Scientists at the Centre for Nano and Soft Matter Sciences, India, have developed an electrically switchable device that can be set to be transparent and translucent.
As an autonomous institute under the Union Department of Science and Technology (DST), the Centre of Nano and Soft Matter Sciences (CeNS) created a device, titles ‘Fog on-demand’, which can be flipped between transparent and translucent modes.
Researchers used an electric field which chose between the two situations, of matching or mismatched indices between the polymer and liquid crystal. This electric effect results in an optical output which, once the switch is flipped, alters between scattering and transparent states of the device.
The encapsulation of the active material between glass sheets or flexible substrates leads to smart switchable windows which have a wide range of possible applications spanning household, healthcare, privacy creation, smart displays and energy saving domains.
According to the DST: “It can be changed from transparent to scattering states by the application of an electrical field and would be useful as screens for windows along with applications in household, healthcare, privacy creation, smart displays and saving energy.”
“The device involves the principle of nano-level phase separation for two specifically chosen soft materials (liquid crystal and a polymer) with tailor-made refractive index values.
“The situation is similar to the atmospheric fog wherein the two materials – water droplets and air – satisfy similar conditions,” continued DST.
The smart switchable windows that are currently available have a major drawback that the operating voltage is not only high but is temperature-dependent. This places stringent demands on the control circuitry both in terms of power levels and in the compensation for the ambient temperature change.
The smart switchable window developed by S Krishna Prasad and his team of researchers from CeNS in Bengaluru, India, overcomes both deficiencies. Additionally, this device also reduces the risk of damage due to mechanical shocks.