Activity: Talk or presentation › Talk at conference or symposium › Science to science
At present, air pollution monitoring is carried out at low spatial resolution due to high costs coming along with high accurate measurement equipment. To overcome this issue a much denser sensor network is required, which is directly able to monitor air pollution values. A low power photoacoustic based nitrogen dioxide (NO2) sensor with wireless sensor network (WSN) capability, is presented in this work. Due to low power consumption and development costs it is qualified for utilization in high numbers. A differential photoacoustic cell has been simulated and constructed with a Q factor of 25. According to the photoacoustic principle, a modulated light beam of a low power light emitting diode (LED) excites the gas inside the cell, which produces a sound pressure wave. The acoustic wave is measured by a microphone with a second microphone being used for background noise cancelation. With this technique, NO2 concentrations in the low ppm region can be detected, whereby the detection limit is still under investigation. This could easily be improved by using a high power LED. The sensor is managed by a microcontroller which is directly connected to a low power wide area network (LPWAN) long range (LoRaTM) transceiver. Using LoRaTM we are able to reach communication distances exceeding 1.7 km, having a packet delivery ratio of more than 40 percent. This enables large scale sensor networks which do not require existing infrastructure for communication or power management.