Indian scientists have made a unique discovery of an eco friendly screen using groundnut shell that is believed to help in energy conservation. A group of researchers led by S Krishna Prasad and Dr Shankar Rao of the Centre for Nano and Soft Matter Sciences (CeNS), Bangalore came up with the screen that preserves not only privacy but also reduces air conditioning load.
The researchers used liquid crystal molecules in a polymer matrix. The matrix was built using cellulose nanocrystals prepared from discarded groundnut shells. The refractive index of the liquid crystal molecules along a particular direction were altered by an electric field. When there was no electric field, there was a mismatch between refractive indices that led to the scattering of light. When few volts of electric field were applied, the liquid crystal molecules underwent a direction change that resulted in matching of refractive indices. This made the device transparent. When turned off, the system recovered the scattering state.
The study was published in Applied Physics Letters. The device used the same principle that causes fog on winter mornings. When the water droplets are of the right size, it can co-exist along with air. The light that comes sees these two as materials of different refractive indices and gets scattered. This gave a foggy appearance.
The researchers said that the eco friendly and energy saving screen could be developed from any cellulose or agricultural waste. They pointed out that groundnut waste was found to be most efficient than any other agriculture waste.