Microfluidically-tunedminiaturized planar microwave resonators

This paper presents two frequency tuning techniques, applied to planar microwave lumped LC and CPW resonators. Both methods are based on employing the reactive loading effect of a fluid metal placed on top of planar microwave circuits. The frequency tuning is achieved by moving the fluid metal inside the micro-channel and on top of different sections of each resonator. Realization of tunable resonators using common PCB technology and PDMS structure is demonstrated. The metal fluidic used is a non-toxic eutectic alloy of Gallium, Indium, and Tin known as Galinstan. Two implemented prototypes are measured and tuning ranges of 1.45–2.35 GHz and 2.8–3.9 GHz are achieved for lumped LC and CPW resonators, respectively.