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  • 1.
    Berglund, Martin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Palmer, Kristoffer
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Lotfi, Sara
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Kratz, Henrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Thornell, Greger
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Dynamic characterization and modelling of a dual-axis beam steering device for performance understanding, optimization, and control design2013Inngår i: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 23, nr 4, s. 045020-Artikkel i tidsskrift (Fagfellevurdert)
    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 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.

  • 2.
    Jonsson, Jonas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Sundqvist, Johan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Nguyen, Hugo
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Berglund, Martin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Ogden, Sam
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Palmer, Kristoffer
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Smedfors, Katarina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Johansson, Linda
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Hjort, Klas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Thornell, Greger
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Instrumentation and vehicle platform of a miniaturized submersible for exploration of terrestrial and extraterrestrial aqueous environments2012Inngår i: Acta Astronautica, ISSN 0094-5765, E-ISSN 1879-2030, Vol. 79, s. 203-211Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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.

  • 3.
    Jonsson, Jonas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Sundqvist, Johan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Nguyen, Hugo
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Kratz, Henrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Berglund, Martin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Ogden, Sam
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Palmer, Kristoffer
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Smedfors, Katarina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Wagner, Sven
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Hjort, Klas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Thornell, Greger
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Miniaturized submersible for exploration of aqueous environments on Earth and beyond2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    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.

  • 4.
    Jonsson, Jonas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Sundqvist, Johan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Nguyen, Hugo
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Kratz, Henrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Berglund, Martin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Ogden, Sam
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Palmer, Kristoffer
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Smedfors, Katarina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Wagner, Sven
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Thornell, Greger
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Miniaturized submersible for exploration of small aqueous environments2011Inngår i: Oceans’11 MTS/IEEE Kona, Hilton Waikoloa Village, Kona, Hawai‘i September 19-22, 2011, 2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    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.

  • 5.
    Lekholm, Ville
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Ericson, Fredric
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Palmer, Kristoffer
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Greger, Thornell
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Ceramic microcomponents for high-temperature fluidics2010Inngår i: Technical DigestPowerMEMS 2010, The 10th International Workshop on Micro and Nanotechnology for Power Generation and Energy Conversion Applications, Leuven, Belgium, December 1-3, 2010: Poster Sessions, 2010, s. 291-294Konferansepaper (Fagfellevurdert)
    Abstract [en]

    For aggressive environments, the material properties of silicon become a limitation. Macroscopically, ceramics are as abundant for high-temperature applications as is silicon in miniaturized systems, but this group of materials has been little exploited for MEMS components. A major reason is the lack of means for high-resolution structuring. This paper describes the application of silicon-based manufacturing processes in the fabrication of ceramic yet truly micromechanical structures and devices for very high-temperature applications, and demonstrates the technique’s implementation in, and significance for, high-temperature microfluidics. Embossing of structures down to 2 µm wide is demonstrated, as well as deep embossing (50 µm), punching through 15 µm tape, and lamination of structured layers. The resulting samples survive temperatures of 1400ºC.

  • 6.
    Lekholm, Ville
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Palmer, Kristoffer
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Ericson, Fredric
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Thornell, Greger
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Ceramic cold gas microthruster with integrated flow sensor2011Inngår i: PowerMEMS 2011 Technical digest: The 11th International Workshop on Micro and Nanotechnology for Power Generation and Energy Conversion Applications / [ed] Young-Ho Cho, Daejeon, Republic of Korea: Cell Bench Research Center, KAIST , 2011, s. 167-170Konferansepaper (Fagfellevurdert)
    Abstract [en]

    For aggressive environments, the material properties of silicon become a limitation. Macroscopically, ceramics are as common for high-temperature applications as is silicon in miniaturized systems, but this group of materials has been little exploited for MEMS components. This paper describes the  design, manufacturing and characterization of a ceramic, heated cold-gas microthruster with integrated flow sensor, using HTCC processing and silicon tools. The calorimetric flow sensor is integrated in the structure, and heaters are embedded in the stagnation chamber of the nozzle. The heater was shown to improve the efficiency of the thruster, as confirmed by measurements of the flow rate. Flow rate changes were seen as changes in resistance of the fabricated flow sensor. The choice of yttria stabilized zirconia as material for the components make them robust and capable of withstanding  very high temperatures. Samples have been shown  capable of achieving temperatures locally exceeding 1000ºC.

  • 7.
    Lekholm, Ville
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Palmer, Kristoffer
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Johansson, Håkan
    Rangsten, Pelle
    Thornell, Greger
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Verifying microexhausts with schlieren imaging2010Inngår i: Proceedings of the 2nd International Conference on Space Propulsion, San Sebastián, Spain, May 3-6, 2010, 2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Schlieren imaging is a method to visualize differences in refractive index within a medium. It is an inexpensive, yet powerful and straightforward tool, for sensitive and high-resolution visualization of gas flows. Here, heated cold gas microthrusters were studied with schlieren imaging techniques. The thruster chips are manufactured using MEMS technology, and measure 22*22*0.85 mm. The nozzles are approximately 20 µm wide at the throat, and 350 µm wide at the exit. Through these studies, verification and direct visualization of the functionality of the thrusters were possible. At atmospheric pressure, slipping of the exhaust was observed, due to the severe overexpansion of the nozzle. In vacuum, the nozzle was underexpanded, and the flow was seen to be supersonic. There was a measurable change in the exhaust with heaters activated. It was also shown that the method can be used to detect leaks, making it a valuable, quick, safe, and inexpensive aid in quality control of the thrusters.

  • 8.
    Lekholm, Ville
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Palmer, Kristoffer
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Thornell, Greger
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Schlieren Imaging of Microthruster Exhausts for Qualitative and Quantitative Analysis2012Inngår i: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 23, nr 8, s. 085403-Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 9.
    Lekholm, Ville
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Persson, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Palmer, Kristoffer
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Ericson, Fredric
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Thornell, Greger
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    High-temperature zirconia microthruster with integrated flow sensor2013Inngår i: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 23, nr 5, s. 055004-Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 10.
    Lotfi, Sara
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Palmer, Kristoffer
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Kratz, Henrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Thornell, Greger
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Hybrid microtransmitter for free-space optical spacecraft communication: design, manufacturing, and characterization2009Inngår i: Proc. SPIEPhotonics West, MOEMS and Miniaturized Systems VIII, Jan 24-29, San Jose, CA, 2009, s. 72080N-12-Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Opticalintra-communication links are investigated by several currently operational qualification missions.Compared with RF communication systems, the optical domain obtains awider bandwidth, enables miniaturized spacecraft and reduced power consumption. Inthis project, a microtransmitter is designed and manufactured for formationflying spacecraft with transmission rates of 1 Gbit/s. Simulations inMatlab and Simulink show that a BER of 10-9 canbe achieved with aperture sizes of 1 cm and atransmitter output peak power of 12 mW for a distanceof 10 km. The results show that the performance ofthe communication link decreases due to mechanical vibrations in thespacecraft together with a narrow laser beam. A dual-axis microactuatordesigned as a deflectable mirror has been developed for thelaser beam steering where the fabrication is based on adouble-sided, bulk micromachining process. The mirror actuates by joints consistingof v-grooves filled with SU-8 polymer. The deflection is controlledby integrated resistive heaters in the joints causing the polymerto expand thermally. Results show that the mirror actuates 20-30°in the temperature interval 25-250°C. Flat Fresnel lenses made ofPyrex 7740 are used to collimate the laser beam. Theselenses are simulated in the Comsol software and optimized fora 670 nm red VCSEL. The lenses are manufactured usinglithography and reactive ion etching. All tests are made ina normal laboratory environment, but the effect of the spaceenvironment is discussed

  • 11.
    Palmer, Kristoffer
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik, Ångström Space Technology Centre (ÅSTC).
    Development of Microcomponents for Attitude and Communication Systems on Small Vehicles in Space and Extreme Environments2013Doktoravhandling, med artikler (Annet vitenskapelig)
    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.

    Delarbeid
    1. Schlieren Imaging of Microthruster Exhausts for Qualitative and Quantitative Analysis
    Åpne denne publikasjonen i ny fane eller vindu >>Schlieren Imaging of Microthruster Exhausts for Qualitative and Quantitative Analysis
    2012 (engelsk)Inngår i: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 23, nr 8, s. 085403-Artikkel i tidsskrift (Fagfellevurdert) 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.

    sted, utgiver, år, opplag, sider
    Institute of Physics (IOP), 2012
    Emneord
    Schlieren imaging, microthrusters, MEMS, shock cells
    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot mikrosystemteknik
    Identifikatorer
    urn:nbn:se:uu:diva-186252 (URN)10.1088/0957-0233/23/8/085403 (DOI)000306366600039 ()
    Forskningsfinansiär
    VINNOVA
    Tilgjengelig fra: 2012-11-29 Laget: 2012-11-28 Sist oppdatert: 2017-12-07bibliografisk kontrollert
    2. Investigation of exhausts from fabricated silicon micronozzles with rectangular and close to rotationally symmetric cross sections
    Åpne denne publikasjonen i ny fane eller vindu >>Investigation of exhausts from fabricated silicon micronozzles with rectangular and close to rotationally symmetric cross sections
    2013 (engelsk)Inngår i: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 23, nr 10, s. 105001-Artikkel i tidsskrift (Fagfellevurdert) 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.

    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot mikrosystemteknik
    Identifikatorer
    urn:nbn:se:uu:diva-186774 (URN)10.1088/0960-1317/23/10/105001 (DOI)000324672700002 ()
    Tilgjengelig fra: 2012-11-29 Laget: 2012-11-29 Sist oppdatert: 2017-12-07bibliografisk kontrollert
    3. High-temperature zirconia microthruster with integrated flow sensor
    Åpne denne publikasjonen i ny fane eller vindu >>High-temperature zirconia microthruster with integrated flow sensor
    Vise andre…
    2013 (engelsk)Inngår i: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 23, nr 5, s. 055004-Artikkel i tidsskrift (Fagfellevurdert) 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.

    Emneord
    Keywords: Zirconia, YSZ, HTCC, schlieren imaging, flow sensor, microthruster
    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot mikrosystemteknik
    Identifikatorer
    urn:nbn:se:uu:diva-186257 (URN)10.1088/0960-1317/23/5/055004 (DOI)000317739100004 ()
    Forskningsfinansiär
    Vinnova
    Tilgjengelig fra: 2012-11-28 Laget: 2012-11-28 Sist oppdatert: 2017-12-07bibliografisk kontrollert
    4. Fabrication and evaluation of a free molecule micro-resistojet with thick silicon dioxide insulation and suspension
    Åpne denne publikasjonen i ny fane eller vindu >>Fabrication and evaluation of a free molecule micro-resistojet with thick silicon dioxide insulation and suspension
    2013 (engelsk)Inngår i: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 23, nr 6, s. 065006-Artikkel i tidsskrift (Fagfellevurdert) 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.

    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot mikrosystemteknik
    Identifikatorer
    urn:nbn:se:uu:diva-186775 (URN)10.1088/0960-1317/23/6/065006 (DOI)000319451300006 ()
    Tilgjengelig fra: 2012-11-29 Laget: 2012-11-29 Sist oppdatert: 2017-12-07bibliografisk kontrollert
    5. A highly integratable silicon thermal gas flow sensor
    Åpne denne publikasjonen i ny fane eller vindu >>A highly integratable silicon thermal gas flow sensor
    2012 (engelsk)Inngår i: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 22, nr 6, s. 065015-Artikkel i tidsskrift (Fagfellevurdert) 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.

    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot mikrosystemteknik
    Identifikatorer
    urn:nbn:se:uu:diva-176814 (URN)10.1088/0960-1317/22/6/065015 (DOI)000304609600015 ()
    Tilgjengelig fra: 2012-06-27 Laget: 2012-06-26 Sist oppdatert: 2017-12-07bibliografisk kontrollert
    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
    Åpne denne publikasjonen i ny fane eller vindu >>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 (engelsk)Inngår i: Sensors and Actuators A-Physical, ISSN 0924-4247, E-ISSN 1873-3069, Vol. 201, s. 49-57Artikkel i tidsskrift (Fagfellevurdert) 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.

    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot mikrosystemteknik
    Identifikatorer
    urn:nbn:se:uu:diva-186776 (URN)10.1016/j.sna.2013.05.018 (DOI)000325836400006 ()
    Tilgjengelig fra: 2012-11-29 Laget: 2012-11-29 Sist oppdatert: 2017-12-07bibliografisk kontrollert
    7. Two-Dimensional Thermal Velocity Sensor for Submersible navigation and Minute Flow Measurements
    Åpne denne publikasjonen i ny fane eller vindu >>Two-Dimensional Thermal Velocity Sensor for Submersible navigation and Minute Flow Measurements
    2013 (engelsk)Inngår i: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 13, nr 1, s. 359-370Artikkel i tidsskrift (Fagfellevurdert) 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.

    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot mikrosystemteknik
    Identifikatorer
    urn:nbn:se:uu:diva-171767 (URN)10.1109/JSEN.2012.2216866 (DOI)000313685400028 ()
    Tilgjengelig fra: 2012-03-27 Laget: 2012-03-27 Sist oppdatert: 2017-12-07bibliografisk kontrollert
    8. A micromachined dual-axis beam steering actuator for use in a miniaturized optical space communication system
    Åpne denne publikasjonen i ny fane eller vindu >>A micromachined dual-axis beam steering actuator for use in a miniaturized optical space communication system
    Vise andre…
    2010 (engelsk)Inngår i: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 20, nr 10, s. 105007-Artikkel i tidsskrift (Fagfellevurdert) 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.

    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-134362 (URN)10.1088/0960-1317/20/10/105007 (DOI)000282270300020 ()
    Tilgjengelig fra: 2010-11-25 Laget: 2010-11-24 Sist oppdatert: 2017-12-12
    9. Dynamic characterization and modelling of a dual-axis beam steering device for performance understanding, optimization, and control design
    Åpne denne publikasjonen i ny fane eller vindu >>Dynamic characterization and modelling of a dual-axis beam steering device for performance understanding, optimization, and control design
    Vise andre…
    2013 (engelsk)Inngår i: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 23, nr 4, s. 045020-Artikkel i tidsskrift (Fagfellevurdert) 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 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.

    HSV kategori
    Forskningsprogram
    Teknisk fysik med inriktning mot mikrosystemteknik; Teknisk fysik med inriktning mot elektronik
    Identifikatorer
    urn:nbn:se:uu:diva-185627 (URN)10.1088/0960-1317/23/4/045020 (DOI)000316299900021 ()
    Tilgjengelig fra: 2012-11-27 Laget: 2012-11-27 Sist oppdatert: 2017-12-07bibliografisk kontrollert
  • 12.
    Palmer, Kristoffer
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Berglund, Martin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Kratz, Henrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Thornell, Greger
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    A miniaturized optical communication system for microspacecraft2010Konferansepaper (Fagfellevurdert)
  • 13.
    Palmer, Kristoffer
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Jonsson, Jonas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Nguyen, Hugo
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Thornell, Greger
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Two-Dimensional Thermal Velocity Sensor for Submersible navigation and Minute Flow Measurements2013Inngår i: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 13, nr 1, s. 359-370Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 14.
    Palmer, Kristoffer
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Kratz, Henrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Nguyen, Hugo
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Thornell, Greger
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    A highly integratable silicon thermal gas flow sensor2012Inngår i: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 22, nr 6, s. 065015-Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 15.
    Palmer, Kristoffer
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Kratz, Henrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Nguyen, Hugo
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Thornell, Greger
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Infrared imaging of an integratable, robust thermal flow sensor with a thick silicon dioxide membrane and through-going silicon heat conductors2011Inngår i: 17th International Workshop on Thermal Investigations of ICs and Systems, 2011, s. 70-73Konferansepaper (Fagfellevurdert)
  • 16.
    Palmer, Kristoffer
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Lekholm, Ville
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Johansson, H.
    Rangsten, P.
    Thornell, Greger
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Verification of microrocket exhausts using schlieren imaging2010Inngår i: Proceedings of Micronano System Workshop 2010, Stockholm, Sweden, May 4-5, 2010, 2010Konferansepaper (Fagfellevurdert)
  • 17.
    Palmer, Kristoffer
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Lekholm, Ville
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Kratz, Henrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Nguyen, Hugo
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Thornell, Greger
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Development of a suspended, robust, thermally insulated micro chamber of thick silicon dioxide for microthrusters and micoreactors2011Inngår i: PowerMEMS 11 Technical digest: The 11th International Workshop on Micro and Nanotechnology for Power Generation and Energy Conversion Applications / [ed] Young-Ho Cho, 2011, s. 62-65Konferansepaper (Fagfellevurdert)
  • 18.
    Palmer, Kristoffer
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Lotfi, Sara
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Berglund, Martin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Thornell, Greger
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Kratz, Henrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    A micromachined dual-axis beam steering actuator for use in a miniaturized optical space communication system2010Inngår i: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 20, nr 10, s. 105007-Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 19.
    Palmer, Kristoffer
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrostrukturteknik.
    Lotfi, Sara
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrostrukturteknik.
    Kratz, Henrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrostrukturteknik.
    Thornell, Greger
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrostrukturteknik.
    A micromachined dual-axis actuator for Use in a miniaturized optical communication system2008Inngår i: Proceeding of the International Astronautical Congress, Sep 29 - Oct 3, Glasgow, Scotland, 2008Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A micromachined beam-steering device for use in a miniaturized free-space optical communication system is presented. This device is part of a communication system intended for microspacecraft flying in kilometer-sized formations. Central to it, is a laser-reflecting mirror tiltable in two orthogonal directions using electrothermal actuators based on heating of a polymer confined in silicon v-grooves. The device is fabricated using standard microstructure technology. Successful experiments show a maximum mechanical scan range of 19º in two orthogonal directions. The voltages applied are below 100 V, and the power consumption is less than 2.4 W. Thermal coupling between orthogonal joints has been investigated with infrared imaging. The overall results are very promising, and improvement in the design and fabrication can be suggested.

  • 20.
    Palmer, Kristoffer
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Nguyen, Hugo
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Thornell, Greger
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Fabrication and evaluation of a free molecule micro-resistojet with thick silicon dioxide insulation and suspension2013Inngår i: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 23, nr 6, s. 065006-Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 21.
    Palmer, Kristoffer
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Nguyen, Hugo
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Thornell, Greger
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Finite Element Analysis of the Effect on Employing Thermal Through Vias and Heat Fingers to Increase Heat Transfer to Fluid in Calorimetric Flow Sensors2013Inngår i: Sensors and Actuators A-Physical, ISSN 0924-4247, E-ISSN 1873-3069, Vol. 201, s. 49-57Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 22.
    Palmer, Kristoffer
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Vargas Catalan, Ernesto
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Lekholm, Ville
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Thornell, Greger
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Investigation of exhausts from fabricated silicon micronozzles with rectangular and close to rotationally symmetric cross sections2013Inngår i: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 23, nr 10, s. 105001-Artikkel i tidsskrift (Fagfellevurdert)
    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.

1 - 22 of 22
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