Fig. 10. Dynamic metasurfaces based on external fields, mechanical deformation and phase change materials. (a) Schematic of the reprogrammable coding metasurfaces hologram. By applying DC voltages across the positive-intrinsic-negative diode, the reflection coefficient can be controlled and reprogrammable holographic images can be realized. (b) Illustration of a strain-multiplexed metasurface hologram. As the substrate is stretched, the two-plane hologram image moves away from the device. If the detection plane is fixed, the switch of holographic image can be observed. (c) Experimentally measured image switching from “ONE” to “TWO”. (d) Illustration and (e) SEM image of the dynamic plasmonic color generation based on VO₂. Scale bar: 600 nm. (f) Measured reflection images of the flower pattern at 20 °C (left) and at 80 °C (right), demonstrating the changing of multiple plasmonic colors. Scale bar: 40 μm. (g) Schematic of dynamic metasurfaces holograms using chemical reactions. The hydrogen-responsive Mg nanorods undergo a phase transition from metal to dielectric (MgH₂) upon hydrogen loading. (h) Measured holographic images during hydrogenation and dehydrogenation. By switching the input state from On to Off, the left holographic pattern (harmony) diminishes while the right holographic pattern (peace) remains. (a) Reproduced with permission.¹⁵¹ (b and c) Reproduced with permission.¹⁵² (d–f) Reproduced with permission.¹⁵³ (g and h) Reproduced with permission.¹⁵⁴.