Fig. 1. Typical “bottom-up” laser processing of micro/nano structures. (a) Laser-induced assembly^[21]; (b) comparison of laser sintering and bulk heating^[27]; (c) laser-induced hydrothermal growth^[28]

Fig. 2. Typical manufacturing process of the direct laser writing based on the copper ionic precursor

Fig. 3. Effect of laser parameters on the written copper structure^[48]. (a) Width of structure; (b) composition;(c) microstructure

Fig. 4. Comparison of resistivity and microstructure of the laser written copper structures based on different precursors

Fig. 5. Direct laser writing of Cu-based composite micro-nano structure. (a) Schematic diagram of the formation mechanism of the Cu-C composite structure^[45]; (b) microstructure and elements distribution of the typical Cu-C composite structure; (c) comparison of oxidation resistance of Cu and Cu-C structures^[47]; (d) structure of the directly written Cu oxides at a low laser power^[48]

Fig. 6. Typical applications of the conductive Cu structures. (a) Flexible electrode^[47]; (b) monitoring the finger movement using the strain sensor^[44]; (c) response of the proximity/touch sensor to finger touch^[71]; (d) planar antenna and its bandwidth^[45]

Fig. 7. Typical applications of the laser written functional Cu-based structures. (a) Flexible heater^[47]; (b) quasi-solid capacitor and its cyclic voltammogram^[46]; (c) monitoring the breath rate using the strain sensor^[48]; (d) temperature sensor and its temperature response curves^[84]