Wearable Wireless Sensor System With RF Remote Activation for Gas Monitoring Applications

Nowadays, the safety standards for industrial plants are tougher with respect to employee state monitoring and monitoring of working environmental conditions. Combining wireless sensor with wearable technology is possible to significantly improve safety delivery capability of such systems and add new functionality to them. Since wireless sensors use batteries as the sole energy source, the energy efficiency becomes critical. One of the solutions to reduce the energy consumption of the wireless sensor nodes is to use appropriate control for radio data transmission. In this paper, we have developed a wireless sensor system which can be attached to a uniform and used for working condition monitoring in places which could be prone to gas leakage. The main feature of the system is the possibility to be activated remotely by an RF control signal at a frequency of 866 MHz. It performs various functions of wearable sensor system, such as switching the system from sleep, measurement, and data transmission modes when external RF signal is available and its power is greater than an appropriate level. The experimental data demonstrate that the activation distance is about 2.75 m from an RF-generator that has a power of 30 dBm. The wearable sensor system is able to signalize about employee presence in relation to working facilities and to monitor temperature and combustible gases concentration. It consists of light-weight distributed parts attached to clothes and has low power consumption.