Low-Loss Graded Dielectrics via Active Mixing of Nanocomposite Inks during 3D Printing

Additive manufacturing has emerged as a promising approach for fabricating graded refractive index structures that control the electromagnetic response of radio frequency (RF) devices. However, current 3D printing methods cannot produce continuous gradients from multiple materials. Here, low-loss graded dielectrics via active mixing of nanocomposite inks composed of block copolymers and oxide nanoparticles are designed and printed. By simultaneously tailoring their rheological, printing, and their local filler particle-to-polymer ratio using an active mixing printhead, a conductive microstrip-graded substrate matching network with a gradually changing dielectric response, is created. In these printed devices, the impedance of the RF signal is controlled by the graded substrate rather than by varying the conductive microstrip geometry, enabling the fabrication of smaller RF devices. This approach enables the rapid design and fabrication of high-performance RF devices with locally tunable dielectric properties.