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Kratz, Henrik
Publications (10 of 33) Show all publications
Berglund, M., Palmer, K., Lotfi, S., Kratz, H. & Thornell, G. (2013). Dynamic characterization and modelling of a dual-axis beam steering device for performance understanding, optimization, and control design. Journal of Micromechanics and Microengineering, 23(4), 045020
Open this publication in new window or tab >>Dynamic characterization and modelling of a dual-axis beam steering device for performance understanding, optimization, and control design
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2013 (English)In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 23, no 4, p. 045020-Article in journal (Refereed) Published
Abstract [en]

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

National Category
Communication Systems
Research subject
Engineering Science with specialization in Microsystems Technology; Engineering Science with specialization in Electronics
Identifiers
urn:nbn:se:uu:diva-185627 (URN)10.1088/0960-1317/23/4/045020 (DOI)000316299900021 ()
Available from: 2012-11-27 Created: 2012-11-27 Last updated: 2017-12-07Bibliographically approved
Berglund, M., Persson, A., Kratz, H. & Thornell, G. (2013). Microfluidics integrable plasma source powered by a silicon through-substrate split-ring resonator. In: Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS EUROSENSORS XXVII): . Paper presented at 2013 Transducers Eurosensors XXVII: The 17th International Conference on (pp. 2608-2611).
Open this publication in new window or tab >>Microfluidics integrable plasma source powered by a silicon through-substrate split-ring resonator
2013 (English)In: Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS EUROSENSORS XXVII), 2013, p. 2608-2611Conference paper, Oral presentation only (Other academic)
Abstract [en]

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.

Keywords
elemental semiconductors, ignition, microfluidics, micromechanical resonators, microstrip resonators, plasma instability, plasma pressure, plasma sources;silicon, MEMS, Si, microfluidics integrable plasma source, plasma discharge gap, plasma ignition modes, quality factors, silicon through-substrate split-ring resonator, Electrodes, Microstrip, Nickel, Optical resonators, Plasma sources, Substrates, Micro-fluidics, Microplasma source, Ni plating, RF, Split-ring resonator
National Category
Other Physics Topics Engineering and Technology
Research subject
Engineering Science with specialization in Microsystems Technology; Engineering Science with specialization in Microwave Technology
Identifiers
urn:nbn:se:uu:diva-212362 (URN)10.1109/Transducers.2013.6627340 (DOI)
Conference
2013 Transducers Eurosensors XXVII: The 17th International Conference on
Available from: 2013-12-09 Created: 2013-12-09 Last updated: 2016-04-21
Jonsson, J., Berglund, M., Kratz, H., Nguyen, H. & Thornell, G. (2012). A compact system to extract topography information from scenes viewed by a miniaturized submersible explorer. Paper presented at The 16th International Conference on Solid-State Sensors, Actuators and Microsystems, 5-9 June, 2011, Beijing, CHINA. Sensors and Actuators A-Physical, 188(SI), 401-410
Open this publication in new window or tab >>A compact system to extract topography information from scenes viewed by a miniaturized submersible explorer
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2012 (English)In: Sensors and Actuators A-Physical, ISSN 0924-4247, E-ISSN 1873-3069, Vol. 188, no SI, p. 401-410Article in journal, Meeting abstract (Refereed) Published
Abstract [en]

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

Keywords
Photogrammetry, Diffractive, Laser, Underwater, Images, Miniaturized
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Microsystems Technology
Identifiers
urn:nbn:se:uu:diva-171732 (URN)10.1016/j.sna.2012.02.034 (DOI)000312692500054 ()
Conference
The 16th International Conference on Solid-State Sensors, Actuators and Microsystems, 5-9 June, 2011, Beijing, CHINA
Projects
Deeper Access, Deeper Understanding (DADU)
Available from: 2012-03-26 Created: 2012-03-26 Last updated: 2017-12-07Bibliographically approved
Palmer, K., Kratz, H., Nguyen, H. & Thornell, G. (2012). A highly integratable silicon thermal gas flow sensor. Journal of Micromechanics and Microengineering, 22(6), 065015
Open this publication in new window or tab >>A highly integratable silicon thermal gas flow sensor
2012 (English)In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 22, no 6, p. 065015-Article in journal (Refereed) Published
Abstract [en]

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

National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Microsystems Technology
Identifiers
urn:nbn:se:uu:diva-176814 (URN)10.1088/0960-1317/22/6/065015 (DOI)000304609600015 ()
Available from: 2012-06-27 Created: 2012-06-26 Last updated: 2017-12-07Bibliographically approved
Jonsson, J., Lekholm, V., Kratz, H., Monica, A. & Thornell, G. (2012). Enclosure-Induced Interference Effects in a Miniaturized Sidescan Sonar. IEEE Journal of Oceanic Engineering, 37(2), 236-243
Open this publication in new window or tab >>Enclosure-Induced Interference Effects in a Miniaturized Sidescan Sonar
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2012 (English)In: IEEE Journal of Oceanic Engineering, ISSN 0364-9059, E-ISSN 1558-1691, Vol. 37, no 2, p. 236-243Article in journal (Refereed) Published
Abstract [en]

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

Keywords
Beam shape, finite element analysis (FEA), miniaturize, Schlieren, sidescan sonar
National Category
Fluid Mechanics and Acoustics
Research subject
Engineering Science with specialization in Microsystems Technology
Identifiers
urn:nbn:se:uu:diva-171730 (URN)10.1109/JOE.2012.2188160 (DOI)000303326500007 ()
Projects
Deeper Access, Deeper Understanding (DADU)
Available from: 2012-03-26 Created: 2012-03-26 Last updated: 2017-12-07Bibliographically approved
Jonsson, J., Berglund, M., Kratz, H., Nguyen, H. & Thornell, G. (2011). A compact projection system enabling topographical measurements for a miniaturized submersible explorer. In: Proceedings of the 16th International Conference on Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS), 2011: . Paper presented at 16th International Conference on Solid-State Sensors, Actuators and Microsystems (Transducers 2011), 5-9 June 2011, Beijing (pp. 2518-2521). IEEE conference proceedings
Open this publication in new window or tab >>A compact projection system enabling topographical measurements for a miniaturized submersible explorer
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2011 (English)In: Proceedings of the 16th International Conference on Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS), 2011, IEEE conference proceedings, 2011, p. 2518-2521Conference paper, Published paper (Refereed)
Abstract [en]

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.

Place, publisher, year, edition, pages
IEEE conference proceedings, 2011
Keywords
Diffractive optical element, miniaturization, photogrammetry
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Microsystems Technology
Identifiers
urn:nbn:se:uu:diva-163024 (URN)10.1109/TRANSDUCERS.2011.5969758 (DOI)978-1-4577-0157-3 (ISBN)
Conference
16th International Conference on Solid-State Sensors, Actuators and Microsystems (Transducers 2011), 5-9 June 2011, Beijing
Projects
Deeper Access, Deeper Understanding (DADU)
Available from: 2012-01-04 Created: 2011-12-07 Last updated: 2016-04-20Bibliographically approved
Palmer, K., Lekholm, V., Kratz, H., Nguyen, H. & Thornell, G. (2011). Development of a suspended, robust, thermally insulated micro chamber of thick silicon dioxide for microthrusters and micoreactors. In: Young-Ho Cho (Ed.), PowerMEMS 11 Technical digest: The 11th International Workshop on Micro and Nanotechnology for Power Generation and Energy Conversion Applications. Paper presented at PowerMEMS 2011, Nov 15-18, Seoul, Republic of Korea (pp. 62-65).
Open this publication in new window or tab >>Development of a suspended, robust, thermally insulated micro chamber of thick silicon dioxide for microthrusters and micoreactors
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2011 (English)In: PowerMEMS 11 Technical digest: The 11th International Workshop on Micro and Nanotechnology for Power Generation and Energy Conversion Applications / [ed] Young-Ho Cho, 2011, p. 62-65Conference paper, Published paper (Refereed)
National Category
Other Materials Engineering
Research subject
Engineering Science with specialization in Materials Science
Identifiers
urn:nbn:se:uu:diva-164831 (URN)978-89-967591-0-2 (ISBN)
Conference
PowerMEMS 2011, Nov 15-18, Seoul, Republic of Korea
Available from: 2012-01-04 Created: 2011-12-28 Last updated: 2016-04-20Bibliographically approved
Janhunen, P., Merikallio, S., Toivanen, P., Polkko, J., Haeggström, E., Seppänen, H., . . . Giusti, N. (2011). Electric Solar Wind Sail in tailwind. In: EPSC-DPS Joint Meeting 2011. Paper presented at European Planetary Science Congress - DPS Joint Meeting 2011 - La Cité Internationale des Congrès Nantes Métropole, 02 – 07 October 2011, Nantes, France.
Open this publication in new window or tab >>Electric Solar Wind Sail in tailwind
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2011 (English)In: EPSC-DPS Joint Meeting 2011, 2011Conference paper, Published paper (Refereed)
Abstract [en]

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.

Series
EPSC Abstracts ; 6
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Microsystems Technology
Identifiers
urn:nbn:se:uu:diva-163743 (URN)
Conference
European Planetary Science Congress - DPS Joint Meeting 2011 - La Cité Internationale des Congrès Nantes Métropole, 02 – 07 October 2011, Nantes, France
Available from: 2011-12-19 Created: 2011-12-14 Last updated: 2013-03-21Bibliographically approved
Janhunen, P., Toivanen, P., Merikallio, S., Polkko, J., Haeggström, E., Seppänen, H., . . . Giusti, N. (2011). Electric Solar Wind Sail Propulsion System Development. In: International Electric Propulsion Conference: . Paper presented at International Electric Propulsion Conference.
Open this publication in new window or tab >>Electric Solar Wind Sail Propulsion System Development
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2011 (English)In: International Electric Propulsion Conference, 2011Conference paper, Published paper (Refereed)
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Microsystems Technology
Identifiers
urn:nbn:se:uu:diva-163760 (URN)
Conference
International Electric Propulsion Conference
Available from: 2011-12-14 Created: 2011-12-14 Last updated: 2016-04-20
Palmer, K., Kratz, H., Nguyen, H. & Thornell, G. (2011). Infrared imaging of an integratable, robust thermal flow sensor with a thick silicon dioxide membrane and through-going silicon heat conductors. In: 17th International Workshop on Thermal Investigations of ICs and Systems: . Paper presented at 17th International Workshop on Thermal Investigations of ICs and Systems (pp. 70-73).
Open this publication in new window or tab >>Infrared imaging of an integratable, robust thermal flow sensor with a thick silicon dioxide membrane and through-going silicon heat conductors
2011 (English)In: 17th International Workshop on Thermal Investigations of ICs and Systems, 2011, p. 70-73Conference paper, Published paper (Refereed)
National Category
Other Materials Engineering
Research subject
Engineering Science with specialization in Microsystems Technology
Identifiers
urn:nbn:se:uu:diva-164832 (URN)978-2-35500-018-8 (ISBN)
Conference
17th International Workshop on Thermal Investigations of ICs and Systems
Available from: 2011-12-28 Created: 2011-12-28 Last updated: 2016-04-20
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