A metamaterial-inspired temperature stable inkjet-printed microfluidic-tunable bandstop filter

A low-cost and disposable microfluidic-tunable bandstop filter is presented which is fabricated utilizing a novel inkjet-printing based microfluidics platform. The proposed bandstop filter is based on a split-ring-resonator (SRR) unit cell embedded within the ground of a co-planar waveguide (CPW) transmission line. By loading the capacitive gap of the SRR with an array of fluids with different permittivities, the resonant frequency of the resonator can be tuned over a wide bandwidth. Utilizing only 6 μL of fluid, which is approximately one twentieth of a drop of water, a 30%, or 0.4%/ε_r change in resonant frequency can be achieved which is higher than current cleanroom-fabricated microfluidic RF devices in the literature. The high temperature stability of the low-cost microfluidic filter is presented, which demonstrates below 1% variance in resonant frequency for operating temperatures ranging from 273K to 332 K.