Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International



Home > Press > Big range of behaviors for tiny graphene pores: Like biological channels, graphene pores are selective for certain types of ions

Researchers created pores in a graphene sheet (in purple) and then placed it over a layer of silicon nitride (in blue) that had been punctured by an ion beam. This allows specific hydrated ions, which are surrounded by a shell of water molecules, to pass through.

Image: Jose-Luis Olivares/MIT
Researchers created pores in a graphene sheet (in purple) and then placed it over a layer of silicon nitride (in blue) that had been punctured by an ion beam. This allows specific hydrated ions, which are surrounded by a shell of water molecules, to pass through.

Image: Jose-Luis Olivares/MIT

Abstract:
The surface of a single cell contains hundreds of tiny pores, or ion channels, each of which is a portal for specific ions. Ion channels are typically about 1 nanometer wide; by maintaining the right balance of ions, they keep cells healthy and stable.

Big range of behaviors for tiny graphene pores: Like biological channels, graphene pores are selective for certain types of ions

Cambridge, MA | Posted on October 6th, 2015

Now researchers at MIT have created tiny pores in single sheets of graphene that have an array of preferences and characteristics similar to those of ion channels in living cells.

Each graphene pore is less than 2 nanometers wide, making them among the smallest pores through which scientists have ever studied ion flow. Each is also uniquely selective, preferring to transport certain ions over others through the graphene layer.

"What we see is that there is a lot of diversity in the transport properties of these pores, which means there is a lot of potential to tailor these pores to different applications or selectivities," says Rohit Karnik, an associate professor of mechanical engineering at MIT.

Karnik says graphene nanopores could be useful as sensors -- for instance, detecting ions of mercury, potassium, or fluoride in solution. Such ion-selective membranes may also be useful in mining: In the future, it may be possible to make graphene nanopores capable of sifting out trace amounts of gold ions from other metal ions, like silver and aluminum.

Karnik and former graduate student Tarun Jain, along with Benjamin Rasera, Ricardo Guerrero, Michael Boutilier, and Sean O'Hern from MIT and Juan-Carlos Idrobo from Oak Ridge National Laboratory, publish their results today in the journal Nature Nanotechnology.

Dynamic personality

In living cells, the diversity of ion channels may arise from the size and precise atomic arrangement of the channels, which are slightly smaller than the ions that flow through them.

"When nanopores get smaller than the hydrated size of the ion, then you start to see interesting behavior emerge," Jain says.

In particular, hydrated ions, or ions in solution, are surrounded by a shell of water molecules that stick to the ion, depending on its electrical charge. Whether a hydrated ion can squeeze through a given ion channel depends on that channel's size and configuration at the atomic scale.

Karnik reasoned that graphene would be a suitable material in which to create artificial ion channels: A sheet of graphene is an ultrathin lattice of carbon atoms that is one atom thick, so pores in graphene are defined at the atomic scale.

To create pores in graphene, the group used chemical vapor deposition, a process typically used to produce thin films. In graphene, the process naturally creates tiny defects. The researchers used the process to generate nanometer-sized pores in various sheets of graphene, which bore a resemblance to ultrathin Swiss cheese.

The researchers then isolated individual pores by placing each graphene sheet over a layer of silicon nitride that had been punctured by an ion beam, the diameter of which is slightly smaller than the spacing between graphene pores. The group reasoned that any ions flowing through the two-layer setup would have likely passed first through a single graphene pore, and then through the larger silicon nitride hole.

The group measured flows of five different salt ions through several graphene sheet setups by applying a voltage and measuring the current flowing through the pores. The current-voltage measurements varied widely from pore to pore, and from ion to ion, with some pores remaining stable, while others swung back and forth in conductance -- an indication that the pores were diverse in their preferences for allowing certain ions through.

"The picture that emerges is that each pore is different and that the pores are dynamic," Karnik says. "Each pore starts developing its own personality."

New frontier

Karnik and Jain then developed a model to interpret the measurements, and used it to translate the experiment's measurements into estimates of pore size. Based on the model, they found that the diameter of many of the pores was below 1 nanometer, which -- given the single-atom thickness of graphene -- makes them among the smallest pores through which scientists have studied ion flow.

With the model, the group calculated the effect of various factors on pore behavior, and found that the observed pore behavior was captured by three main characteristics: a pore's size, its electrical charge, and the position of that charge along a pore's length.

Knowing this, researchers may one day be able to tailor pores at the nanoscale to create ion-specific membranes for applications such as environmental sensing and trace metal mining.

"It's kind of a new frontier in membrane technologies, and in understanding transport through these really small pores in ultrathin materials," Karnik says.

###

This research was funded, in part, by the U.S. Department of Energy.

####

For more information, please click here

Contacts:
Abby Abazorius

617-253-2709

Copyright © Massachusetts Institute of Technology

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

Chemistry

What heat can tell us about battery chemistry: using the Peltier effect to study lithium-ion cells March 8th, 2024

Two-dimensional bimetallic selenium-containing metal-organic frameworks and their calcinated derivatives as electrocatalysts for overall water splitting March 8th, 2024

Discovery of new Li ion conductor unlocks new direction for sustainable batteries: University of Liverpool researchers have discovered a new solid material that rapidly conducts lithium ions February 16th, 2024

News and information

Researchers develop artificial building blocks of life March 8th, 2024

How surface roughness influences the adhesion of soft materials: Research team discovers universal mechanism that leads to adhesion hysteresis in soft materials March 8th, 2024

Two-dimensional bimetallic selenium-containing metal-organic frameworks and their calcinated derivatives as electrocatalysts for overall water splitting March 8th, 2024

Graphene/ Graphite

First human trial shows ‘wonder’ material can be developed safely: A revolutionary nanomaterial with huge potential to tackle multiple global challenges could be developed further without acute risk to human health, research suggests February 16th, 2024

NRL discovers two-dimensional waveguides February 16th, 2024

$900,000 awarded to optimize graphene energy harvesting devices: The WoodNext Foundation's commitment to U of A physicist Paul Thibado will be used to develop sensor systems compatible with six different power sources January 12th, 2024

Mining/Extraction/Drilling

Chile coating and composite industry makes leap forward leveraging graphene nanotube solutions April 9th, 2021

CEA-Leti and Davey Bickford Enaex Extend R&D Collaboration To Bring More Digital Solutions to Mining and Blasting Industries That Improve Safety for Workers and Increase Productivity November 17th, 2020

Membrane technology could cut emissions and energy use in oil refining July 17th, 2020

Extraction of lithium from its largest source, i.e. seawater, by nanostructured membranes January 27th, 2020

Govt.-Legislation/Regulation/Funding/Policy

What heat can tell us about battery chemistry: using the Peltier effect to study lithium-ion cells March 8th, 2024

Researchers’ approach may protect quantum computers from attacks March 8th, 2024

The Access to Advanced Health Institute receives up to $12.7 million to develop novel nanoalum adjuvant formulation for better protection against tuberculosis and pandemic influenza March 8th, 2024

Optically trapped quantum droplets of light can bind together to form macroscopic complexes March 8th, 2024

Possible Futures

Two-dimensional bimetallic selenium-containing metal-organic frameworks and their calcinated derivatives as electrocatalysts for overall water splitting March 8th, 2024

Curcumin nanoemulsion is tested for treatment of intestinal inflammation: A formulation developed by Brazilian researchers proved effective in tests involving mice March 8th, 2024

The Access to Advanced Health Institute receives up to $12.7 million to develop novel nanoalum adjuvant formulation for better protection against tuberculosis and pandemic influenza March 8th, 2024

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Sensors

$900,000 awarded to optimize graphene energy harvesting devices: The WoodNext Foundation's commitment to U of A physicist Paul Thibado will be used to develop sensor systems compatible with six different power sources January 12th, 2024

A color-based sensor to emulate skin's sensitivity: In a step toward more autonomous soft robots and wearable technologies, EPFL researchers have created a device that uses color to simultaneously sense multiple mechanical and temperature stimuli December 8th, 2023

New tools will help study quantum chemistry aboard the International Space Station: Rochester Professor Nicholas Bigelow helped develop experiments conducted at NASA’s Cold Atom Lab to probe the fundamental nature of the world around us November 17th, 2023

TU Delft researchers discover new ultra strong material for microchip sensors: A material that doesn't just rival the strength of diamonds and graphene, but boasts a yield strength 10 times greater than Kevlar, renowned for its use in bulletproof vests November 3rd, 2023

Discoveries

What heat can tell us about battery chemistry: using the Peltier effect to study lithium-ion cells March 8th, 2024

Researchers’ approach may protect quantum computers from attacks March 8th, 2024

High-tech 'paint' could spare patients repeated surgeries March 8th, 2024

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Announcements

What heat can tell us about battery chemistry: using the Peltier effect to study lithium-ion cells March 8th, 2024

Curcumin nanoemulsion is tested for treatment of intestinal inflammation: A formulation developed by Brazilian researchers proved effective in tests involving mice March 8th, 2024

The Access to Advanced Health Institute receives up to $12.7 million to develop novel nanoalum adjuvant formulation for better protection against tuberculosis and pandemic influenza March 8th, 2024

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers/Posters

Researchers develop artificial building blocks of life March 8th, 2024

How surface roughness influences the adhesion of soft materials: Research team discovers universal mechanism that leads to adhesion hysteresis in soft materials March 8th, 2024

Curcumin nanoemulsion is tested for treatment of intestinal inflammation: A formulation developed by Brazilian researchers proved effective in tests involving mice March 8th, 2024

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Nanobiotechnology

High-tech 'paint' could spare patients repeated surgeries March 8th, 2024

Researchers develop artificial building blocks of life March 8th, 2024

Curcumin nanoemulsion is tested for treatment of intestinal inflammation: A formulation developed by Brazilian researchers proved effective in tests involving mice March 8th, 2024

The Access to Advanced Health Institute receives up to $12.7 million to develop novel nanoalum adjuvant formulation for better protection against tuberculosis and pandemic influenza March 8th, 2024

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project