Carbon nanotubes (CNTs) have great potential applications in making ballistic-resistance materials. The remarkable properties of CNTs makes them an ideal candidate for reinforcing polymers and other materials, and could lead to applications such as bullet-proof vests as light as a T-shirt, shields, and explosion-proof blankets. For these applications, thinner, lighter, and flexible materials with superior dynamic mechanical properties are required. A new study by researchers in Australia explores the energy absorption capacity of a single-walled carbon nanotube under a ballistic impact. The result offers a useful guideline for using CNTs as a reinforcing phase of materials to make devices to prevent from ballistic penetration or high speed impact.
If current research is an indicator, wearable electronics will go far beyond just very small electronic devices. Not only will such devices be embedded on textile substrates, but an electronics device or system could become the fabric itself. Electronics textiles will allow the design and production of a new generation of garments with distributed sensors and electronic functions. Such e-textiles will have the revolutionary ability to sense, act, store, emit, and move (think biomedical monitoring functions or new man-machine interfaces) while leveraging an existing low-cost textile manufacturing infrastructure. Today, only a few steps towards new architectural possibilities of realizing circuit topologies that can be implemented with textile technique have been made: one an example of nonplanar devices and one of textile based devices. Researchers in Italy have now developed an organic field effect transistor (OFET) fully compatible with textile processing techniques.
You might have seen our recent Nanowerk Spotlight on modern military nanotechnology (Military nanotechnology - how worried should we be?) and read about the hundreds of millions of dollars that the U.S. military pours into nanotech research every year. Well, it turns out that metalsmiths in India perhaps as early as 300 AD, and presumably with a much lower budget, developed a new technique known as wootz steel that produced a high-carbon steel of unusually high purity. Wootz, which are small steel ingots, was widely exported and became particularly famous in the Middle East, where it became known as Damascus steel. This steel had extraordinary mechanical properties and an exceptionally sharp cutting edge. The original Damascus steel swords were made possibly as early as 500 AD to as late as 1750 AD. What's so interesting about this? It turns out that the secret of Damascus steel is carbon nanotubes. Recently discovered in the nanostructure of a 17th century Damascus saber, the nanotubes could have encapsulated iron-carbide (cementite) nanowires that might give clues to the mechanical strength and sharpness of these swords.
The electrical properties of CNTs are extremely sensitive to defects which can be introduced during the growth, by mechanical strain, or by irradiation with energetic particles such as electrons, heavy ions, alpha-particles, and protons. When highly energetic particles collide, a latchup, electrical interference, charging, sputtering, erosion, and puncture of the target device can occur. Therefore the information on the effects of various types of high energetic irradiation on CNTs and other nanomaterials will be important in developing radiation-robust devices and circuits of nanomaterials under aerospace environment. As a result, degradation of the device performance and lifetime or even a system failure of the underlying electronics may happen. Researchers in South Korea conducted a systematic study of the effects of proton irradiation on the electrical properties of CNT network field effect transistor (FET) devices showing metallic or semiconducting behaviors. The most important outcome of this work is that no significant change in the electrical properties of CNT-based FET was observed, even after high-energy proton beam irradiated directly on the device. This result show that CNT-based devices can be a promising substitute for classical silicon-based devices, which are known to be very fragile against proton radiations
Zinc oxide (ZnO) is considered a workhorse of technological development exhibiting excellent electrical, optical, and chemical properties with a broad range of applications as semiconductors, in optical devices, piezoelectric devices, surface acoustic wave devices, sensors, transparent electrodes, solar cells, antibacterial activity etc. Thin films or nanoscale coating of ZnO nanoparticles on suitable substrates are viewed with great interest for their potential applications as substrates for functional coating, printing, UV inks, e-print, optical communication (security-papers), protection, barriers, portable energy, sensors, photocatalytic wallpaper with antibacterial activity etc. Various methods like chemical, thermal, spin coating, spray pyrolysis, pulsed laser deposition have been used for thin film formation but they are limited to solid supports such as metal, metal oxides, glass or other thermally stable substrates. Coating of ZnO nanoparticles on thermolabile surfaces is scarce and coating on paper was yet to be reported. Paper as a substrate is an economic alternative for technological applications having desired portability and flexibility. Researchers from the National Tsing Hua University in Taiwan found a way of coating paper with ZnO nanoparticles using ultrasound.
Synthetic nanopores are promising biosensors, possibly as a robust and versatile replacement for their biological counterparts in characterizing DNA, RNA, and polypeptides. In the past few years since their first introduction, synthetic nanopores have been found in a wide range of biological and nonbiological applications, including characterization of double-stranded DNA length and folding, detection of immune complexes, profiling of optical traps, and basic studies of nanoscale ion transport mechanisms. Given the broad technological importance of synthetic nanopores, it is highly desirable to develop a reliable technique for fabricating these devices using low-cost materials. Researchers at Brown University now report a systematic study of nanopore formation in a plastics system. They also developed a lithography-free technique for fabricating nanopores with biomolecular sensing capabilities.
Back in March Nanowerk Spotlight reported on work by Sandia researchers who developed a range of novel platinum nanostructures with potential applications in fuel and solar cells (see: Novel platinum nanostructures). Through the use of liposomal templating and a photocatalytic seeding strategy the Sandia team produced a variety of novel dendritic platinum nanostructures such as flat dendritic nanosheets and various foam nanostructures (nanospheres and monoliths). In an intriguing follow-up report on the growth of hollow platinum nanocages, they now show for the first time a one-to-one correspondence between the porphyrin photocatalyst molecules and the seed particles that go on to grow the dendrites. This indicates that the whole process might be used for nanotagging biological molecules and other structures that have been labeled with a photocatalytic porphyrin.
All major powers are making efforts to research and develop nanotechnology- based materials and systems for military use. Asian and European countries, with the exception of Sweden (Swedish Defence Nanotechnology Programme), do not run dedicated programs for defense nanotechnology research. Rather, they integrate several nanotechnology- related projects within their traditional defense-research structures, e.g., as materials research, electronic devices research, or bio-chemical protection research. Not so the U.S. military. Stressing continued technological superiority as its main strategic advantage, it is determined to exploit nanotechnology for future military use and it certainly wants to be No. 1 in this area. The U.S. Department of Defense (DoD) is a major investor, spending well over 30% of all federal investment dollars in nanotechnology. Of the $352m spent on nanotech by the DoD in 2005, $1m, or roughly 0.25%, went into research dealing with potential health and environmental risks. In 2006, estimated DoD nanotechnology expenditures will be $436m - but the risk-related research stays at $1m.