And so another Sunday arrives, what news will it bear? This has been the week of technology for me. All of the posts have been on either electrical or optical advancements. And in spirit of these engineering discoveries I have a piece of philosophy. Close enough to all technological advancements are appropriated by the military of their respective countries; and inventions take much longer to reach the public they were designed for as a result. The mobile phone is a perfect example. Is it intrinsically part of the human condition that we face the mortal coil with violence and adapt whatever we can to aid us in this quest. Nevertheless enduring is what humans do best and no matter how many times peaceful devices are corrupted to venal ends people will not hesitate in their innovation. That’s ultimately what puts humans above every other animal (assuming we are which is a debate that I don’t have time to go into) and hopefully means we won’t go extinct like so many species in the past. And with that cheery thought on humanities plight, happy Sunday to all, and to all a good night.
In order to see something light needs to interact and bounce off it, then something needs to detect this light and use it to form and image of take a photograph. These are the key principles of photodetectors and since the creation of this field semiconductors made from various materials has been the only option. But recently scientists have discovered that using the spectral sensitivity of lead sulphide crystals it is possible it is possible to make relatively low cost, highly processable and substrate compatible optical devices. By surrounding the lead sulphide in a ring of aluminium and applying a gate voltage allows a greater channel length when combined with a dielectric and also a much greater spectral range of between 200 and 2400nm. This technology could revolutionise the optical aspects of medical physics along with helping overcome challenges involved in viewing more complex micromolecular systems.
The way atoms and material are going to behave is mostly determined by the energy surface (energy described through geometry) of a objects ground state. But in the past there was no reliable way to measure the energy surface around an atom directly. But now scientists have discovered that by scattering X-rays of the atoms they can not only determine the potential energy store but also how this changes with distance from the atom. This process can be applied to single molecules like O2 or complex systems such as metal alloy lattices of frozen crystalline water. By using this method it will be possible to understand how materials will act under certain conditions and improve our knowledge of material science. Such methods still have a long way to go, however, with certainly more advancements coming in the near future.
Holograms have been around since the invention of the laser in the in 1960s and the idea for holograms had existed for many years before that. The two main aspects that plague holography are recording and creating light at the same phase (where then wave is) and amplitude (how big the wave is) but making this light originate from two different directions. The reason, however, that we don’t see holograms in every corner shop is because the materials that are required to make holograms have a very narrow range of wavelength of phase aligned light they can produce. These materials also must be constructed perfectly, a single molecular floor could make the entire system useless. But material scientists have recently developed a new material that could be used to almost triple the allowed wavelength of the light. By placing a aluminium with tiny microscopic holes called nanoapertures over a layer of SiO2. This material is very rugged and doesn’t require the same level of perfection as the other holographic materials and could very well be essential for creating the kind of holograms that we so often see on TV and films.
Superconductors work due to the fact that when certain metals are cooled to extremely low temperatures the electrons within the lattice form what are known as Cooper Pairs. Cooper Pairs stop acting like fermions and begin acting like bosons which means that the resistance of the wire drops to zero. A problem has always been effectively cooling the metal so that the electrons become cold enough to form the bond required for the Cooper Pairs. This is because the energy transfer between the electrons and the metal lattice becomes poorer the colder the metal lattice becomes, but scientists using a special oxide tunnel barrier improved the conduction of heat away from the electrons speeding up their cooling. This small boost will of coarse help the eternal quest to find a room temperature superconductor however unlikely such a thing may be.
Nikola Tesla famously pioneered the idea of wireless energy transfer but only recently has it become a reality with iPads that can charge by simply being placed on top a charging port. Originally the efficiency of these systems was low rarely getting higher than 40% over distances of about half a meter but recently researchers have developed a new method for wireless power transfer that they hope could be used over long distances with relatively high efficiency. The old method required two copper coils to resonate at the same frequency allowing power to transfer between them through a magnetic field in a similar way to the way transformers operate. By replacing the copper with dielectric material with a high refractive index, the energy efficiency of the transfer was improved to up to 80% at a fifth of meter with only a small drop in efficiency at increased distances. This research could mean that entire buildings could be designed to act as charging ports for all compatible devices within them requiring no classical plug sockets at all.
The Hall Effect is a well known occurrence where a current carrying wire in a magnetic field has its electrons shunted to one side leaving half the conductor positive and the other half negative. Due to spin being related to intrinsic magnetism an analogous effect can occur where all up spins gather on one side and all downs in another. This is known as the Spin Hall Effect. When electrons are in a two dimensional crystal lattice they demonstrate a valley degree of freedom (a local minimum or maximum relating to the conduction band). Researchers have discovered that by placing two layers of MoS2 together they can, without anomaly, manipulate the electrons in the lattice using perpendicular electric fields. Since the polarisation of the electrons is strongly related to the strength of the electric field affecting them this method can be used to store data using these electrons in similar way to spintronics and may eventually lead to the smallest data storage devices the world has ever seen.