The internet of Things (IoT) stands for smart objects that communicate each other directly through internet without human involvement. In the next years, the number of smart objects will grow exponentially. In particular, the existence of objects or smart nodes (IoT nodes, hereafter) able to sense, wirelessly communicate and energetically autonomous opens the door to new applications that would not be economically feasible if the nodes had to be wired. Thus, an IoT node will consist of sensors and their electronic interfaces, a microcontroller, a wireless transceiver an a local energy source. A critical issue of the nodes is their local power source. Two main alternatives exist: use of primary batteries or environmental or transmited (e.g. by radiofrequency signals) energy harvesting. Primary batteries lead to simpler designs but have a limited energy budget. Their use is feasible whenever the available energy is enough to power the IoT node during a fair period of time. Such a period can be lower than the operating time of the IoT nodes but enough whenever the maintenance costs due to the periodic replacement of the primary batteries is acceptable. Contrariwise, energy harvesting leads to more complex designs but the available energy is unlimited. However, the available average power is limited by the primary energy source and the size of the energy transducer and needs to be higher than the average power required by the IoT node. Anyway, in order to increase the energy autonomy of the IoT node, a low power consumption of the node and a high power efficiency of its local power supply is required. This research project tackles the power supply of the IoT nodes in a holistic way for both alternatives: primary batteries and energy harvesting. Such a holistic approach takes into account the mutual interdependencies of the different blocks of the power supply so as to optimize the overall power efficiency, which is crucial for the lifetime of the IoT nodes.The increase of power efficiency will lead, for the power supply with primary batteries, to prolong the replacement period, in case it was shorter than the operating time of the IoT node, with the consequent reduction of costs. Alternatively, the replacement period can be held using smaller primary batteries. This is not a minor progress because in many cases primary batteries are the most expensive and largest device of the IoT node. Instead, the efficiency increase in energy harvesting based power supplies will lead to an increase of the available power. Alternatively, for environmental energy, average power can be held using a smaller energy transducer, whereas for transmitted energy, the distance from the harvester to the emitter can be increased. All that will lead in significant progress for the power supply of the IoT nodes and, as a consequence, for the effective deployment and feasibility of the IoT. The proposed techniques will be applied to three cases: power supply by 1) primary batteries, 2) solar cells, and 3) transmitted radiofrequency energy.
Plan Estatal de Investigación Científica y Técnica y de Innovación 2013-2016
Programa Estatal de Fomento de la Investigación Científica y Técnica de Excelencia
Subprograma Estatal de Generación de Conocimiento
Excelencia: Proyectos I+D
Gobierno De España. Ministerio De Economía Y Competitividad, Mineco
Gasulla, M.; Robert, F. J.; Jordana, J.; Ripoll, Edgar; Berenguer-Sau, J.; Reverter, F. Eurosensors Conference p. 1-5 DOI: 10.3390/proceedings2131049 Presentation's date: 2018-09-09 Presentation of work at congresses