What is nanotechnology? Nanotechnology is the design, characterization, production, and application of structures, devices, and systems by controlling the shape and size at the nanometer scale. A nanometer (nm) is one billionth of a meter. For comparison, a single human hair is about 100,000 nm wide, a red blood cell is approximately 7,000 nm wide and a water molecule is almost 0.3 nm across.

Nanotechnology Concerns structures, devices and phenomena that are on a scale between atomic distances and the wavelength of visible light.

SCALE Millimeter: One thousandth of a meter, or about 1/26 of an inch. Micron: One millionth of a meter, or about 1/25,000 of an inch. Nanometer: One billionth of a meter; approximately the length of three to six atoms placed side-by-side, or the width of a single strand of DNA; the thickness of a human hair is between 50,000 and 100,000 nanometers.

Microscale Micron: One millionth of a meter, or about 1/25,000 of an inch Larger than nanoscale; often implies a design that humans can indirectly interact,Through Microscopes

Macroscale orMesoscale Macroscale: Larger than microscale; often implies a design that humans can directly interact with; too large to be built by a single assembler (one cubic micron of diamond contains 176 billion atoms).

Megascale

Microworld Mesoworld or Macroworld

Laws of these worlds (physics,chemistry,biology……)are the same

Nanoworld Nanometer: One billionth of a meter; approximately the length of three to six atoms placed side-by-side, or the width of a single strand of DNA; the thickness of a human hair is between 50,000 and 100,000 nanometers. Nanoworld:Ranged between 0.1 to 100 nanometers

Fields and Branches of Nano-Technology

Laws of Nanoworld Laws of this world (physics,chemistry,biology……)are different and unique

Mechanochemistry Chemistry accomplished by mechanical systems directly controlling the reactant molecules; the formation or breaking of chemical bonds under direct mechanical control.

MECHANOSYNTHETIC REACTIONS Based on quantum chemistry by Walch and Merkle [Nanotechnology, 9, 285 (1998)], to deposit carbon, a device moves a vinylidenecarbene along a barrier-free path to bond to a diamond (100) surface dimer, twists 90° to break a pi bond, and then pulls to cleave the remaining sigma bond.

Molecular manufacturing   This refers to the concept of building complicated machines out of precisely designed molecules

The building of complex structures by mechanochemical processes

How does 'mechanosythesis' work? Mechanosynthesis has many advantages over solution-phase synthesis, and should have as broad a range of products. It can apply positional control to select between similar reaction sites and keep reactive molecules isolated.   

The process works a bit like enzymes: you fix onto a molecule or two, then twist or pull or push in a precise way until a chemical reaction happens right where you want it. This happens in a vacuum, so you don't have water molecules bumping around. It's a lot more controllable. If you want to add an atom to a surface, you start with that atom bound to a molecule called a "tool tip" at the end of a mechanical manipulator. You move the atom to the point where you want it to end up.

TOOLS and DESIGNS Fabricator: A small nano-robotic device that can use supplied chemicals to manufacture nanoscale products under external control. Fabricators could work together to build macroscale products by convergent assembly. Similar to assemblers, but less complex, easier to build, and probably more efficient.

Assembler Assembler: A nano-robotic device controlled by an onboard computer that can use available chemicals to manufacture nanoscale products. It has been proposed that advanced designs could communicate, cooperate, and maneuver to build macroscale products. Assemblers are much more complex, and probably less efficient, than fabricators.

Convergent assembly Convergent assembly: A process of fastening small parts to obtain larger parts, then fastening those to make still larger parts, and so on; convergent assembly can be used to build a product from many, much smaller, components.

Diamondoid Diamondoid: Structures that resemble diamond in a broad sense, strong stiff structures containing dense, three dimensional networks of covalent bonds; diamondoid materials could be as much as 100 to 250 times as strong as titanium, and far lighter.

Since the advent of scanning probe microscopy, researchers have been able to not only visualize the nanoworld, but to begin to manipulate and create structures. Nearly all scientific disciplines are seeking to explore the interaction of materials in sizes less than 100 nanometers. Today, affordable tools are now available which allow new methods of constructing.  

Nano-Tools Nanoscale investigation. NanoInk has pioneered the development of systems and methods using Dip Pen Nanolithography (DPN) which allow researchers to use molecular building blocks to create customized nanostructures. Recent advances enable scalability, reproducibility and the evolution toward true nanomanufacturing.  

Optical nanolithography Optical nanolithography receives a boost as researchers claim that their new approach is a major step forward in generating arbitrary nanopatterns.  

 

Nanoelectromech-anical systems or NEMS and MEMS

Nanoelectromechanical systems Nanoelectromechanical systems or NEMS are similar to Microelectromechanical systems (MEMS) but smaller. They hold promise to improve abilities to measure small displacements and forces at a molecular scale, and are related to nanotechnology and nanomechanics. There are two approaches most researchers accept as standard paths to NEMS.

1.The top-down approach Can be summarized as “a set of tools designed to build a smaller set of tools”. For example, a millimeter sized factory that builds micrometer sized factories which in turn can build nanometer sized devices.

Chemical vapor deposition (CVD) Nanotubes being grown by plasma enhanced chemical vapor deposition: a process to grow aligned carbon nanotube arrays of 18 mm length on a FirstNano ET3000 carbon nanotube growth system

Microscope AFM The atomic force microscope (AFM) or scanning force microscope (SFM) is a very high-resolution type of scanning probe microscope Topographic scan of a glass surface

The information is gathered by "feeling" the surface with a mechanical probe. Piezoelectric elements that facilitate tiny but accurate and precise movements on (electronic) command enable the very precise scanning.

The AFM consists of a microscale cantilever with a sharp tip (probe) at its end that is used to scan the specimen surface. The cantilever is typically silicon or silicon nitride with a tip radius of curvature on the order of nanometers. When the tip is brought into proximity of a sample surface, forces between the tip and the sample lead to a deflection of the cantilever according to Hooke's law.

Force spectroscopy Another major application of AFM (besides imaging) is force spectroscopy, the measurement of force-distance curves. For this method, the AFM tip is extended towards and retracted from the surface as the static deflection of the cantilever is monitored as a function of piezoelectric displacement. These measurements have been used to measure nanoscale contacts, atomic bonding, Van der Waals forces, and Casimir forces, dissolution forces in liquids and single molecule stretching and rupture forces (Hinterdorfer & Dufrêne). Forces of the order of a few pico-Newton can now be routinely measured with a vertical distance resolution of better than 0.1 nanometer

STM Friction force microscope Scanning tunneling microscope Scanning probe microscopy Scanning voltage microscopy

The Bioscope AFM facility supports many projects in BioNanoTechnology. It is used to measure surface topography, magnetic force, and mechanical properties of physical and biological materials.

2.Bottom-up approach The other approach is the bottom-up approach, and can be thought of as putting together single atoms or molecules until a desired level of complexity and functionality has been achieved in a device. Such an approach may utilize molecular self-assembly or mimic molecular biology systems.

The prefix nano means a one-billionth part, so for instance a nanometr (nm) is one billionth of a meter. Chemists, physicists and biologists each view nanotechnology as a branch of their own subject, and collaborations in which they each contribute equally are common.

Nanotechnology is often considered as a new revolution, as was the industrial revolution, because nanotechnology manipulates matter at the atomic scale to create new applications in materials, medicine, robotics, electronics, energy…..