Carbon nanotube ink for writing on cellulose paper.

Highlights: [•] Water based conductive carbon nanotube ink is synthesized. [•] Direct writing on paper is demonstrated with off-the-shelf nib of fountain pen. [•] Dual sided and multilayered paper circuit boards are demonstrated with the pen. [•] Excellent robustness against bending, folding, crumpling are confirmed. [Copyright &y& Elsevier]