Capillary number encouraged the construction of smart biomimetic eyes

Successful integration of advanced semiconductor devices with biological systems has greatly accelerated fundamental scientific discovery. In view of imaging/illumination applications, a facile and high-yield strategy is thus highly desirable for fabricating biomimetic eyes bearing the advantages of insects' compound eyes and the human eye. In this work, the capillary number, determining the viscous-capillary balance, is controlled to construct life-sized biomimetic eyes with a large field-of-view (FOV) and superior varifocal capability. These proposed biomimetic eyes of ∼800 honeycomb-patterned liquid microlenses omnidirectionally arranged along a hemispherical polymer dome, which has a wide FOV (up to 160°) similar to an insect's compound eye. The imitative ommatidia are realized by a liquid microlens array, which autonomously responds to the capillary number and thus exhibits an excellent varifocal ranging from 28 μm to 145 μm. This optical system, by means of the controllable capillary number, successfully produces a high-resolution and visible output signal. Herein, our work paves a new avenue for adaptive optical systems with a large FOV and an outstanding varifocal capability in compact setups.