Smart Systems Integration for Autonomous Wireless Communications

Integration of sensors and wireless transceivers for system networking aims at emerging applications that are highly integrated, self-powered, and low cost, relying on efficient power management schemes to prolong lifetime, thus eliminating the need for batteries as a limited primary source of energy. These applications include: health monitoring and body-area networks, environment and infrastructure monitoring, security, and building automation. Autonomous wireless transmitter sensor nodes that harvest solar energy outdoors and light energy indoors via a solar cell or photovoltaic module are developed for ultra-wideband 3-10 GHz communications. Photovoltaic (PV) antennas are used as both DC power source and radio-frequency (RF) radiator or receptor. Sharing the area consumed by the primary DC power source with the antenna reduces the size and overall cost of the transceiver, resulting in a smarter integrated wireless system. The overall package consists of a temperature sensor, a supercapacitor or a rechargeable battery, DC power management, digital signal processing, analog, RF circuitry, and a PV antenna. One transmitter node uses a single solar cell behaving as a broadband monopole antenna to generate up to 20 mW-peak power outdoors and consumes an average power of 10 µW when transmitting 1 kbps every minute. Other sensor nodes employ a PV dipole antenna for outdoor applications and a flexible PV loop antenna for in an indoor environment, transmitting data packets at 10 kbps with average power consumptions of 15 µW. These sensor nodes are light weight (< 10 g), suitable for portable and wearable applications.MicroelectronicsElectrical Engineering, Mathematics and Computer Scienc