AIST in Japan has demonstrated light-controlling sheet that lets its users transform windows to mirrors faster than what current technologies allow. The technology makes use of the production of hydrogen by water electrolysis to make the sheet either transparent or reflective. For comparison, the Boeing 787 Dreamliner windows feature glass that can be made transparent or reflective. However, the aircraft’s windows take about 30 seconds to change between states while this new technology allows for the same size glass to change states in just about 5 seconds, AIST says.
Refer:
- http://hight3ch.com/new-light-controlling-sheet-paves-way-for-faster-mirror-to-window-glass-change/.
- https://www.aist.go.jp/aist_e/list/latest_research/2013/20130304/20130304.html.
- https://www.nanowerk.com/news/newsid=24852.php.
- https://phys.org/wire-news/166787886/switchable-mirror-with-visible-transmittance-of-over-70-in-the-t.html.
Different Switchable Glass Technologies and detailed below
- Thermochromic Glass: Uses heat from direct sunlight to tint the windows when necessary – more direct and intense the sunlight is on the glass the darker it will become.
- Liquid Crystal Glass: Allows you to switch between transparency and translucence at the push of a button. It comprises laminated glass, with a minimum of two clear or colored sheets of glass and a liquid crystal film, assembled between at least two plastic interlayers. In the ‘off’ state, the liquid crystals are not aligned, which prevents vision, yet allows light to pass through the glass. When is it switched ‘on’, the liquid crystals align, turning the glass transparent and allowing visibility. The change in transparency takes place within milliseconds.
- PDLC: Polymer-Dispersed Liquid-Crystal Devices (PDLCs) are dissolved or dispersed into a liquid polymer followed by solidification or curing of the polymer. During the change of the polymer from a liquid to solid, the liquid crystals become incompatible with the solid polymer and form droplets throughout the solid polymer. The curing conditions affect the size of the droplets that in turn affect the final operating properties of the “smart window”. Typically, the liquid mix of polymer and liquid crystals is placed between two layers of glass or plastic that include a thin layer of a transparent, conductive material followed by curing of the polymer, thereby forming the basic sandwich structure of the smart window. This structure is in effect a capacitor.
Refer:
- http://ebglasstech.com/product/switchable-smart-pdlc-film/.
- http://www.glimmdisplay.com/projection-films-foils/smart-intelligent-film-foil/.
- http://www.vattiglass.com/product/pdlc-film/product_show_360.html.
- Suspended Particles Glass: Thin film laminate of rod-like Nano-Scale particles are suspended in a liquid and placed between two pieces of glass or plastic or attached to one layer. When no voltage is applied, the suspended particles are randomly organized, thus blocking and absorbing light. When voltage is applied, the suspended particles align and let light pass. Varying the voltage of the film varies the orientation of the suspended particles, thereby regulating the tint of the glazing and the amount of light transmitted.
- Suspended-particle Devices (SPDs): Thin film laminate of rod-like Nano-scale particles are suspended in a liquid and placed between two pieces of glass or plastic or attached to one layer. When no voltage is applied, the suspended particles are randomly organized, thus blocking and absorbing light. When voltage is applied, the suspended particles align and let light pass.
- Switchable Glass: Is operated by a simple electrical switch, controlling the opacity of the glass from clear to translucent. It can easily be integrated into automation systems too, giving you even more control. Refer:
- http://intelligentglass.net/categories/switchable-glass/.
- http://www.australianig.com.au/switchable/
- E-TransFlector™, This is an electrically switchable trans-reflective mirror that was developed by Kent Optronics. Is a solid-state thin film device made from a special liquid crystal material, which can be rapidly switched between pure reflection, half-reflection and total transparent states through a push button. Refer – http://www.kentoptronics.com/mirror.html.
- Photochromes: It is the reversible transformation of a chemical species between two forms by the absorption of electromagnetic radiation (photoisomerization), where the two forms have different absorption spectra. Trivially, this can be described as a reversible change of color upon exposure to light.
- Electro-Chromic Glass: They change light transmission properties in response to voltage and thus allow control over the amount of light and heat passing through. Electrochromic windows, the electrochromic material changes its opacity: it changes between a transparent and a tinted state. A burst of electricity is required for changing its opacity, but once the change has been affected, no electricity is needed for maintaining the shade.
- Transition-Metal Switchable mirrors (TMSMs). TMSMs are glass panels with a coating capable of switching back and forth between a transparent state and a reflective one. The new coating was developed by Thomas Richardson of Berkeley Lab’s Environmental Energy Technologies Division with assistance from Jonathan Slack – refer http://www2.lbl.gov/Science-Articles/Archive/sb-Apr-04-EETD-switchable-mirror.html.
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