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CMOS-Compatible Carbon Dioxide Sensors

  • Zeyu CaiEmail author
  • Robert van Veldhoven
  • Hilco Suy
  • Ger de Graaf
  • Kofi A. A. Makinwa
  • Michiel Pertijs
Chapter

Abstract

This chapter presents two cost-effective sensors that measure ambient carbon dioxide (CO2) concentration, intended for application in smart ventilation systems in buildings or in mobile devices. Both sensors employ a suspended hot-wire transducer to detect the CO2-dependent thermal conductivity (TC) of the ambient air. The resistive transducer is realized in the VIA layer of a standard CMOS process using a single etch step. The first sensor determines the transducer’s CO2-dependent thermal resistance to the surrounding air by measuring its steady-state temperature rise and power dissipation. A ratiometric measurement is realized by employing an identical but capped transducer as a reference. An incremental delta-sigma ADC digitizes the temperature and power ratios of the transducers, from which the ratio of the thermal resistances is calculated. The second sensor is based on a transient measurement of the CO2-dependent thermal time constant of the transducer. The readout circuit periodically heats up the transducer and uses a phase-domain delta-sigma modulator to digitize the CO2-dependent phase shift of the resulting temperature transients. Compared to the ratiometric steady-state measurement, this approach significantly reduces the measurement time and improves the energy efficiency, resulting in a state-of-the-art CO2 resolution of 94 ppm at an energy consumption of 12 mJ per measurement.

Notes

Acknowledgments

This work was in part supported by NXP Semiconductors, The Netherlands, and in part by ams AG, The Netherlands. The authors want to thank Lukasz Pakula and Zu-yao Chang for their technical support.

References

  1. 1.
    Emmerich SJ, Persily AK. Literature review on CO2-based demand-controlled ventilation. ASHRAE Trans. 1997;103:229–43.Google Scholar
  2. 2.
    SenseAir K30 datasheet, SenseAir [Online]. Available: http://www.senseair.com/.
  3. 3.
    SGX Sensortech IR11BD datasheet, SGX Sensortech [Online]. Available: http://www.sgxsensortech.com/.
  4. 4.
    Frodl R, Tille T. A high-precision NDIR CO2 gas sensor for automotive applications. IEEE Sensors J. 2006;6(6):1697–705.CrossRefGoogle Scholar
  5. 5.
    Cai Z, et al. A ratiometric readout circuit for thermal-conductivity-based resistive CO2 sensors. IEEE J Solid-State Circuits. 2016;51(10):2463–74.CrossRefGoogle Scholar
  6. 6.
    Kliche K, et al. Sensor for thermal gas analysis based on micromachined silicon-microwires. IEEE Sensors J. 2013;13(7):2626–35.CrossRefGoogle Scholar
  7. 7.
    Kliche K, et al. Sensor for gas analysis based on thermal conductivity, specific heat capacity and thermal diffusivity. In: Proceedings of IEEE international conference on MEMS. 2011 p. 1189–92.Google Scholar
  8. 8.
    XEN-5310 datasheet. Xensor Integration [Online]. Available: http://www.xensor.nl/.
  9. 9.
    Cai Z, et al. A phase-domain readout circuit for a CMOS-compatible hot-wire CO2 sensor. IEEE J. Solid-State Circuits. (in press) doi: 10.1109/JSSC.2018.2866374CrossRefGoogle Scholar
  10. 10.
    Simon I, Arndt M. Thermal and gas-sensing properties of a micromachined thermal conductivity sensor for the detection of hydrogen in automotive applications. Sens. Actuators A: Phys. 2002;97–98:104–8.CrossRefGoogle Scholar
  11. 11.
    Ali SZ, et al. Tungsten-based SOI microhotplates for smart gas sensors. J Microelectromech Syst. 2008;17:1408–17.CrossRefGoogle Scholar
  12. 12.
    Cai Z, et al. An integrated carbon dioxide sensor based on ratiometric thermal-conductivity measurement. In: Proceedings of IEEE international conference on solid-state sensors, actuators and microsystems (Transducers ’15). 2015. p. 622–5.Google Scholar
  13. 13.
    Bult K, Geelen GJGM. A fast-settling CMOS op amp for SC circuits with 90-dB DC gain. IEEE J Solid-State Circuits. 1990;25(6):1379–84.CrossRefGoogle Scholar
  14. 14.
    Fiedler H, et al. A 5-bit building block for 20 MHz A/D converters. IEEE J Solid-State Circuits. 1981;16(3):151–5.CrossRefGoogle Scholar
  15. 15.
    FIGARO TGS8100 datasheet (rev06), FIGARO [Online]. Available: http://www.figaro.co.jp/.
  16. 16.
    Mahdavifar A, et al. Transient thermal response of micro-thermal conductivity detector (μTCD) for the identification of gas mixtures: an ultra-fast and low power method. Microsyst Nanoeng. 2015;1:15025.CrossRefGoogle Scholar
  17. 17.
    van Vroonhoven C, de Graaf G, Makinwa KAA. Phase readout of thermal conductivity-based gas sensors. In: Proceedings of IEEE International Workshop on Advances in Sensors and Interfaces (IWASI). 2011. p. 199–202.Google Scholar
  18. 18.
    van Vroonhoven CPL, Makinwa KAA. A thermal-diffusivity-based temperature sensor with an untrimmed inaccuracy of ±0.5°C (3σ) from –40 to 105°C. In: Digest ISSCC. 2008. p. 576–7.Google Scholar
  19. 19.
    Kashmiri M, Xia S, Makinwa KAA. A temperature-to-digital converter based on an optimized electrothermal filter. IEEE J Solid-State Circuits. 2009;44(7):2026–35.CrossRefGoogle Scholar
  20. 20.
    Kashmiri SM, Souri K, Makinwa KAA. A scaled thermal-diffusivity-based 16 MHz frequency reference in 0.16 μm CMOS. IEEE J Solid-State Circuits. 2012;47(7):1535–45.CrossRefGoogle Scholar
  21. 21.
    Vincent TA, Gardner JW. A low cost MEMS based NDIR system for the monitoring of carbon dioxide in breath analysis at ppm levels. Sens Actuators B Chem. 2016;236:954–64.CrossRefGoogle Scholar

Copyright information

© Springer Nature Switzerland AG 2019

Authors and Affiliations

  • Zeyu Cai
    • 1
    • 2
    Email author
  • Robert van Veldhoven
    • 2
  • Hilco Suy
    • 3
  • Ger de Graaf
    • 1
  • Kofi A. A. Makinwa
    • 1
  • Michiel Pertijs
    • 1
  1. 1.Delft University of TechnologyDelftThe Netherlands
  2. 2.NXP SemiconductorsEindhovenThe Netherlands
  3. 3.ams AGEindhovenThe Netherlands

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