Fig. 1. LIG formed on PI^[36]. (a) Schematic of the preparation of LIG using a CO₂ laser to ablate PI; (b) SEM image of LIG, the pattern is owl-shaped and the scale bar is 1 mm; (c) SEM image of the circled part in Fig.1(b), the scale bar is 10 μm, the inset is the corresponding SEM image with higher magnification and the scale bar is 1 μm; (d) SEM image of the cross-section of the LIG layer on PI substrate,

Fig. 2. Preparation and processing of LIG^[56]. (a) Schematic of LOM process; (b) “R” shaped three-dimensional graphene after polishing, and the height of the graphene foam is about 1 mm; (c) schematic of laser milling process; (d) preparation of three-dimensional graphene foam combined with LOM and fiber laser milling

Fig. 3. In situ and ex situ modification of compounds. (a)-(d) EDS images show that boron, carbon and oxygen are distributed evenly in the LIG synthesized from PI containing boric acid, and the scale bar is 5 μm^[55]; (e) equipment scheme for preparing LIG in different gas environments^[65]; (f) cross-sectional SEM image of LIG with MnO₂ deposited^{[Download full size}

Fig. 4. High magnification SEM image of LIG^[78-79]. (a) Non-uniform large pore foam, and the scale bar is 5 μm^[78]; (b) corrugation, and the scale bar is 1 μm^[78]; (c) tubes, and the scale bar is 500 nm^[78]; (d) fiber forest, and the scale bar is 500 nm^[

Fig. 5. SEM images and Raman spectra^[50]. (a)-(c) SEM images of the products obtained when the laser energy density is 4.4, 4.9 and 5.5 J·cm^-2, the insets in each SEM image are images of the same point, and the scale of each inset is 50 μm; (d) variation of Raman spectrum with laser energy density

Fig. 6. I_G/I_D of LIG processed on glass, PET and aluminum sheet substrates, respectively^[49]. (a) Relationship between I_G/I_D with resistivity; (b) relationship between I_G/I_D and power

Fig. 7. LIG from diverse carbon precursors^[54]. (a) Defocusing the laser on the substrate to increase the size of the laser spot, thereby exposing the overlapping area multiple times; different patterns of LIG were prepared on (b) coconut, (c) potato, (d) bread and (e) cloth

Fig. 8. Supercapacitor based on LIG^[84]. (a) Schematic of micro-supercapacitors structure; (b)(c) supercapacitors manufactured using series and parallel structures; (d)(e) corresponding charge and discharge curves when the current density is 0.5 mA·cm^-2

Fig. 9. Application of LIG in sensing equipment^[86]. (a) Tester wearing LIG artificial throat; (b) LIG responds to the throat vibration of the tester who coughed, hummed, screamed, swallowed and nodded twice in a row

Fig. 10. Schematic of LIG-based gas sensor^[85]. (a) Flexible LIG-PI gas sensor; (b) refractory gas detector embedded in cement; (c) LIG-based gas detector produces different and fast responses to different types of gases

Fig. 11. Schematics of bacterial filtration and sterilization by Joule heating^[87]. (a) Schematic of air filtration, the LIG filter is installed on a vacuum filtration system with PES test filter, and bacteria and endotoxins are marked in the figure; (b) schematics of filtration and (c) Joule heating sterilization; (d) schematic of a Joule heating device in which Joule heating is performed by applying a voltage to a filter; (e) infrared image of LIG filte

Fig. 12. Triboelectric nanogenerator based on LIG composite material^[88]. (a) Operation diagram of triboelectric nanogenerator composed of LIG/PI double-layer composite material; (b) operation diagram of triboelectric nanogenerator composed of LIG/cork; (c) SEM image of the cross section of LIG/PI composite material; (d) open circuit voltage of LIG/PI composite material; (e) SEM image of the cross-section of LIG/cork composite; (f) open circuit voltage of

Fig. 13. THz imaging for LIG-FZPs^[49]. (a) Photographs of LIG-FZPs with focal lengths of 20 mm and 5 mm; (b) measured THz field distribution on the plane with a distance of 5 mm from the sample without LIG (only glass substrate and PI); (c)-(f) measured THz field distributions on the focal plane, corresponding to the FZPs with focal lengths of 5, 10, 15, and 20 mm; (g)-(j) measured field-intensity distribution of the x axis on the focal plane, corr