SUMMARY

Flexible hybrid electronics (FHE) has wide range of applications including medical devices, wearable technology, communication devices, automotive and aerospace sensors, and various consumer Internet of Things (IoT). This thesis has a focus on inkjet-printed antenna, and inkjet printing is a maskless, material-saving and fully additive technique which allows a variety conductive inks to be deposited on a wide range of flexible substrates. During usage, the FHE components are often stretched, bent, folded, and/or twisted to conform to underlying structure. Therefore, the electrical and mechanical characteristics of flexible printed electronic components should be studied under such deformation during operation.

In this work, tests have been developed for characterizing the mechanical and high-frequency electrical behavior of inkjet-printed patch antennas under uniaxial and biaxial bending. The antenna samples have been fabricated by inkjet printing silver nanoparticle ink on flexible polyethylene terephthalate (PET) substrates. Polycarbonate cylindrical mandrels of different diameters have been used as test fixtures for the uniaxial bending test. Special sculptured surfaces have been 3D printed in polylactic acid (PLA) to perform the biaxial bending test. During bending tests, the S11 (return loss) response has been measured by a vector network analyzer (VNA) in both bent and flat configurations. Mechanical simulations have been performed to study the strain distribution in the printed elements which will lead to changes in electrical behavior. High-frequency electrical simulations have also been performed to correlate with the bending experimental data. It’s seen that, the conductivity of the printed structure changes differently in different zones, due to the various values of strain they undergo. Although the cracks are observed in the printed structures, the maximum shift in the measured resonant frequency is less than 80 MHz in both tests.