Fig. 1. Preparation process of plane bionic compound eye. (a) Schematic diagram of optical path of femtosecond laser two-photon polymerization processing system; (b) the plane bionic compound eye prepared by femtosecond laser two-photon polymerization processing

Fig. 2. Structure characterization of ommatidium. (a) The laser scanning confocal microscope images of ommatidia at different powers; (b) SEM image of ommatidium at 18 mW

Fig. 3. Morphological characterization of planar bionic compound eyes. (a) Laser confocal microscope image; (b) laser confocal microscope three-dimensional image; (c) SEM image; (d) partial details of laser confocal microscope; (e) partial details of SEM

Fig. 4. Measurement of the height and diameter of the plane bionic compound eye. (a) The height measurement results of each small eye, are 5.463, 5.894, 5.949, 5.776 and 5.404 µm respectively; (b) the diameter measurement results of each small eye, are 30.622, 30.622, 30.116, 30.369 and 30.116 µm respectively

Fig. 5. Preparation process of flexible bionic compound eye. (a) A layer of PDMS spun on the surface of the obtained bionic compound eye and solidified at 80 ℃; (b) compound eye template with reverse structure obtained by soft lithography; (c) the template treated with fluorinated silane copied by soft lithography and cured at 80 ℃; (d) the obtained flexible bionic compound eye

Fig. 6. Morphological characterization of flexible bionic compound eye. (a) Laser confocal microscope image; (b) laser confocal microscope three-dimensional image; (c) SEM image

Fig. 7. Focusing and imaging characteristics of the flexible bionic compound eye. (a) Focusing results of flexible biomimetic compound eyes; (b) imaging results of flexible biomimetic compound eyes

Fig. 8. Motion monitoring using flexible bionic compound eyes. (a) Schematic diagram of experimental device for motion monitoring; (b) image captured by the first small eye; (c) image captured by the third small eye