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Characterization of dielectric properties of polycrystalline aluminum nitride for high temperature wireless sensor nodes
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
2013 (English)In: 13th International Conference on Micro And Nanotechnology for Power Generation and Energy Conversion Applications (Powermems 2013), 2013Conference paper, Published paper (Refereed)
Abstract [en]

An aluminium nitride (AIN) passive resonance circuit intended for thermally matched high temperature wireless sensor nodes (WSN) was manufactured using thick-film technology. Characterization was done for temperatures up to 900 C in both a hot-chuck for frequencies below 5 MHz, and using wireless readings of resonating circuits at 15 MHz, 59 MHz, and 116 MHz. The substrate for the circuits was sintered polycrystalline AIN. Using a simplified model for the resonators where the main contribution of the frequency-shift was considered to come from a shift of the dielectric constant for these frequencies, the temperature dependency of the dielectric constant for AIN was found to decrease with increasing frequency up to 15 MHz. With an observed frequency shift of 0.04% at 15 MHz, and up to 0.56% at 59 MHz over a temperature range of 900 C, AIN looks as a promising material for integration of resonance circuits directly on the substrate.

Place, publisher, year, edition, pages
2013.
Series
Journal of Physics Conference Series, ISSN 1742-6588 ; 476
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:uu:diva-218528DOI: 10.1088/1742-6596/476/1/012101ISI: 000329347500100OAI: oai:DiVA.org:uu-218528DiVA: diva2:696339
Conference
13th International Conference on Micro- and Nano-Technology for Power Generation and Energy Conversion Applications (PowerMEMS), DEC 03-06, 2013, London, ENGLAND
Available from: 2014-02-13 Created: 2014-02-12 Last updated: 2015-09-07Bibliographically approved
In thesis
1. Microsystems for Harsh Environments
Open this publication in new window or tab >>Microsystems for Harsh Environments
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

When operating microsystems in harsh environments, many conventionally used techniques are limiting. Further, depending on if the demands arise from the environment or the conditions inside the system, different approaches have to be used. This thesis deals with the challenges encountered when microsystems are used at high pressures and high temperatures.

For microsystems operating at harsh conditions, many parameters will vary extensively with both temperature and pressure, and to maintain control, these variations needs to be well understood. Covered within this thesis is the to-date strongest membrane micropump, demonstrated to pump against back-pressures up to 13 MPa, and a gas-tight high pressure valve that manages pressures beyond 20 MPa.

With the ability to manipulate fluids at high pressures in microsystems at elevated temperatures, opportunities are created to use green solvents like supercritical fluids like CO2. To allow for a reliable and predictable operation in systems using more than one fluid, the behavior of the multiphase flow needs to be controlled. Therefore, the effect of varying temperature and pressure, as well as flow conditions were investigated for multiphase flows of CO2 and H2O around and above the critical point of CO2. Also, the influence of channel surface and geometry was investigated.

Although supercritical CO2 only requires moderate temperatures, other supercritical fluids or reactions require much higher temperatures. The study how increasing temperature affects a system, a high-temperature testbed inside an electron microscope was created.

One of the challenges for high-temperature systems is the interface towards room temperature components. To circumvent the need of wires, high temperature wireless systems were studied together with a wireless pressure sensing system operating at temperatures up to 1,000 °C for pressures up to 0.3 MPa.

To further extend the capabilities of microsystems and combine high temperatures and high pressures, it is necessary to consider that the requirements differs fundamentally. Therefore, combining high pressures and high temperatures in microsystems results in great challenges, which requires trade-offs and compromises. Here, steel and HTCC based microsystems may prove interesting alternatives for future high performance microsystems.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2015. 50 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1263
Keyword
Microsystems, harsh environments, high pressures, high temperatures, supercritical microfluidics
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Microsystems Technology
Identifiers
urn:nbn:se:uu:diva-253558 (URN)978-91-554-9272-4 (ISBN)
Public defence
2015-09-11, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 09:15 (English)
Opponent
Supervisors
Available from: 2015-08-19 Created: 2015-05-29 Last updated: 2015-09-07

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Knaust, StefanKhaji, ZahraKlintberg, Lena

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