Bioinspired Artificial Compound Eyes: Characteristic, Fabrication, and Application

Abstract

the visual nerve perception. This type of eyes has ultrahigh resolution, which can get clear image information. Inspired by this imaging system, people have put significant efforts over a long time for development of camera-related optical system for various applications, such as endoscope, digital camera, smartphones, robot eyes, visual implants. [7][8][9][10] Because of the rapid progress in micro/nano technologies, the artificial eyes structures can achieve extremely high resolution that is close to or even exceeding the human eye. However, the low field of view (FOV) (the maximum value is only 90°) hinders its wider applications. To solve this problem, multiple cameras need to be put together to work, which not only increases the cost, but also makes the entire optical system cumbersome. Hence, an optical device with portable, integrated, and large FOV features is highly desired.Different from the single-lens eyes, the insect eyes adopt another visual system. Figure 1b shows a honeybee's apposition compound eye, which has thousands of ommatidia arranged on a curved surface so that each ommatidium points in different directions. [11] Each unit consists of a lens, a crystalline cone, and a rhabdom. The focused light signal is transmitted to the photosensitive area by the crystalline cone, and then visual perception is generated after passing through the rhabdom. Each of the ommatidium can image which enables the insects to obtain sufficient information in a complex environment and exhibits the characteristics of large FOV, low aberration, and high sensitivity to moving objects. [12] In addition to the honeybee's compound eyes, the eyes of other insects in nature, such as mosquito eye, [13] fly's eye, [14] moth's eye, [15] and dragonfly's eye [16] also have similar structure and have attracted much attention due to the deep research on bionics. [4,9,12,[17][18][19][20][21] The characteristics of the compound eyes in nature and the advanced micro/nano-processing technologies provide great technical support and inspiration for the researchers to prepare artificial compound eyes (ACEs) with close-packed microlens arrays (MLAs) as optical imaging elements. [22][23][24][25][26][27][28][29][30] Such MLAs compose of microscale lenses with the same surface feature and the regular arrangements are important microoptical components. The great light field (LF) regulation and focusing abilities of MLAs have made it essentially in various applications such as imaging, [31][32][33][34][35][36][37][38][39] dynamic target capture, [40][41][42] beaming homogenizing, [43][44][45][46] sensing, [47][48][49] light extractionThe natural compound eyes provide great inspiration for design of advanced imaging devices. Artificial compound eyes (ACEs) with close-packed microlens arrays (MLAs) have attracted enormous research interests due to their remarkable advantages in modern micro-optical systems, such as miniaturization, high integration, tunable focal length, large field of view, and moving objects tracking. Over a decade of intens...

Hierarchies in Visual Pathway: Functions and Inspired Artificial Vision

“…Two typical imaging systems among creatures: single-lens eyes and compound eyes have evolved with advantages in high-resolution imaging, wide field of view, and focal length tunability and inspire a variety of optical components (tunable lens, micromirror arrays, antireflective nanostructures, etc.). [185,[199][200][201] More coupled integrations between imaging and processing systems demand fabrication technologies with higher precision and compatibility of the materials. We conclude by noting that biological features and functions of visual pathways serve as a great inspiration to develop neuromorphic devices and circuits for achieving real-time, low latency, and lower-power machine vision systems.…”

Mold-Free Self-Assembled Scalable Microlens Arrays with Ultrasmooth Surface and Record-high Resolution

“…So far, MLAs with high ll-factor have been mostly produced through inkjet printing [13], laser direct writing [14,15], screen printing [16], lithography [17], photopolymerization [18], hot melt re ow [19], nanoimprinting [20] and chemical vapor deposition [21]. These preparation methods can be predominantly categorized into direct method and indirect method [22]. The indirect method relies on mold and replicates the microlens based on molding or injection molding, where the geometry of microlens is determined by the mold [23].…”

Four-Dimensional Stimuli-Responsive Hydrogels Micro-Structured via Femtosecond Laser Additive Manufacturing

“…For example, the traditional actuation uses a residual stress-driven method for thermal shape deformation [30,31]. Some researchers use a unique laser writing process for pre-designed shape morphing [32], or a doping carbon nanotube to enhance the light-responsive behavior [33,34], or use a bio-environment to tune the optical properties [35,36]. Although having achieved tremendous progress [29][30][31][32][33][34][35][36], the stimuliresponsive behavior still deserves further investigation for complex high-freedom shape reconfiguration.…”

“…Some researchers use a unique laser writing process for pre-designed shape morphing [32], or a doping carbon nanotube to enhance the light-responsive behavior [33,34], or use a bio-environment to tune the optical properties [35,36]. Although having achieved tremendous progress [29][30][31][32][33][34][35][36], the stimuliresponsive behavior still deserves further investigation for complex high-freedom shape reconfiguration. The material limitation and monotonous laser scanning methods are now restraining this micro/nanoscale additive manufacturing from innovative development and broadband applications.…”