Manchester University’s National Graphene Institute (NGI) has found a way to electrically control water flow through graphene membranes.
These smart membranes could help revolutionize artificial biological systems and nanofluidic devices for various applications.
According to the NGI team, graphene is capable of forming a tuneable filter or even a perfect barrier when dealing with liquids and gases.
The new membranes can even be used to completely block water from passing through when required.
Led by Professor Rahul Nair, the NGI researchers embedded conductive filaments within the electrically insulating graphene oxide membrane.
An electric current passed through these nano-filaments accordingly created a large electric field which ionizes the water molecules and thus controls the water transport through the graphene capillaries in the membrane.
Prof Nair said: “This new research allows us to precisely control water permeation, from ultrafast permeation to complete blocking. Our work opens up an avenue for further developing smart membrane technologies.”
The research group has previously demonstrated that graphene oxide membranes can be used as a sieve to remove salt from seawater for desalination alternatives.
The research world has long been trying to control water flow through membrane by using an external stimuli due to its importance for healthcare and related areas.
Currently such adjustable membranes are limited to the modulation of wetting of the membranes and controlled ion transport, but not the controlled mass flow of water.
According to Dr Kai-Ge Zhou, lead author for the research paper, the NGI graphene smart membrane technology is not just limited to controlling the water flow:
“The same membrane can be used as a smart adsorbent or sponge. Water adsorbed on the membrane can be preserved in the membrane even in desert conditions if a current is applied. We could release this water on demand by switching the current off.”
Dr Vasu – second lead author of the paper, said that their work not only opens new applications for graphene membranes but it allows them to understand the effect of electrical field on the nanoscale properties of confined water.
“Our work shows that large electric field can ionize water in to its constituent ions.”
Image credits and content: NGI/University of Manchester