We have successfully fabricated SnO₂ thin film CO gas sensors on nanospiked polyurethane (PU) polymer surfaces that are replicated with a low-cost soft nanolithography method from nanospiked silicon surfaces formed with femtosecond laser irradiations. The sensors show sensitive responses to the CO gas at room temperature because of the sharp structures of the nanospikes. This is much different from the sensors of SnO₂ thin film coated on smooth surfaces that show no response to the CO gas at room temperature. To make the nanostructure sensor surface behave self-cleaning like lotus leaves, we deposited a silane monolayer on the surface of the sensors with the 1H,1H,2H,2H-perfluorooctyltrichlorosilane (PFOTS) which has low surface energy. The contact angle measurement conducted on the PFOTS monolayer-coated SnO₂ gas sensors indicates that a super-hydrophobic surface formed on the nanospike sensor. The CO gas response sensitivity of the PFOTS-coated SnO₂ sensors is almost the same to that of the as-fabricated SnO₂ sensors without the PFOTS coating. Such a super-hydrophobic surface can protect the sensors exposed to moisture and heavy particulates, and can perform cleaning-in-place operations to prolong the lifetime of the sensors. These results show a great potential to fabricate thousands of identical gas sensors at low cost.

Date Published: 31 March 2010
PDF: 8 pages
Proc. SPIE 7647, Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2010, 76474R (31 March 2010); doi: 10.1117/12.847260

Published in SPIE Proceedings Vol. 7647:
Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2010
Masayoshi Tomizuka, Editor(s)