Introduction

The glasswing butterfly (Greta oto) has, as its name suggests, transparent wings with remarkable low haze and reflectance over the whole visible spectral range even for large view angles of 80°. This omnidirectional anti-reflection behaviour is caused by small nanopillars covering the transparent regions of its wings. In difference to other anti-reflection coatings found in nature, these pillars are irregularly arranged and feature a random height and width distribution. Here we simulate the optical properties with the effective medium theory and transfer matrix method and show that the random height distribution of pillars significantly reduces the reflection not only for normal incidence but also for high view angles.

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Hot embossing of polypropylene micro-tubes into functional tubular components with controlled inner-pore sizes

Zhao

Qin

2018

MATEC Web Conf.

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To meet ever-increasing demands on the micro-components for medical and non-medical applications, a new micro-shaping technology - “hot embossing of micro-tubes”, had been developed for the forming of polymeric tubular micro-components. The paper presents the results from the forming of Polypropylene(PP) micro-tubes with outer diameters of 1.3mm and inner diameters 0.6mm, to achieve various reduced inner-features. The study was effected by combining experiment, numerical simulation and SEM analysis. FE simulation was implemented by using the material data obtained from the material characterisation tests. The forming experiment was conducted with a high-precision hot-embossing machine, developed in-house, with automated handling and good reliability and repeatability. The Polypropylene (PP) micro-tubes were successfully formed into the desired features at the temperatures of 60°C and 100°C respectively. The influences of the parameters/factors, such as tool design, temperature, forming pressure and holding time, on the quality of the shaped parts, are discussed in details. Based on this study, it is concluded that PP is an ideal candidate material among the polymeric materials for hot embossing of tubular micro-components, due to its good ductility, low transition temperature and low viscosity. Keywords: Micro forming, Manufacturing process, Tool geometry

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Introduction

Cited by 5 publications

References 5 publications

Flexible and Low-cost Production of Waveguide Based Integrated Photonic Devices

Flexible and Low-cost Production of Waveguide Based Integrated Photonic Devices

The role of random nanostructures for the omnidirectional anti-reflection properties of the glasswing butterfly

Hot embossing of polypropylene micro-tubes into functional tubular components with controlled inner-pore sizes

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