Researchers at the University of Manchester’s National Graphene Institute (NGI) have achieved a long-sought-after objective of electrically controlling water flow through graphene smart membranes.
This is the latest membrane development benefitting from the unique properties of graphene. The new research opens an avenue for developing graphene smart membranes and could revolutionise the field of artificial biological systems, tissue engineering and filtration.
Graphene can form a tuneable filter or even a perfect barrier when dealing with liquids and gases. New ‘smart’ membranes developed using an inexpensive form of graphene, called graphene oxide, have been shown to allow precise control of water flow by using an electrical current.
The membranes can even be used to completely block water from passing through when required.
How was the research into graphene smart membranes conducted?
The research team, led by Professor Rahul Nair, embedded conductive filaments within the electrically insulating graphene oxide membrane. An electric current then passed through these nano-filaments and created a large electric field which ionises the water molecules and controls water transport through the graphene capillaries in the membrane.
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.
“Developing smart membranes that allow precise and reversible control of molecular permeation using external stimuli would be of intense interest for many areas of science; from physics and chemistry, to life-sciences.”
What wider advantages will this research have?
The achievement of electrical control of water flow through membranes is a step change because of its similarity to several biological process where the main stimuli are electrical signals. Controlled water transport is a key for renal water conservation, regulation of body temperature and digestion.
The reported electrical control of water transport through graphene smart membranes therefore opens a new dimension in developing artificial biological systems and advanced nanofluidic devices for various applications.
Dr Kai-Ge Zhou, lead author for the research paper, said, “The reported 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.”