Doctoral Defense

Energy-Efficient RF Powered Tag-Based Sensory Network

Yasha Karimi

January 18, 2019
2:00 PM
Light Engineering room 250
Advisor: Prof. Milutin Stanacevic

Similar to social media platforms, like Facebook, which connect millions of people around the world, Internet of Things (IoT) will connect billions of devices in decades to come. IoT is described as a "ubiquitous network" where connectivity should be available to anything, everywhere, and anytime. To satisfy these conditions, IoT devices have to be cordless. To obtain the required power to operate, these devices can either harvest energy or use a battery. One of the harvesting resources is Radio Frequency (RF) wave, available in modern society environment in different radio spectrum as WiFi, TV signal, etc.

The main objective of this dissertation is to investigate and propose enabling technologies to realize near zero power sensing platform meeting the requirements for IoTs, "anything", "everywhere", and "anytime". We focus on two different applications of this sensing platform in two different mediums and in two separate operating regions of the applied electromagnetic (EM) field; near-field and far-field regions.

Far-field is the region from a distance of two wavelengths to infinity where far-field antenna, like a dipole, is needed to absorb and transmit EM waves. We envision a paradigm shift toward a backscatter tag-to-tag network (BTTN) where RF tags completely rely on the harvested energy, and at the same time gather information about the environment in excess of the tag identification and localization. These tags would communicate through backscatter and sense environment either through self-powered sensors or monitoring the tag-to-tag channel. BTTN tags can be utilized for applications that require low data rate, few kbits/s, communication when multi-hopping will help to overcome the short communication range.

In the reactive near field, energy is stored in the field and can be absorbed by the coupling antenna (inductive link). We applied the concept of the passive tag to tag network to a near-field system like a network of miniature implanted tags. This network of introdes (intelligent electrodes) injected in brain powered by an external antenna array. This tags would be able to stimulate the brain by electrical pulses and also monitor neural activities which would help neurologists to study the brain.