Mimicking the Brain: Long-Term Memory and Synapse-Like Dynamics in 2D Nanofluidic Channels

Key highlights

• Tiny channels of nanometer scale (1 nanometer = 1/billionth of a meter) are found in nature that allow substances to pass through and filter out impurities. These are present in human cell linings and in the neurons in brain. Scientists have only recently begun to understand the importance of these channels. Creating these structures artificially could be useful for many things, such as testing medicines, delivering drugs, and filtering water.
• Nanofluidics is the study of the transport of fluids that are confined to structures of nanometer length scale. Manchester’s Professor Radha Boya investigates nanocapillaries’ design and fabrication. The first paper that described the fabrication of the angstrom scale 2D channels was co-led by Prof Sir Andre Geim and Prof Radha Boya.
• The brain uses ions, chemicals and water to make its calculations and store 'memory' whereas artificial computers use electrons in their operation.  The emerging field of nanofluidic computing, also called ionic computing, raises the possibility of devices that operate similarly to the human brain.
   

The link between nanofluidics and computing

Imagine a computer that runs like our brains, consuming minimal energy and seamlessly processing information. That's the promise of nanofluidic computing, a radical departure from conventional computing architectures. Instead of relying on rigid binary systems, nanofluidics harness the flow of ions in fluids, mimicking the brain's efficiency and adaptability. This innovative approach could lead to computers that are not only more energy-efficient but also capable of handling complex tasks with ease.

Manchester researcher, Professor Radha Boya, is trying to mimic the behaviour of neuronal learning mechanisms using ions in water. Her research investigates utilising Ångstrom-scale (that is, one ten-billionth, or 0.1 nanometre) designer capillaries for molecular transport, ion sieving and sensing, energy harvesting and neuromorphic ion memory applications.

Building nanocapillaries

The team’s latest research involves the design and fabrication of capillary devices with atomically thin 2D materials assembled as 2D heterostructures. The capillaries are layer-by-layer structures of 2D materials such as graphene, with cavities running through the middle of the stack. To put it simply – this is the fabrication of atomic-scale channels with atomically smooth walls.

The 2D channel is created by the absence of 2D material, hence is a 2D-empty space. They can be fabricated on any relatively flat substrate and with the flexibility to choose any combination of 2D material walls ranging from hydrophilic to hydrophobic or insulating to conducting. Such customisation allows to exploration of anomalous or quantum properties of ultra-confined flows at ambient conditions and validates century-old theories.

This novel architecture of capillaries provides atomic scale tunability of dimensions and atomically smooth walls. Despite the Ångstrom (Å) scale, this is essentially a top-down lithographic technique which ensures its high reproducibility and flexibility.

The future of nanocapillaries and nanofluidic computing

Professor Boya’s team of physics and chemistry researchers investigates novel properties of materials in confinements, the aforementioned capillaries, at the limits of molecular sizes for unravelling their emergent physical and chemical properties. The group is exploring new perspectives in nanofluidics by pushing the boundaries of nanofabrication with angstrom-scale two-dimensional channels.

These devices are now a step closer to ‘nanofluidic computing’. Memory achieved using simple salt solutions in water is an exciting prospect hinting at the possibility of devices that operate similarly to the human brain.

Making  a difference: the impact of research

Membrane-based applications with nanoscale channels, such as osmotic power generation, desalination, and molecular separation would benefit from understanding the mechanisms of sieving, ways to decrease fluidic friction, and increasing the overall efficiency of the process.

However, mechanisms that allow fast flows are not fully understood yet. Professor Radha’s work on angstrom-capillaries that are only few atoms thick, opens an avenue to investigate fundamental sieving mechanisms behind important applications such as filtration, separation of ions, molecules and gases, desalination, and fuel gas separation from refinery off-gases.

About Professor Radha Boya

Professor Radha Boya is Royal Society University Research and Kathleen Ollerenshaw fellow at the University of Manchester (UoM), where she is exploring the fundamentals and applications of atomic scale nanocapillaries. She has been funded through a series of highly competitive and prestigious international fellowships, including Indo-US pre- and postdoctoral, as well as European Union's Marie Sklodowska-Curie and Leverhulme early career fellowships. Radha was named as UNESCO L’Oréal-women in science fellow, and was recognized as an inventor of MIT Technology Review's "Innovators under 35" list, RSC Marlow award, Philip Leverhulme Prize, and Analytical Chemistry Young Innovator Award and is an ERC starting grant awardee.

Recent relevant papers :

• Long-term memory and synapse-like dynamics of ionic carriers in two-dimensional nanofluidic channels
• Liquid-activated quantum emission from pristine hexagonal boron nitride for nanofluidic sensing
• Beyond steric selectivity of ions using ångström-scale capillaries

To discuss this research further contact Professor Radha Boya.

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