July 25th, 2011 | Published in Nanosensor, Terahertz Radiation
The idea of smart dust has been around for ages, but now researchers are working to make it a reality. A nanoprocessor coupled with a nanomemory, nanobattery and nanoantenna would be the basic building blocks for such a device. A difficult problem for researchers is figuring out how these sensors can communicate with one another and send their data back to be examined. The concept of wireless nanosensor networks (WNSN) would be to use electromagnetic radiation in the terahertz spectrum (100 gigahertz to 10 terahertz). Terahertz (THZ) radiation has been adapted for a number of applications which include higher resolution medical imaging and surveillance. The THZ spectrum has the capability of transferring large amount of data. This rate could be up to several hundred terabits per second over distances that are shorter than a meter. That’s over 12 gigabytes every second. The WNSN wouldn’t obviously really need this capacity and will actually operate at much lower levels. A nano-hard drive by itself can only store a very small amount of data, but it won’t need to retain it for very long. A large group of nanosensors that could immediately release information wirelessly can have a much higher aggregate storage capacity than their small design would suggest. The number one constraint would likely be how much information the sensor gathers in a given time.
The technique for a WNSN is called time spread on-off keying ( TS-OOK ). It would be based on an asynchronous transmission of femtosecond-long pulses utilizing an on-off keying modulation spread over time. A main motivation for these kinds of short pulses is that there are energy constraints to the nanosensors. The higher carrier photon frequency is harder to support with such a small device. The network also has to be able to deal with a considerable amount of noise due to collisions with molecules. This is especially true in a biological environment.
The WNSN is planned to be employed in intra-body disease detection and a cooperative drug delivery system. Picture being able to release targeted molecules anywhere in biological tissue. This could be a highly coordinated way of administering healthcare. The sensors may also be able to take specific readings on how a person’s organs were functioning. So if a patient was at high risk for something catastrophic happening, the nanochips might serve as an early warning system. They would be able to wirelessly beam the information to an outside computer that analyzes the data thoroughly. Then the doctor would gain more insight in to the disease process. At first glance, this sounds like a great idea. However, it might be difficult to pull off without activating the body’s defense mechanisms or causing unwanted toxicity. These small sensors could have some deleterious effects like causing cancer.
The extent of its uses might be actually more mundane than kurzweilian forecasts of eminent nanorobots. These devices would most likely be wielded prominently on studying animals. There is plenty of research on drug delivery using novel nanotechnology for instance. Clinically, though, a lot of it hasn’t been translated into therapies at the hospital. Trying to get products to doctors can be difficult because companies are chasing after niche markets. Receiving regulatory approval is a huge hurdle that needs to be overcome.
“Enabling Electromagnetic Communication in Wireless Nanosensor Networks”
Nanotechnology is enabling the development of miniaturized sensors that can detect with unprecedented accuracy nanoscale events such as the presence of chemical compounds in concentrations as low as one part per billion or the existence of different biological agents such as virus, bacteria or cancerous cells. Wireless nanosensor networks (WNSNs) will expand the capabilities of single nanosensors by allowing them to cooperate and share information.Terahertz or subterahertz wireless is still an up and coming method of communication. So its viability has not been proven to a high degree.
Review of terahertz and subterahertz wireless communications
Over the past ten years, several groups have considered the prospects of using sub-terahertz (THz) and THz waves (100–2000 GHz) as a means to transmit data wirelessly. Some of the reported advantages of THz communications links are inherently higher bandwidth compared to millimeter wave links, less susceptibility to scintillation effects than infrared wireless links, and the ability to use THz links for secure communications.There may be potential cellular effects from exposure to THZ radiation, which could put a damper on some of the possible uses of the technology.
No biological effects could be detected on human lymphocytes, DNA bases, epithelial cell cultures and membrane model systems under a variety of exposures. However, under some specific types of conditions, changes in the membrane permeability of liposomes were detected and an induction of genetoxicity could be observed to occur in lymphocytes. These studies suggest that THZ medical imaging employing appropriate exposure parameters is most likely not harmful at least for a few exposures.Nanonetworks: a novel communication paradigm PDF
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