Formulation of a Graphene Based Ink for Inkjet Printing Wearable 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. A formulation process based on bath sonication and solvent exchange allows a graphene rich ink to be created with advantageous fluid properties that allow it to be printed easily.  Small flake size of the graphene will allow us to avoid the issue of clogging the nozzle with flake aggregation and eventually a flexible hydration sensor will be printed out with this graphene-based conductive ink.