A Long-Range and Self-Powered Intelligent Food Monitoring System Based on Far-Field Energy Harvesting and Pressure Measurement

Abstract

Introduction Radiofrequency (RF) energy harvesting has recently become a promising solution to power wireless sensors networks. As this emerging technology allows low-power sensors and systems to be charged wirelessly, it is advantageous in various applications with low cost and fewer requirements for periodical maintenance [1]. On the other hand, food quality is one of the most concerned problems of our society, foodborne illnesses caused by eating spoilt food has been a serious threat to human health. Therefore, development of a low cost, rapid and sensitive monitoring system is essential to ensure food safety and security. However, conventional food monitoring methods, which are usually based on measuring gas concentration show some drawbacks in terms of power consumption, cost, and reliability [2]. In this study, we developed a high-efficient battery-less system that can be used for food monitoring based on the far-field RF energy harvesting technique. Methods Our proposed system consists of an RF energy harvester and a sensing circuit. The RF energy harvester can harvest energy from radio waves at an ultra-high frequency (UHF) of 915 MHz to supply the power for the operation of all tag components. To improve the received power and enhance the distance of power transfer, a Yagi type structure antenna with three elements (driver, director, and reflector) was implemented to achieve a high gain and fit into a compact footprint [3]. Besides, to overcome the disadvantages of conventional food monitoring methods, our study focuses on measuring the increase in air pressure inside the food package caused by gas emission during storage. To confirm the effectiveness of the proposed system, we performed experiments on different sorts of food such as chicken, pork and fish. Results and Conclusions As a result, the sensor module is designed using a high accuracy pressure sensor and other ultra-low-power components, allowed it to consume low average power of only 1mW. The designed Yagi antenna has a high gain of 5.23dBi in the direction of the maximum radiation and voltage standing wave ratio (VSWR) better than 1.3 in approximately 60Mhz band (890-950Mhz). Finally, the increase in air pressure during food spoilage was used to categorize food freshness, demonstrating the feasibility of our proposed system.