UV radiation can cause sunburn, premature ageing of skin, and even skin cancer. For protection, dermatologists suggest surface modified textiles. Recently, a team led by JBB Rayappan from the SASTRA Deemed University, Thanjavur came up with a new modified cotton fabric that filters ultraviolet radiation and also senses poisonous gases. They integrated nano-structured zinc oxide on cotton fabric for protection from harmful ultraviolet light and common industrial pollutants such as acetaldehyde, ammonia and ethanol.
Zinc oxide is nontoxic and biocompatible. It has the versatility required to fabricate nanostructures with tunable electrical, optical, electronic, piezoelectric, and pyro-electric properties. The team incorporated zinc oxide into cotton fabric using two different methods. The first involved dipping the fabric in a sol-gel of zinc oxide. In the second, the researchers grew a zinc oxide seed layer on cotton substrates, using sputtering.
The hydroxyl group present in cotton favoured adhesion of hexagonal zinc oxide nanostructures. The modified fabric has high surface resistance as zinc oxide interacts with oxygen molecules. On introducing ammonia, ethanol and acetaldehyde, surface resistance decreases as these are reducing gases. The change in resistance helps sense these gases.
When the fabric is exposed to ultraviolet interaction, the zinc oxide generates electron-hole pairs. Oxygen ions from the depletion layer absorb those holes and release oxygen molecules. This is a continuous process that provides protection from ultraviolet radiation.
The team believes that zinc oxide integrated cotton textiles are suitable for fabricating flexible gas sensors and ultraviolet filters for people working in hostile conditions.
As the process of fabrication is simple and viable, textile industries can use this research to produce protective garments, hope the scientists.
Clean. Prod., 194: 372-382 (2018) DOI: 10.1016/j.jclepro.2018.05.110
Jiumoni Lahkar, CSIR-North East Institute of Science and Technology