A Modular Wireless Sensor Platform With Fully Integrated Battery

This paper presents the design and development of a miniaturized, modular, system platform with fully integrated battery for wireless sensor nodes. It uses commercial off-the-shelf components and overcomes many of the limitations that attach to more conventional wireless sensor nodes based on planar vertical stacking of circuit boards. The platform is based around a plastic cubic framework that also acts as a receptacle for the battery. Six printed circuit boards (PCBs), interconnected with flex-PCB, are folded around the six faces of the cube, with two of the PCBs making contact with the two terminals of the battery. The sensor node architecture is partitioned in a modular fashion so that the main node circuit blocks (power, sensors, processing, and communications) are allocated to the individual PCBs on the six faces of the cube. Each of the PCBs has a common edge-connection layout, and each of the flex tapes joining the PCBs is identical in layout, giving a common ¿bus¿ between the PCBs. This makes it easy to change any of the individual circuit blocks without having to redesign the whole system. The use of a cube also means that the sensors and antenna can each be on an external face of the node instead of being limited to the two external faces typical of planar vertical stacks. The functionality of the platform is verified by the design, assembly, and testing of a four-sensor environment sensing node working at 868 MHz.