Title page for etd-0730112-162409


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URN etd-0730112-162409
Author Po-Han Chen
Author's Email Address No Public.
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Department Electrical Engineering
Year 2011
Semester 2
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title Study of Extended-gate FET-based Microsensor for Detecting the Carbon Dioxide in Water
Date of Defense 2012-07-14
Page Count 76
Keyword
  • Carbon dioxide
  • Extended-gate field effect transistor
  • MEMS
  • Gas permeable membrane
  • Dioctyl sebacate
  • Abstract The large carbon dioxides produced by highly developed industries not only result in serious air pollution and health problems, but also cause ocean acidification and decrease the survival rate of fry in aquaculture. Therefore, to develop a system for real-time detection of the concentration of carbon dioxide in aquaculture has become a very important research issue. Optical analysis and gas-chromatography are the two main methods adopted in conventional gas detection. Although the conventional carbon dioxide detectors presented high sensitivity and accuracy, the high fabrication cost, large dimension, low capability of batch fabrication and without real-time monitoring function will limit their applications.
    This thesis utilizes MEMS technology to implement an extended-gate field-effect transistor (EGFET) with an integrated gas permeable membrane for development of a high-sensitivity, small size and low cost carbon dioxide microsensor. The main material of the carbon dioxide gas permeable membrane adopted in this research is dioctyl sebacate. The main processing steps of the proposed microsensor include four photolithography and four thin-film deposition processes. In addition, the influences of the channel width/length ratio of EGFET and the coating of gas permeable membrane on the sensing performances of presented microsensor are also investigated in this study.
    The chip size of the implemented carbon dioxide microsensor is 11 mm×13 mm× 0.5 mm and the sensing area is 1 mm×1 mm. As the carbon dioxide concentration varies from 0.25 mM to 50 mM, a very high sensitivity (42.3 mV/ppm) and sensing linearity (99.2%) of the proposed EGFET microsensor can be demonstrated. In addition, the response time of the presented carbon dioxide microsensor is only about 100 seconds, hence it is very suitable for developing a real-time monitoring microsystem.
    Advisory Committee
  • HUANG RUI XING - chair
  • FANG WEI LUN - co-chair
  • LIN YU CHENG - co-chair
  • HUANG I YU - advisor
  • Files
  • etd-0730112-162409.pdf
  • Indicate in-campus at 99 year and off-campus access at 99 year.
    Date of Submission 2012-07-30

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