Screen Printed rGO-Pd Nana-Composite films on a Flexible Substrate as Temperature Sensor

We report, a screen printed nano-composite films made with reduced Graphene Oxide (rGO) and Palladium (Pd) for temperature sensor application. The rGO was synthesized using modified Hummer's method and Pd was mixed with as-synthesized rGO to avoid the agglomeration formed by rGO nano sheets. An array of rGO-Pd nano-composite films were fabricated on flexible kapton substrate using screen printing technique, which is of low cost and simple process. As-synthesized rGO and rGO-Pd nano-composite's surface morphology and crystallinity were studied using Field Emission-Scanning Electron Microscope (FE-SEM) and X-ray diffraction (XRD). As-prepared nanocomposite films were tested using cold and hot chamber to verify it's response with respect to change in temperature. It was observed that the film responds linearly with negative temperature coefficient (NTC). The sensitivity and temperature coefficient of resistance (TCR) of the as-fabricated nanocomposite films were observed to be \pmb0.7028 Ω/K and. \pmb-2.0312 x \pmb10^-3 Ω/Ω/K respectively. These flexible temperature sensors can be used in the field of biomedical, food processing, aerospace, communication and automobile for monitoring of temperature.

I. Introduction

Graphene, a single atom thick, an ideal two-dimensional (2D) material has gained researcher's attention tremendously in recent years and has been emerging as promising material due to its excellent mechanical, electrical and optical properties. It has a perfect honeycomb lattice structure formed by tightly bonded, single atom thick sp² carbon atoms. Graphene has Young's modulus as high as 1 TPa and breaking strength as 42 N m⁻¹ and it can sustain tensile elastic strains are up to 25%. A zero band gap graphene with semiconductor properties has electron mobility as at room temperature and thermal conductivity above , which are high compare to other materials [1]–[3].