A Sensing Systems Platform Designed For Wireless Sensor Network Applications

In this work we describe a sensing platform, de- signed to condition a generic micropower energy harvester to supply different sensors sets and to manage the achieved information. It includes a power management circuit and a wireless transmitting module. The energy from the harvester supply is stored in a condenser and used to asynchronously acquire and send data, using a microcontroller and a 802.15.4 compliant integrated circuit (IC). Thus, data stream presents an intermittent behaviour depending on the instantaneous electric power produced by the supply. The system offers up to nine digital/analog inputs to be connected to sensors and is customiz- able, in order to match different power supplies to different sensing needs. In particular, number and power consumption of sensors and harvester performance represent the system design constrains while the small area, a large usability (no cable, no maintenance, no external supply) and reduced cost reflect the platform peculiarities. To validate the work, we also present a demonstration circuit in which a smart and autonomous wireless sensor node is realized. It uses a 0.35-micrometer BCD SOI technology-based photovoltaic harvester IC within an occupation area of 4 mm2 and a three sensors set for light irradiance and temperature monitoring.