In physics, a plasmon is the quasi-particle resulting from the quantization of plasma oscillations just as photons and phonons are quantizations of light and sound waves, respectively. As the name indicates, surface plasmons are those plasmons that are confined to surfaces. The control of these surface plasmons has become increasingly attractive for optical signal processing, surface enhanced spectroscopy and sensor nanotechnology. The plasmonic properties of nanoparticles depend on various parameters such as their size or shape, and the refractive index of the environment. Surface plasmons form the basis of localized surface plasmon resonance (LSPR) sensing, which allows the detection of single molecules. Researchers have now demonstrated for the first time that the absorption and emission properties of few-atom metal nanoclusters respond dramatically to changes in the chemical environment.
The thing with technology is that the science behind it isn't good or bad but the way it is used could make all the difference. There are plenty of examples throughout history. Military nanotechnology is a good present day example. And we don't even need to talk about the weird, far-out stuff like nanobots and the Casimir force. Take explosives. While on one side there is research going on to improve high explosives through nanoscale structuring, other research teams are putting a lot of effort into detecting ever smaller trace amounts of explosives and building the ultimate nanoscale bomb dog. A recent example has been demonstrated by scientists in China, who obtained organic super-nanostructures via a simple solution process, and, for the first time, demonstrated that such structures can be applied as chemosensors to detect explosives.
Scintillation - a flash of light, lasting only nanoseconds to microseconds, produced in a particular material when it absorbs ionizing radiation - is one of the main methods used for the detection of ionizing radiation. Scintillators are very versatile and can be used for detecting almost all types of radiation in a wide range of energy from several electron volts (eV) to tens of billion of electron volts (GeV). Scintillation is useful for sensing alpha, beta and gamma radiation as well as other nuclear particles and in some cases determining the particle type. For example, organic scintillators can sense fast neutrons emitted spontaneously from fissile isotopes of uranium and plutonium, enabling passive detection of nuclear weapons. The detection and identification of subatomic particles is not only important for nuclear nonproliferation efforts but is a wide-ranging scientific problem with implications for medical devices, radiography, biochemical analysis, particle physics, and even astrophysics. Scientists from the Sandia National Laboratories in California have now proposed that metal-organic frameworks (MOFs) could potentially offer the desired level of structural control, leading to an entirely new class of radiation detection materials.
Olfaction, our sense of smell, depends on the capability of specialized sensory cells in the nose to detect airborne odorant molecules. These olfactory cells contain specific protein molecules that acts as 'olfactory receptors' - they bind only to specific odorant molecules present in the air inhaled through the nose. When such a binding event occurs, the olfactory receptors change their shape and this deformation triggers chemical and electrical signals which are eventually transmitted to the brain through neurons. So, in a nutshell, this is how we smell. Human and especially some animal noses (think bomb-sniffing dogs) are very sophisticated and extremely sensitive gas sensors that can distinguish between very similar gas molecules. Researchers have been trying for a while to replicate the human olfactory sense - a concept called electronic nose (e-nose). While most nanotechnology-based efforts have focused on nanowires, new research conducted in Korea has demonstrated the detection of specific odorant molecules with a single-carbon-atomic resolution using a human olfactory receptor-functionalized carbon nanotube based sensor.
Miniaturizing traditional laboratory assays to automated lab-on-a-chip devices holds tremendous potential for enabling multiplex, efficient, cost-effective and accurate pathogen sensing systems for both security and medical applications. These sensors could be used to detect bacteria such as E. coli and Salmonella, but also other pathogens that could be used for bioterrorism. Traditional identification methods required time intensive cell culturing processes but novel pathogen sensors based on nanomaterials are promising vastly improved and speedy detection technologies. A recent example is a label-free sensor chip assembled from peptide nanotubes that enables the electrical detection of viruses with an extremely low detection limit. This could lead to compact super-sensitive pathogen detection chips for point of care applications that have a high tolerance against false-positive signals.
Genomics and proteomics, the studies of genes and proteins, provide the underlying basis for many advances in drug development and effective treatments of diseases. These studies heavily rely on unveiling the behavior of a single DNA or protein in an investigative sample. You could compare this challenge to somehow finding, then catching and monitoring a particular fish in a vast ocean. The scientific term for 'catching the fish' is 'immobilization' - a powerful technique for the study of biochemical systems that allows for the continuous observation of dynamic behavior of a chosen target. Immobilization methods anchor the to be observed molecule onto a surface in order to restrict it from escaping the observation volume. Researchers have now developed a new platform which consists of a carbon nanotube nanoneedle for capturing, isolating and measuring the activity of miniscule amounts of proteins.
Artificial skin already exists that can detect pressure and recently, thanks to carbon nanotube rubber, it now even is stretchable. Then there is stretchable artificial skin that is used, for instance, to provide grafts for human burns victims, but it is insensitive to heat and pressure. Skin-like sensitivity, or the capability to recognize tactile information, will be an essential feature of future generations of robots. Of course you could also dream up some sci-fi scenarios where artificial electronic skin vastly enhances human perception and performance. The development of electronic skin requires high-performance tactile sensors that mimic human skin in terms of touch sensation over a large area, high flexibility, resolution, and sensitivity comparable to a human finger, as well as ease of signal extraction for speed and implementation. A recent review article summarizes the current state of developing artificial touch, an area where significant progress has been made over the past few years.
'Smart' is the key buzz word used by materials engineers when they describe the future of coatings, textiles, building structures, vehicles and just any material that you can think of. Materials are made 'smart' when they are engineered to have properties that change in a controlled manner under the influence of external stimuli such as mechanical stress, temperature, humidity, electric charge, magnetic fields etc. Smart materials have some form of sensor capability that detects a change in the material or its environment that then triggers some kind of action. Not only for use in smart materials but as general sensor materials, especially for monitoring large areas, the development of materials that act as 'chemical paints' - or coatings - by responding to a (bio)chemical parameter with a change in their optical properties has developed into an exciting new field. In a typical application, the object of interest is painted and the color or fluorescence of the paint is monitored by methods of optical imaging. This technique represents a simple but exciting new technology to monitor (bio)chemical and even physical parameters over relatively large areas and in real time without having to look at only a minute sample through a microscope.