Microwave resonance sensing has found a wide variety of applications and exhibits promising potentials in compact integrated sensors. However, its distinguishing ability to trace-amount targets remains challenging, which can be characterized by the effective wavelength and the quality factor (Q-factor). Here, a contactless sensing scheme for detecting sub-micromole glucose using a deep-subwavelength spoof localized surface plasmon (SLSP) resonator working at the decimeter-wave band is proposed. The SLSP resonator sustains a mixed-mode of an electric monopole and a magnetic dipole, compressing the electromagnetic mode into a diameter smaller than λ₀/41 (λ₀ is the free-space wavelength) and achieving a measured Q-factor of 187. In experiments, contactless sensing has been realized using a polydimethylsiloxane (PDMS) microfluidic channel, which separates the resonator and the solution. The solution sample under test features an ultra-compact volume of 3.7 × 10^–8 λ₀³, and a detection limit of 0.45 µmol glucose is demonstrated. This work envisions the applications of spoof localized surface plasmons in the contactless and trace-amount biomedical sensing.

中文翻译：

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使用深亚波长分米波等离子体谐振器在亚微摩尔水平上进行非接触式葡萄糖传感

微波共振传感已经发现了广泛的应用，并在紧凑型集成传感器中展现出巨大的潜力。然而，它对痕量目标的区分能力仍然具有挑战性，这可以通过有效波长和品质因数（Q-factor）来表征。在这里，提出了一种使用在分米波段工作的深亚波长欺骗局域表面等离子体 (SLSP) 谐振器来检测亚微摩尔葡萄糖的非接触式传感方案。SLSP 谐振器维持电单极子和磁偶极子的混合模式，将电磁模式压缩成直径小于λ ₀ /41 ( λ ₀是自由空间波长），并实现了 187 的测量 Q 因子。在实验中，使用聚二甲基硅氧烷 (PDMS) 微流体通道实现了非接触式传感，该通道将谐振器和溶液分开。^{待测溶液样品具有 3.7 × 10 –8}  λ ₀ ³的超紧凑体积，并证明了 0.45 µmol 葡萄糖的检测限。这项工作设想了欺骗局部表面等离子体在非接触和微量生物医学传感中的应用。