Title:  Low-energy and Spectrally-efficient IoT Sensors with Low-cost Additive Manufacturing

Committee: 

Dr. Tentzeris, Advisor  

Dr. Zajic, Chair

Dr. Durgin

Abstract:

The goal of this thesis work is to develop complete sensor networks for environmental monitor- ing, smart home applications, and wearable devices for the Internet of Things (IoT). To minimize the energy footprint of these sensors, the devices will exploit backscatter radio principles for com- munication, instead of power-demanding active radios. The networks will utilize new topologies which allow for extended ranges that are longer than those achieved in commercial radio frequency identification (RFID) systems. This sets requirements for custom implementations of communica- tion algorithms for the network’s physical layer between the sensors/tags and the reader, as well as custom readers, carrier emitters, and tag antennas. Apart from the optimized network topology, custom tag front-ends need to be designed to increase the sensors’ maximum range and incorporate RF energy harvesters for battery recharging or battery exclusion. Custom, non-conventional front- ends are needed that a) maximize the backscattering efficiency, b) incorporate harvesters without compromising the tag-to-reader communication link, and c) are able to generate smooth, arbitrary waveforms for reduced per-sensor bandwidth occupancy that will allow high network density. All sensor electronics need to be integrated into compact packages that are additively manufactured with 3D printing and feature on-package inkjet-printed antennas to minimize system volume. To reduce the fabrication time and material cost that are inherent in 3D printing, nonconventional fab- rication techniques have to be used, inspired by Origami art principles, that enable the manufac- turing of high-frequency reconfigurable, foldable electronics for the first time. Moreover, inkjet printing processes have to be re-designed for successful on-package antenna integration, due to the typical fabrication challenges of 3D-printed materials. The final goal of this thesis is to offer a broad range of flexible printed RF devices ranging from low-bitrate, long-range sensors at UHF fre- quencies to ultra-wideband backscatter communicators operating at mm-Wave bands for real-time, high-datarate applications.