Scientists develop gold micro-structure substrate that can repel water

New Delhi, January 20

Scientists have developed a gold micro-structure substrate that can repel water as well as bubbles with tunable wettability, which can be used in designing micro-fluidic devices, bio-sensors and useful in water transportation and self-cleaning, the Department of Science and Technology (DST) said on Tuesday.

Wettability, or the ability of a liquid to maintain contact with a solid surface, is an important property in surface and interface science.

Its influence is seen in many biochemical processes, sensing, micro-fluidics, water transportation, self-cleaning, industrial processes. The tunable wettability results from tunability in surface energy of the substrate, which can be utilised to regulate the direction of flow in water transportation and self-cleaning applications.

According to the recent work published in 'Journal of Applied Physics', P Viswanath and his group from the Centre for Nano and Soft Matter Sciences (CeNS), an autonomous institute under the DST, have developed a substrate exhibiting morphological gradient that helps one to tune the wettability because of surface energy change.

The morphological gradient in the substrate ranges from domes to elliptical holes.

Water and oil wetting studies at each position on the substrate revealed that wetting is tunable with morphology, the statement added.

The substrate showed hydrophobic nature, which gets magnified when coated with a self-assembled monolayer of octadecane thiol — a water-soluble sulphur compound with a carbon alkyl chain. The coating results in a reduction in surface energy, which in turn facilitates an enhancement in hydrophobic behaviour.

Underwater wettability investigations on the substrate showed that it mainly repelled bubbles and when functionalised with coating of octadecanethiol, it repels mainly oil. PTI 

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