Fig. 1. Development of photo-responsive droplet manipulation functional surface

Fig. 2. Schematic of droplet transportation by wetting gradient force^[41]. (a) Contact angle of equilibrium droplet; (b) Gradient force upon droplet induced by photo-thermal effect; (c) Stress analysis of droplet transportation

Fig. 3. Mechanism of droplet manipulation on photo-thermal paraffin phase-change ultra-slippery surface^[45]. (a) Stress analysis of droplet sliding; (b) Sliding of droplets in different paraffin phase

Fig. 4. Photo-thermal bouncing of droplet on a cavity trap-assisted superhydrophobic surface^[48]

Fig. 5. Mechanism of wettability conversion in the photo-thermal shape-memory polymer functional surface^[40]

Fig. 6. Schematic of droplet manipulation on photo-pyroelectric functional surface^[39]. (a) Generation of dielectric electrophoresis force; (b) Manipulation process

Fig. 7. Mechanism of droplet manipulation on photo-voltaic functional surface^[51]. (a) Sketch of the donor and acceptor levels of iron impurities and electron transport; (b) Schematic of directional photoexcitation of an Fe²⁺ impurity in the lithium niobate crystal, schematic of photo-voltaic electric field lines near the surface for (c) an x-cut crystal and (d) a z-cut crystal

Fig. 8. Electric wettability translation modulated by photo-pyroelectric effect^[53]

Fig. 9. Structure and operation of photo-thermal droplet manipulation surfaces which are categorized as the (a) silicone oil infusion^[37], (b) paraffin infusion^[38], and (c) shape-memory^[40]

Fig. 10. Laser ablation machining of micro and nano functional surfaces. (a) Schematic of laser ablation^[40] ; (b) Femto laser ablation^[40]; (c) Picosecond laser ablation^[50]; (d) Nanosecond laser ablation^[47]

Fig. 11. Reverse moulding of photo-thermal layer micro-nano functional structure with AAO^[41]

Fig. 12. Variation of contact and sliding angle of droplet on photo-thermal functional surface lubricant layers. (a) Non-phase transition lubricant layer^[41]; (b) Phase transition lubricant layer^[56]

Fig. 13. Structure and operation of photo-electric droplet manipulation surfaces which are categorized as the (a) photo-pyroelectric dielectric electrophoresis force^[39], (b) photo-voltaic dielectric electrophoresis force^[51], (c) photo-pyroelectric wettability^[53], and (d) photo-conductive electric wettability^[61]

Fig. 14. Image of micro-nano structures on superhydrophobic surface^[39]

Fig. 15. Basic functional units of photo-conductive electric wettability surface^[61]

Fig. 16. Transportation of different droplets by light with (a) lubricant infused functional surface^[37], (b) photo-pyroelectric dielectric electrophoresis force functional surface^[66], and (c) tunnel based on lubricant infused material^[67]

Fig. 17. Droplet merging and splitting with light^[39]. (a) Merging of droplets; (b) Splitting of droplet; (c) Dispensing of droplet

Fig. 18. Capture and release of droplets. (a) Selective releasing of droplet with light remote control^[40]; (b) Capture and lossless transfer with optical pipet^[53]

Fig. 19. Manipulate a droplet to move a cargo, go through a tunnel, and clean the stains^[70]

Fig. 20. Motion of liquid metal “vehicle robot” in liquid condition with light manipulation ^[71]

Fig. 21. Photo-responsive LMs "engine"^[72]. (a) Motion of plastic boat with laser pumped “engine”; (b) Nonlinear movement of two-engine plastic boat pumped by sunlight

Fig. 22. Cell culture chip based on photo-responsive droplet manipulation functional surface^[38]

Fig. 23. Photo-responsive micro-fluidic biological chip^[76]. (a) Construction and operation of fluidic chip; (b) Thrombin culture and monitor experiment; (c) Cell in situ stimulation and detection experiment

Fig. 24. Photo-responsive droplet fusion and reaction control of chemical reagents^[62]

Fig. 25. Photo-responsive automatic sampling chemical reaction chip^[45]. (a) Photograph of the chip; (b)~(h) Automatic liquid feeding process based on optical response

Fig. 26. Photo-responsive functional surface for CdS nanocrystal chemical synthesis^[81]. (a) Schematic diagram of droplet manipulation;(b) Physical diagram and transmission electron microscopy image of CdS nanocrystals; (c) Parallel detection of multi samples

Fig. 27. Under-water bubble manipulation based on photo-responsive droplet manipulation functional surface^[82]

Fig. 28. Microparts assembly by controllable bubbles based on photo-thermal functional surface^[83]

Fig. 29. Light navigated bubble bouncing within water based on thermally conductive surface^[84]