Bioinspired Anti‐Fogging and Anti‐Fouling Artificial Compound Eyes

Abstract

compound eyes with distinguished advantages, such as large field of view (FOV), low aberration, high sensitivity to moving objects, and high temporal resolution. [2] Moreover, the periodically arranged nanoripples make the eyes have superhydrophobicity and anti-fogging property. [3,4] Motivated by these unique features, bionics on the geometrics and optical performance of natural compound eyes have been investigated and have shown great potential in medical endoscopic imaging, digital cameras, and wide-field imaging. [5][6][7][8][9][10] In recent years, various methods have been proposed to fabricate artificial compound eyes (ACEs), such as self-assembly method, inkjet printing and air-assisted deformation, single-pulse femtosecond laser wet etching with thermal embossing, and so on. [11][12][13][14][15] However, in highly humid or low-temperature environments, fog easily forms on the surface of these ACE elements and thus scatters light by the condensed water droplets. Up to now, very few researchers have achieved antifogging surfaces that could be used for optical imaging purposes. Generally speaking, they are working through the following two aspects. The first one is superhydrophobic-induced surfaces that prevent fog from adhering to the micro-lens surface. [16] Another one is superhydrophilic-induced surfaces that can suppress fogging behavior by the rapid spread of condensing water droplets. [17] The disadvantages of these methods are obvious. Superhydrophobic surfaces always require hexagonal nipples or close-packed protuberances of nanoscale on the surface of microstructures, which brings a great challenge to current micro/nano manufacturing processes, and is not conducive to mass production. Furthermore, these superwetting surfaces are unstable when suffering from high pressure, long-term working, or abrasion, which results in the loss of anti-fogging ability. Therefore, it still remains a challenge to develop a more facile process to fabricate bioinspired artificial compound eyes that reproduces the functionality of the natural compound eyes.It is interesting that Nepenthes pitcher plants can prevent insects to stand on their pitcher and, instead make them slide down from the rim to the bottom. [18] This excellent characteristic benefits from a layer of lubricating fluid stored in Curved artificial compound eyes (ACEs) attract enormous research interest owing to their potential applications in medical devices, surveillance imaging, target tracking, and so on. However, fog, dust, or other liquids are likely to condense on the device surface under a humid, low-temperature environment or outdoors, thus affecting the optical performance. In this work, a multifunctional ACE (MF-ACE) is fabricated by a combination of i) femtosecond laser wet etching, ii) soft lithography, and iii) polydimethylsiloxane (PDMS) swelling methods. The fabricated device is close-packed with over 3000 microlenses (≈108 µm diameter and ≈15 µm height) on a spherical macrolens (6.56 cm diameter and 0.87 cm height). The trapped silicone...

Slippery quartz surfaces for anti‐fouling optical windows

“…The formation of the microholes and the nanoscale structures is ascribed to the material removal and particle recasting during the interaction of the femtosecond laser on the quartz glass. When a single pulse of the laser is injected onto the sample surface, part of the laser energy is absorbed by electrons through a series of nonlinear effects, such as multiphoton ionization, avalanche ionization, Coulomb microexplosion, and shock wave effect occurring at the focal point in an ultrashort time 36–38 . Some energy is transferred from electrons to the lattice, and then forms a high temperature/pressure plasma until the thermal equilibrium between electrons and ions appears.…”

“…When a single pulse of the laser is injected onto the sample surface, part of the laser energy is absorbed by electrons through a series of nonlinear effects, such as multiphoton ionization, avalanche ionization, Coulomb microexplosion, and shock wave effect occurring at the focal point in an ultrashort time. [36][37][38] Some energy is transferred from electrons to the lattice, and then forms a high temperature/pressure plasma until the thermal equilibrium between electrons and ions appears. As the plasma instantaneously expands and erupts out of the laser-ablated area, the sample surface is permanently destroyed.…”

“…Moreover, the resistance against mechanical damage of SLIPS was further demonstrated by sandpaper abrasion, as shown in The details of the definition can be seen in our previous work. 37 After laser ablation, the as-prepared samples were cleaned with alcohol and distilled water, respectively.…”

“…The AD is determined by the interval of adjacent laser scanning parameters and the scanning speed and it can be controlled by a computer program. The details of the definition can be seen in our previous work 37 . After laser ablation, the as‐prepared samples were cleaned with alcohol and distilled water, respectively.…”

Continuous roller nanoimprinting: next generation lithography

“…anti-reflective Si solar cells and perovskite solar cells) 157 industrial manufacturing (e.g. anti-fogging and anti-fouling material on car windows, sunglasses, and magnetic storage) [158][159][160] and biotechnology (Fig. 6).…”