Catching an Optical Photograph via a Focus-Tunable Real-Time Imaging System
Visual systems are the primary interface for humans to perceive the external environment. Mimicking the human eye, which integrates adjustable lenses with a curved retina, bio-inspired curved image sensors effectively mitigate field curvature and vignetting. To realize focus-tunable imaging, sensors must possess dynamic curvature while maintaining high sensitivity and mechanical stability. However, transitioning from rigid architectures to flexible devices often results in poor surface conformity through simple bending. Flexible sensors have explored intrinsic and structural designs for better flexibility and less stress concentration. Recent advances suggest that ultrathin devices with mesh-inspired designs offer a superior strategy, achieving seamless alignment with the curved surface without compromising optoelectronic performance. He et al. have developed a focus-tunable real-time curved imaging system inspired by the human visual system, based on an ultrathin perovskite curved image sensor with a hierarchical mesh architecture. They introduced an ultrathin image sensor with 5.4 μm thickness and soft interconnections, enabling it to be readily deformed into a hemispherical geometry. The ultrathin structure significantly reduces intrinsic mechanical behaviors, while interconnections effectively release twisting and stretching stress among pixels under various curvature conditions. As a result, the curved sensor array achieves a low detection limit of 10 nW cm−2, approaching the light sensitivity level of human photoreceptors. The focus-tunable imaging system integrates a curved image sensor with a shape-tunable convex lens, forming a conformal, skin-like architecture on a hemispherical surface. Finite element analysis revealed that when deformed to a curvature radius of 17.8 mm, the maximum strain on the Parylene C substrate reaches 5.72% and is primarily localized at pixel interconnections and edge regions. The curved image sensor achieves an overall thickness of approximately 5.4 μm and integrates a perovskite photodetector array comprising 127 pixels, enabling mechanically robust operation under pronounced curvature.