Scavenging Residual Energy from WiFi Sources Using a Rectenna Circuit With the increasing popularity of wireless devices, the need to develop ways to charge, or to expand the battery life, also increases. This paper proposes a hybrid rectification circuit for collecting energy from nearby WiFi networks. The circuit scavenges the energy emitted, but not used, by routers when they send information through the air, and stores the energy within a capacitor. The proposed architecture consists of two main building blocks: a bridgeless converter, and a diode bridge. The incident power on the antenna of the harvester is passed through the network of the LC lumped circuit, which helps in rectifying and boosting the voltage level. The second building block takes the output of the first block and further rectifies it, helping to further enhance voltage. The proposed system has been tested by using two distinct capacitive loads: 0.47 uF and 1000 uF. It was found that in the case of 1000 uF, the capacitor was able to charge 2.47 V within a span of 16.5 hours when kept directly next to the transmitting source antenna. In the case of 0.47 uF, it was able to charge within a span of 12 hours when kept 10 feet away from the transmitting source. The energy stored was used to light an LED, which was successful in the proximity circuit, albeit briefly.

A Hybrid Energy Harvesting Design for OnBody InternetofThings (IoT) Networks The Internetofthings (IoT) has been gradually paving the way for the pervasive connectivity of wireless networks. Due to the ability to connect a number of devices to the Internet, many applications of IoT networks have recently been proposed. Though these applications range from industrial automation to smart homes, healthcare applications are the most critical. Providing reliable connectivity among wearables and other monitoring devices is one of the major tasks of such healthcare networks. The main source of power for such lowpowered IoT devices is the batteries, which have a limited lifetime and need to be replaced or recharged periodically. In order to improve their lifecycle, one of the most promising proposals is to harvest energy from the ambient resources in the environment. For this purpose, we designed an energy harvesting protocol that harvests energy from two ambient energy sources, namely radio frequency (RF) at 2.4 GHz and thermal energy. A rectenna is used to harvest RF energy, while the thermoelectric generator (TEG) is employed to harvest human thermal energy. To verify the proposed design, extensive simulations are performed in Green Castalia, which is a framework that is used with the Castalia simulator in OMNeT. The results show significant improvements in terms of the harvested energy and lifecycle improvement of IoT devices.