A differential capacitive thin film hydrogen sensor

A compact, differential, hydrogen-specific sensor based on the lattice expansion of LaAl 0.3Ni 4.7 metal hydride thin films has been fabricated and characterized. Characterization of LaAl 0.3Ni 4.7 films performed using a capacitance dilatometer revealed that the lattice expansion was proportional t...

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Bibliographic Details
Published in:Sensors and actuators. B, Chemical Chemical, 2009-09, Vol.141 (2), p.424-430
Main Authors: Kirby, D.J., Chang, D.T., Stratton, F.P., Zinck, J.J.
Format: Article
Language:English
Subjects:
Capacitance dilatometer
Capacitance measurement
Differential measurement
Hydrogen sensor
LaM xNi 5− x alloys
Lattice expansion
MEMS
Metal hydride
Thin film
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Summary:A compact, differential, hydrogen-specific sensor based on the lattice expansion of LaAl 0.3Ni 4.7 metal hydride thin films has been fabricated and characterized. Characterization of LaAl 0.3Ni 4.7 films performed using a capacitance dilatometer revealed that the lattice expansion was proportional to the partial pressure of H 2 over the range 0.01–1.3 atm used in this experiment. The films were mechanically robust to cycling between vacuum and partial pressures of H 2 up to 1.3 atm and were not poisoned by exposure to atmosphere's containing up to 24% carbon monoxide. A wafer level process has been established for the fabrication of the differential hydrogen sensor which includes both an active LaAl 0.3Ni 4.7 sensing capacitor and an inert Au reference capacitor. A minimum sensitivity of 400 ppm hydrogen is calculated for the differential device.
ISSN:0925-4005
1873-3077
DOI:10.1016/j.snb.2009.06.030