Fig. 1: Fabrication of flexible painting electronic devices and integrated systems with MoWNb MEAs inks.

a (i) Schematic diagram of the synthesis process of MoWNb MEA nanoparticles. Zoomed-in schematic shows the hydrogen reduction of the metal salts to MEA elements. Insets are photographs of materials in a ceramic boat before and after thermal annealing. (ii) Photograph of the MEA powders in a gram scale. (iii) Photograph of the prepared MEA ink. (iv) Schemes of the patterning process on an aircraft wing using mask printing and direct writing. Inset is a photograph of the direct writing process. b Schematic illustration showing the printed sensors and the integration with a wireless module on a morphing aircraft. Four sensors are attached to the wings for monitoring the flying and morphing status of the aircraft at various extreme conditions with different temperature regimes. c Sensing mechanism of the printed MoWNb MEA sensors. (i) Simulated stress distribution in the macroscopical film and the calculated resistance variation as a function of bending strains at 500 °C, showing a linear correlation. The calculated GF is 448.5. (ii) Simulated stress distribution in the nanoscale structure under tensile strain. (iii) Lattice structure and the calculated electronic conductivity of MoWNb MEAs under various lattice strains based on DOS results in the DFT calculation, showing a high linear correlation. d–i Photographs of the printed flexible and stretchable circuits and conductive structures on various intricate surfaces, such as hemi-glass tube, wavy plastic, oblique ceramic, flexible polymer, and serpentine aluminum. LEDs are also mounted in the circuits to verify the high conductivity and the stability of the printed lines.