| 1. |
- Bejhed, Johan, 1973-
(author)
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Fluidic Microsystems for Micropropulsion Applications in Space
- 2006
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Doctoral thesis (other academic/artistic)abstract
- Spacecraft on interplanetary missions or advanced satellites orbiting the Earth all require propulsion systems to complete their missions. Introducing microelectromechanical systems technology to the space industry will not only reduce size and weight of the propulsion system, but can also increase the performance of the mission.Fluid handling systems are used in chemical and electric propulsion. Some components incorporated in a fluidic handling system are presented and evaluated in this work.Microsystems are very sensitive to contamination. Reliable, robust, and easily integrated filters were modeled, manufactured, and experimentally verified.A fluid connector, designed to withstand large temperature variations and aggressive propellants was manufactured and characterized. Similar designs was also be used as a thermally activated minute valve.The feasibility of a cold gas system for precise attitude control has been demonstrated. Steps towards improving the performance (from specific im-pulse 45 s) have been taken, by the integration of suspended heater elements.For electric propulsion, two thermally regulated flow restrictors have been characterized. These devices can fine-tune the propellant flow to e.g. an ion engine.A single-use valve using a soldered seal has also been successfully dem-onstrated within a pressure range of 5 to 100 bar.The microsystem-based propulsion systems of tomorrow’s spacecraft need to be demonstrated in space, in order to gain necessary credibility.
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| 2. |
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| 3. |
- Berglund, Martin, 1985-, et al.
(author)
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Dynamic characterization and modelling of a dual-axis beam steering device for performance understanding, optimization, and control design
- 2013
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In: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 23:4, s. 045020-
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Journal article (peer-reviewed)abstract
- 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 actuating temperature range of 20–200 °C. The model of the physical device was examined by evaluating its performance in vacuum, and by changing physical parameters, such as thickness and material composition. By this, design parameters were evaluated for performance gain and usability. For example, the crosstalk between the two actuators deflecting the mirror along its two axes in atmospheric pressure is projected to go down from 97% to 6% when changing the frame material from silicon to silicon dioxide. A feedback control system was also designed around the model in order to examine the possibility to make a robust control system for the physical device. In conclusion, the model of the actuator presented in this paper can be used for further understanding and development of the actuator system.
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| 4. |
- Berglund, Martin, 1985-, et al.
(author)
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Evaluation of a microplasma source based on a stripline split-ring resonator
- 2013
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In: Plasma sources science & technology. - : Institute of Physics (IOP). - 0963-0252 .- 1361-6595. ; 22:5, s. 055017-
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Journal article (peer-reviewed)abstract
- 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.
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| 5. |
- Berglund, Martin, 1985-, et al.
(author)
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Evaluation of dielectric properties of HTCC alumina for realization of plasma sources
- 2015
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In: Journal of Electronic Materials. - : Springer Science and Business Media LLC. - 0361-5235 .- 1543-186X. ; 44:10, s. 3654-3660
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Journal article (peer-reviewed)abstract
- 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.
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| 6. |
- Berglund, Martin, 1985-, et al.
(author)
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Extreme-temperature lab on a chip for optogalvanic spectroscopy of ultra small samples – key components and a first integration attempt
- 2016
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In: 27th Micromechanics And Microsystems Europe Workshop (MME 2016). - : Institute of Physics (IOP).
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Conference paper (peer-reviewed)abstract
- 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.
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| 7. |
- Berglund, Martin, 1985-, et al.
(author)
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Manufacturing Miniature Langmuir probes by Fusing Platinum Bond Wires
- 2015
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In: Journal of Micromechanics and Microengineering. - Bristol : Institute of Physics Publishing (IOPP). - 0960-1317 .- 1361-6439. ; 25:10
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Journal article (peer-reviewed)abstract
- This paper reports on a novel method for manufacturing microscopic Langmuir probes with spherical tips from platinum bond wires by fusing for plasma characterization in microplasma sources. Here, the resulting endpoints, formed by droplets on the ends of a fused wire, are intended to act as spherical Langmuir probes. For studying the fusing behavior, bond wires were wedge bonded over a 2 mm wide slit, to emulate the final application, and fused with different voltages and currents. 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 its dynamics. Four characteristic tip shapes were observed: spherical, folded, serpentine shaped and semi-spherical. The stub length leveled out at ~400 μm as the fusing power increased. The fusing of the coated wires required a higher power to yield a spherical shape. Finally, a Parylene coated bond wire was integrated into a stripline split-ring resonator (SSRR) microplasma source, and was 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 further integration.
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| 8. |
- Berglund, Martin, 1985-, et al.
(author)
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Microfluidics integrable plasma source powered by a silicon through-substrate split-ring resonator
- 2013
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In: Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS EUROSENSORS XXVII). ; , s. 2608-2611
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Conference paper (other academic/artistic)abstract
- 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 should offer straightforward integration with other MEMS components, and has a plasma discharge gap with a controlled volume and geometry, with potential for microfluidics. Two realized devices were resonant at around 2.9 GHz with quality factors of 26.6 and 18.7. Two different plasma ignition modes were observed, where the plasma at low pressures was not confined to the gap but rather appeared between the ends of the electrodes on the backside.
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| 9. |
- Berglund, Martin, 1985-, et al.
(author)
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Microplasma source for optogalvanic spectroscopy of nanogram samples
- 2013
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In: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 114:3, s. 033302-
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Journal article (peer-reviewed)abstract
- 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.
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| 10. |
- Berglund, Martin, 1985-
(author)
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Miniature Plasma Sources for High-Precision Molecular Spectroscopy in Planetary Exploration
- 2015
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Doctoral thesis (other academic/artistic)abstract
- 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.
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| 11. |
- Berglund, Martin, et al.
(author)
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Operation characteristics and optical emission distribution of a miniaturized silicon through-substrate split-ring resonator microplasma source
- 2014
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In: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158. ; 23:6, s. 1340-1345
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Journal article (peer-reviewed)abstract
- 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.
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| 12. |
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| 13. |
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| 14. |
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| 15. |
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| 16. |
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| 17. |
- Böhnke, Tobias, et al.
(author)
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Surfaces with high solar reflectance and high thermal emittance on structured silicon for spacecraft thermal control
- 2008
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In: Optical materials (Amsterdam). - : Elsevier BV. - 0925-3467 .- 1873-1252. ; 30:9, s. 1410-1421
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Journal article (peer-reviewed)abstract
- Presented here is an examination of unstructured and structured (by anisotropic etching), monocrystalline silicon wafers coated with sputter deposited aluminum and chemical vapor deposited silicon dioxide for high solar reflectance and high thermal emittance, respectively. The topography of the samples was characterized with optical and scanning electron microscopy. Optical properties were examined with reflectance and transmittance spectroscopy, partly by usage of an integrating sphere. The measurement results were used to estimate the equilibrium temperature of the surfaces in space. The suitability of the surfaces with high solar reflectance and high thermal emittance to aid in the thermal control of miniaturized, highly integrated components for space applications is discussed. A silicon dioxide layer on a metal layer results in a slightly lower reflectance when compared to surfaces with only a metal layer, but might be beneficial for miniaturized space components and modules that have to dissipate internally generated heat into open space. Additionally, it is an advantage to microstructure the emitting surface for enhanced radiation of excess heat.
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| 18. |
- Edqvist, Erik, 1975-
(author)
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Applications of active materials
- 2009
-
Doctoral thesis (other academic/artistic)abstract
- Energy efficiency is a vital key component when designing and miniaturizing self sustained microsystems. The smaller the system, the smaller is the possibility to store enough stored energy for a long and continuous operational time. To move such a system in an energy efficient way, a piezoelectrical locomotion module consisting of four resonating cantilevers has been designed, manufactured and evaluated in this work. The combination of a suitable substrate, a multilayered piezoelectric material to reduce the voltage, and a resonating drive mechanism resulted in a low power demand. A manufacturing process for multilayer cantilever actuators made of P(VDF-TrFE) with aluminum electrodes on a substrate of flexible printed circuit board (FPC), has been developed. An important step in this process was the development of an etch recipe for dry etching the multilayer actuators in an inductive plasma equipment. Formulas for the quasi static tip deflection and resonance frequency of a multilayered cantilever, have been derived. Through theses, it was found that the multilayered structures should be deposited on the polymer side of the FPC in order to maximize the tip deflection. Both a large and a miniaturized locomotion module were manufactured and connected by wires to verify that the three legged motion principal worked to move the structures forward and backward, and turn it right and left. By touching and adding load, to a fourth miniaturized cantilever, its ability to act as a contact sensor and carry object was verified. The presented locomotion module is part of a multifunctional microsystem, intended to be energy efficient and powered by a solar panel with a total volume of less than 25 mm3 and weight 65 mg. The whole system, consisting of a solar cell, an infra red communication module, an integrated circuit for control, three capacitors for power regulating, the locomotion module and an FPC connecting the different modules, was surface mounted using a state of the art industrial facility. Two fully assembled systems could be programmed both through a test connector and through optical sensors in the multifunctional solar cell. One of these was folded together to the final configuration of a robot. However, the entire system could not be tested under full autonomous operating conditions. On the other hand, using wires, the locomotion module could be operated and used to move the entire system from a peak-to-peak voltage of 3.0 V.
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| 19. |
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| 20. |
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| 21. |
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| 22. |
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| 23. |
- Janhunen, Pekka, et al.
(author)
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Electric Solar Wind Sail in tailwind
- 2011
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In: EPSC-DPS Joint Meeting 2011.
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Conference paper (peer-reviewed)abstract
- The Electric Solar Wind Sail (E-sail) is a novelpropulsion concept that enables faster space travel tomany solar system targets. E-sail uses charged solarwind particles as the source of its propulsion. This isachieved by deploying long, conducting and chargedtethers, which get pushed by the solar wind byCoulomb drag [1].E-sail technology is being developed to technicalreadiness level (TRL) 4-5 by the European Union’sSeventh Framework Programme for Research andTechnological Development, EU FP7, in a projectnamed ESAIL (http://www.electric-sailing.fi/fp7).Prototypes of the key parts are to be produced. Thedesign will be scalable so that a real solar winddemonstration mission could be scaled up from them.We review here the latest results of the constantlyevolving E-sail project.
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| 24. |
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| 25. |
- Janhunen, P., et al.
(author)
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Invited Article: Electric solar wind sail : Toward test missions
- 2010
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In: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 81:11, s. 111301-
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Journal article (peer-reviewed)abstract
- The electric solar wind sail (E-sail) is a space propulsion concept that uses the natural solar wind dynamic pressure for producing spacecraft thrust. In its baseline form, the E-sail consists of a number of long, thin, conducting, and centrifugally stretched tethers, which are kept in a high positive potential by an onboard electron gun. The concept gains its efficiency from the fact that the effective sail area, i.e., the potential structure of the tethers, can be millions of times larger than the physical area of the thin tethers wires, which offsets the fact that the dynamic pressure of the solar wind is very weak. Indeed, according to the most recent published estimates, an E-sail of 1 N thrust and 100 kg mass could be built in the rather near future, providing a revolutionary level of propulsive performance (specific acceleration) for travel in the solar system. Here we give a review of the ongoing technical development work of the E-sail, covering tether construction, overall mechanical design alternatives, guidance and navigation strategies, and dynamical and orbital simulations.
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| 26. |
- Jonsson, Jonas, 1979-, et al.
(author)
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A compact projection system enabling topographical measurements for a miniaturized submersible explorer
- 2011
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In: Proceedings of the 16th International Conference on Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS), 2011. - : IEEE conference proceedings. - 9781457701573 ; , s. 2518-2521
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Conference paper (peer-reviewed)abstract
- To enable photogrammetry of underwater images using a miniaturized submersible explorer, a compact projection system has been developed. By registering the deformation of a known projected pattern, using a laser and a diffractive optical element (DOE), the distance to, shape and size of an object can be calculated. The DOE has been designed, using in-house developed software, and manufactured using microstructure technology. Distances to objects 45 to 30 cm away were determined to within 0.5 cm, and the developed GUI was able to recreate the shape from the measurements for easier examination of the object.
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| 27. |
- Jonsson, Jonas, et al.
(author)
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A compact system to extract topography information from scenes viewed by a miniaturized submersible explorer
- 2012
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In: Sensors and Actuators A-Physical. - : Elsevier BV. - 0924-4247 .- 1873-3069. ; 188:SI, s. 401-410
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Journal article (peer-reviewed)abstract
- 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.
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| 28. |
- Jonsson, Jonas, et al.
(author)
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Acoustically enriching, large-depth aquatic sampler
- 2012
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In: Lab on a Chip. - 1473-0197 .- 1473-0189. ; 12:9, s. 1619-1628
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Journal article (peer-reviewed)abstract
- 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.
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| 29. |
- Jonsson, Jonas, et al.
(author)
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Enclosure-Induced Interference Effects in a Miniaturized Sidescan Sonar
- 2012
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In: IEEE Journal of Oceanic Engineering. - 0364-9059 .- 1558-1691. ; 37:2, s. 236-243
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Journal article (peer-reviewed)abstract
- 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.
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| 30. |
- Jonsson, Jonas, et al.
(author)
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Instrumentation and vehicle platform of a miniaturized submersible for exploration of terrestrial and extraterrestrial aqueous environments
- 2012
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In: Acta Astronautica. - : Elsevier BV. - 0094-5765 .- 1879-2030. ; 79, s. 203-211
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Journal article (peer-reviewed)abstract
- An example of an extraterrestrial environment likely to support life is the vast liquid body believed to hide underneath the frozen crust of Jupiter's moon Europa. The hypothetical exploration of this, as well as the more accessible subglacial lakes on Earth, has been used as model applications for the development of a heavily miniaturized, yet qualified, submersible with the potential to be deployable either in itself through a long and narrow borehole or as the daughter craft of an ice-penetrating cryobot.Onboard the submersible, which is only 20 cm in length and 5 cm in diameter, accommodation of a versatile set of sensors and instruments capable of characterizing and imaging the surroundings, and even collecting water samples with microorganisms for return, is facilitated through the use of miniaturization technologies. For instance, together with a small camera, a laser-based, microoptic device enables the 3-D reconstruction of imaged objects for topographical measurements. As a complement, when the water is turbid or a longer range is wanted, the world's smallest side-scanning sonar, exhibiting centimeter resolution and a range of over 30 m, has been developed. The work on miniaturizing a CTD, which is a widely employed oceanographic instrument used to measure and correlate conductivity, temperature, and depth, has commenced. Furthermore, a device employing acoustics to trap microscopic particles and organisms, and, by this, enrich water samples, is under development. To ensure that the gathered samples are pristine until analyzed at the end of a mission, the device is equipped with high-pressure, latchable valves.Remote operation and transfer of measurement data and images, or even live streaming of video, is made possible through a kilometer-long fiber optic cable being reeled out from the vehicle underway and tethering it to a terminal. To extend the missions, the same fiber shall also be capable of charging the onboard batteries.In this paper, the vehicle and its subsystems are summarized. Subsystems essential for the vehicle's operation, e.g., hull structure, communication and power management, are treated separately from those of more mission-specific nature, like the instruments mentioned above.
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| 31. |
- Jonsson, Jonas, 1979-
(author)
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Microsystems Technology for Underwater Vehicle Applications
- 2012
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Doctoral thesis (other academic/artistic)abstract
- 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.
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| 32. |
- Jonsson, Jonas, et al.
(author)
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Miniaturized submersible for exploration of aqueous environments on Earth and beyond
- 2011
-
Conference paper (peer-reviewed)abstract
- Some of the most likely environments to support extraterrestrial life in our solar system are the ice-covered moons, suchas Europa, thought to harbor a liquid ocean underneath its frozen crust. Exploration, however, necessitates an ice-penetratingcryobot, or a long and narrow borehole, and the subsequent deployment of a small submersible, a hydrobot, with severe sizerestrictions imposed on its scientific payload. As a stepping stone for exploration of such environments, a small instrumentladenedsubmersible vehicle is currently under development.Employment of a large set of instruments capable of characterizing the aqueous environment, imaging the surroundingsand collecting microorganisms is essential for the determination of habitability. Despite the submersible being only 20 cm inlength and 5 cm in diameter, a high degree of functionality is facilitated here through the use of miniaturization technologies. Forinstance, a compact laser-illuminated diffractive optical element, paired with a high-resolution camera, enable photogrammetryand the reconstruction of objects’ shapes in 3-D space. Also for imaging, the world’s smallest side-scanning sonar has beendeveloped to acoustically image, either where water is too turbid for the camera, or where longer range is necessary. Currently,the sonar exhibits centimeter resolution and ranges over 30 meters. On the sensor side, a most vital oceanographic instrument, theCTD, used to measure the conductivity, temperature, and depth of water, has been heavily miniaturized and preliminaryevaluated. Additionally, a water sampler combining integrated selection and enriching capabilities to filter out and accommodate,e.g., microbes in the size range of 1-10 μm, is under development. Among other parts, its high-pressure valves and microfluidicacoustic traps have already been realized.For remote operation and upload of measurement data or images, or even live streaming of video, the submersible will betethered with a bi-directionally transmitting fiber optic cable, also capable of charging the onboard batteries for long missions.The one kilometer long fiber will be fitted within the hull, and by reeling out the fiber from the submersible, drag will be reduced.Herein, test results and images of the vehicle and its complete, and continuously developed, subsystems are presented.The vehicle, and its subsystems as stand-alone instruments, will enable the exploration of previously unreachable analogenvironments on Earth, vital to the field of astrobiology, and act as a forerunner to a submersible hydrobot that can explore icecoveredoceans elsewhere in our solar system.
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| 33. |
- Jonsson, Jonas, et al.
(author)
-
Miniaturized submersible for exploration of small aqueous environments
- 2011
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In: Oceans’11 MTS/IEEE Kona, Hilton Waikoloa Village, Kona, Hawai‘i September 19-22, 2011.
-
Conference paper (peer-reviewed)abstract
- Remotely operated vehicles (ROVs) are commonlyused for sub-surface exploration. However, multi-functionalROVs tend to be fairly large, while preferred small and compactROVs suffer from limited functionality. The Deeper Access,Deeper Understanding (DADU) project aims to develop a smallsubmersible concept using miniaturization technologies to enablea high functionality. An operator is able to maneuver the vehiclewith five degrees of freedom using eight small thrusters, while aset of accelerometers and gyros monitor the orientation of thesubmersible. A single fiber optic cable will connect thesubmersible to a control station and enable simultaneous dataand command transfers. Rechargeable battery packs providepower to the submersibles subsystems during operation. Thesewill be rechargeable through the fiber connection. A forwardlooking camera is aided by a laser topography measurementsystem, where distances, sizes and shapes of objects in view canbe determined to within 0.5 cm. For murkier environments, orwhen a more extensive mapping of the surroundings is needed,the small high-frequency side-scanning sonar can be used.Salinity calculations of the water will be available throughmeasurements of the conductivity, temperature and depth.Samples of water and particles within it will be enabled through awater sampler with an enriching capability. Flow sensors will beable to measure the water movement around the submersible’shull. The submersible and its subsystems are under continuousdevelopment. The vehicle itself, and its subsystems as stand-aloneinstruments, will enable the exploration of previouslyunreachable submerged environments, such as the sub-glaciallakes found in Iceland and Antarctica, or other submerged smallenvironments, such as pipe and cave systems.
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| 34. |
- Jonsson, Jonas, et al.
(author)
-
Simulation and Evaluation of Small High-Frequency Side Scan Sonars Using COMSOL
- 2009
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In: COMSOL Conference 2009 Milan.
-
Conference paper (other academic/artistic)abstract
- High frequency side-scan sonar, to be fitted on a miniaturized submersible explorer, have been simulated and built. The purpose of this study is to see if COMSOL Multiphysics can be used to predict the performance of the sonar, especially the beam width, setting the resolution of the system. Four models were created, from simple 2-D geometries to more complex 3-D models. The simulated beam widths were compared with measurements to see which of the models agreed best. It was found that all models agree with the experimental results to varying degrees, and mostly with a difference of less than 6%. . It was found that the simplest model agreed best with the measurements, closely followed by the most complex model. Also taking the computational load into consideration the simpler model might then be a better choice to use.
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| 35. |
- Jonsson, Jonas, 1979-, et al.
(author)
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Simulation, manufacturing, and evaluation of a sonar for a miniaturized submersible explorer
- 2010
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In: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control. - 0885-3010 .- 1525-8955. ; 57:2, s. 490-495
-
Journal article (peer-reviewed)abstract
- 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.
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| 36. |
- Jonsson, Jonas, et al.
(author)
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Towards chip-based salinity measurements for small submersibles and biologgers
- 2013
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In: International Journal of Oceanography. - : Hindawi Publishing Corporation. - 1687-9406 .- 1687-9414. ; 2013, s. 529674-
-
Journal article (peer-reviewed)abstract
- 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.
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| 37. |
- Khaji, Zahra, et al.
(author)
-
Alumina-based monopropellant microthruster with integrated heater, catalytic bed and temperature sensors
- 2016
-
In: 27th Micromechanics And Microsystems Europe Workshop (Mme 2016). - : Institute of Physics (IOP).
-
Conference paper (peer-reviewed)abstract
- A liquid propellant alumina microthruster with an integrated heater, catalytic bed and two temperature sensors has been developed and tested using 30 wt. % hydrogen peroxide. The temperature sensors and the catalytic bed were screen-printed using platinum paste on tapes of alumina that was stacked and laminated before sintering. In order to increase the surface of the catalytic bed, the platinum paste was mixed with a sacrificial paste that disappeared during sintering, leaving behind a porous and rough layer. Complete evaporation and combustion, resulting in only gas coming from the outlet, was achieved with powers above 3.7 W for a propellant flow of 50 μl/min. At this power, the catalytic bed reached a maximum temperature of 147°C. The component was successfully operated up to a temperature of 307°C, where it cracked.
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| 38. |
- Khaji, Zahra, et al.
(author)
-
Catalytic Effect of Platinum and Silver in a Hydrogen Peroxide Monopropellant Ceramic Microthruster
- 2020
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In: Propulsion and power research. - : Elsevier. - 2212-540X. ; 9:3, s. 216-224
-
Journal article (peer-reviewed)abstract
- Ceramic microthrusters with an embedded Pt resistive heater, two temperature sensors, and a Pt or Ag catalytic bed were made of high-temperature co-fired alumina ceramics. To increase the surface area by a factor of 1.21, and so the catalytic effect, the Pt catalytic bed was made porous by mixing the Pt paste with 15–20vol.% graphite sacrificial paste before screen printing it. Ag was in-situ electroplated on the porous Pt surface after sintering. Decomposition of 50wt.% hydrogen peroxide as a monopropellant was studied both qualitatively and quantitatively by changing the catalyst (between Ag and Pt), flow rate (15–55 μl/min), and operating temperature (115–300 °C). A reference device without catalyst exhibited an unstable behavior as a result of no, or very little, decomposition, whereas the Ag catalyst was more stable, and the Pt one even more stable. Also, Pt was found to be slightly more effective. Quantitatively, there were small differences between Pt and Ag in the power needed to maintain the temperature. The inventive methods to make the Pt bed porous as well as in-situ electroplating Ag were successfully demonstrated.
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| 39. |
- Khaji, Zahra, et al.
(author)
-
Design and fabrication of a miniaturized combustor with integrated oxygen storage and release element
- 2014
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In: 25th Micromechanics and Microsystems Europe workshop (MME 2014),2014, P19 (4 pp).
-
Conference paper (peer-reviewed)abstract
- A miniature combustor for converting organic samples into CO2 with application in carbon isotopic measurements of small samples has been manufactured and evaluated. The combustor was made by machining and laminating High-Temperature Co-fired Ceramic (HTCC) 99.99% alumina green tapes and screen printing platinum conductors on them. The device has a built-in heater and a temperature sensor made of platinum, which were co-sintered with the ceramic. A metal oxide (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 decompo-sition processes.
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| 40. |
- Khaji, Zahra, et al.
(author)
-
Endurance and Failure of an Alumina-based Monopropellant Microthruster with Integrated Heater, Catalytic Bed and Temperature Sensors
- 2017
-
In: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 27:5, s. 1-11
-
Journal article (peer-reviewed)abstract
- 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.
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| 41. |
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| 42. |
- Khaji, Zahra, 1983-
(author)
-
Extending Microsystems to Very High Temperatures and Chemically Harsh Environments
- 2016
-
Doctoral thesis (other academic/artistic)abstract
- Aiming at applications in space exploration as well as for monitoring natural hazards, this thesis focuses on understanding and overcoming the challenges of extending the applicability of microsystems to temperatures above 600°C as well as chemically harsh environments. Alumina and zirconia high-temperature co-fired ceramics (HTCC) with platinum as the conductor material, have in this thesis, been used to manufacture a wide range of high-temperature tolerant miniaturized sensors and actuators, including pressure and flow sensors, valves, a combustor, and liquid monopropellant microthrusters.Interfacing for high temperatures is challenging. One solution is to transfer the signal wirelessly. Here, therefor, wireless pressure sensors have been developed and characterized up to 1000°C.It is usually unwanted that material properties change with temperature, but by using smart designs, such changes can be exploited to sense physical properties as in the gas flow sensor presented, where the temperature-dependent electrical conductivity of zirconia has been utilized. In the same manner, various properties of platinum have been exploited to make temperature sensors, heaters and catalytic beds. By in-situ electroplating metals after sintering, even more capabilities were added, since many metals that do not tolerate HTCC processing can be added for additional functionality. An electroplated copper layer that was oxidized and used as an oxygen source in an alumina combustor intended for burning organic samples prior to sample analysis in a lab on a chip system, and a silver layer used as a catalyst in order to decompose hydrogen peroxide in a microthuster for spacecraft attitude control, are both examples that have been explored here.Ceramics are both high-temperature tolerant and chemically resistant, making them suitable for both thrusters and combustors. The corresponding applications benefit from miniaturization of them in terms of decreased mass, power consumption, integration potential, and reduced sample waste.Integrating many functions using as few materials as possible, is important when it comes to microsystems for harsh environments. This thesis has shown the high potential of co-fired ceramics in manufacturing microsystems for aggressive environments. However, interfacing is yet a major challenge to overcome.
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| 43. |
- Khaji, Zahra, et al.
(author)
-
Investigation of the storage and release of oxygen in a Cu-Pt element of a high-temperature microcombustor
- 2014
-
In: The 14th International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications(PowerMEMS 2014). - : Institute of Physics (IOP).
-
Conference paper (peer-reviewed)abstract
- 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.
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| 44. |
- Khaji, Zahra, et al.
(author)
-
Manufacturing and characterization of a ceramic microcombustor with integrated oxygen storage and release element
- 2015
-
In: Journal of Micromechanics and Microengineering. - Bristol : Institute of Physics (IOP). - 0960-1317 .- 1361-6439. ; 25:10
-
Journal article (peer-reviewed)abstract
- A microscale ceramic high-temperature combustor with a built-in temperature sensor and source of oxygen has been designed, manufactured and characterized. The successful in situ electroplating and oxidation of copper, and the use of copper oxide as the source of oxygen were demonstrated. It was shown that residual stresses from electroplating, copper oxidation and oxide decomposition did not cause much deformation of the substrate but influenced mainly the integrity and adhesion of the metal films. The process had influence on the electrical resistances, however. Calibration of the temperature sensor and correlation with IR thermography up to 1000°C revealed a nearly linear sensor behavior. Demonstration of combustion in a vacuum chamber proved that no combustion had occurred before release of oxygen from the metal oxide resource.
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| 45. |
- Khaji, Zahra, et al.
(author)
-
Manufacturing and characterization of a ceramic single-use microvalve
- 2016
-
In: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 26:9
-
Journal article (peer-reviewed)abstract
- 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.
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| 46. |
- Klintberg, Lena, et al.
(author)
-
A large stroke, high force paraffin phase transition actuator
- 2002
-
In: Sensors and Actuators A-Physical. - 0924-4247 .- 1873-3069. ; 96:2-3, s. 189-195
-
Journal article (peer-reviewed)abstract
- An actuator that uses the volume expansion related to the solid-to-liquid phase transition of paraffin wax has been fabricated and evaluated. The actuator consists of a ring-shaped paraffin cavity confined by two joint silicon diaphragms with rigid centers. When the paraffin is melted, the resulting hydrostatic pressure deflects the joined rigid centers in one direction only. The magnitude of the deflection is primarily a function of the geometrical relation between the two diaphragms, giving the opportunity to tailor the behavior of the actuator in a large range. Conventional IC-processing techniques have been used to fabricate a prototype with a width of 68 mm and a thickness of 825 μm. The prototype attained a maximum deflection of ca. 90 μm. Loaded with 3 N it still exhibits a deflection of ca. 75 μm. The device can be used as a thermal switch.
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| 47. |
- Klintberg, Lena, et al.
(author)
-
A thermal microactuator made by partial impregnation of polyimide with paraffin
- 2002
-
In: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 12:6, s. 849-854
-
Journal article (peer-reviewed)abstract
- We have fabricated and tested thermal, paraffin-impregnated polyimide actuators, utilizing the large volume increase associated with the solid-to-liquid phase transition of paraffin. In the bimorph-like device, the top layer was made porous by ion track technology. Stochastically distributed pores of various lengths (95, 70, 45 and 20 µm) and various lateral coverages (5–45%) were filled with paraffin by liquid substitution or from vacuum, and sealed with epoxy. Actuators, 125 µm thick, 35 mm long and 7 mm wide, have been characterized with respect to tip deflection and load-carrying capacity with one end rigidly clamped. Loaded with 0.6 g or about ten times their own weight at their free end, about 50% of the maximum stroke (17 mm) was still attained.
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| 48. |
- Klintberg, Lena, et al.
(author)
-
A thermally activated paraffin-based actuator for gas-flow control in a satellite electrical propulsion system
- 2003
-
In: Sensors and Actuators A-Physical. - 0924-4247 .- 1873-3069. ; 105:3, s. 237-246
-
Journal article (peer-reviewed)abstract
- Microstructured silicon devices consisting of three inflatable paraffin-filled, corrugated caddies suspended in springs to minimize thermal losses have been fabricated and evaluated with a valve application in mind. The large volume expansion associated with the thermally induced solid-to-liquid phase transition of paraffin is used to activate the caddies’ diaphragms. Theses components all with a thickness of 600 μm and a diameter of 39 mm, but with three different corrugations, have been fabricated with deep reactive etching (DRIE). Whereas the corrugated diaphragms could endure a deflection larger than 50 μm, only strokes of 15 μm on each side were attained when the components were activated. Together with the valve seats proposed, the investigated devices have a potential in electrical propulsion systems for satellites.
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| 49. |
- Klintberg, Lena, et al.
(author)
-
Fabrication of a paraffin actuator using hot embossing of polycarbonate
- 2003
-
In: Sensors and Actuators A-Physical. - 0924-4247 .- 1873-3069. ; 103:3, s. 307-316
-
Journal article (peer-reviewed)abstract
- In this paper a fabrication process for integrating paraffin-actuated structures in polycarbonate is outlined. A paraffin-actuated membrane with a diameter of 2.5 mm, where the volume expansion of 10–15% associated with the solid-to-liquid phase transition of paraffin is utilized, has been fabricated and evaluated. Microstructures fabricated in silicon have via an electroplated nickel mould been replicated in polycarbonate by hot embossing and the resulting structures have been sealed by thermal bonding. The bonding strength was measured by a pressurizing test, and the polycarbonate surfaces were characterized with electron spectroscopy for chemical analysis (ESCA). It was found that the bond strength increased when an oxygen plasma treatment was used prior to bonding. ESCA measurements showed a corresponding increase in oxygen content on the plasma treated surfaces. This procedure also improved the wetting properties. The contact angle between paraffin and polycarbonate decreased from 10° after embossing to about 5° after plasma treatment. The fabricated actuator had a total thickness of 1 mm and the membrane deflected about 140 μm when heating the actuator above the melting point of paraffin. Paraffin wax actuators are possible to integrate in plastic structures making them promising candidates in applications such as disposable microfluidic systems where inexpensive and robust valves and pumps are needed.
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| 50. |
- Klintberg, Lena, et al.
(author)
-
Förmedling av komplexa begrepp i multidisciplinär kurs på avancerad niv
- 2013
-
Conference paper (peer-reviewed)abstract
- Vid undervisning på avancerad nivå i en multidisciplinär kurs används och behandlas vanligtvis komplexa begrepp från flera olika ämnesområden. Vid samläsning över olika program, skiljer sig studenternas förkunskaper åt även om studenterna från de olika programmen formellt uppfyller förkunskapskraven. Detta inverkar på studenternas förmåga att tillgodogöra sig kursens innehåll.En studie har gjorts på en kurs i mikro- och nanoteknik, som ges under 4:e året på flera olika civilingenjörsprogram. Med anledning av de identifierade skillnaderna, har en undersökning av tidigare studenters erfarenhet av kursen gjorts. Dessutom har de blivande studenternas förkunskaper inventerats och jämförts med de begrepp som används i kursen.Resultatet visar att studenterna i kemiteknik i viss utsträckning förfördelats även om skillnaderna är små.16% av studenterna som läst teknisk fysik med materialvetenskap (MV) når högsta betyg på kursen jämfört med 10% för studenterna i kemiteknik (KT), men i medelbetyg är det ingen signifikant skillnad mellan studentgrupperna. Vid rankning av påståendet ”Nya begrepp introducerades på ett bra och tydligt sätt” gav MV-studenterna 4,0 i medel medan KT studenterna gav 3,5 på skalan 1 (aldrig) till 5 (alltid). Syftet med denna undersökning är att, utifrån de identifierade skillnaderna, kunna hitta nya sätt att introducera och exemplifiera begreppen så att studentgrupperna får likvärdiga förutsättningar att tillgodogöra sig kursens innehåll.
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