Design and development of multi-node based wireless system for efficient measuring of resistive and capacitive sensors

In this work, a design of wireless system for multi-sensors monitoring has been presented. The main purpose of this research is to develop an efficient telemetry system for measuring water pressure and temperature signals. The system reads data from two types of sensors, temperature (resistive) and pressure (capacitive). Anderson circuit configuration has been used for the resistive sensor, since it offers linear like behavior. The capacitive interface is based on capacitance–frequency–voltage conversion that uses phase lock loop to convert the frequency to voltage. A developed pressure sensors based on polyethylene and polyvinylidene fluoride, were used to evaluate the performance of the capacitive interface. A small size wireless module has been built separately to test the capacitive interface for a certain range of pressure. Two mechanisms have been adopted to reduce the overall power consumption. These are power scheduling and wakeup circuit for the capacitive interface. The first one is implemented fully by the micro-controller unit (MCU) in order to switch on/off all the system units. A wakeup circuit has been designed to interrupt the MCU when it is in the sleep mode and the capacitive samples are changing significantly. A platform for wireless sensor network (WSN) has been developed so that the receiver side can communicate with more than one sensor node.

► A design of wireless system for multi-sensors monitoring has been presented.
► The system reads data from two types of sensors, temperature (resistive) and pressure (capacitive).
► Capacitive pressure sensors were fabricated using sandwich structure and two materials polyethylene (PE) and polyvinylidene fluoride (PVDF).
► The pressure sensing properties of sandwich capacitors based on PE and PVDF were evaluated using the specially constructed wireless data acquisition system.
► Number of features was introduced in the node system design to achieve low power consumption goal.