###### Abstract  
Solvent-free aerosol jet printing has been investigated for fabricating metallic and semiconductor (gas-sensitive) microstructures based on copper nanoparticles on alumina, borosilicate glass, and silicon substrates. The synthesis of nanoparticles was carried out using a spark discharge directly in the printing process without the stage of preparing nano-ink. Printed lines with a width of 100-150 \(\upmu\)m and a height of 5-7 \(\upmu\)m were formed from submicron agglomerates consisting of primary nanoparticles 10.8 \(\pm\) 4.9 nm in size with an amorphous oxide shell. The electrical resistivity, surface morphology, and shrinkage of printed lines were investigated depending on the reduction sintering temperature. Sintering of copper oxides of nanoparticles began at a temperature of 450 \({}^{\circ}\)C in a hydrogen atmosphere with shrinkage at the level of 45-60%. Moreover, aerosol heat treatment was used to obtain highly conductive lines by increasing the packing density of deposited nanoparticles, providing in-situ transformation of submicron agglomerates into spherical nanoparticles with a size of 20-50 nm. Copper lines of spherical nanoparticles demonstrated excellent resistivity at 5 \(\upmu\)\(\Omega\)-cm, about three times higher than that of bulk copper. In turn, semiconductor microstructures based on unsintered agglomerates of oxidized copper have a fairly high sensitivity to NH\({}_{3}\) and CO. Values of response of the sensor based on non-sintered oxidized copper nanoparticles to ammonia and carbon monoxide concentration of 40 ppm were about 20% and 80%, respectively. dry aerosol jet printing; copper nanoparticles; spark discharge; conductive lines; gas-sensitive microstructure +
Footnote †: journal: Applied Sciences  
Article Fabrication of Conductive and Gas-Sensing Microstructures Using Focused Deposition of Copper Nanoparticles  
Synthesized by Spark Discharge  
[PERSON]  
1 Moscow Institute of Physics and Technology, National Research University, 141701 Dolgoprudny, Russia; [EMAIL_ADDRESS] (D.V.K. ); [EMAIL_ADDRESS] (A.I.B. ); [EMAIL_ADDRESS] (E.I.K. ); [EMAIL_ADDRESS] (A.I.B. ); [EMAIL_ADDRESS] (E.I.K. ); [EMAIL_ADDRESS] (A.I.B. ); [EMAIL_ADDRESS] (E.I.K. ); [EMAIL_ADDRESS] (A.A.L. ); [EMAIL_ADDRESS] (P.V.A. ); [EMAIL_ADDRESS] (V.V.I)  
[PERSON]  
3 Institute of Electrophysics, Ural Branch of RAS, 620216 Vekaterinburg, Russia; [EMAIL_ADDRESS] (N.B.P. ); [PERSON]ADDRESS] (A.V.N.) [PERSON]  
3 Institute of Electrophysics, Ural Branch of RAS, 620216 Vekaterinburg, Russia; [EMAIL_ADDRESS] (N.B.P. ); [EMAIL_ADDRESS] (A.V.N.) [PERSON]  
1 Moscow Institute of Physics and Technology, National Research University, 141701 Dolgoprudny, Russia; [EMAIL_ADDRESS] (D.V.K. ); [EMAIL_ADDRESS] (A.I.B. ); [EMAIL_ADDRESS] (E.I.K. ); [EMAIL_ADDRESS] (A.I.B. ); [EMAIL_ADDRESS] (A.I.B. ); [EMAIL_ADDRESS] (E.I.K. ); [EMAIL_ADDRESS] (A.A.L. ); [EMAIL_ADDRESS] (P.V.A. ); [EMAIL_ADDRESS] (V.V.I)  
NRC \"Kurchatov Institute\", 21328 Moscow, Russia; [EMAIL_ADDRESS] 3  
Institute of Electrophysics, Ural Branch of RAS, 620216 Vekaterinburg, Russia; [EMAIL_ADDRESS] (N.B.P. ); [EMAIL_ADDRESS] (A.V.N.) ###### Abstract  
Solvent-free aerosol jet printing has been investigated for fabricating metallic and semiconductor (gas-sensitive) microstructures based on copper nanoparticles on alumina, borosilicate glass, and silicon substrates. The synthesis of nanoparticles was carried out using a spark discharge directly in the printing process without the stage of preparing nano-ink. Printed lines with a width of 100-150 \(\upmu\)m and a height of 5-7 \(\upmu\)m were formed from submicron agglomerates consisting of primary nanoparticles 10.8 \(\pm\) 4.9 nm in size with an amorphous oxide shell. The electrical resistivity, surface morphology, and shrinkage of printed lines were investigated depending on the reduction sintering temperature. Sintering of copper oxides of nanoparticles began at a temperature of 450 \({}^{\circ}\)C in a hydrogen atmosphere with shrinkage at the level of 45-60%.