All Screen-Printed, Polymer-Nanowire Based Foldable Electronics for mm-Wave Applications

With the surge in devices for Internet of Things (IoT) applications, there is great interest in flexible electronics to be mass manufactured at lower costs. Screen-printing is well-known for mass manufacturing, however, this method has mostly focused on printing metallic patterns. Rare efforts have been devoted to print substrates for high frequency (mm-wave) electronics, which requires low dielectric loss to ensure a decent system efficiency. This paper presents a novel screen-printable composite ink comprising of acrylonitrile-butadiene-styrene and ceramic particles, through which, dielectric substrates with various thicknesses (down to few microns), lateral dimensions, and relative permittivities can be printed. A low dielectric loss of 0.0063 at 28 GHz (fifth generation (5G) communication band) makes the substrates suitable for mm-wave electronics. A custom silver nanowires based screen-printable ink is utilized for metallic printing to provide high conductivity (3.4 x 106 S m(-1)) and stable electrical response under bent or folded conditions. As a proof of concept for fully printed mm-wave electronics, a flexible quasi-Yagi antenna operating at 5G band (26.5-29.5 GHz) is demonstrated that exhibits decent performance in flat as well as bent conditions, confirming the suitability of the material system and printing processes for mass production of IoT and wearable electronics.