This work shows an ultrahigh sensitivity microwave sensor for microfluidic applications. The proposed sensor is made of a microstrip line loaded with a complementary split-ring resonator (CSRR). The meander slot is adopted in the CSRR to achieve high field confinement and is therefore covered with a polydimethylsiloxane (PDMS) microfluidic channel to enable strong interaction between the field and the liquid sample. The complex permittivity of the liquid sample can be retrieved by the variations in the resonant frequency and peak attenuation. The proposed design requires a very small liquid volume of $\sim 0.5~\mu \text{L}$ while offering a high sensitivity. A prototype is fabricated and tested, with a good agreement achieved between the extracted values and the reference data.

中文翻译：

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用于微流体应用的超高灵敏度微波传感器

这项工作展示了一种用于微流体应用的超高灵敏度微波传感器。建议的传感器由加载了互补裂环谐振器 (CSRR) 的微带线制成。CSRR 中采用曲流槽以实现高场限制，因此覆盖有聚二甲基硅氧烷 (PDMS) 微流体通道，以实现场与液体样品之间的强相互作用。液体样品的复介电常数可以通过谐振频率和峰值衰减的变化来恢复。所提出的设计需要非常小的液体体积 $\sim 0.5~\mu \text{L}$ 同时提供高灵敏度。制造并测试了一个原型，在提取的值和参考数据之间取得了很好的一致性。