Fig. 1. Relationship between wettability of solid substrates in air and water. (a) Schematic of water contact angle (θ_w) in air and the bubble contact angle (θ_b) in water; (b) superhydrophobic/superaerophilic surface; (c) superhydrophilic/superaerophobic surface

Fig. 2. Schematic diagram of maximum (θ_max) and minimum (θ_min) static underwater bubble contact angles

Fig. 3. Different underwater superaerophobic surfaces fabricated by femtosecond laser. (a)(b) Aluminium alloy surface^[76];(c)-(f) silicon surface^[77]

Fig. 4. Different underwater superaerophilic surfaces fabricated by femtosecond laser. (a)-(c) PDMS surface^[77]; (d)-(h) aluminum surface and corresponding buoyancy device^[82]; (i)(j) PTFE surface^[83]

Fig. 5. Switchable underwater superaerophilic/superaerophobic PTFE surfaces fabricated by femtosecond laser^[96]. (a)(b) Surface microstructure; (c)(d) reversible switching between underwater superaerophilicity and superaerophobicity

Fig. 6. Switchable underwater superaerophilic/superaerophobic PDMS surface fabricated by femtosecond laser^[97].(a)-(c) Surface microstructure; (d)-(g) switching between underwater superaerophilicity and superaerophobicity

Fig. 7. Switchable underwater superaerophilic/superaerophobic titanium surface fabricated by femtosecond laser.(a)-(d) Sample treated by Jiao et al.^[98]; (e)-(i) sample fabricated by Jiao et al.^[99]

Fig. 8. Reversible switching between underwater superaerophilicity and superaerophobicity on the femtosecond laser treated aluminum surface^[100]

Fig. 9. Underwater superaerophilic PTFE surfaces with shape gradient fabricated by femtosecond laser. (a)-(d) Sample treated by Yin et al.^[104]; (e)-(h) sample treated by Duan et al.^[105]

Fig. 10. PTFE surfaces with underwater asymmetric wettability fabricated by femtosecond laser^[106]. (a) Schematic of the laser ablation process; (b)(c) surface microstructure; (d)(e) underwater bubble contact angle on both sides

Fig. 11. Bubble transportation surface fabricated by femtosecond laser. (a)-(c) Janus aluminum membrane^[107]; (d) light-responsive interface^[108]