Schematic of an integrated approach we developed for manufacturing electrodes on paper substrates, combining inkjet printing and ultrafast laser micromachining. The process begins with printing of electrode materials onto the paper surface in the overall shape desired for the final device, followed by ultrafast laser machining to divide the shape into two insulated electrodes with fine patterns beneficial for their applications. What is special about this approach is that it integrates the capability of inkjet printing in depositing various functional materials with the controlled ultrafast laser micromachining to achieve patterns with high definition beyond the resolution of inkjet printing. [Xue, Han, et al. Carbon Energy 6.5 (2024): e442., https://doi.org/10.1002/cey2.442]  

Characterization of a multi-layer electrode manufactured on paper using inkjet printing and ultrafast laser micromachining. The electrode featured a paper-PEDOT:PSS-MXene structure, where MXene offers desired electrical performance and  PEDOT:PSS (a conductive polymer) was added to improve the adhesion without degrading the overall conductivity. The small picture in the middle shows the entire device, and the right and left figures show the zoom-in top and side view of the micromachined channel, respectively. What is special about this demonstration is that it shows that ultrafast laser micromachining is efficient in shaping various materials, even in a stacked configuration, while preserving the integrity of the paper substrate. Moreover, no catastrophic damage to the surrounding materials and the substrate, which would be expected for continuous-wave lasers, was observed. [Xue, Han, et al. Carbon Energy 6.5 (2024): e442., https://doi.org/10.1002/cey2.442]  

An array of 100 pairs of electrodes in series manufactured on paper using inkjet printing and ultrafast laser micromachining. The top-right figure shows the zoom-in top view of the electrodes, with each of them covered with electrolyte. Every pair of electrodes was measured to be insulated before depositing the electrolyte, and the electrical current can pass through the entire array after the electrolyte deposition. What is special about this demonstration is that it shows the high reliability and scalability of our approach, which is crucial for its applicability to complex inkjet-printed electronics, since the failure of any component in such a circuit would largely degrade the performance of the entire system. [Chen, Shiqian, et al. Advanced Science 11.22 (2024): 2400697., https://doi.org/10.1002/advs.202400697]