Evaluation of Inkjet-Printed Reduced and Functionalized Water-Dispersible Graphene Oxide and Graphene on Polymer Substrate—Application to Printed Temperature Sensors

Abstract

The present work reports on the detailed electro-thermal evaluation of a highly water dispersible, functionalized reduced graphene oxide (f-rGO) using inkjet printing technology. Aiming in the development of printed electronic devices, a flexible polyimide substrate was used for the structures’ formation. A direct comparison between the f-rGO ink dispersion and a commercial graphene inkjet ink is also presented. Extensive droplet formation analysis was performed in order to evaluate the repeatable and reliable jetting from an inkjet printer under study. Electrical characterization was conducted and the electrical characteristics were assessed under different temperatures, showing that the water dispersion of the f-rGO is an excellent candidate for application in printed thermal sensors and microheaters. It was observed that the proposed f-rGO ink presents a tenfold increased temperature coefficient of resistance compared to the commercial graphene ink (G). A successful direct interconnection implementation of both materials with commercial Ag-nanoparticle ink lines was also demonstrated, thus allowing the efficient electrical interfacing of the printed structures. The investigated ink can be complementary utilized for developing fully printed devices with various characteristics, all on flexible substrates with cost-effective, few-step processes.

Graphene-Based Composites with Silver Nanowires for Electronic Applications

“…Flexible printed electronics (FPEs) are expected to dominate soon in the field of electronics because they have shown great potential in a wide range of applications [1] including sensors and microheaters [2,3], transistors [4], light-emitting diodes (LEDs) and organic LEDs (OLEDs) [5,6], solar cells [7], and wearable electronics and e-textiles [8,9]. FPE development requires the connection of flexible conductive structures, interfaces, and contacts, which can be created through the printing of conductive, semiconductive, and dielectric nanomaterials on suitable substrates.…”

Flexible Inkjet-Printed Heaters Utilizing Graphene-Based Inks

“…It is prepared via a reliable, affordable, facile, one-pot method that allows the simultaneous reduction and functionalization of GO using sulfonated aromatic diamines. Furthermore, our previous studies have shown that due to these properties, it is a promising material in the field of printed electronics [ 38 , 39 , 40 ], for example, as a pigment in conductive water-based inks for gravure and flexography or as an ink for inkjet-printed temperature sensors. In this work, a water dispersion of this highly hydrophilic material was used without any surfactant or additive.…”

“…An aqueous graphene oxide (GO) dispersion (1 mg/mL) was prepared following a previously described method [ 38 , 39 ]. Then, an appropriate amount of 2,4-diaminobenzenesulfonic acid (2,4-DBSA) was added in the GO dispersion using a mass ratio GO:2,4-DBSA equal to 1:3.…”

“…Droplet generation analysis and inkjet settings have been covered in a previously work [ 38 ]; in short, graphene and f- rGO inks were inkjet-printed using unipolar square wave pulses of 90 V amplitude for 10 μs and −90 V for 50 μs, respectively, while droplet spacing was set at 65 μm for both axes. A Thetametrisis FR-DEPOSIT (Athens, Greece) drop-on-demand piezoelectric inkjet printer was used for the sample formation.…”

“…This approach allows for cost-effective mass production of custom-patterned heaters with minimal material waste. These materials have been evaluated for their thermal response as temperature sensors [ 38 ], and their performance was an indicator of their ability to operate as printed microheaters.…”