LARGE-AREA ELECTRONICS FOR WIRELESS-SENSING APPLICATIONS

Abstract

Future intelligent sensing systems envision seamless integration of a large number of physical objects and sensors, which can be wirelessly addressed with high spatial specificity to enable context-awareness for perception tasks. In order to do so, the systems require monolithic, flexible, and large-area form factors. While mainstream technologies like Si-CMOS are limited by chip size and rigid substrate, large-area electronics (LAE) has the potential to meet these requirements thanks to low-temperature processing. However, due to the low performance of the LAE devices, i.e., thin-film transistors (TFTs), thus far, the highest operation frequency achieved in LAE is only about 10 MHz, far below the system requirements in the gigahertz range. In this work, we address this challenge by device, circuit, and system co-designs. First, at the device level, gigahertz cut-off frequencies for zinc-oxide (ZnO) TFTs, acting as both active and passive devices, are demonstrated. They bring LAE into the radio frequency (RF) domain and open an unprecedented design space for realizing high spatial resolutions in wireless systems. Next, we develop oscillator circuits and resonant RF switches. Using them as building blocks, we design and build three wireless systems operating at gigahertz frequencies: (1) a phased antenna array, which enables fine beam control; (2) a reconfigurable antenna with dynamically tunable operating frequency and directionality; and (3) a fully passive backscatterer with zero static power consumption, enabling blind beamforming in the incident beam direction.