Inkjet-Printing of Carbon Nano Onions for Sensor Applications in Flexible Printed Electronics

Flexible and printed electronics can profit from novel 2D- and nano-materials for specific chemical, mechanical and electrical functionality. Here, carbon nano onions (CNO) are deposited on flexible polymer substrates using piezoelectric drop-on-demand inkjet printing. First, the drop generation conditions for the low-viscosity (similar to 1.2 cP) ethanol-based CNO suspensions are optimized for best resolution and line continuity. The CNO material can be deposited in multiple printing passes without requiring intermediate curing between layers and without degradation of the resolution. The printed structures are inspected by optical microscopy and profilometry. Electrical characterization is performed to obtain the electrical resistivity of the inkjet-printed CNO material (593 +/- 79 Omega.m), the temperature coefficient of resistance (-0.896 +/- 0.238 % degrees C-1) and the relative humidity dependency. The printed CNO devices are suitable for temperature compensation, humidity sensing, gas sensing, and possibly other applications.