Browsing by Author "Ho, Cheng-Long"

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A Single-Walled Carbon Nanotube Network Gas Sensing Device
(2011-08-01)
Wang, Li-Chun
;
Tang, Kea-Tiong
;
Teng, I-Ju
;
Kuo, Cheng-Tzu
;
Ho, Cheng-Long
The goal of this research was to develop a chemical gas sensing device based on single-walled carbon nanotube (SWCNT) networks. The SWCNT networks are synthesized on Al(2)O(3)-deposted SiO(2)/Si substrates with 10 nm-thick Fe as the catalyst precursor layer using microwave plasma chemical vapor deposition (MPCVD). The development of interconnected SWCNT networks can be exploited to recognize the identities of different chemical gases by the strength of their particular surface adsorptive and desorptive responses to various types of chemical vapors. The physical responses on the surface of the SWCNT networks cause superficial changes in the electric charge that can be converted into electronic signals for identification. In this study, we tested NO(2) and NH(3) vapors at ppm levels at room temperature with our self-made gas sensing device, which was able to obtain responses to sensitivity changes with a concentration of 10 ppm for NO(2) and 24 ppm for NH(3).
Portable electronic nose system with chemiresistor sensors to detect and distinguish chemical warfare agents
(2010-07-01)
Wang, Li-Chun
;
Tang, Kea Tiong
;
Kuo, Cheng-Tzu
;
Ho, Cheng-Long
;
Lin, Shiao-Ray
An electronic nose (E-Nose) has been studied as a means to realize artificial olfaction. Electronic nose "instruments" are currently relatively large, since the signal manipulation and classification are still done by a personal computer (PC) or a laptop. For this reason, we have developed a portable electronic nose system based on a handheld machine by using a vapor detection array made of carbon-black polymer composites and a sensor circuit. In an effort to make a portable electronic nose, we used thin-film chemical sensors based on the carbon-black polymer nanocomposite to reliably detect chemical warfare agents. To replace the large volume of PCs, we used a field-programmable gate array to perform system control, signal manipulation, and classification. This E-Nose system was exposed to dimethyl-methyl phosphonate (DMMP) and dichloromethane (DCM) in parts per million concentration levels. DMMP and DCM were considered as simulants of the nerve agent sarin and the incapacitating agent BZ gases, respectively. (c) 2010 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.3466797]