Vol. 91, Issue 4, April 2008, pp.91-99

A Sensor for Gas Detection Fabricated by a Circular Single-wall Carbon Nanotube

 Lun-Wei Chang^a, Yi-Chen Yeh^a and Juh-Tzeng Lue^b*

^aDepartment of Electrical Engineering and ^bDepartment of Physics,

National Tsing Hua University, Hsin Chu, Taiwan,

E-mail: jtlue@phys.nthu.edu.tw

Received: 8 April 2008   /Accepted: 21 April 2008   /Published: 30 April 2008

Abstract: This work endeavors to describe a circular shape of carbon nanotubes (CNT) performed by ultrasonic agitation and assisted by a surfactant implemented for gas detection. In a well-dispersed CNT solution, we observed that the thinner thickness and the larger diameter CNT rings were formed than those of our previous study. This fact can be elucidated more fully that the depletion contact energy is modulated by theoretical estimation with the corresponding tendency in our samples. The separated CNT ring possessed with negative charges in sodium dodecyl sulfate (SDS) surfactant solution can be easily absorbed on the sliced surface. Through the e-beam lithography and the lift-off process, a CNT ring was exploited as a gas sensor to detect an extremely low concentration of methane gas. The circular CNT sensor has a prominent conduction response embodied in the existence of more defects in the ring CNT sensor than those of the straight CNT sensor. Moreover, the much fast response time in the circular CNT illustrates the demand of the shorter length of CNTs. The CNT ring features with longer persistent to current conduction after long time measurements appraising to be a robust and durable material in the sensor applications.

Keywords: Circular carbon-nanotubes, Gas sensors, Ultrasonic agitation, Dodecyl sulfate surfactant

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