Electromagnetic Skyrmions in a Deep‐Subwavelength Plasmonic Resonator for Vitro Diabetic Nephropathy Diagnostic

ABSTRACT Microwave resonance sensors integrated in an ultra‐compact planar circuit enable real‐time and label‐free biosensing, offering significant potential for in vitro diagnostics and home healthcare. However, the detection of weak biological signals at low concentrations has fundamental limitations due to the large disparity between the microwave wavelength and the molecular scale of biomolecules. Here, we realize an electromagnetic (EM) skyrmion mode in a microwave plasmonic resonator with an electrical size of 1/50 wavelength. The combination of strong EM field confinement and a high quality factor of 185 yields markedly enhanced wave‐matter interactions, resulting in a 105‐fold sensitivity improvement over the traditional microstrip ring resonator operating at the same frequency. The sensing capability is experimentally validated through the detection of diabetic nephropathy (DN), with a reporting limit for DN‐associated proteins down to 12.5 pmol in amount of substance and 125 nmol/L in concentration at an operating wavelength of 0.33m. These findings constitute a major advance in microwave resonance sensing, dramatically advancing its detection limits and paving the way for rapid and early diagnostic platforms in integrated systems.