Plasmonic Skyrmion-Based Microfluidic-Integrated Flexible Microwave Meta-Resonator for Noninvasive Intelligent Flow Rate Sensing

In this article, we propose a novel microfluidic-integrated flexible metamaterial resonator patch based on dynamically tuned plasmonic skyrmions for fluid flow rate sensing. The resonator patch is designed by integrating a flexible skyrmionic metamaterial resonator with a matching spiral microfluidic channel. The ultrathin metamaterial resonator can effectively excite multiple Néel-type electric and magnetic plasmonic skyrmion modes in the microwave regime, characterized by diverse multi-$\pi $-twist topological spin textures. Importantly, the resonance characteristics of these plasmonic skyrmion modes can be dynamically tuned by adjusting the fluid level within the matched microfluidic channel, thereby enabling real-time flow rate detection through resonance tracking. The proposed metamaterial resonator patch offers several distinct advantages, including compactness, robustness, mechanical flexibility, high sensitivity, and strong multimodal sensing capability. To further enhance the accuracy and robustness of flow rate detection, an artificial neural network (ANN)-enabled analytical framework is developed to interpret the multimodal resonance responses. A series of experiments is carried out to evaluate the performance of the proposed metamaterial resonator patch-based sensing system. The results strongly demonstrate and validate its effectiveness for real-time, continuous, accurate, and robust noninvasive fluid flow rate detection in microfluidic applications.