micromachined silicon substrates; small honeycomb cells with wall thickness of 16 μm and inner wall length of 87 μm are etched using deep reactive ion etch (DRIE) to 475 μm depth in each of two 525 μm 4 in. high ohmic wafers. These two wafers are bonded together with the etched side of both wafers facing each other. A manufactured coaxial-fed disk-patch S-band antenna illustrates the method to reduce the dielectric constant for a circular zone with a diameter of 50 mm. The antenna is designed for a center frequency of 2.5 GHz based on a lossless substrate with a dielectric constant of 3.8. Adjusting the simulation model to fit the measured values of the antenna indicates a dielectric constant of 2.2, a dielectric loss tangent of 0.002, a bulk conductivity loss of 0.006 S/m, and a resonance frequency of 3.2 GHz. A low frequency analysis in the interval 200–500 MHz with a lumped element model and a low frequency formula for the capacitance between the patch and ground plane indicates a dielectric constant in the order of 2.7–2.8. Based on measurements in an SEM, a corrected average dielectric constant is found to be 2.9. This correction is due to thinner walls than expected in the manufactured honeycomb structure. Antenna lobe characteristics have been measured with a half-power beamwidth of ∼76° in both the E-plane and H-plane at 3.2 GHz.

  • 12.
    Köhler, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Bejhed, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Kratz, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Bruhn, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Lindberg, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Hjort, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Stenmark, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    A Hybrid Cold Gas Microthruster System for Spacecraft2002In: Sensors and Actuators A-Physical, ISSN 0924-4247, E-ISSN 1873-3069, Vol. 97-98, p. 587-98Article in journal (Refereed)
    Abstract [en]

    A hybrid cold gas microthruster system suitable for low Δv applications on spacecraft have been developed. Microelectromechanical system (MEMS) components together with fine-mechanics form the microthruster units, intergrating four independent thrusters. These are designed to deliver maximum thrusts in the range of 0.1–10 mN.

    The system includes three different micromachined subsystems: a nozzle unit comprising four nozzles generating supersonic gas velocity, i.e. 455 m/s, four independent piezoelectric proportional valves with leak rates at 10−6 scc/s He, and two particle filters. The performances of all these MEMS subsystems have been evaluated.

    The total system performance has been estimated in two parameters, the system-specific impulse and the mass ratio of the propulsion system to the spacecraft mass. These figures provide input for spacecraft design and manufacture.

  • 13.
    Lekholm, Ville
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Klintberg, Lena
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Persson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Thornell, Greger
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Hafnium oxide in high-temperature microelectromechanical systemsManuscript (preprint) (Other academic)
  • 14.
    Palmer, Kristoffer
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology, Ångström Space Technology Centre (ÅSTC).
    Development of Microcomponents for Attitude and Communication Systems on Small Vehicles in Space and Extreme Environments2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis, components intended for vehicles in space and other extreme environments have been realized using microsystems technology to facilitate miniaturized, yet high-performing systems beneficial for small spacecraft and other vehicles with limited size and power.

    Cold gas thrusters commonly used on spacecraft basically accelerate a gaseous propellant stored under high pressure. When miniaturized, their performance is reduced because of viscous forces. Here, with a special masking and etching scheme, making silicon micronozzles close to rotationally symmetric, this shortcoming was mitigated as indicated by schlieren imaging of the rocket exhaust and a comparison with conventionally manufactured micronozzles with rectangular cross-sections. Schlieren imaging was also used to detect leakage, quantify thrust vector deviation, and measure shock cell periods in the exhaust. Correlation was made to operational conditions.

    Similarly operating zirconia thrusters with integrated heaters and flow sensors were developed to allow for higher operating temperature. Successful testing at 1000°C, suggests that the propellant efficiency could be increased by 7.5%, and also makes them candidates for chemical propulsion.

    A silicon thruster operating in rarefied gas regimes was also developed. Being suspended in a silicon dioxide frame reducing heat losses, a total efficiency of 17% was reached.

    Relating to the integrated micropropulsion systems, two types of flow sensors were developed. Through finite element modeling, the insertion of sensor fingers in the fluid was shown to be an interesting concept for high-pressure applications.

    Utilizing the same principle, a velocity sensor for a miniaturized submersible was developed. With a power consumption below 15 mW, it was able to measure directions with an accuracy of ±8º, and speed with an error less than 22%.

    To enable high-speed optical communication between spacecraft, a Free Space Optics communication system, and particularly its dual-axis beam-steering actuator, was developed. Through thermal actuation, optical angles larger than 40º were obtained. A lumped thermal model was used to study design changes, vacuum operation and feedback control.

    Understanding and mastering heat transfer in microsystems have been vital in many of the studies conducted. Throughout, advanced micromachining and modeling have been used as a step towards high-performance systems for space and other extreme environments.

    List of papers
    1. Schlieren Imaging of Microthruster Exhausts for Qualitative and Quantitative Analysis
    Open this publication in new window or tab >>Schlieren Imaging of Microthruster Exhausts for Qualitative and Quantitative Analysis
    2012 (English)In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 23, no 8, p. 085403-Article in journal (Refereed) Published
    Abstract [en]

    Abstract. Schlieren imaging is a method used to visualize differences in refractiveindex within a medium. It is a powerful and straightforward tool for sensitiveand high-resolution visualization of, e.g., gas flows. Here, heated cold gasmicrothrusters were studied with this technique. The thrusters are manufacturedusing microelectromechanical systems technology, and measure 22×22×0.85 mm. Thenozzles are approximately 20 µm wide at the throat, and 350 µm wide at the exit.Through these studies, verification of the functionality of the thrusters, and directvisualization and of the thruster exhausts was possible. At atmospheric pressure,slipping of the exhaust was observed, due to severe overexpansion of the nozzle. Invacuum (3 kPa), the exhaust was imaged while feed pressure was varied from 100 to450 kPa. The nozzle was overexpanded, and the flow was seen to be supersonic. Theshock cell period was linearly dependent on feed pressure, ranging from 320 to 610 µm.With activated heaters, the shock cell separation increased. The effect of the heaterswas more prominent at low feed pressure, and an increase in specific impulse of 20%was calculated. It was also shown that schlieren imaging can be used to detect leaks,making it a valuable, safe, and noninvasive aid in quality control of the thrusters.

    Place, publisher, year, edition, pages
    Institute of Physics (IOP), 2012
    Keywords
    Schlieren imaging, microthrusters, MEMS, shock cells
    National Category
    Other Engineering and Technologies not elsewhere specified
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-186252 (URN)10.1088/0957-0233/23/8/085403 (DOI)000306366600039 ()
    Funder
    VINNOVA
    Available from: 2012-11-29 Created: 2012-11-28 Last updated: 2017-12-07Bibliographically approved
    2. Investigation of exhausts from fabricated silicon micronozzles with rectangular and close to rotationally symmetric cross sections
    Open this publication in new window or tab >>Investigation of exhausts from fabricated silicon micronozzles with rectangular and close to rotationally symmetric cross sections
    2013 (English)In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 23, no 10, p. 105001-Article in journal (Refereed) Published
    Abstract [en]

    Close to rotationally symmetric in-plane silicon micronozzles with throat and exit diameters of 45 and 260 µm, respectively, have been fabricated using semi-isotropic SF6 etching through an array mask utilizing microloading and reactive ion etching lag. Comparison with nozzles fabricated using deep reactive ion etching (DRIE) and having a rectangular cross-section but a similar hydraulic diameter in the throat, showed that the Reynolds numbers were almost equal even though the DRIE-etched nozzle had an almost five times larger cross-sectional area, hence implying less viscous losses and higher efficiency with the nearly symmetrical nozzles. The nozzle shapes have been studied using x-ray computed tomography. Comparison of the nozzles' exhaust jets using schlieren imaging, showed that the rectangular nozzles' jets deviate from the nozzle axis direction. It is believed that it is caused by the inclined side walls resulting from the DRIE etching. The results from intentionally misaligning the wafers, each containing half a nozzle, 50 µm parallel with or perpendicular to the nozzle axis, showed that the exhaust deviated and widened, respectively. The findings show that the nozzle symmetry affects both the shape and the pointing direction of the exhaust and that schlieren imaging is a powerful tool for determining nozzle thrust vector deviations.

    National Category
    Engineering and Technology
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-186774 (URN)10.1088/0960-1317/23/10/105001 (DOI)000324672700002 ()
    Available from: 2012-11-29 Created: 2012-11-29 Last updated: 2017-12-07Bibliographically approved
    3. High-temperature zirconia microthruster with integrated flow sensor
    Open this publication in new window or tab >>High-temperature zirconia microthruster with integrated flow sensor
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    2013 (English)In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 23, no 5, p. 055004-Article in journal (Refereed) Published
    Abstract [en]

    This paper describes the design, fabrication and characterization of a ceramic, heated cold-gas microthruster device made with silicon tools and high temperature co-fired ceramic processing. The device contains two opposing thrusters, each with an integrated calorimetric propellant flow sensor and a heater in the stagnation chamber of the nozzle. The exhaust from a thruster was photographed using schlieren imaging to study its behavior and search for leaks. The heater elements were tested under a cyclic thermal load and to the maximum power before failure. The nozzle heater was shown to improve the efficiency of the thruster by 6.9%, from a specific impulse of 66 to 71 s, as calculated from a decrease of the flow rate through the nozzle of 13%, from 44.9 to 39.2 sccm. The sensitivity of the integrated flow sensor was measured to 0.15 m Omega sccm(-1) in the region of 0-15 sccm and to 0.04 m Omega sccm(-1) above 20 sccm, with a zero-flow sensitivity of 0.27 m Omega sccm(-1). The choice of yttria-stabilized zirconia as a material for the devices makes them robust and capable of surviving temperatures locally exceeding 1000 degrees C.

    Keywords
    Keywords: Zirconia, YSZ, HTCC, schlieren imaging, flow sensor, microthruster
    National Category
    Other Engineering and Technologies not elsewhere specified
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-186257 (URN)10.1088/0960-1317/23/5/055004 (DOI)000317739100004 ()
    Funder
    Vinnova
    Available from: 2012-11-28 Created: 2012-11-28 Last updated: 2017-12-07Bibliographically approved
    4. Fabrication and evaluation of a free molecule micro-resistojet with thick silicon dioxide insulation and suspension
    Open this publication in new window or tab >>Fabrication and evaluation of a free molecule micro-resistojet with thick silicon dioxide insulation and suspension
    2013 (English)In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 23, no 6, p. 065006-Article in journal (Refereed) Published
    Abstract [en]

    A silicon free molecule micro-resistojet (FMMR) with a thermally insulating suspension frame composed of silicon dioxide has been designed, fabricated and tested. The concept was developed to increase the efficiency of FMMRs, especially in silicon-based integrated systems. Fabrication of the thick insulating frame was performed through oxidation of high-aspect ratio silicon trenches. The thermal properties of the 1 cm(2) thruster were evaluated using an IR camera, and it was found that when the volume inside the frame is heated more than 200 degrees C using integrated nickel heaters, the temperature increase in the volume outside the frame is less than 50 degrees C. During operation in vacuum, the thrust range was calculated to be about 13-1070 mu N and the maximum specific impulse 54 s. At maximum thrust, and a power consumption of 1.6 W, the total efficiency of the thruster was 17%. Designs of more efficient and versatile systems are discussed.

    National Category
    Engineering and Technology
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-186775 (URN)10.1088/0960-1317/23/6/065006 (DOI)000319451300006 ()
    Available from: 2012-11-29 Created: 2012-11-29 Last updated: 2017-12-07Bibliographically approved
    5. A highly integratable silicon thermal gas flow sensor
    Open this publication in new window or tab >>A highly integratable silicon thermal gas flow sensor
    2012 (English)In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 22, no 6, p. 065015-Article in journal (Refereed) Published
    Abstract [en]

    Thermal flow sensors have been designed, fabricated, and characterized. All bulk material in these devices is silicon so that they are integratable in silicon-based microsystems. To mitigate heat losses and to allow for use of corrosive gases, the heating and sensing thin film titanium/platinum elements, injecting and extracting heat, respectively, from the flow, are placed outside the channel on top of a membrane consisting of alternating layers of stress-balancing silicon dioxide and silicon nitride. For the fabrication, an unconventional bond surface protection method using sputter-deposited aluminum instead of thermal silicon dioxide is used in the process steps prior to silicon fusion bonding. A method for performing lift-off on top of the transparent membrane was also developed. The sensors, measuring 9.5 x 9.5 mm(2), are characterized in calorimetric and time-of-flight modes with nitrogen flow rates between 0 sccm and 300 sccm. The maximum calorimetric sensor flow signal and sensitivity are 0.95 mV and 29 mu V sccm(-1), respectively, with power consumption less than 40 mW. The time-of-flight mode is found to have a wider detectable flow range compared with calorimetric mode, and the time of flight measured indicates a response time of the sensor in the millisecond range. The design and operation of a sensor with high sensitivity and large flow range are discussed. A key element of this discussion is the configuration of the array of heaters and gauges along the channel to obtain different sensitivities and extend the operational range. This means that the sensor can be tailored to different flow ranges.

    National Category
    Engineering and Technology
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-176814 (URN)10.1088/0960-1317/22/6/065015 (DOI)000304609600015 ()
    Available from: 2012-06-27 Created: 2012-06-26 Last updated: 2017-12-07Bibliographically approved
    6. Finite Element Analysis of the Effect on Employing Thermal Through Vias and Heat Fingers to Increase Heat Transfer to Fluid in Calorimetric Flow Sensors
    Open this publication in new window or tab >>Finite Element Analysis of the Effect on Employing Thermal Through Vias and Heat Fingers to Increase Heat Transfer to Fluid in Calorimetric Flow Sensors
    2013 (English)In: Sensors and Actuators A-Physical, ISSN 0924-4247, E-ISSN 1873-3069, Vol. 201, p. 49-57Article in journal (Refereed) Published
    Abstract [en]

    Measurement results of a robust silicon calorimetric flow sensor with a 25 μm thick silicon dioxide membrane with thermal silicon vias have been compared with results obtained from three-dimensional Finite Element Analysis (FEA). Based on the fabricated device, the sensor has been further developed to include heat-exchanging fingers extending down into the integrated flow channel for increased heat transfer. Using FEA, different designs of the fingers have been compared with respect to signal strength, sensitivity, power consumption and pressure loss in the channel at flow rates from 0 to about 650 sccm. Using heat fingers, the sensor signal was improved by a factor of five. The sensor signal, i.e. the temperature difference between downstream and upstream elements, was more than 60 °C when the central heater was heated 300 °C above room temperature, which was comparable to a thin-membrane device modeled. The maximum sensitivity using the finger design was about 1.4 °C sccm−1, and the maximum power consumption was almost 700 mW, which is considerably higher than for thin-membrane sensors. A figure of merit used for evaluation, was the ratio of signal strength to power consumption. The results show that the device design is a promising concept that is suitable in systems requiring robust monolithically integratable flow sensors.

    National Category
    Engineering and Technology
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-186776 (URN)10.1016/j.sna.2013.05.018 (DOI)000325836400006 ()
    Available from: 2012-11-29 Created: 2012-11-29 Last updated: 2017-12-07Bibliographically approved
    7. Two-Dimensional Thermal Velocity Sensor for Submersible navigation and Minute Flow Measurements
    Open this publication in new window or tab >>Two-Dimensional Thermal Velocity Sensor for Submersible navigation and Minute Flow Measurements
    2013 (English)In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 13, no 1, p. 359-370Article in journal (Refereed) Published
    Abstract [en]

    A 2-D thermal velocity microsensor for use as a navigational aid and for flow measurements on a miniaturized submersible is developed in this paper. The sensor with nickel heater and temperature sensors on a Pyrex substrate, designed for mounting on the outside of the submersible hull, is fabricated and tested in an application-like environment and proven to be able to measure water speed from zero to 40 mm/s with a power consumption less than 15 mW and determine the flow direction with an error less than ±8°. Finite Element Analysis is used to investigate design and operation parameters and possible biofouling effects on the sensor signal. The effect on shape and orientation of the sensor's mounting surface is also studied.

    National Category
    Other Materials Engineering
    Research subject
    Engineering Science with specialization in Microsystems Technology
    Identifiers
    urn:nbn:se:uu:diva-171767 (URN)10.1109/JSEN.2012.2216866 (DOI)000313685400028 ()
    Available from: 2012-03-27 Created: 2012-03-27 Last updated: 2017-12-07Bibliographically approved
    8. A micromachined dual-axis beam steering actuator for use in a miniaturized optical space communication system
    Open this publication in new window or tab >>A micromachined dual-axis beam steering actuator for use in a miniaturized optical space communication system
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    2010 (English)In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 20, no 10, p. 105007-Article in journal (Refereed) Published
    Abstract [en]

    The design, fabrication and evaluation of an electrothermally actuated micromachined beam steering device for use in a free-space optical communication system intended for use on micro-and nanospacecraft in kilometer-sized formations are presented. SU-8 confined in v-grooves is heated to create bending movement in two orthogonal directions for two-axial steering with large static bending angles and low actuation voltages. Standard MEMS processing is used to fabricate the devices with square mirror side lengths of 1, 3.5 and 5 mm. In addition, a method to prevent thermal damage to SU-8 during deep reactive ion etching has been successfully developed. Characterization shows optical scan ranges larger than 40 degrees in both directions with the maximum driving voltage of 16 V corresponding to a total power consumption of 1.14 W. Infrared imaging is used to investigate thermal cross-talk between actuators for the two scanning directions. It is found that a silicon backbone on the joint backside is crucial for device performance. Differences from expected performance are believed to arise from the SU-8 curing process and excessive heating during fabrication. A finite element method simulation is used to find the eigenfrequencies of the structures, and these are in good agreement with the measured frequency response.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-134362 (URN)10.1088/0960-1317/20/10/105007 (DOI)000282270300020 ()
    Available from: 2010-11-25 Created: 2010-11-24 Last updated: 2017-12-12
    9. Dynamic characterization and modelling of a dual-axis beam steering device for performance understanding, optimization, and control design
    Open this publication in new window or tab >>Dynamic characterization and modelling of a dual-axis beam steering device for performance understanding, optimization, and control design
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    2013 (English)In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 23, no 4, p. 045020-Article in journal (Refereed) Published
    Abstract [en]

    This paper presents a lumped thermal model of a dual-axis laser micromirror device for beam steering in a free-space optical (FSO) communication system, designed for fractionated spacecraft. An FSO communication system provides several advantages, such as larger bandwidth, smaller size and weight of the communication payload and less power consumption. A dual-axis mirror device is designed and realized using microelectromechanical systems technology. The fabrication is based on a double-sided, bulk micromachining process, where the mirror actuates thermally by joints consisting of v-grooves filled with the SU-8 polymer. The size of the device, consisting of a mirror, which is deflectable versus its frame in one direction, and through deflection of the frame in the other, is 15.4 × 10.4 × 0.3 mm3. In order to further characterize and understand the micromirror device, a Simulink state-space model of the actuator is set up using thermal and mechanical properties from a realized actuator. A deviation of less than 2% between the modelled and measured devices was obtained in an a