Conducting carbon nanofibre networks: dispersion optimisation, evaporative casting and direct writing

The optimisation of vapour-grown carbon nanofibres (VGCNFs) dispersed in the biopolymer gellan gum (GG) and its usage as an ink for the direct writing of conducting networks are reported. Sonication optimisation showed that dispersing 10 mg per mL VGCNFs required 3 mg per mL GG solution and 4 minutes of low energy probe sonication. Free-standing films prepared by evaporative casting were found to exhibit electrical conductivity values of up to 35 ± 2 S cm-1. It is demonstrated that sonolysis has a detrimental effect on electrical conductivity. The dispersions were easily modified to allow for direct writing of conducting networks on paper using a commercial fountain pen. The electrical characteristics of these direct written electrodes (on paper) improved with increasing number of layers. The written electrodes on paper were used to connect a battery to a light emitting diode to demonstrate that they can be used in simple devices.