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)