Key Takeaways & Executive Findings
- •• • The ultrathin perovskite curved image sensor achieves a thickness of 5.4 μm, enabling conformal deformation to a hemispherical geometry with a curvature radius of 17.8 mm, while maintaining a maximum substrate strain of 5.72% localized at interconnections and edges, critical for flexible imaging applications. • • The sensor array achieves a low detection limit of 10 nW cm−2, approaching human photoreceptor sensitivity, which is essential for low-light imaging and biomedical applications. • • The hierarchical mesh design with serpentine interconnections effectively releases twisting and stretching stress, ensuring mechanical robustness under dynamic curvature, as validated by finite element analysis. • • The integration of a shape-tunable lens with the curved sensor enables real-time focus adjustment, mimicking human visual accommodation, which is pivotal for advanced imaging systems requiring variable depth of field.
Abstract
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.
1. Introduction
Conventional rigid image sensors, while offering high performance, are fundamentally limited by their planar geometry, which introduces optical aberrations such as field curvature and vignetting when used with simple lenses. Bio-inspired curved sensors have emerged as a solution, but their adoption has been hindered by the mechanical mismatch between rigid sensing elements and flexible substrates, leading to poor surface conformity and stress-induced failure upon bending. Existing flexible sensors often compromise optoelectronic performance or mechanical stability, failing to meet the demands of dynamic focus-tunable imaging systems.
This work addresses these bottlenecks by introducing an ultrathin perovskite curved image sensor with a hierarchical mesh architecture. The 5.4 μm-thick device, combined with serpentine interconnections, achieves seamless conformity to hemispherical surfaces while maintaining a low detection limit of 10 nW cm−2. Finite element analysis confirms that the design minimizes strain transmission to active layers, with a maximum substrate strain of 5.72% at a curvature radius of 17.8 mm. By integrating this sensor with a shape-tunable lens, the system achieves real-time focus adjustment, emulating the human eye's accommodation mechanism. This approach provides a viable pathway for high-performance, mechanically robust curved imagers suitable for next-generation cameras and medical endoscopes.
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Jianguo Xi, Zuqing Yuan, Qunwen Leng (2026). Catching an Optical Photograph via a Focus-Tunable Real-Time Imaging System. SCIENCE CHINA Materials. https://doi.org/10.1007/s40843-025-3958-8
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Frequently Asked Questions
What is the maximum strain experienced by the substrate at a curvature radius of 17.8 mm, and where does it concentrate?
At a curvature radius of 17.8 mm, the maximum strain on the Parylene C substrate reaches 5.72%, primarily localized at pixel interconnections and edge regions, as revealed by finite element analysis.
How does the ultrathin design (5.4 μm) contribute to mechanical robustness under bending?
Thickness-dependent FEA results demonstrate that reducing overall device thickness significantly lowers average strain in both substrate and functional layers, underscoring the necessity of an ultrathin configuration for achieving mechanical robustness under pronounced curvature.
What is the detection limit of the curved perovskite image sensor, and how does it compare to human photoreceptors?
The curved sensor array achieves a low detection limit of 10 nW cm−2, approaching the light sensitivity level of human photoreceptors, making it suitable for low-light imaging applications.
How does the hierarchical mesh design mitigate stress during deformation?
The serpentine hierarchical mesh (SHM) design embeds active sensing units within hexagonal pixels, with narrow connecting lines arranging pixels into a ring-like symmetric configuration, further connected by serpentine wide lines. This architecture effectively releases twisting and stretching stress among pixels under various curvature conditions, as confirmed by FEA.
What is the pixel count of the perovskite photodetector array, and what is the overall device thickness?
The curved image sensor integrates a perovskite photodetector array comprising 127 pixels, with an overall device thickness of approximately 5.4 μm.
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