Silver Nanowires

Silver nanowires are a type of silver nanomaterials that are expressively different in comparison to silver nanoparticles. As the name indicates, these nanomaterials have three dimensions.

The unique properties of this conductive nanomaterial have led to increasing use of silver nanowire-based technologies, such as in the manufacturing of flexible touchscreen displays. However, the potential adverse effects of these "thin but long" and highly reactive silver nanowires have been poorly understood so far. The goal should be the development of new and safer technological applications of silver nanowires.

Silver nanowires of different sizes, coatings, and shapes are being synthesized and analyzed by the consortium for potential human and environmental impacts. The properties of the nanowires that cause concern are identified and new synthetic methods are developed to produce silver nanowires with lower potential risks. New approaches to the recovery of silver nanowires are being developed to avoid possible landfill release and to facilitate the recycling of flexible electronics.

Properties of Silver Nanowires

The major properties of silver nanowires are given below:

• They have distinct electrical, thermal, and optical properties and they can be used to produce a variety of products ranging from biological sensors to photovoltaics.
• Silver nanowires are remarkable in absorption and reflection of light.
• Silver nanowires interact with molecules in the solution and create a double layer of charge that inhibits aggregation and stabilizes the silver nanowires.
• Silver nanowires are highly conductive.
• Silver nanowires can be dispersed in water, ethanol IPA (isopropyl alcohol), ethylene glycol, and epoxy resin.

Production of Silver Nanowires

Silver nanowires can be produced by multiple techniques, some of them are stated below:

• Rapid synthesis: Copper chloride and polyvinyl pyrrolidone are mixed in disposable glass vials to produce silver nanowires.
• Electroless deposition: The metal amplification technique is used to produce silver nanowires and in this technique, electroless deposition of silver into the polycarbonate membranes occurs.
• Polyol method: In this method, Silver nanowires are manufactured by an aqueous solvent which is heated in an autoclave at the temperature of 120 °C for approximately 8 hours.
• Template method: This technique uses supramolecular nanotubes of an amphiphilic cyanine dye in an aqueous solution for the production of silver nanowires.

Applications of Silver Nanowires

Silver nanowires have a plethora of applications, the main ones are stated below:

• Conductive applications: Computer boards, high-intensity LEDs, and Touchscreen displays.
• Antibacterial applications: Clothing, Bandages, sterile equipment, cosmetics, and paints.
• Optical sector: Medical imaging, Surface plasmons, Raman spectroscopy, optical limiters, and solar films.
• Optical applications: Optical spectroscopies, for example, metal-enhanced fluorescence and surface-enhanced Raman scattering.

Latest inventions of Silver Nanowires

• Silver nanowires garments

According to the latest invention, silver nanowires protect against the cold. This new invention is part of a new concept, name as "personal thermal management". It is manufactured by coating the garment with silver nanowires (wires with a diameter of one nanometer, which is one billionth of a meter). As these metallic nanowires are conductors, the garment conducts the energy and serve as a portable "heater". In other words, it can be actively heated with a source of electricity, such as a small battery.

But, in addition, the silver nanowires make the garment become a good insulator, able to reflect more than 90% of body heat. This reflection is much greater than that of the warmest wool sweater, which at most reflects around 20% of body heat. So the clothes coated with silver nanowires would work as active heating and as passive insulation. On the other hand, these garments would be breathable, due to the porous structure of the nanowires; and it would feel practically the same as normal clothes.

• Ultra-light aerogel

A group of researchers from the Lawrence Livermore National Laboratory (LLNL) in the US has developed a new type of ultra-light aerogel, so light could be held up by a rose without having to lower or bend it. It is a metal foam that is grafted into that new class of material with very light unique properties that can be used in particular in the electronic energy industries.

This material, in particular, uses ultra-light and conductive silver nanowires. According to Fang Qian, lead author of the study published in Nano Letters, "The high porosity and excellent mechanical/electrical properties of these silver nanotube aerogels can lead to better device performance and open up new possibilities for cell fuel, energy storage, medical devices, catalysis, and sensors”.

Future of Silver Nanowires

• The increasing demand for micro integration of electronic systems has caused extensive research on metal nanowires due to their optical properties. This has caused the development of numerous advanced technologies in different sectors.
• Silver has good electrical conductivity which is the reason that Silver nanowires have greater electrical conductivity with enhanced optical transparency and optical flexibility. These factors are important for manufacturing optoelectronic and electronic devices.
• Research has also indicated that silver nanowires can be employed for the miniaturization of ultra large electrical circuits and quantum devices in the coming time.
• Silver nanowires are likely to allow the next generation to create flexible touch panels, including the rotation of the car's entire dashboard in a vast finger-sensitive surface. This is because they are better in electrical conduction than indium-tin-oxide and the current touch-sensor material. Silver nanowires can be easily applied to flexible plastic substrates. Moreover, they are also highly transparent.
• They are not only useful in touch panels, but highly conductive silver nanowires also have applications in high-efficiency solar panels and lighting panels, which also benefit from the fact that nanowires are practically indestructible.

Silver nanowires have great potential for developing advanced technology applications. This is due to their exciting electrical, thermal and optical properties. They have applications in almost all the sectors such as optics, electronics, magnetics, textile, automobile, high-performance catalysts, and acoustics. A lot of researches are currently underway to discover more and more of its applications.