Gas sensor using a multi-walled carbon nanotube sheet to detect hydrogen molecules

• MWCNT sheets do not require purification, separation and dispersion process.
• MWCNT sheet can be transferred easily another substrates to be used as a sensor.
• Larger carrier gas flow could improve the recovery response of the sensor.
• Thermal annealing completely recovered the original resistance value of the sensor.

In this paper, a gas sensor with a fabricated multi-walled carbon nanotube (MWCNT) sheet, which can sense hydrogen (H2) gas, is proposed and its output properties were evaluated. The key contribution of this study is a novel fabrication technique that introduces a simple transfer method. Easy transfer from initial substrate to another substrate, the simple process and integration ability, and low cost make CNT-based sensors more suitable for future nano-material based sensor. Moreover, the MWCNT sheet does not need a complex purification process to be used as a sensor, making it suitable for practical applications. The MWCNT-sheet gas sensor had a large surface area and many contact points; these facts were further confirmed through morphological analyses. In addition, the effects of thermal annealing and carrier gas flow on gas desorption were investigated in order to improve the recovery response of the gas sensor. It was found that a thermal annealing temperature of 100 °C and a larger flow (2000 sccm) of carrier gas recovered original resistance values, resulting in high performance, faster response time, and improved reproducibility for the MWCNT-sheet gas sensor.