A concept for an ultra-low power sensor network - detecting and monitoring disaster events in underground metro systems

In this paper, the concept for an ultra-low power wireless sensor network (WSN) for underground tunnel systems is presented highlighting the chosen sensors. Its objectives are the detection of emergency events either from natural disasters, such as flooding, or from terrorist attacks. Earlier works have demonstrated that the power consumption for the communication can be reduced such that the data acquisition (i.e. sensor subsystem) becomes the most significant energy consumer. By using ultra-low power components for the smoke detector, a hydrostatic pressure sensor for water ingress detection and a passive acoustic emission sensor for explosion detection, all considered threats are covered while the energy consumption can be kept very low in relation to the data acquisition. The total average consumption for operating the sensor sub-system is calculated to be less than 35.9 mu W.