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Chemical Vapor Detection Using a Capacitive Micromachined Ultrasonic Transducer

Title
Chemical Vapor Detection Using a Capacitive Micromachined Ultrasonic Transducer
Author
박관규
Issue Date
2011-11
Publisher
Amer Chemical SOC
Citation
Analytical Chemistry, 15 December 2011, 83(24), P9314-9320
Abstract
Distributed sensing of gas-phase chemicals using highly sensitive and inexpensive sensors is of great interest for many defense and consumer applications. In this paper we present ppb-level detection of dimethyl methylphosphonate (DMMP), a common simulant for sarin gas, with a ppt-level resolution using an improved capacitive micromachined ultrasonic transducer (CMUT) as a resonant chemical sensor. The improved CMUT operates at a higher resonant frequency of 47.7 MHz and offers an improved mass sensitivity of 48.8 zg/Hz/mu m(2) by a factor of 2.7 compared to the previous CMUT sensors developed. A low-noise oscillator using the CMUT resonant sensor as the frequency-selective device was developed for real-time sensing, which exhibits an Allan deviation of 1.65 Hz (3 sigma) in the presence of a gas flow; this translates into a mass resolution of 80.5 zg/mu m(2). The CMUT resonant sensor is functionalized with a 50-nm thick DKAP polymer developed at Sandia National Laboratory for dimethyl methylphosphonate (DMMP) detection. To demonstrate ppb-level detection of the improved chemical sensor system, the sensor performance was tested at a certified lab (MIT Lincoln Laboratory), which is equipped with an experimental chemical setup that reliably and accurately delivers a wide range of low concentrations down to 10 ppb. We report a high volume sensitivity of 34.5 +/- 0.79 pptv/Hz to DMMP and a good selectivity of the polymer to DMMP with respect to dodecane and 1-octanol.
URI
http://pubs.acs.org/doi/abs/10.1021/ac201626b
ISSN
0003-2700; 1520-6882
DOI
10.1021/ac201626b
Appears in Collections:
COLLEGE OF ENGINEERING[S](공과대학) > MECHANICAL ENGINEERING(기계공학부) > Articles
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