Environmentally friendly Graphene-Based conductive inks for multitouch capacitive sensing surfaces

Conductive graphene-based inks can be tailored for functional applications and, in particular, for printed electronics. Transparent, flexible, and easy printable materials are nowadays increasingly required for sensing applications. In this context, a capacitive multitouch sensing surface is developed using conductive graphene nanoparticles-based ink with carboxymethyl cellulose as a binder. The rheological properties of the ink are tailored to be printed by the screen-printing technique. The touchscreen is based on printed conductive lines and columns and thus the characteristics of the printed lines are optimized based on the line width and number of printing steps. The optimal printed conditions are 0.5 mm of width and five printing steps, leading to electrical resistance of 2.4 kΩ. The screen-printed flexible touchscreen is composed of 40 columns × 28 rows. An electric circuit and a graphic interface are also developed leading to an 8” touchscreen with multitouch capabilities and fast signal processing.
Fundação para a Ciência e Tecnologia (FCT) within the Strategic Project UID/FIS/04650/2021 and grants SFRH/BPD/110914/2015 (P.C.) and SFRH/BD/145741/2019 (M.F.). The authors also thank the Fundo Europeu de Desenvolvimento Regional (FEDER) and Agência Nacional de Inovação (ANI) project with reference POCI-01-0247-FEDER-033566. Basque Government Industry Department under the ELKARTEK programs. Graphenest would like to thank Vitor Abrantes and João França for their contribution in graphene optimization