A self-powered transmitter for wireless health monitoring network

With the growing use of sensors for the health monitoring in various structural and mechanical systems, the powering and communication network of these sensors become a critical factor. Opportunely, the permanent decreasing electrical power requirement for electronic circuits allows now the use of autonomous micropower piezoelectric generators exploiting the structural vibrations. Our goal was to implement an energy harvesting system for powering a single integrated wireless transmitter using our SSH (Synchronised Swtich Harvesting) method. This self powered system has two main functions: The generation of an identifier code to the central receiver and the generation of a Lamb wave for the health monitoring. The interest of this method is its very low energy requirement. Such an autonomous transmitter has been evaluated on a 300×50×2 mm ³ composite cantilever beam. Two 33×11 × 0.3 mm ³ piezoelements are used for the energy harvesting and for the wave lamb generation. An energy quantity of 1.5 mJ is sufficient for the RF emission and for the wave Lamb emission.