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Inspired by insect compound eyes (CEs) that feature unique optical schemes for imaging, there has recently been growing interest in developing optoelectronic CE cameras with comparable size and functions. However, considering the mismatch between the complex 3D configuration of CEs and the planar nature of available imaging sensors, it is currently challenging to reach this end. Here, we report a paradigm in miniature optoelectronic integrated CE camera by manufacturing polymer CEs with 19~160 logarithmic profile ommatidia via femtosecond laser two-photon polymerization. In contrast to μ-CEs with spherical ommatidia that suffer from defocusing problems, the as-obtained μ-CEs with logarithmic ommatidia permit direct integration with a commercial CMOS detector, because the depth-of-field and focus range of all the logarithmic ommatidia are significantly increased. The optoelectronic integrated μ-CE camera enables large field-of-view imaging (90°), spatial position identification and sensitive trajectory monitoring of moving targets. Moreover, the miniature μ-CE camera can be integrated with a microfluidic chip and serves as an on-chip camera for real-time microorganisms monitoring. The insect-scale optoelectronic μ-CE camera provides a practical route for integrating well-developed planar imaging sensors with complex micro-optics elements, holding great promise for cutting-edge applications in endoscopy and robot vision. The defocusing problem has been considered the main bottleneck for developing optoelectronic μ-compound eye (CE) cameras. Here, the authors report miniature optoelectronic CE cameras with an ommatidia logarithmic-profile. The camera enables large field-of-view imaging, spatial position identification, and sensitive trajectory monitoring of moving targets. [ABSTRACT FROM AUTHOR]

Femtosecond laser machining of biomimetic micro/nanostructures with high aspect ratio (larger than 10) on ultrahard materials, such as sapphire, is a challenging task, because the uncontrollable surface damage usually results in poor surface structures, especially for deep scribing. Here, we report an inside-out femtosecond laser deep scribing technology in combination with etching process for fabricating bio-inspired micro/nanostructures with high-aspect-ratio on sapphire. To effectively avoid the uncontrollable damage at the solid/air interface, a sacrificial layer of silicon oxide was employed for surface protection. High-quality microstructures with an aspect ratio as high as 80:1 have been fabricated on sapphire surface. As a proof-of-concept application, we produced a moth-eye inspired antireflective window with sub-wavelength pyramid arrays on sapphire surface, by which broadband (3–5 μm) and high transmittance (98% at 4 μm, the best results reported so far) have been achieved. The sacrificial layer assisted inside-out femtosecond laser deep scribing technology is effective and universal, holding great promise for producing micro/nanostructured optical devices. [ABSTRACT FROM AUTHOR]

Inspired from butterfly wings that exhibit unique dewetting properties and brilliant structural color synchronously, we reported here the preparation of biomimetic few-layer graphene films through a template-directed chemical vapor deposition method using laser-structured Cu foil as substrates. Hierarchical micronanostructures, including microscale stripes derived from the laser scanning and nanoscale laser-induced periodic surface structures (LIPSS), formed on Cu foil after a simple femtosecond laser treatment. By tuning the laser power, the surface roughness of the resultant Cu foils can be well controlled. Using the laser structures Cu foil as templates, biomimetic few-layer graphene films with both iridescence and superhydrophobicity have been successfully prepared. The present work may open up a new way to design and prepare structured graphene film in a biomimetic manner, and we deem that the bioinspired few-layer graphene films may find broad applications in the near future. [ABSTRACT FROM AUTHOR]

Summary: Femtosecond laser direct writing (FsLDW) has been established as a nano-enabler to solve problems that are otherwise not possible in diversified scientific and industrial fields, because of its unique three-dimensional processing capability, arbitrary-shape designability, and high fabricating accuracy up to tens of nanometers, far beyond the optical diffraction limit. We briefly review the underlying mechanisms for achievement of the superhigh fabrication spatial resolution and surface smoothness, and then discuss the rule and photochemical strategies that are currently exploited for FsLDW. Finally, applications of the delicate nanoprototyping approach in microelectronics, micromechanics, microoptics and microfluidics are introduced. [ABSTRACT FROM AUTHOR]

Natural musculoskeletal systems have been widely recognized as an advanced robotic model for designing robust yet flexible microbots. However, the development of artificial musculoskeletal systems at micro-nanoscale currently remains a big challenge, since it requires precise assembly of two or more materials of distinct properties into complex 3D micro/nanostructures. In this study, we report femtosecond laser programmed artificial musculoskeletal systems for prototyping 3D microbots, using relatively stiff SU-8 as the skeleton and pH-responsive protein (bovine serum albumin, BSA) as the smart muscle. To realize the programmable integration of the two materials into a 3D configuration, a successive on-chip two-photon polymerization (TPP) strategy that enables structuring two photosensitive materials sequentially within a predesigned configuration was proposed. As a proof-of-concept, we demonstrate a pH-responsive spider microbot and a 3D smart micro-gripper that enables controllable grabbing and releasing. Our strategy provides a universal protocol for directly printing 3D microbots composed of multiple materials. Musculoskeletal systems are recognized as a model for designing robust yet flexible microbots but the development of artificial musculoskeletal systems at nanoscale currently remains challenging. Here the authors report a laser programmed artificial musculoskeletal systems for prototyping 3D microbots, using relatively stiff SU-8 as the skeleton and pH-responsive proteins as the smart muscle. [ABSTRACT FROM AUTHOR]

Compound eyes are natural multiaperture optical imaging systems and have substantial potential in the field of modern optics. However, both natural and artificial compound eyes are composed of ommatidia with fixed focal lengths, and thus incapable of variable‐focus imaging. In this study, inspired by the tunable crystalline lens of human eyes, smart stimuli‐responsive compound eyes based on the bovine serum album (BSA) protein are fabricated via femtosecond laser direct writing. Due to the swelling and shrinking effect of BSA under different pH conditions, a tunable field of view (FOV, 35°–80°) and variable focal length of ommatidia are achieved. In addition to the direct prototyping of an entire protein‐based compound eye, the ability to flexibly integrate the smart protein ommatidia with a conventional optical lens (an SU‐8 lens in this study) to form a composite compound eye is shown. The composite compound eye achieves nearly 400% of focal length tuning at a fixed FOV. It is anticipated that femtosecond laser fabrication and the integration of smart protein‐based compound eyes may emerge as an enabler for fabricating miniature tunable imaging systems. [ABSTRACT FROM AUTHOR]

With high thermal and mechanical stability, glass artificial compound eyes have great potential applications in wide field‐of‐view (FOV) imaging and fast detection. However, the rapid fabrication of large‐area, high integration, uniform, and well‐designed three‐dimensional (3D) glass compound eyes is still a great challenge. Here, a dry‐etching‐assisted femtosecond laser machining (DE‐FsLM) technology is proposed for fabrication of cm‐sized concave compound eye from a curved sapphire substrate, with which the fabrication efficiency can be improved by over two orders of magnitude compared with direct laser ablation. With high hardness and thermal stabilities, the sapphire concave compound eyes can be used as high‐temperature and hard‐casting templates for the replication of convex compound eyes on K9 glass. The replicated cm2‐size all‐glass compound eye consists of a spherical macrolens (1 cm diameter and 2.3 mm height) and over 190 000 close‐packed ommatidia (≈20 µm diameter and 1.5 µm height). The compound eyes exhibit excellent optical properties with wide FOV (up to 90°) imaging and focusing. These results indicate that the DE‐FsLM and casting replication technology will open new opportunities in micro‐/nanofabrication of hard materials. [ABSTRACT FROM AUTHOR]

We report controllable assembly of silver nanoparticles (Ag NPs) for patterning of silver microstructures. The assembly is induced by femtosecond laser direct writing (FsLDW). A tightly focused femtosecond laser beam is capable of trapping and driving Ag NPs to form desired micropatterns with a high resolution of ∼190 nm. Taking advantage of the ‘direct writing’ feature, three microelectrodes have been integrated with a microfluidic chip; two silver-based microdevices including a microheater and a catalytic reactor have been fabricated inside a microfluidic channel for chip functionalization. The FsLDW-induced programmable assembly of Ag NPs may open up a new way to the designable patterning of silver microstructures toward flexible fabrication and integration of functional devices. [ABSTRACT FROM AUTHOR]