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Nano Engineering and Microsystems

(Stanford University - Jaclyn Chen)



- Nanoscale Materials

When we consider the properties of materials, we usually think of them based solely on the composition of the material. A metal conducts electricity because its atoms bond to the metal—a metal bond that allows electrons to drift freely through the material when an electric field is applied. Concrete is strong because it contains cement that holds incompressible sand and gravel firmly together. Vulcanized rubber is flexible but still durable because it is made of flexible polymer chains that are firmly linked together. 

However, there are other factors that affect the behavior of a material: its size. This is especially true when the size of certain materials is reduced to the nanometer scale (i.e. their dimensions can be reasonably expressed in nanometers -- often less than a few hundred nanometers, or even less than a nanometer). Electrical conductivity, chemical reactivity, mechanical properties, and even the interaction of materials with light can all change at the nanoscale. 

As our ability to create and study nanomaterials continues to advance, fascinating and unexpected new properties are being discovered. This opens up entirely new avenues for future technologies that depend on material size and its bulk properties. We are truly entering the age of nanotechnology.


- Classifications of Nanomaterials

Nanomaterials can be roughly classified according to their total number of nanometer sizes:

  • If all three dimensions of a material are nanoscale, it is called a 0D (zero-dimensional) material, often referred to as a nanoparticle.
  • If two dimensions of a material are nanoscale, and the other dimension is much larger (like a string shrinking to a tiny size), then it's a one-dimensional material or "nanotube/nanowire".
  • If only one dimension was nanoscale, then it would be a 2D material—similar to a large but very thin sheet (like a sheet of paper).
  • Finally, a material is not a nanomaterial if it does not have any dimensions small enough to be considered nanoscale. Instead, it should be called "bulk" material, the class we deal with in our daily lives.


- Nanoscale and Nanoscience

Nanoscale, the size range roughly 1 to 100 nanometers, where many of the fundamental structures of biology are formed, composite materials may take on their distinctive characteristics, and many important physical phenomena are found. (Note: a nanometer equals to one billionth of a metre or 0.000000001 m).

Nanoscience, the study of unique properties of matter at the nanoscale; an interdisciplinary field of science combining physics, materials science, the chemistry of complex molecules, and related disciplines.

The nanometre (international spelling as used by the International Bureau of Weights and Measures; SI symbol: nm) or nanometer (American spelling) is a unit of length in the metric system, equal to one billionth (short scale) of a metre (0.000000001 m). One nanometre can be expressed in scientific notation as 1×10−9 m, in engineering notation as 1 E−9 m.


Nanotechnology is the Future

Nanoscience and nanotechnology involve the ability to see and to control individual atoms and molecules. But something as small as an atom is impossible to see with the naked eye. In fact, it’s impossible to see with the microscopes typically used in a high school science classes. The microscopes needed to see things at the nanoscale were invented relatively recently (1981). Once scientists had the right tools, such as the scanning tunneling microscope (STM) and the atomic force microscope (AFM), the age of nanotechnology was born. 

Although modern nanoscience and nanotechnology are quite new, nanoscale materials were used for centuries. Alternate-sized gold and silver particles created colors in the stained glass windows of medieval churches hundreds of years ago. The artists back then just didn’t know that the process they used to create these beautiful works of art actually led to changes in the composition of the materials they were working with. 

Today's scientists and engineers are finding a wide variety of ways to deliberately make materials at the nanoscale to take advantage of their enhanced properties such as higher strength, lighter weight, increased control of light spectrum, and greater chemical reactivity than their larger-scale counterparts. 

Structure of Atom_123120A
[Structure of Atom - Tutorialspoint]

- What is Nanotechnology?

Nanotechnology is science, engineering, and technology conducted at the nanoscale, which is about 1 to 100 nanometers.  

Nanoscience and nanotechnology are the study and application of extremely small things and can be used across all the other science fields, such as chemistry, biology, physics, materials science, and engineering.  

Nanotechnology is helping to considerably improve, even revolutionize, many technology and industry sectors: information technology, homeland security, medicine, transportation, energy, food safety, and environmental science, among many others.

Today's scientists and engineers are finding a wide variety of ways to deliberately make materials at the nanoscale to take advantage of their enhanced properties such as higher strength, lighter weight, increased control of light spectrum, and greater chemical reactivity than their larger-scale counterparts.

- How it Started

The ideas and concepts behind nanoscience and nanotechnology started with a talk entitled “There’s Plenty of Room at the Bottom” by physicist Richard Feynman at an American Physical Society meeting at the California Institute of Technology (CalTech) on December 29, 1959, long before the term nanotechnology was used. In his talk, Feynman described a process in which scientists would be able to manipulate and control individual atoms and molecules. Over a decade later, in his explorations of ultraprecision machining, Professor Norio Taniguchi coined the term nanotechnology. It wasn't until 1981, with the development of the scanning tunneling microscope that could "see" individual atoms, that modern nanotechnology began. 

When the idea of nanotechnology was developed in the 1960s, it was just that – an idea. Scientists couldn’t do much to make nanotechnology happen, as they didn’t have the tools to see or work at the nanoscale. So, in some ways, nanotechnology has advanced alongside developments of microscopes.


- The Challenges in The Manufacturing Industry

The past 70 years have seen the way we live and work transformed by two tiny inventions. The electronic transistor and the microchip are what make all modern electronics possible, and since their development in the 1940s they've been getting smaller. Today, one chip can contain as many as 60 billion transistors. 

But to keep this progress going we need to be able to create circuits on the extremely small, nanometre scale. A nanometre (nm) is one billionth of a metre and so this kind of engineering involves manipulating individual atoms. We can do this, for example, by firing a beam of electrons at a material, or by vaporising it and depositing the resulting gaseous atoms layer by layer onto a base.  

The real challenge is using such techniques reliably to manufacture working nanoscale devices. The physical properties of matter, such as its melting point, electrical conductivity and chemical reactivity, become very different at the nanoscale, so shrinking a device can affect its performance. If we can master this technology, however, then we have the opportunity to improve not just electronics but all sorts of areas of modern life.


[More to come ...]

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