Development of highly sensitive nitrogen dioxide monitoring device and its application to wide-area ubiquitous network

We have developed an NO2 sensing device with high time resolution for application to a wide-area ubiquitous network. The NO2 sensing device employs the colorimetric reaction between NO2 and diazo-coupling reagents. We estimated the formation and decomposition rate of the azo dye in the sensor elements and found that no decomposition occurred and that the formation rate was fast enough for us to measure NO2 concentration at 10 min intervals with a detection limit of 12 ppb. We have constructed sensing terminal units containing the NO2 sensing device, a GPS device, a compass, a switch, LEDs and a wireless terminal unit for a wide-area ubiquitous network. We successfully monitored the outdoor NO2 level at 10 min intervals using the developed terminal units mounted on a bicycle in certain areas of several cities. We also designed and implemented an application where bicycles collect geo-tagged air quality samples and post them on a map that other cyclists can use to determine their route.