Differential photoacoustic gas cell based on LTCC for ppm gas sensing

Kimmo Keränen, Kari Kautio, Jyrki Ollila, Mikko Heikkinen, I. Kauppinen, T. Kuusela, B. Matveev, M. E. McNie, R. M. Jenkins, P. Karioja

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

Abstract

Silicon MEMS cantilever-based photoacoustic technology allows for the sensing of ultra low gas concentrations with very wide dynamic range.
The sensitivity enhancement is achieved with a cantilever microphone system in which the cantilever displacement is probed with an optical interferometer providing a pico-meter resolution. In the gas sensor, the silicon cantilever microphone is placed in a two-chamber differential gas cell.
By monitoring differential pressure changes between the two chambers, the differential cell operates as a differential infra-red detector for optical absorption signals through a measurement and reference path. The differential pressure signal is proportional to gas concentration in the optical measurement path. We have designed, implemented and tested a differential photo-acoustic gas cell based on Low Temperature Co-fired Ceramic (LTCC) multilayer substrate technology.
Standard LTCC technology enables implementation of 2.5D structures including holes, cavities and channels into the electronic substrate. The implemented differential photoacoustic gas cell structure includes two 10 mm long cylindrical cells, diameter of 2.4 mm.
Reflectance measurements of the cell showed that reflectivity of the substrate material can be improved by a factor 15 - 90 in the 3 - 8 μm spectral region using gold or silver paste coatings. A transparent window is required in the differential gas cell structure in order to probe the displacement of the silicon cantilever.
The transparent sapphire window was sealed to the LTCC substrate using two methods: screen printed Au80/Sn20 solder paste and pre-attached glass solder paste (Diemat DM2700P/H848). Both methods were shown to provide hermetic sealing of sapphire windows to LTCC substrate.
The measured He-leak rate for the 10 sealed test samples implemented using glass paste were under 2.0 ×10-9 atm×cm3/s, which meets the requirement for the leak rate according to MIL-STD 883. The achieved hermeticity level suggests that the proof-of-principle packaging demonstrator paves the way for implementing a novel differential photoacoustic gas cell for a future miniature gas sensor module.
The future module consisting of a sample gas cell and immersion lens IR LEDs together with interferometric probing of the cantilever microphone is expected to be capable of measuring ultra low concentrations of a wide range of gases with their fundamental absorption bands at 3 - 7 μm wavelength, such as CO, CO2 and CH4.
Original languageEnglish
Title of host publicationProceedings of the SPIE
Subtitle of host publicationOptoelectronic Interconnects and Component Integration IX
PublisherInternational Society for Optics and Photonics SPIE
Number of pages12
ISBN (Print)978-0-8194-8003-3
DOIs
Publication statusPublished - 2010
MoE publication typeA4 Article in a conference publication
EventOptoelectronic Interconnects and Component Integration IX - San Francisco, CA, United States
Duration: 25 Jan 201027 Jan 2010

Publication series

Name
Volume7607

Conference

ConferenceOptoelectronic Interconnects and Component Integration IX
CountryUnited States
CitySan Francisco, CA
Period25/01/1027/01/10

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ceramics
cells
gases
microphones
differential pressure
solders
sapphire
silicon
modules
chambers
reflectance
glass
sensors
sealing
infrared detectors
optical measurement
packaging
submerging
microelectromechanical systems
dynamic range

Cite this

Keränen, K., Kautio, K., Ollila, J., Heikkinen, M., Kauppinen, I., Kuusela, T., ... Karioja, P. (2010). Differential photoacoustic gas cell based on LTCC for ppm gas sensing. In Proceedings of the SPIE : Optoelectronic Interconnects and Component Integration IX [760714] International Society for Optics and Photonics SPIE. Proceedings of SPIE, Vol.. 7607 https://doi.org/10.1117/12.841363
Keränen, Kimmo ; Kautio, Kari ; Ollila, Jyrki ; Heikkinen, Mikko ; Kauppinen, I. ; Kuusela, T. ; Matveev, B. ; McNie, M. E. ; Jenkins, R. M. ; Karioja, P. / Differential photoacoustic gas cell based on LTCC for ppm gas sensing. Proceedings of the SPIE : Optoelectronic Interconnects and Component Integration IX. International Society for Optics and Photonics SPIE, 2010. (Proceedings of SPIE, Vol. 7607).
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abstract = "Silicon MEMS cantilever-based photoacoustic technology allows for the sensing of ultra low gas concentrations with very wide dynamic range. The sensitivity enhancement is achieved with a cantilever microphone system in which the cantilever displacement is probed with an optical interferometer providing a pico-meter resolution. In the gas sensor, the silicon cantilever microphone is placed in a two-chamber differential gas cell. By monitoring differential pressure changes between the two chambers, the differential cell operates as a differential infra-red detector for optical absorption signals through a measurement and reference path. The differential pressure signal is proportional to gas concentration in the optical measurement path. We have designed, implemented and tested a differential photo-acoustic gas cell based on Low Temperature Co-fired Ceramic (LTCC) multilayer substrate technology. Standard LTCC technology enables implementation of 2.5D structures including holes, cavities and channels into the electronic substrate. The implemented differential photoacoustic gas cell structure includes two 10 mm long cylindrical cells, diameter of 2.4 mm. Reflectance measurements of the cell showed that reflectivity of the substrate material can be improved by a factor 15 - 90 in the 3 - 8 μm spectral region using gold or silver paste coatings. A transparent window is required in the differential gas cell structure in order to probe the displacement of the silicon cantilever. The transparent sapphire window was sealed to the LTCC substrate using two methods: screen printed Au80/Sn20 solder paste and pre-attached glass solder paste (Diemat DM2700P/H848). Both methods were shown to provide hermetic sealing of sapphire windows to LTCC substrate. The measured He-leak rate for the 10 sealed test samples implemented using glass paste were under 2.0 ×10-9 atm×cm3/s, which meets the requirement for the leak rate according to MIL-STD 883. The achieved hermeticity level suggests that the proof-of-principle packaging demonstrator paves the way for implementing a novel differential photoacoustic gas cell for a future miniature gas sensor module. The future module consisting of a sample gas cell and immersion lens IR LEDs together with interferometric probing of the cantilever microphone is expected to be capable of measuring ultra low concentrations of a wide range of gases with their fundamental absorption bands at 3 - 7 μm wavelength, such as CO, CO2 and CH4.",
author = "Kimmo Ker{\"a}nen and Kari Kautio and Jyrki Ollila and Mikko Heikkinen and I. Kauppinen and T. Kuusela and B. Matveev and McNie, {M. E.} and Jenkins, {R. M.} and P. Karioja",
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Keränen, K, Kautio, K, Ollila, J, Heikkinen, M, Kauppinen, I, Kuusela, T, Matveev, B, McNie, ME, Jenkins, RM & Karioja, P 2010, Differential photoacoustic gas cell based on LTCC for ppm gas sensing. in Proceedings of the SPIE : Optoelectronic Interconnects and Component Integration IX., 760714, International Society for Optics and Photonics SPIE, Proceedings of SPIE, vol. 7607, Optoelectronic Interconnects and Component Integration IX, San Francisco, CA, United States, 25/01/10. https://doi.org/10.1117/12.841363

Differential photoacoustic gas cell based on LTCC for ppm gas sensing. / Keränen, Kimmo; Kautio, Kari; Ollila, Jyrki; Heikkinen, Mikko; Kauppinen, I.; Kuusela, T.; Matveev, B.; McNie, M. E.; Jenkins, R. M.; Karioja, P.

Proceedings of the SPIE : Optoelectronic Interconnects and Component Integration IX. International Society for Optics and Photonics SPIE, 2010. 760714 (Proceedings of SPIE, Vol. 7607).

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

TY - GEN

T1 - Differential photoacoustic gas cell based on LTCC for ppm gas sensing

AU - Keränen, Kimmo

AU - Kautio, Kari

AU - Ollila, Jyrki

AU - Heikkinen, Mikko

AU - Kauppinen, I.

AU - Kuusela, T.

AU - Matveev, B.

AU - McNie, M. E.

AU - Jenkins, R. M.

AU - Karioja, P.

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N2 - Silicon MEMS cantilever-based photoacoustic technology allows for the sensing of ultra low gas concentrations with very wide dynamic range. The sensitivity enhancement is achieved with a cantilever microphone system in which the cantilever displacement is probed with an optical interferometer providing a pico-meter resolution. In the gas sensor, the silicon cantilever microphone is placed in a two-chamber differential gas cell. By monitoring differential pressure changes between the two chambers, the differential cell operates as a differential infra-red detector for optical absorption signals through a measurement and reference path. The differential pressure signal is proportional to gas concentration in the optical measurement path. We have designed, implemented and tested a differential photo-acoustic gas cell based on Low Temperature Co-fired Ceramic (LTCC) multilayer substrate technology. Standard LTCC technology enables implementation of 2.5D structures including holes, cavities and channels into the electronic substrate. The implemented differential photoacoustic gas cell structure includes two 10 mm long cylindrical cells, diameter of 2.4 mm. Reflectance measurements of the cell showed that reflectivity of the substrate material can be improved by a factor 15 - 90 in the 3 - 8 μm spectral region using gold or silver paste coatings. A transparent window is required in the differential gas cell structure in order to probe the displacement of the silicon cantilever. The transparent sapphire window was sealed to the LTCC substrate using two methods: screen printed Au80/Sn20 solder paste and pre-attached glass solder paste (Diemat DM2700P/H848). Both methods were shown to provide hermetic sealing of sapphire windows to LTCC substrate. The measured He-leak rate for the 10 sealed test samples implemented using glass paste were under 2.0 ×10-9 atm×cm3/s, which meets the requirement for the leak rate according to MIL-STD 883. The achieved hermeticity level suggests that the proof-of-principle packaging demonstrator paves the way for implementing a novel differential photoacoustic gas cell for a future miniature gas sensor module. The future module consisting of a sample gas cell and immersion lens IR LEDs together with interferometric probing of the cantilever microphone is expected to be capable of measuring ultra low concentrations of a wide range of gases with their fundamental absorption bands at 3 - 7 μm wavelength, such as CO, CO2 and CH4.

AB - Silicon MEMS cantilever-based photoacoustic technology allows for the sensing of ultra low gas concentrations with very wide dynamic range. The sensitivity enhancement is achieved with a cantilever microphone system in which the cantilever displacement is probed with an optical interferometer providing a pico-meter resolution. In the gas sensor, the silicon cantilever microphone is placed in a two-chamber differential gas cell. By monitoring differential pressure changes between the two chambers, the differential cell operates as a differential infra-red detector for optical absorption signals through a measurement and reference path. The differential pressure signal is proportional to gas concentration in the optical measurement path. We have designed, implemented and tested a differential photo-acoustic gas cell based on Low Temperature Co-fired Ceramic (LTCC) multilayer substrate technology. Standard LTCC technology enables implementation of 2.5D structures including holes, cavities and channels into the electronic substrate. The implemented differential photoacoustic gas cell structure includes two 10 mm long cylindrical cells, diameter of 2.4 mm. Reflectance measurements of the cell showed that reflectivity of the substrate material can be improved by a factor 15 - 90 in the 3 - 8 μm spectral region using gold or silver paste coatings. A transparent window is required in the differential gas cell structure in order to probe the displacement of the silicon cantilever. The transparent sapphire window was sealed to the LTCC substrate using two methods: screen printed Au80/Sn20 solder paste and pre-attached glass solder paste (Diemat DM2700P/H848). Both methods were shown to provide hermetic sealing of sapphire windows to LTCC substrate. The measured He-leak rate for the 10 sealed test samples implemented using glass paste were under 2.0 ×10-9 atm×cm3/s, which meets the requirement for the leak rate according to MIL-STD 883. The achieved hermeticity level suggests that the proof-of-principle packaging demonstrator paves the way for implementing a novel differential photoacoustic gas cell for a future miniature gas sensor module. The future module consisting of a sample gas cell and immersion lens IR LEDs together with interferometric probing of the cantilever microphone is expected to be capable of measuring ultra low concentrations of a wide range of gases with their fundamental absorption bands at 3 - 7 μm wavelength, such as CO, CO2 and CH4.

U2 - 10.1117/12.841363

DO - 10.1117/12.841363

M3 - Conference article in proceedings

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BT - Proceedings of the SPIE

PB - International Society for Optics and Photonics SPIE

ER -

Keränen K, Kautio K, Ollila J, Heikkinen M, Kauppinen I, Kuusela T et al. Differential photoacoustic gas cell based on LTCC for ppm gas sensing. In Proceedings of the SPIE : Optoelectronic Interconnects and Component Integration IX. International Society for Optics and Photonics SPIE. 2010. 760714. (Proceedings of SPIE, Vol. 7607). https://doi.org/10.1117/12.841363