Laser-Induced Forward Transfer: A Digital Approach for Printing Devices on Regular Paper

Inkjet printing (IJP) is the most widespread direct-write technique in paper electronics. However, this technique cannot be used for printing devices on untreated regular paper, since its low-viscosity nanoinks leak through the cellulose fibers. Thus, a planarization coating is frequently used as a barrier, even though this makes substrates more expensive and less eco-friendly. Alternatively, high solid content screen printing (SP) inks could allow printing on regular paper due to their high viscosity and large particle size; however, they cannot be printed through IJP. Another digital technique is then required: laser-induced forward transfer (LIFT). This work aims at proving the feasibility of LIFT for printing devices on regular paper. The main transfer parameters are systematically varied to obtain uniform Ag-SP interconnects, whose performance is improved by a multiple-printing approach. It results in low resistances with much better performance than those typical of IJP. After optimizing the functionality of the printed lines, a proof-of-concept consisting of a radio-frequency inductor is provided. The characterization of the device shows a substantially higher performance than that of the same device printed with IJP ink in similar conditions, which proves the potential of LIFT for digitally fabricating devices on regular paper.