Powering Mobile Sensor Nodes in Fluidized Beds: A Non-Invasive RF Energy Harvesting Proof-of-Concept

Abstract Real-time monitoring within industrial processing vessels is essential for advancing process analytical technology. Flow-following sensors represent an ideal approach for delivering continuous, in-line data from the process stream. However, deploying these mobile sensors is constrained by the physical barriers of sealed metallic vessels and harsh, battery-hostile environments. To overcome these limitations, a non-invasive, retrofittable wireless power transfer system is presented. The metallic vessel is structurally repurposed into a 5.23 GHz multi-mode microwave cavity resonator by coupling microwave energy through existing standard flanges. Electromagnetic simulations validate that this method generates continuous energy coverage throughout dynamic flow zones, demonstrated using a fluidized bed granulator as an application example. To harness this energy, an omnidirectional antenna and a compact RF-to-DC rectifier prototype were developed. By enabling the continuous operation of autonomous, battery-free mobile sensor nodes, this framework provides a practical, scalable foundation for high-density spatial analytics and data-driven industrial optimization.