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Sensors 2012, 12(7), 8770-8781; doi:10.3390/s120708770
Article

Comparisons between Membrane, Bridge and Cantilever Miniaturized Resistive Vacuum Gauges

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Received: 16 May 2012; in revised form: 11 June 2012 / Accepted: 15 June 2012 / Published: 27 June 2012
(This article belongs to the Section Physical Sensors)
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Abstract: Using bulk micromachining, meander-shaped resistor elements consisting of 20 nm Cr and 200 nm Au were fabricated on 1 µm thick silicon nitride membranes, bridges, and cantilevers. The resistance change as a function of pressure depends strongly on the thermal resistance of the two metal lines connecting the heated resistor to the silicon bulk (cold junction) and on the thermal resistance of the silicon nitride. Relative resistance changes ranging from about 3% (small membrane) to 20% (bridge) per mW of input power were obtained when operating the devices in constant voltage mode. The pressure where maximum sensitivity of these gauges occurs depends on the distance ‘d’ between the periphery of the heated resistor element and the silicon cold junction. Devices with ‘d’ ranging from 50 µm to 1,200 µm were fabricated. Assuming that pressures can be reliably measured above the 10% and below the 90% points of the resistance versus pressure curve, the range of these devices is about two orders of magnitude. By integrating two devices, one with d = 65 µm and one with d = 1,200 µm on the same chip and connecting them in series, the range can be increased by about a factor of three. By fabricating the cantilever devices so that they curl upon release, it will be shown that these devices also exhibit larger range due to varying ‘d’.
Keywords: miniaturized vacuum and pressure gauges; MEMS-based Pirani gauges; silicon bulk micromachining; thermal conductivity of metals; insulators; air; low power sensing miniaturized vacuum and pressure gauges; MEMS-based Pirani gauges; silicon bulk micromachining; thermal conductivity of metals; insulators; air; low power sensing
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Punchihewa, K.G.; Zaker, E.; Kuljic, R.; Banerjee, K.; Dankovic, T.; Feinerman, A.; Busta, H. Comparisons between Membrane, Bridge and Cantilever Miniaturized Resistive Vacuum Gauges. Sensors 2012, 12, 8770-8781.

AMA Style

Punchihewa KG, Zaker E, Kuljic R, Banerjee K, Dankovic T, Feinerman A, Busta H. Comparisons between Membrane, Bridge and Cantilever Miniaturized Resistive Vacuum Gauges. Sensors. 2012; 12(7):8770-8781.

Chicago/Turabian Style

Punchihewa, Kasun Gardiye; Zaker, Evan; Kuljic, Rade; Banerjee, Koushik; Dankovic, Tatjana; Feinerman, Alan; Busta, Heinz. 2012. "Comparisons between Membrane, Bridge and Cantilever Miniaturized Resistive Vacuum Gauges." Sensors 12, no. 7: 8770-8781.


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