Fig. 2.

Additive control of the chemical architecture with a single nozzle. a, b Fast switching between two metals printed from a two-channel nozzle. a Summed mass spectrometry (MS) ion currents of Cu⁺ (red) and Ag⁺ (blue) cations ejected upon switching the anodic voltage between a Cu and a Ag electrode at different intervals. Switching between two ejected ion species is highly selective. b Overlaid SE micrograph and EDX elemental map of trajectories printed with the same switching profile as in (a) (Cu-L signal, red, and Ag-L signal, blue). The corresponding EDX line profiles show that the switching between Cu and Ag is resolved up to the smallest pulse width. Scale bar: 2 μm. c, d Examples of chemically heterogeneous structures printed using a single nozzle. c Sequence of pillars with different numbers of Cu and Ag modulation periods. Scale bars: 1 μm. d Out-of-plane Cu wall with the letters ‘Ag’ embedded in silver, printed with a continuous layer-by-layer printing mode (Supplementary Movie 1). Scale bars: 1 μm. For printing parameters, see Supplementary Table 1