Tunable and reconfigurable metamaterials with metal ink printing on a paper

Here we report a novel approach to create tunable and reconfigurable microwave metamaterials using metal ink printing on a paper. Our approach enables easy-to-fabricate but still highly functional and tunable elements. An array of asymmetric split ring resonators was printed on a photopaper to induce Fano resonances in the microwave region (~ 10 GHz). Then, the printed paper was cut line by line and folded, so that a step height between neighboring unit cells can be created and tuned. With the varying step height between neighboring cells, our sample demonstrates significant spectral shifts and resonance tuning despite its simple geometry. Depending on the cutting direction, we observe either spectral redshift or blueshift. We explain our experimental observations based on the interactions between electric/magnetic dipoles in the neighboring unit cell. Moreover, we observe phase singularity at the zero amplitude position of the Fano resonance spectrum. The spectral phase exhibits a drastic change at this singularity point, and the phase spectrum can be also largely tuned with the geometry change in our sample. The drastic changes in phase could be very useful for various applications, such as optical sensing and beam steering.