Thermomechanical properties and performance of ceramic resonators for wireless pressure reading in high temperatures. Micromechanics and Microengineering, 25(9) Abstract -This paper reports on the design, fabrication and thermomechanical study of ceramic LC resonators for wireless pressure reading, verified at room temperature, at 500 °C and at 1000 °C for pressures up to 2.5 bar. Five different devices were fabricated of high-temperature co-fired ceramics (HTCC) and characterized. Alumina green tape sheets were screen printed with platinum paste, micromachined, laminated and fired. The resulting samples were 21 x 19 mm 2 with different thicknesses. An embedded communicator part was integrated with either a passive backing part or with a pressure-sensing element, including an 80 µm thick and 6 mm diameter diaphragm. The study includes measuring thermally and mechanically induced resonance frequency shifts, and thermally induced deformations. For the pressure sensor device, contributions from changes in the relative permittivity and from expanding air, trapped in the cavity, were extracted. The devices exhibited thermomechanical robustness during heating, regardless of the thickness of the backing. The pressure sensitivity decreased with increasing temperature from 15 050 ppm/bar at room temperature to 2400 ppm/bar at 1000°C, due to the decreasing pressure difference between the external pressure and the air pressure inside the cavity. Journal of

Manufacturing and characterization of a ceramic microcombustor with integrated oxygen storage and release element. Micromechanics and Microengineering, 25(10) Abstract -A microscale ceramic high-temperature combustor with a built-in temperature sensor and source of oxygen has been designed, manufactured and characterized. The successful in situ electroplating and oxidation of copper, and the use of copper oxide as the source of oxygen were demonstrated. It was shown that residual stresses from electroplating, copper oxidation and oxide decomposition did not cause much deformation of the substrate but influenced mainly the integrity and adhesion of the metal films. The process had influence on the electrical resistances, however. Calibration of the temperature sensor and correlation with IR thermography up to 1000 °C revealed a nearly linear sensor behavior. Demonstration of combustion in a vacuum chamber proved that no combustion had occurred before release of oxygen from the metal oxide resource. Journal of

Monopropellant ceramic microthrusters with an integrated heater, catalytic bed and two temperature sensors, but of various designs, were manufactured by milling a fluidic channel and chamber, and a nozzle, and screen printing platinum patterns on green tapes of alumina that were stacked and laminated before sintering. In order to increase the surface area of the catalytic bed, the platinum paste was mixed with a sacrificial paste that disappeared during sintering, to leave behind a porous and rough layer. As an early development level in manufacturing robust and high-temperature tolerant microthrusters, the influence of design on the temperature gradients and dry temperature tolerance of the devices was studied. On average, the small reaction chambers showed a more than 1.5 times higher dry temperature tolerance (in centigrade) compared to devices with larger chambers, independent of the heater and device size. However, for a given temperature, big devices consumed on average 2.9 times more power than the small ones. It was also found that over the same area and under the same heating conditions, devices with small chambers were subjected to approximately 40% smaller temperature differences. A pressure test done on two small devices with small chambers revealed that pressures of at least 26.3 bar could be tolerated. Above this pressure, the interfaces failed but the devices were not damaged. To investigate the cooling effect of the micropropellant, the endurance of a full thruster was also studied under wet testing where it was fed with 31 wt.% hydrogen peroxide. The thruster demonstrated complete evaporation and/or full decomposition at a power above 3.7 W for a propellant flow of 50 µl min−1. At this power, the catalytic bed locally reached a temperature of 147 °C. The component was successfully heated to an operating temperature of 307 °C, where it cracked. Under these firing conditions, and assuming complete decomposition, calculations give a thrust and specific impulse of 0.96 mN and 106 s, respectively. In the case of evaporation, the corresponding values are calculated to be 0.84 mN and 92 s.

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Söderberg, J. et al. (2016) Optogalvanic spectroscopy with microplasma sources -Current status and development towards lab on a chip. Journal of Micromechanics and MicroengineeringAccess to the published version may require subscription. N.B. When citing this work, cite the original published paper.Filen arkiveras tills dess att information om publikationen kommer in. Det är post-print och inga problem att ha i DiVA. Abstract. Miniaturized optogalvanic spectroscopy shows excellent prospects of becoming a highly sensitive method for gas analysis in micro total analysis systems. Here, a status report on the current development of microwave induced microplasma sources for optogalvanic spectroscopy is presented, together with the first comparison of the sensitivity of the method to conventional single-pass absorption spectroscopy. The studied microplasma sources are stripline split-ring resonators, with typical ring radii between 3.5 and 6 mm and operation frequencies around 2.6 GHz. A linear response (R 2 =0.9999), and a stability of more than 100 s are demonstrated when using the microplasma source as an optogalvanic detector. Additionally, saturation effects at laser powers higher than 100 mW are observed, and the temporal response of the plasma to periodic laser perturbation with repletion rates between 20 Hz and 200 Hz are studied. Finally, the potential of integrating additional functionality with the detector is discussed, with the particular focus on a pressure sensor and a miniaturized combustor to allow for studies of solid samples.