High-Sensitivity Microfluidic Sensor Based on Quarter-Mode Interdigitated Spoof Plasmons

A novel microfluidic sensor based on quarter-mode localized surface equipartition excitations for liquid detection is proposed in this article. The sensor has a compact size and ultrahigh sensitivity. With the excellent properties of field enhancement and field confinement of the localized surface plasmon (LSP), a double-interdigitated structure is employed to further improve the sensitivity. The proposed sensor is validated in a microwave frequency regime, and the confined electric field is fully employed by placing a microfluidic channel etched on polydimethylsiloxane (PDMS), which is aligned on top of the internal interdigitation. The results show that the simulated results are in good agreement with the experimental measurements. The ultrahigh sensitivity with 0.34% is excited by the addition of interdigitated structure. The ultrahigh sensitivity and compact size make it a good choice for sensing applications, which can be widely used in environmental monitoring, medical health, and other fields and have great potential in the microwave and terahertz regions.