9Currie J F, Essalik A and Marusic J C. Micromachined thin filmsolid state electrochemical CO2, NO2 and SO2 gas sensors [ J ]. Sensors and Actuators B: Chemical, 1999, 59 (23) : 235 - 241.
10Orozeo J, Baldi A, Baena R, et al. Portable system based on mierosensors for environmental monitoring applications [J]. Meas Sci Technol. 2007, 18(3) : 935 - 940.