Miniaturized Microwave Microfluidic Sensor Based on Spoof Localized Surface Plasmons

In this paper, a miniaturized folded SLSP microwave microfluidic sensor for detecting liquid permittivity is proposed. The sensor has single-layer structure and fed with microstrips and coupling branches. The quarter-mode design can produce resonance corresponding to the full-mode case while reducing the size and the amount of liquid. By introducing additional capacitance in the vertical direction, the folded structure enhances the slow wave effect and further reduces the size of the resonator. A PDMS chip with a microfluidic channel is placed above the resonator. The injection of liquid sample would cause frequency deviation, so as to retrieve the liquid property. The sensor is also expected to be used in the field of blood glucose monitoring and wearable devices.