An Experimental Study of Graphene-Based Conductive Ink for Inkjet-Printable Electronics

The field of printable electronics and sensors has been experiencing increased interest and growth to meet the demands of low-cost, flexible, and lightweight devices. From this subset of devices, graphene-based printable electronics and sensors are of specific interest due to their transparency, flexibility, biocompatibility, and high conductivity. Among all modern ink printing technology, screen printing, spray coating, 3D printing, and inkjet printing are often utilized to fabricate flexible electronic applications from conductive ink. Compared with the other three, inkjet printing has received the most attention due to the simple printing process, high repeatability, economy, and time-savings compared to other printing techniques. However, inkjet printing often suffers from nozzle clogging due to aggregation of the particles in the conductive inks. In this research, a conductive graphene-based ink is developed to be used in a regular inkjet printer. Our goal is to fabricate this ink such that it is flexible, biocompatible, and easily manufacturable. This method seeks to create a low viscosity, high surface tension ink that addresses the clogging of the nozzle due to an aggregation of particles and is capable of being printed through a regular inkjet printer. By selectively choosing and modifying the composition and processes of ink formulation methodologies of past research, a graphene-based conductive ink that is compatible with inkjet printing is formulated. A flexible hydration sensor is printed out with this graphene-based conductive ink through which its conductivity and sensitivity are compared with the same sensor printed with commercially available graphene ink.