| 1. |
- 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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| 2. |
- Nguyen, Hugo, 1955-, et al.
(author)
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Material- and fabrication-governed performance of a tunnelling magnetometer
- 2010
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In: Advances in Natural Sciences. - : Institute of Physics (IOP). - 2043-6254 .- 2043-6262. ; 1:4, s. 045006-
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Journal article (peer-reviewed)abstract
- Miniaturization of sensitive magnetic sensors for nano- and picosatellites has come to the point where the traditional sensors with magnetic coils soon can be replaced. Thin film technology offers the possibility of making extremely small magnetic field sensors that employ the effect of anisotropic, giant and tunneling magnetoresistance (AMR, GMR and TMR). In this paper, the development status of sensors based on microelectromechanical systems technology (MEMS), starting from a TMR layer structure is presented. The sensors have been successfully fabricated and integrated onto an electronic circuit designed for space application. The system as a whole, and the sensors in particular, have not only been characterized with respect to sensitivity, resolution, and noise level, but also to launch vibration and space radiation. The sensor performance and limitations are strongly dependent on the deposited materials, sensor design, and fabrication process. Since the sensor elements are small and sensitive (with lateral dimensions of some tens of micrometres, and resolution of 100 pT at frequencies of MHz), they are also promising for other MEMS applications.
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| 3. |
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| 4. |
- Persson, Anders, et al.
(author)
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Changing the attitude towards magnetoresistance
- 2011
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In: Changing the attitude towards magnetoresistance.
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Conference paper (peer-reviewed)abstract
- Magnetometers are one of the most common instruments on spacecrafts. They are used for both satellite attitude determination and for scientific purposes, such as mapping of Earth’s magnetic field. The most common magnetometer for low-frequency applications is the fluxgate. High-end fluxgates are generally quite bulky, with a mass of around 1 kg, but there exist miniature version, weighing only around 100 g, but with worse noise figure. Interest in such miniature models has increased with the adaption of the Faster-Better-Cheaper philosophy, and the introduction of small satellite classes. However, downscaling of fluxgates beyond the present 100 g has proven difficult, wherefore other technologies have earned more and more interest, especially those employing different kinds of magnetoresistance.Here, a review of different magnetoresistive techniques, and their past, present and potential use in space is presented. Magnetoresistive sensors based on anisotropic, giant, and tunneling magnetoresistance is covered, and extra attention is directed towards sensors based on the planar Hall effect. The latter have the potential of overcoming some of the major disadvantages of other magnetoresistive sensors, such as poor detectivity at low frequencies, and the need for external biasing coils to improve linearity and reduce hysteresis by, e.g., set-reset protocols and magnetic feedback.Moreover, the design of two such planar Hall effect sensors is tailored to meet the requirements set on a magnetometer aimed for, firstly, attitude determination and, secondly, mapping of Earth’s magnetic field. It is concluded that planar Hall effect sensors is one of the prime candidates for the next generation of miniaturized low-frequency space magnetometers.
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| 5. |
- Persson, Anders, 1982-, et al.
(author)
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Disrupting Blood Gas Analysis, Path to Rapid, Gentle and Continuous Monitoring : DBGA
- 2020
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Conference paper (other academic/artistic)abstract
- For prematurely born children, yearly amounting to 15 million, monitoring of CO2 content in the blood is vital. Clinically, either ablood sample is taken, limiting the number of measurements and delaying the information, or a method detecting the gas escapingthrough the skin on heating it, is used. The latter poses severe risks of injury either by the heat itself or from skin rupturing onremoving the sensor. Here, a truly non-invasive concept has been fully prototyped and benchmarked. It allows for continuous, nonlagging,measurements of a quality seemingly outperforming state-of-the-art equipment, also on body parts previously considereddisqualified.
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| 6. |
- Persson, Anders, 1982-, et al.
(author)
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Micro- and nanostructured magnetic field sensor for space applications
- 2009
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In: 15th International Conference on Solid-State SensorsTransducers 2009. ; , s. 1190-1193
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Conference paper (peer-reviewed)abstract
- Magnetometers are popular payloads on scientific space missions. Here, the design and fabrication process of a miniaturized magnetometer based on tunneling magnetoresistance is presented. The process is capable of making magnetic tunnel junctions in a wide size range, by employing both UV lithography and focused ion beam milling and deposition. Ga implantation in the ferromagnetic electrodes of the junction is studied in more detail. It was shown that Ga implantation may harm the magnetometer if the irradiation dose exceeds 1014 Ga+ cm-2.
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| 7. |
- Seton, Ragnar, 1985-, et al.
(author)
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Compliance of a microstructured, soft sampling device for transcutaneous blood gas monitoring
- 2020
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In: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 10:60, s. 36386-36395
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Journal article (peer-reviewed)abstract
- Premature neonates are too small for repeated blood sampling, but still require precise monitoring of blood gas levels. The standard method therefore involves transcutaneous blood gas monitoring (TBM),i.e.analyzing gas that permeates the skin. The method involves skin heating and requires frequent relocation of a rigid sensor that is adhesively mounted to the skin, which makes the monitoring intermittent and can cause tissue damage. To mitigate this, this paper introduces a TBM concept that replaces the sensor with a small, non-adhesive, flexible, polydimethylsiloxane patch, routing the gases through skin-facing microchannels laid out in various configurations, to an external optical emission spectroscopy system (OES). As the OES depends on a constant flow of gas, we have investigated the effects external loads, both vertical and with a transverse component, have on the aerodynamic resistance of the patches. The experiments show that patches with 200 mu m wide channels can withstand uniformly distributed forces up to 25 N with a change in aerodynamic resistance of about 0.01 mbar per sccm per newton. In subsequent measurements, the proof of concept (POC) TBM system showed a strong and fast blood gas signal that was unaffected by all likely loads in the intended application. Moreover, the rise time of the signal is shown to be inversely proportional to the aerodynamic resistance, and the signal strength to be proportional to the skin area exposed to the microchannels. With these results, the POC TBM system is a viable first step towards truly continuous blood gas monitoring of prematurely born children.
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| 8. |
- Sturesson, Peter, 1981-, et al.
(author)
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Effect of Resistive and Plasma Heating on the Specific Impulse of a Ceramic Cold Gas Thruster
- 2019
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In: Journal of microelectromechanical systems. - 1057-7157 .- 1941-0158. ; 28:2, s. 235-244
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Journal article (peer-reviewed)abstract
- The research and development of small satellites has continued to expand over the last decades. However, the propulsion systems with adequate performance have persisted to be a great challenge. In this paper, the effects of three different heaters on the specific impulse and overall thrust efficiency of a cold gas microthruster are presented. They consisted of a conventional, printed resistive thick-film element, a freely suspended wire, and a stripline split-ring resonator microplasma source, and were integrated in a single device made from the high-temperature co-fired ceramics. The devices were evaluated in two setups, where the first measured thrust and the other measured shock cell geometry. In addition, the resistive elements were evaluated as gas temperature sensors. The microplasma source was found to provide the greatest improvement in both specific impulse and thrust efficiency, increasing the former from an un-heated level of 44–56 s when heating with a power of 1.1 W. This corresponded to a thrust efficiency of 55%, which could be compared with the results from the wire and printed heaters which were 51s and 18%, and 45s and 14%, respectively. The combined results also showed that imaging the shock cells of a plasma heated thruster was a simple and effective way to determine its performance, when compared to the traditional thrust balance method.
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| 9. |
- Åkerfeldt, Erika, et al.
(author)
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Integration and characterization of a zeolite material in a microcomponent for measurements of environmental carbon dioxide
- 2024
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In: Applied Research. - : John Wiley & Sons, Ltd. - 2702-4288.
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Journal article (peer-reviewed)abstract
- This study demonstrates integration of a zeolite material in a ceramic microcomponent intended for use in sampling and analysis of environmental carbon dioxide (CO2). The zeolite material was integrated in bulk form, allowing for adsorption of large quantities of CO2 compared to previous integration attempts as thin films. To obtain a porous bulk material, an injectable slurry was developed, where expandable polymeric microspheres were added as a sacrificial template. By varying water and sphere contents of the slurry, it was possible to tune the porosity of the zeolite material between 55% and 72%. This in turn affected the flow resistance of the microcomponents, where an increase in the porosity of the filling from 62% to 72% reduced the flow resistance from 84 to 28 kPa min cm-3. In addition, the spheres facilitated complete fillings free from cracks. The zeolite material was seen to retain its ability to adsorb CO2 after processing, but it was not possible to quantify the level of retention compared to unprocessed zeolite.
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