Internet of Meta-Material Things: A New Paradigm for Passive Wireless Sensing Systems

Passive wireless sensors have attracted much attention due to their battery-less characteristic in the Internet of Things. However, existing passive wireless sensors cannot reach satisfactory sensing accuracy and transmission range as part of the energy from wireless signals is used for signal processing. To address this issue, we design the meta-material sensors based on the specific working principle of simultaneous sensing and transmission. As a result, the transceiver can detect the sensing target by analyzing the reflected signals from the sensor, bypassing the signal processing at the sensor to further enhance its transmission range and sensing accuracy. In this article, we propose the Internet of Meta-material Things (meta-IoT), which encompasses meta-material sensors, as a new paradigm for passive wireless sensing systems. We begin with an introduction of meta-material sensors and then describe the meta-IoT system where sensing accuracy and transmission range are jointly optimized. In what follows, we present a prototype of the meta-IoT system for anomaly detection as an example. The experiment results show that 10x transmission range can be achieved compared to the state-of-the-art implementation with optimal sensing accuracy. Finally, potential extensions of meta-IoT systems and relevant research challenges are discussed.

Introduction

In the upcoming 6G system, the increasing number of Internet of Things (IoT) sensors requires them to be low-maintenance and cost-efficient. However, conventional IoT sensors require power supplies from batteries, which need regular main-tenance. Moreover, the high price of RF units and delicate chips equipped with IoT sensors make it difficult to reduce the cost of sensors. In contrast to batteries and RF units in conventional sensors, passive wireless sensors, which do not rely on the battery, have been proposed and implemented in daily applications [1]. The most representative is the radio-frequency identification (RFID) technique based on backscatter communications and energy harvesting. However, RFID sensors also have the following two limitations:

The authors propose the Internet of Meta-material Things, which encompasses meta-material sensors, as a new paradigm for passive wireless sensing systems.

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The sensor still depends on delicate chips, which increase the cost and decrease the robustness in open environments.

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As the sensors obtain sensing results by themselves, the finite harvested wireless signal power limits the sensing accuracy and transmission range of sensors.