Nickel Nanowires

Other Unique Engineering Ideas

Bentley calls her microscopic wires "nanowires" after nanotechnology, the booming, cutting-edge science of small. The "nano" in nanotechnology derives from the nanometer, which is equivalent to a billionth of one meter. Several types of nanoparticles are already in use, in products such as sunscreens and inkjet printer ink.

1. Description

2. Why

3. How

4. Future Trends

5. Related Links

Description 

There has been an increasing interest in the fabrication of ferromagnetic metal nanowires in terms of their fundamental importance as well as potential application in magnetic recording technology. Recently, such nanowires have been often prepared by a template technique that involves electrochemical deposition of metal into nanometer-wide channels of anodic aluminium oxide films polycarbonate track etched membranes or nanochannel array glass.  

Why 

Anne Bentley, at the 229th meeting of the American Chemical Society, University of Wisconsin-Madison showed the world how suspended nickel wires - each 200 times thinner than a human hair - could one day serve as magneto-optical switches. The switches could aid in fields such as photonics, where light, rather than electricity, relays information.It is also helpful to study how these wires behave in wet situations because if they are ever medically used, there is little inside our bodies that's dry. Another advantage that 'magnetic fluids' may have over other light-directing devices, such as mirrors, is that fluids can easily take various shapes 

How 

A simple way to make nanowires is to use a mold or template. Nickel nanowires are grown inside the pores of an alumina filter and then the filter is removed by etching to yield magnetic nanowires.Nanoporous membranes were designed for health care applications including virus filtration, sample preparation, and liposome manufacture.

  • These alumina membranes are manufactured by applying a large electrical potential to a piece of aluminum metal submerged in an acid.
  •  Aluminum is oxidized to alumina (Al2O3) and pores are created.
  • The size of the pores depends on the applied potential.
  • This uses electrical tape to hold the filter.
  • It uses less equipment but taping the filters without breaking them requires careful manipulation.
  • Uses a syringe holder, clamps, and an o-ring instead of taping.

Experts generally prepare nickel nanowires using a template synthesis technique and characterize their properties.Electrodeposition of nickel to fill the 200-nm diameter pores of a commercially-available alumina filtration membrane is accomplished using a nickel salt solution and a AA battery. The nanowires, which are ~200 nm in diameter and up to ~50 mm in length, can be liberated from the membrane by dissolving the alumina template with sodium hydroxide. Suspensions of nanowires on a microscope slide can be observed using a common optical microscope. The alignment and movement of the magnetic nanowires can be controlled using magnets.Students in general chemistry carried out the electrolysis reaction to form nickel nanowires. By carrying out the electrolysis for times between 10 and 50 minutes, students evaluated the length of the wires versus the time of the electrolysis. Students discovered that the wires are generated at a rate of about 1 micrometer per minute as shown by the plot of the data.The obtainable lowest diameter is restricted by the lowest attainable inner diameter of the nanochannels in the template materials. None of the nanochannels can easily reach an inner diameter of < 10 nm. Therefore, template method does not allow the construction of ferromagnetic metal nanowires with a diameter of < 10 nm.

(ref:http://www.rsc.org/ej/CC/1999/a904157e.pdf Nickel nanowires of 4 nm diameter in the cavity of carbon nanotubes- Bhabendra , Takashi Kyotani and Akira Tomita ) 

Future Trends 

Nanowires have not yet ventured outside the research arena, but researchers believe they will one day become critical components in ever-shrinking electronic circuits. Nickel nanowires, for instance, could play a key role in storing information. In particular, scientists could use external magnets to dictate the orientation and position of magnetic nickel nanowires within complex and tiny electronic systems. Without such control, working with nano-scale circuit parts could be like "trying to put Legos together with oven mitts on.” Bentley.Maneuvering external magnets, scientists can command the direction in which light bounces off tiny, magnetic wires that sway like matchsticks in thick, slow-moving solutions.

Keywords

Magnetic nanowires; Electrodeposition; Nanochannel alumina

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