Performance Evaluation of RF Novel Microstrip Lines Printed on Flexible Substrates

Additive manufacturing or direct write printing is an attractive way to fabricate electronics due to potentially lower cost, volume production, fast turnout, and less generated waste. RF microstrip line are vital components in signal transfer and communication in many healthcare, biomedical, and IoT applications. In this research, novel microstrip lines were designed and fabricated using the aerosol jet printer (AJP) and dispensing system (DS) on flexible substrates and with two different inks that aimed to study the impact of the conductivity and microstructure of the metallic ink on the RF performance. In addition, novel designs with various aspects, including the shape of the microstrip line and the type of ground plane (hatched with different filling percentages vs. solid), were evaluated in terms of the stability of performance against various environmental and mechanical stresses. The results highlight that the insertion loss of the microstrip transmission lines increases as the microstrip line's meander angles become sharper due to the change in the electromagnetic field patterns. The aging at 85°C/85
^%
RH for several days enhances the conductivity of the lines due to changes in the ink's microstructure that were identified using SEM image analysis. In addition, bending tests of the microstrip lines having various filling percentages of the ground plane increased the deformation level of the microstrip lines as the filling percentages of the ground planes were increased. The difference in the insertion losses of the microstrip lines was also decreased as the ground plane filling rate was reduced.