An optical IR-source and CO2-chamber system for CO2 measurements
2000 (English)In: Journal of microelectromechanical systems, ISSN 1057-7157, E-ISSN 1941-0158, Vol. 9, no 4, 509-516 p.Article in journal (Refereed) Published
A new silicon IR-source and CO2-chamber system for measurement of CO2 concentration is presented. The micromachined IR-source, which consists of four groups of polysilicon filaments coated with silicon nitride suspended across a KOH-etched cavity, is used to generate two switched sample and reference beams. The electrically modulated sources present a modulation time of 10 ms and a power consumption of 1 W. The CO2 chambers, placed beneath the reference sources, are used to produce a reference beam for long term stability and compensation against cuvette window contamination. They consist of 1-mm-deep micromachined cavities in which CO2 is encapsulated during an overpressure anodic bonding procedure. Silicon dioxide is used as an antireflective coating to optimize the filter's optical characteristics. Numerical simulations of the filters are presented and show good agreement with the measurements. The IR-sources and the CO2 filters are both fabricated at wafer level. Using the presented IR-sensor system, measurements with a 9-mm-wide test channel show high CO2-sensitivity for CO2 concentrations between 0 and 10% confirming that the stringent requirements for this respirator application can be fulfilled.
Place, publisher, year, edition, pages
2000. Vol. 9, no 4, 509-516 p.
CO2-filter, gas sensor, infrared IR-source, microfilaments, micromachining
IdentifiersURN: urn:nbn:se:kth:diva-20315DOI: 10.1109/84.896773ISI: 000166597800013OAI: oai:DiVA.org:kth-20315DiVA: diva2:339009
QC 201005252010-08-102010-08-10Bibliographically approved