Controllable liquid colour-changing lenses with microfluidic channels for vision protection, camouflage and optical filtering based on soft lithography fabrication

SpringerPlus, May 2016

In this work, liquid colour-changing lenses for vision protection, camouflage and optical filtering are developed by circulating colour liquids through microfluidic channels on the lenses manually. Soft lithography technology is applied to fabricate the silicone liquid colour-changing layers with microfluidic channels on the lenses instead of mechanical machining. To increase the hardness and abrasion resistance of the silicone colour-changing layers on the lenses, proper fabrication parameters such as 6:1 (mass ration) mixing proportion and 100 °C curing temperature for 2 h are approved for better soft lithography process of the lenses. Meanwhile, a new surface treatment for the irreversible bonding of silicone colour-changing layer with optical resin (CR39) substrate lens by using 5 % (volume ratio) 3-Aminopropyltriethoxysilane solution is proposed. Vision protection, camouflage and optical filtering functions of the lenses are investigated with different designs of the channels and multi-layer structures. Each application can not only well achieve their functional demands, but also shows the advantages of functional flexibility, rapid prototyping and good controllability compared with traditional ways. Besides optometry, some other designs and applications of the lenses are proposed for potential utility in the future.

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Controllable liquid colour-changing lenses with microfluidic channels for vision protection, camouflage and optical filtering based on soft lithography fabrication

Controllable liquid colour-changing lenses with microfluidic channels for vision protection, camouflage and optical filtering based on soft lithography fabrication Min Zhang 0 Songjing Li 0 0 Department of Fluid Control and Automation, Harbin Institute of Technology , Science Park, No. 2, Yikuang Street Nangang District, Box 3040, Harbin 150001 , China In this work, liquid colour-changing lenses for vision protection, camouflage and optical filtering are developed by circulating colour liquids through microfluidic channels on the lenses manually. Soft lithography technology is applied to fabricate the silicone liquid colour-changing layers with microfluidic channels on the lenses instead of mechanical machining. To increase the hardness and abrasion resistance of the silicone colour-changing layers on the lenses, proper fabrication parameters such as 6:1 (mass ration) mixing proportion and 100 °C curing temperature for 2 h are approved for better soft lithography process of the lenses. Meanwhile, a new surface treatment for the irreversible bonding of silicone colour-changing layer with optical resin (CR39) substrate lens by using 5 % (volume ratio) 3-Aminopropyltriethoxysilane solution is proposed. Vision protection, camouflage and optical filtering functions of the lenses are investigated with different designs of the channels and multi-layer structures. Each application can not only well achieve their functional demands, but also shows the advantages of functional flexibility, rapid prototyping and good controllability compared with traditional ways. Besides optometry, some other designs and applications of the lenses are proposed for potential utility in the future. Liquid colour-changing lens; Microfluidic channel; Soft lithography; Vision protection; Camouflage; Optical filtering Background Microfluidics technology has been the focus of intense research and development as it promises a multitude of advantages in a number of markets including chemical and biological analysis (Shih et  al. 2015; Liberale et  al. 2013) , drug delivery (Majedi et  al. 2013) and medical diagnose (Lee et al. 2014; Ng Alphonsus et al. 2010) , such as small sizes, high throughput and low cost of microfluidic systems (Paul et  al. 2006). Microfluidic has also revolutionized some aspects of optical area (Tseng et al. 2009; Liu et al. 2012) . Lim et al. (2014) reported a microfluidic optical fiber devices composed of microfluidic channels which can be used for sensitive refractive index sensing and biosensing applications. Fuentes-Fernandez et  al. (2013 ) proposed an electrowetting-based variable focus liquid lens used for curvature sensors, which can reduce the overall size of the system without the need of extra moving parts. In recent years, a few examples of surface property control (shape, pressure etc.) of materials through microfluidic combined with optics were reported (Iimura et  al. 2015) . Roy and Ghatak (2014) designed an adaptable optofluidic aspherical lenses by using elastocapillary instability induced by surface tension of a soft rubbery layer with microfluidic channels. Chang et  al. (2009 ) presented a flexible material of controlled shape and stiffness embedded with microchannel networks. When the channels were filled with photoresist, deformed and exposed to UV light, the photoresist inside the channels was solidified, locking in the programmed shape of the materials. However, the reports on the applications of colour control in optometry by using microfluidic are few. In our daily life, wearing colour-changing sunglasses has become popular way for vision protection and aesthetic increasing. The traditional colour-changing glasses are made of solid photochromic glass containing silver halides (Armistead and Stookey 1964; Tian and Zhang 2012) inside, which can change their molecular construction for colour changing under different light conditions. But these solid photochromic glasses have shortcomings, such as single colour, poor controllability on colouration process and high price. Camouflage glasses are essential equipments for soldiers or hunters in the wild to blend with the surroundings for self-camouflage. Compared with common used camouflage nets, they have higher transparency and more flexibility for faces concealing. Camouflage technology in the animal field has been extensively studied and increasingly used by human in previous literatures (Surmacki et  al. 2013; Watson et  al. 2014; Dimitrova and Merilaita 2014) . Kang et al. (2015) presented experiments and discussions about the concealing mechanisms of moths during behavioral choice of a resting position, which told us that some species reinforce their crypticity in terms of both background matching and disruptive colouration to improve camouflage against natural predators. Yu et  al. (2014) conducted an adaptive optoelectronic camouflage systems with designs inspired by cephalopod skins, which provided critical capabi (...truncated)


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Min Zhang, Songjing Li. Controllable liquid colour-changing lenses with microfluidic channels for vision protection, camouflage and optical filtering based on soft lithography fabrication, SpringerPlus, 2016, pp. 580, Volume 5, Issue 1, DOI: 10.1186/s40064-016-2231-4