NANOTECH

NANO IN DRUG DELIVERY

noreply@blogger.com (VENKATESH) — Mon, 4 Aug 2008 08:54:00 -0700

Drug delivery is an area that is already showing significant impact from nanotechnology, with some approaches using nanoparticles or nanocapsules to deliver drugs through the skin, lungs, stomach and eyes already in clinical trials and many more in preclinical trials.

The advantages of these approaches are varied, such as increased solubility, resistance to gastric enzymes (offering oral delivery of drugs previously needing intravenous delivery), controlled release or the ability to direct the drug, through various means, to where it is needed—almost all current medications are delivered to the body as a whole, which is fine as long as they only become active in the areas you want them to, but this is not usually the case. When the treatment is designed to kill cells, as in the case of cancer, the side effects are enormous.

Nanostructured Materials

noreply@blogger.com (VENKATESH) — Mon, 4 Aug 2008 08:52:00 -0700

Nanostructured materials, coupled with liquid crystals and chemical receptors offer the possibility of cheap, portable biodetectors that might, for instance, be worn as a badge. Such a badge could change color in the presence of a variety of chemicals and would have applications in hazardous environments.

Nanoparticles and nanowires

noreply@blogger.com (VENKATESH) — Mon, 4 Aug 2008 08:48:00 -0700

Another boon to bioanalysis looks set come from the attaching of nanoparticles to molecules of interest. Nanoparticles small enough to behave as quantum dots can be made to emit light at varying frequencies. If you can get particles that emit at different frequencies to attach to different molecules, you can spectroscopically determine the presence of many different molecules at the same time in a single sample.

Several companies have been created to commercialize this and other variations on nanoparticle bioanalysis. One variation with similar applications, i.e. offering improved parallelism, uses instead nanowires that have distinctive stripes on them, like a bar code.
Others are exploiting the sensitivity of the electrical properties of nanowires (and even nanotubes) to develop highly sensitive biodetectors that could reveal the presence of a single molecule of substance. Quantum dots offer the same capability, for example by being stimulated to emit a photon in the presence of a certain molecule. Recent developments in single-photon detection and emission bear on this space too.

Nanopores and membranes

noreply@blogger.com (VENKATESH) — Mon, 4 Aug 2008 08:46:00 -0700

Nanomembranes also offer the ability to sort biomolecules and have already been shown capable of separating out left- and right-handed versions of molecules that come in mirror image forms. Usually only one of these is desired and the other may even be dangerous, as was the case with thalidomide.
Another intriguing application of tiny holes that is being worked on involves passing a single DNA or RNA thread through a nanosized pore, forcing it to straighten out and traverse the pore through a base at a time (a "base" being the fundamental coding element of nucleic acids). Changing electrical gradients on either side of the structure, containing the pore, or quantum tunneling current across the pore, could be used to identify the particular base that is passing through. The ability to sequence a whole genome (the sum total of genes in an organism) in a matter of hours has been proposed as a potential of this approach.

MEMS and micro fluidics

noreply@blogger.com (VENKATESH) — Mon, 4 Aug 2008 08:36:00 -0700

Micro technology is already making a major impact in the area of biological analysis and discovery. The basic science behind identifying the presence of a particular gene or protein has been developing for some time and is not considered nanotechnology per se, but MEMS and micro fluidics developments, such as the lab on a chip, are now offering a degree of parallelism that hasn't been seen before, the ability to detect much smaller quantities of a substance, equipment that can be taken out of the lab and carried around, increased automation by virtue of the integration of micro circuitry into the devices, and the benefits of the mass production approaches used in the semiconductor industry.

These benefits are typified by an approach to bioanalysis that takes a micro array (a standard tool for parallel biodetection using luminescence), shrinks it greatly, and then uses atomic force microscope tips to measure whether a substance has been detected. Such devices are in development now and expand the number of substances that can be easily used in array technologies because such small amounts are needed—detection using micro arrays often requires an amplification step whereby the substance to be detected is multiplied in quantity first, something that cannot be done with everything.

Nanoscience will have a huge impact on the biological sciences (and thus medicine and agriculture, for example) in the long term, and a significant impact in the short and medium terms, simply by virtue of our growing ability to work on the scale of biological systems. The impact will work both ways too—nature has evolved, over billions of years, mechanisms with a complexity, effectiveness and elegance that we will be hard-pressed to emulate, but which we most certainly can learn from. Nature is also the master of self-assembly. In fact nature makes things that self-assemble into things that self-assemble into other things that self-assemble. In the short term, nature will probably end up having more impact on nanotechnology than the other way around.

Another reason to expect great advances, whether nanotechnology-enabled or just assisted, is how little we still know about the natural world. We still can't explain, let alone cure, a large number of the diseases that afflict us, which means there's a great deal of scope here.

There is good reason to believe that in the not-too distant future we will indeed be able to cure a host of diseases and achieve much in the realm of biology and biotechnology, but it could be argued that most of that development will be attributable to long-established disciplines such as genetics and molecular biology, nanotechnology taking more of a supportive role. In the short and medium term, developments that appear achievable and that are clearly based on nanotechnology are not that dramatic, but do translate into large markets.

NANO IN LIFE SCIENCE

noreply@blogger.com (VENKATESH) — Tue, 8 Jul 2008 05:33:00 -0700

This is the area where nanotech has been most severely hyped, as a technology that will cure cancer, eliminate infections, enhance our intelligence and make us immortal. It is also the area where the bounds of nanotechnology are most blurred. This is because nature’s technology operates predominantly at the nanoscale. However our knowledge of the chemical structure of DNA and the proteins it codes for, and of the cellular machinery used to assemble the proteins, has for many years been classified under more traditional labels. But blurring of the boundaries is inevitable as we extend our senses and our ability to manipulate the world in this realm.

Display technologies

noreply@blogger.com (VENKATESH) — Tue, 8 Jul 2008 05:31:00 -0700

The hang-on-your-wall television (at an affordable price) has been awaited for a long time and nanotechnology may finally bring it into your home. Carbon nanotubes are excellent field emitters, i.e. they can be made to produce a stream of electrons, as does the electron gun in your bulky cathode ray tube TV. Several groups are promising consumer flat screens based on nanotubes by the end of 2003 or shortly after, but there are other competing technologies in the race. E-paper is another much heralded application and nanoparticles figure in several approaches being investigated, some of which promise limited commercialization in the next year or two. Soft lithography is another technology being applied in this area.

Optical Switching

noreply@blogger.com (VENKATESH) — Tue, 8 Jul 2008 05:30:00 -0700

Communications networks will no doubt continue to grow in capacity for some time as more people come to expect more from the Internet. Nanotechnology, or more specifically soft lithography (or nanoimprinting) is already being used in the production of sub-wavelength optical components. This is an area well worth keeping an eye on (the US optical switching market is expected to grow from $1.6 billion to $10.3 billion by 2004).

SPMs for Storage

noreply@blogger.com (VENKATESH) — Tue, 8 Jul 2008 05:29:00 -0700

Several variations on using scanning probe microscopes for data storage are being pursued, the three main varieties being based on using scanning tunneling microscopes on phase change materials (akin to the way Cd's work), magnetic force microscopes, and atomic force microscopes. This latter approach, which makes indentations in a polymer, has received the most publicity through IBM's Millipede project, which recently demonstrated recording densities of a terabit per square inch. The likeliest target for this particular technology is flash memory, used in mobile devices, because of low energy consumption and the potential of increasing memory to 5 - 10 gigabytes, where flash technology is unlikely to surpass 2 gigabytes.

Molecular and nanotube memories

noreply@blogger.com (VENKATESH) — Tue, 8 Jul 2008 05:26:00 -0700

Nanotubes hold promise for non-volatile memory and with a commercial prototype nanotube-based RAM predicted in 1 to 2 years, and terabyte capacity memories ultimately possible. Similar promises have been made of molecular memory from several companies, with one projecting a low-cost memory based on molecule-sized cylinders by end 2004 that will have capacities appropriate for the flash memory market. Note that all these approaches offer nonvolatile memory and if the predicted capacities of up to a terabyte can be achieved at appropriate cost then hard drives may no longer be necessary in PCs.

MAGNETIC RAM

noreply@blogger.com (VENKATESH) — Mon, 23 Jun 2008 03:01:00 -0700

There are several flavors of MRAM and one has seen limited commercial use already. MRAM offers a number of attractive features, including the fact that it is non-volatile, enabling devices such as a PC or mobile phone to boot up in little or no time. Several companies are working on MRAM technologies, and suggestions are that while the data densities might not be as good as with other technologies, cost per bit could be very low.

HARD DRIVES AND TAPES

noreply@blogger.com (VENKATESH) — Mon, 23 Jun 2008 02:59:00 -0700

Hard drives currently on the market for PCs have capacities in the tens of gigabytes and data densities of a few tens of gigabytes per square inch with 100 Gbits/sq. in. expected in the next generation. The use of magnetic nanoparticles offers the potential of terabyte drives, as does the patterned media approach being pursued by IBM and General Electric. Interestingly, this latter approach is being pursued using nanoimprinting technology. Fuji announced late in 2001 new magnetic coating promising 3-gigabyte floppy disks.

MEMORY AND STORAGE

noreply@blogger.com (VENKATESH) — Mon, 23 Jun 2008 02:57:00 -0700

We have noted that part of the difficulty in creating processors with nanotubes or molecular electronics relates to complexity. Data storage structures are far less complex than processors and many new technologies are converging on this area, promising commercialization in five years or less. Information storage requirements continue to grow but vary in nature from one application to another and can be approached in many ways. Magnetic disks in computers have been increasing their capacity in line with Moore's law, and have a market at the moment of over $40 billion. The other type of information storage common to all computers is DRAM (dynamic random access memory). DRAM provides very quick access but is comparatively expensive per bit. Magnetic disks can hold much more information but it takes much longer to access the data. Also, DRAM is volatile—the information disappears when the power is switched off. The trade-offs between access speeds, cost, storage density and volatility dictate the architecture of computers with respect to information storage. While hard disk technology continues to offer increasing data densities and lower costs per bit, a number of nanotechnologies are promising new types of RAM that are non-volatile and could have enough capacity to make disk storage unnecessary for applications such as personal computers. Companies are forecasting commercial products within two to four year time frames. How much penetration each technology will achieve in the variety of areas in which storage is used depends on the complex interplay of factors that have led to the current division of data storage technologies, but it would certainly be surprising if the consequences weren't disruptive for the industries involved.

Quantum Computing

noreply@blogger.com (VENKATESH) — Sun, 8 Jun 2008 07:04:00 -0700

In the much longer term quantum computing, offers staggering potential by virtue of the ability to perform simultaneous calculations on all the numbers that can be represented by an array of quantum bits (qubits). The scale at which quantum effects come into play, the atomic scale, argues for a requirement for nanoscale structures and quantum dots come up regularly in discussions of quantum computing. Primary applications would be in cryptography, simulation and modeling. The realization of a quantum computer is generally believed to be a long way off, despite some very active research. Funding in the area is thus still largely that provided for pure research, though some defense department money has been made available.

Spintronics

noreply@blogger.com (VENKATESH) — Sun, 8 Jun 2008 06:55:00 -0700

Magnetism is dictated by the direction of spin of electrons and increasing research into the use of this property has led to the coining of the term spintronics. The read heads of disk drives already exploit electron spin in an effect called giant magneto Resistance, as does MRAM (see later), which has already seen limited commercial production. An effect called ballistic magneto resistance has recently been demonstrated to have the capability of producing read heads that can deal with storage densities of a terabit per square inch—ten times the density expected in the next generation of hard drives. Commercial application of spintronics in electronics is farther away but the promise is there—a Canadian group recently created a transistor that was switched by the spin of a single electron confined in a quantum dot.

Molecular Nanoelectronics

noreply@blogger.com (VENKATESH) — Sun, 8 Jun 2008 06:53:00 -0700

Organic molecules have also been shown to have the necessary properties to be used in electronics and a single atom transistor was even demonstrated recently. Devices made of molecular components would be much smaller than those made by existing silicon technologies and ultimately offer the smallest electronics theoretically possible without moving into the realm of subatomic particles. The issues of connectivity, and thus mass production, apply to molecular electronics too, but choosing your molecule carefully does offer the potential of using self-assembly (discussed earlier) to create structures, an approach that could offer great economies.

Carbon Nanotubes in Nanoelectronics

noreply@blogger.com (VENKATESH) — Thu, 29 May 2008 09:59:00 -0700

Carbon nanotubes hold promise as basic components for nanoelectronics—they can be conductors, semiconductors and insulators. In 2001 IBM made the most basic logic element, a NOT gate, out of a single nanotube, and researchers in Holland created a variety of more complex structures out of collections of tubes, including memory elements. Recently IBM created nanotube transistors that outperformed the best silicon devices available. There are two big hurdles to overcome for nanotube-based electronics. One is connectibility—it's one thing making a nanotube transistor, it's another to connect millions of them up together. The other is the ability to ramp up to mass production. Traditional lithographic techniques are based on very expensive masks that can then be used to print vast numbers of circuits, bringing the cost per transistor down to one five-hundredth of a US cent. Current approaches to nanotube electronics are typically one-component-at-a-time, which cannot prove economical. Molecular electronics (which, strictly speaking, includes nanotubes) faces similar scaling hurdles. There are some possible solutions, however.

NANO AFTER MORE'S LAW

noreply@blogger.com (VENKATESH) — Thu, 29 May 2008 09:55:00 -0700

You may have heard of Moore's law, which dictates that, the number of transistors in an integrated circuit doubles every 12 to 24 months. This has held true for about 40 years now, but the current lithographic technology has physical limits when it comes to making things smaller, and the semiconductor industry, which often refers to the collection of these as the "red brick wall", thinks that the wall will be hit in around fifteen years (the best resource for information on these limits is the International Technical Road map on Semiconductors - see http://public.itrs.net/). At that point a new technology will have to take over, and nanotechnology offers a variety of potentially viable options.

The total potential for nanotechnology in electronics has been estimated to be about $300 billion per year within 10 years, and another $300 billion per year for global integrated circuit sales (R. Doering, “Societal Implications of Scaling to Nanoelectronics,” 2001). But it's actually much harder to predict the commercially successful technologies in the world of electronics than in the world of materials.

The assumption that continually increasing processing power will automatically slot into a computer hardware market that continues to grow at the rate it has done historically, is not necessarily sound. Most of the growth over the last decade has been driven by personal computers and some argue that this market is nearing saturation. Certainly there will be other applications. Increasing the intelligence of computers, and giving them the capability to interact verbally in a sophisticated manner, would certainly bring benefits, but increasing hardware capabilities is only half the story, with the biggest challenges being designing the software. Another area predicted to see major growth, is ubiquitous computing, whereby processors start to be incorporated in all manner of objects around us, which then communicate with each other and us. However, the requirements here are for relatively simple processors and in many cases there is no need for them to be particularly small either. Cost improvements remain a critical factor and it is the correlation of increasing transistor density with a reduction in cost per transistor that has probably kept Moore's law on track for so long. This relationship need not continue, however and several new approaches, which aren't even nanoscale, hold promise of creating simple circuits cheaply, such as using arrays of MEMS-based micro mirrors to build custom circuits, or the use of ink jet printers to churn out simple ones (interestingly, nanoparticulates figure in the potential of this probably near-market technology). These approaches also offer the ability to create low runs of circuits, or even one-off bespoke designs, at low prices, whereas photo lithographic approaches need massive production runs to achieve economies of scale. Soft lithography, too, offers cheap, micro scale, circuitry and is being pursued in the creation of flexible displays. These technologies could take a share of the existing semiconductor market and certainly future markets such as electronic tagging of goods or the processors required for ubiquitous computing.

High-production-run electronics will continue to be dominated by photo lithographic approaches for years to come, with the advent of the molecular nanotechnologies that could dramatically improve the power and density of processors while competing with photo lithography on cost still way off the radar for the investment community. The reason for this is the challenge of using such approaches to create the complex structures required for processors, an obstacle that doesn't apply to data storage, as we will see later. Soft lithography and nanoimprinting, however, are showing promise of coming into investment range in the near future. A company has already been formed to develop one flavor of soft lithography, the step and flash approach, for nanoelectronics and Stephen Chou of Princeton recently developed a variant of his nanoimprinting approach (already used to make commercially available sub wavelength optical components) to make nanoscale structures by melting silicon.

ELECTRONICS AND INFORMATION TECHNOLOGY

noreply@blogger.com (VENKATESH) — Thu, 29 May 2008 09:53:00 -0700

The impact of the information technology (IT) revolution on our world has far from run its course and will surely outstrip the impact of the industrial revolution. Some might claim it has done so already. Key to this is decades of increasing computer power in a smaller space at a lower cost.

DEVICES

noreply@blogger.com (VENKATESH) — Sat, 17 May 2008 09:42:00 -0700

MEMS. Making machines in the micro realm is something that is already well established. Microelectromechanical systems (MEMS) are generally constructed using the same photolithographic techniques as silicon chips and have been made with elements that perform the functions of most fundamental macro scale device elements - levers, sensors, pumps, rotors, etc. MEMS already represent a $4 billion industry, which is projected to grow to $11 billion by 2005.

NEMS. Moving to the nanoscale will present a host of new issues. For this reason, and possibly a lack of economic drivers for making machines smaller in general (smaller isn’t necessarily better), we shouldn't expect a vast array of products to flow out of MEMS and the nano version, NEMS, in the near future. However, there is sure to be a significant but modest evolution, especially in such areas as lab-on-a-chip type technologies, and NEMS devices have potential in the telecoms industry.

Tiny Medical Devices. MEMS and NEMS hold promise in the medical field, as little devices controlling the release of a drug, for instance, or even in the control functions of prosthetics, such as artificial hearts. However, it should be noted that where a passive system can perform the same function as an active one, the passive one would normally be less expensive and more reliable. Sometimes, however, an active device makes sense—recently a MEMS device was created that can grip and release individual blood cells without harming them. One can imagine such a device being used in a system to inject genes or other substances into cells. The use of nanotubes as syringes has even been suggested.

Advanced Lasers. Lasers constitute an area that is likely to be commercially affected by nanotechnology in the near future. Quantum dots and nanoporous silicon both offer the potential of producing tunable lasers—ones where we can choose the wavelength of the emitted light. Classic lasers, including solid-state ones, are dependent upon the physical and chemical properties of their components and are thus not tunable. Given the market for solid-state lasers, developments in this area are likely to be commercially significant.

DIP-PEN NANOLITHOGRAPHY

noreply@blogger.com (VENKATESH) — Tue, 13 May 2008 10:10:00 -0700

This technique uses atomic force microscope (AFM) tips like old-fashioned quill pens, depositing an ink on a surface, the ink usually being something that forms self-assembled monolayers. A variation uses hollow AFM tips that have a well to hold the ink.

Lines just a few nanometers across have been created and, in theory, a wide variety of different inks can be used. The approach clearly offers great flexibility but not the sort of throughput that would be required for mass production. Throughput can be increased significantly by having arrays of tips, and companies working on the technology talk of potentially hundreds of thousands.

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noreply@blogger.com (VENKATESH) — Tue, 13 May 2008 04:37:00 -0700

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SOFT LITHOGRAPHY

noreply@blogger.com (VENKATESH) — Thu, 8 May 2008 01:14:00 -0700

Soft Lithography

This term covers a variety of approaches akin to traditional printing. A mold is created that can then is used to make an imprint in a material or apply ink to it, plus there are several other variations. A variant already used in creating optical components is nanoimprinting, which uses a hard mold to make an impression in a polymer. A recent variation on this uses a quartz mold, which is placed in contact with silicon. The silicon is then melted with a powerful laser, leaving an impression of the mold.

In general, no special technology is required for these techniques, nor are the fantastically clean environments required for existing silicon chip production, for example. Additionally, a wide variety of materials can be used.

Soft lithography is already used to make micro fluidic systems, such as those in labon- a-chip systems, and it scales readily down to the nanoscale—depending on the variant of the technology used, resolution can get below 10 nanometers. The attraction for nanoelectronics is clear—the technology is simple, offers a high level of parallelism (and thus economies of scale from high production runs), and can produce complex patterns with nanoscale features. As a replacement for traditional lithography for creating electronic devices, however, there is currently a major obstacle—the technique is not well suited to making the precisely aligned, multilayered structures currently used in microelectronics, although work is being done to overcome this limitation.

The alignment problem is lessened if larger feature sizes are acceptable and the approach has been investigated for making flexible displays. Additionally, the creation of the master is much cheaper than for photolithography and the process would become economical for much lower production runs, such as for device specific electronics.

TECHNIQUES FOR BUILDING NANO SCALE STRUCTURES

noreply@blogger.com (VENKATESH) — Thu, 8 May 2008 01:04:00 -0700

Self-assembly. Self-assembly is nature's favorite way of building things. Simply create materials that naturally combine with each other in desired ways. Self-assembled monolayers, which we have already mentioned, are a simple example.

Self-assembly typifies an approach that is often mentioned in writings on nanotechnology, the bottom-up approach. Assembling a car engine, say, from its components is a bottom-up approach (although not an example of self-assembly) and involves little wastage. Machining some of the components out of blocks of material is a top-down approach, and involves more wastage.

Self-assembly potentially offers huge economies, and is considered to have great potential in nanoelectronics for this reason and because it could produce just about the densest electronics feasible. It is a part of some of the promising approaches to making molecular memory that may bear fruit in a few years. Tackling processors is another matter, however, because of the greater complexity involved? In this area self-assembly will likely be combined initially with some more traditional top-down approach, for example, getting molecular components to self-assemble on a patterned substrate in some sort of hybrid system, which many believe will represent the first commercialization of nanoelectronics.

A drawback of self-assembly approaches to date is that they are not that reliable and the results have a much higher rate of variability (read flaws) way to get around this is to design software that takes account of the flaws and allows imperfect circuitry to operate reliably, through testing and selection of viable components. than we are accustomed to with lithographic approaches.