Wireless thin-film microwave resonators for sensing and marking

Abstract

Rapid progress in wireless microwave technology has attracted increasing interest for high-performance wireless devices. The thin- lm microwave technology is now evolving into the mainstream of applications but signi cant advances are required in resonator architectures and processing for operation in the desired frequency ranges. This dissertation studies the thin- lm microwave technology to develop wireless resonators and describes the core elements that give rise to resonators for high performance in wireless sensing and marking. Speci c to wireless sensing, we proposed and developed a novel wireless microwave resonator scheme that enables telemetric strain sensing avoiding the need for calibration at di erent interrogation distances. In this work, we showed that by using both the proposed sensor architecture and wireless measurement method, strain can be successfully extracted independent of the interrogation distance for the rst time. The experimental results indicate high sensitivity and linearity for the proposed system. This approach enables mobile wireless sensing with varying interrogation distance. For wireless marking, we investigated an ultra-thin, exible, passive radio frequency (RF) based resonator compatible with magnetic resonance imaging (MRI) that successfully was tested in clinic. The ultra-thin and exible architecture of the device o ers an e ective and safe MR visualization and improves the feasibility and reliability of anatomic marking at various surfaces of the body. Results show that, at low background ip angles, the proposed structure enables precise and rapid visibility with high marker-to-background contrast as well as high signal-to-noise ratio (SNR). Also clinical studies have led to a successful biopsy procedure using marking functionality of our device. In another work related to marking, we proposed a new method to enhance local SNR and resolution without disturbing the B1- eld. Here we used our passive RF resonator in the inductively uncoupled mode for endocavity MR imaging. T1- and T2-weighted sequences were employed for phantom and in vivo experiments. The obtained images show the feasibility of the proposed technique to improve the SNR and the resolution in the vicinity of the device. These ndings will allow for new possibilities in applications using wireless sensing and marking approaches shown in this thesis.