Drop-on-Demand Electrohydrodynamic Jet Printing of Graphene and Its Composite Microelectrode for High Performance Electrochemical Sensing

An effective approach is required to pattern graphene with high spatial resolution and accuracy for advanced graphene-based sensors. In this work, we describe a simple and effective strategy for direct writing micro-scale graphene patterns by drop-on-demand (DoD) electrohydrodynamic jet (E-Jet) printing, using a highly concentrated graphene dispersion. The uniform micro-scale graphene patterns were formed by droplets produced under the electric field "pulling" force, these droplets are far smaller than the inner diameter of nozzle, which can effectively avoid nozzle clogging. With the control of pulse voltage width and frequency, different micro-scale graphene patterns were directly printed using DoD E-Jet printing technique. Graphene lines with a thickness of 5 nm were produced for 1 time printing, which provided a resistivity of 4.2 mΩ·cm. In addition, the graphene layer was directly written on the Pt microelectrodes to form Graphene/Pt (G/Pt) composite microelectrodes. The electrochemical test shows that the peak current of G/Pt composite microelectrodes was more than twice larger than that of bare Pt microelectrodes. The sensing sensitivity was significantly increased, presenting great potential for high performance electrochemical sensing devices.