High-performance extended gate field-effect-transistor-based dissolved carbon dioxide sensing system with a packaged microreference electrode

Chia-Hsu Hsieh; Wei-Che Hung; Po-Han Chen; I-Yu Huang

doi:10.1117/1.JMM.13.3.033017

19 September 2014 High-performance extended gate field-effect-transistor-based dissolved carbon dioxide sensing system with a packaged microreference electrode

Chia-Hsu Hsieh, Wei-Che Hung, Po-Han Chen, I-Yu Huang

Author Affiliations +

Journal of Micro/Nanolithography, MEMS, and MOEMS, Vol. 13, Issue 3, 033017 (September 2014). https://doi.org/10.1117/1.JMM.13.3.033017

Abstract

We have developed an extended gate field-effect-transistor (EGFET)-based carbon dioxide (CO₂) sensing system with a packaged Ti/Ag/AgCl/KCl-gel microreference electrode using microelectro-mechanical systems (MEMS) technology. The total dimensions of the proposed CO₂ sensing system are only 2.8×1.5×0.1 cm, which is approximately 30 times smaller than a conventional CO₂ sensing system (including the commercial Ag/AgCl RE). All of the manufacturing processes adopted in this work are compatible with standard planar technology and are very suitable for mass production. The presented planar reference electrode shows a very small offset voltage (−3.0 mV) and a very small potential drift (2.5 mV in 30,000 s) that is approximately equal to that of the commercial Ag/AgCl RE (1.6 mV in 30,000 s). Additionally, the implemented EGFET-based CO₂ microsensor with a coated CO₂ solid electrolyte and gas permeable membranes on the gate sensing area demonstrates a very high sensitivity (44.4 mV/decade) and very high sensing linearity (98.37%), while sensing CO₂ concentrations ranging from 0.25 to 50 mM. Furthermore, a very small hysteresis voltage (7.5 mV) was obtained during the sensing cycle of 2.5–5–25–50–25–5–2.5 mM; this result was achieved by improving the surface planarization and enlarging the sensing area of the EGFET to 1 mm².

CC BY: © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

Citation Download Citation

Chia-Hsu Hsieh, Wei-Che Hung, Po-Han Chen, and I-Yu Huang "High-performance extended gate field-effect-transistor-based dissolved carbon dioxide sensing system with a packaged microreference electrode," Journal of Micro/Nanolithography, MEMS, and MOEMS 13(3), 033017 (19 September 2014). https://doi.org/10.1117/1.JMM.13.3.033017

Published: 19 September 2014

ACCESS THE FULL ARTICLE

JOURNAL ARTICLE
8 PAGES

DOWNLOAD PAPER SAVE TO MY LIBRARY