Ultra Low Power MOX Sensor Reading for Natural Gas Wireless Monitoring

We propose a novel method to reveal and measure natural gas presence in air, using commercial off the self MOX gas sensors in wireless sensor networks. This technique reduces the power consumed to read the catalytic sensor by a factor 10x, because it performs an analysis on a reduced sampled period thus it extends the autonomy of battery powered system. The information about the gas concentration is calculated from the sensor transient response through a discrete cosine transform analysis. This allows to immediately discriminate between clean air and hazardous situations. The characterization of the sensing device has been conducted using a range of humidity conditions to demonstrate the effectiveness of the proposed approach. The characterization performed in lab facilities has been validated with further experiment in a real test-bed monitoring network. Two different duty cycle rates are characterized and simulations demonstrate that it is possible to extend more than three years of autonomy using commercial wireless sensor nodes, when powered by two AA batteries.