Browsing by Author "Lin, Tzu Hsuan"

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Application of m-CNTs/NaClO4/Ppy to a fast response, room working temperature ethanol sensor
(2008-08-28)
Wu, Ren-Jang
;
Huang, Yu-Ching
;
Yu, Ming-Ru
;
Lin, Tzu Hsuan
;
Hung, Shih-Lin
A new blended material, m-CNTs/NaClO4/Ppy, was developed as a gas sensor to detect ethanol concentrations at room temperature. The sensing material polypyrrole (Ppy) was synthesized in situ by UV-photo-polymerization. The multiwall carbon nanotubes (m-CNTs) added enhanced the short-term repeatability of the Ppy-sensing material. The relative resistance variation (R-ethanol/R-air) of mCNTs/NaClO4/Ppy was 1.193 when exposed to ethanol of 30,000 ppm. The sensor response and recovery times (both 20s) were very short to this concentration. An unstable baseline of the sensor was explained by theoretical calculation of molecular dynamics made for ethanol adsorption on polypyrrole, which revealed formation of a new bond, N-H center dot center dot center dot O. Adsorption energy decreased with increasing the number of ethanol molecules adsorbed and was 0.8 kcal/mol at eight adsorbed molecules. Sensor responses of three different Ppy samples were measured to ethanol concentrations of 18,000-40,000 ppm. (C) 2008 Elsevier B.V. All rights reserved.
New sensing technology for detection of the common inhalational anesthetic agent sevoflurane using conducting polypyrrole films
(2007-10-01)
Wu, Ren-Jang
;
Huang, Yu-Ching
;
Chavali, Murthy
;
Lin, Tzu Hsuan
;
Hung, Shih-Lin
A new type of gas sensor to measure resistance was developed to detect sevoflurane concentrations at room temperature. The measured FTIR spectrum of sevoflurane vapor was given. The sensing material polypyrrole was synthesized in situ by UV-photopolymerization. The relative resistance variation was 3.9 for a sevoflurane concentration of 1.2%. The sensor response time (60 s) and recovery time (20 s) were very short. Molecular dynamic calculations made for sevoflurane adsorption on polypyrrole revealed formation of a new bond, N-H-F. The bond length was predicted to be in the range of 0.2-0.4 nm. The bond energy was about 7.2 kcal/mol. Sensor responses to the concentrations 0. 1-10% were 1.57-5.9, respectively. (C) 2007 Elsevier B.V. All rights reserved.