1、 SkySpring Carbon nanotubes. Image Credit: RSCNanomaterials have features or particle sizes in the range of 1 to 100 nm. They can be natural or manmade and they have a wide variety of applicationsWhat are Nanomaterials?Nanomaterials are materials possessing one or more dimensional features having a
2、length on the order of a billionth of a meter, or 10-9, to less than 100 billionths of a meter. To illustrate this size, there are 25,400,000 nanometers in an inch and on a comparative scale, if a marble were a nanometer, than one meter would be the size of the earth.Nanotechnology DescriptionThe te
3、rm nanomaterial includes all nanosized materials, including materials that can be engineered or found in nature. They are important because they exhibit unique properties because of the size of their features and scientists and engineers have learned how to manipulate and understand the relationship
4、 of their properties to size. The National Nanotechnology Initiative （NNI） website puts these ideas in a simple phrase, At the nanoscale, the physical, chemical, and biological properties of materials differ in fundamental and valuable ways from the properties of individual atoms and molecules or bu
5、lk matter.NanoScale. Image Credit: Nano.govRecent discoveries in areas such as microscopy have given scientists and engineers new tools to observe and manipulate the phenomena that occur when matter is organized at the nanoscale level. The scanning tunneling microscope （STM） and the atomic force mic
6、roscope （AFM） have made nanotechnology possible to enable scientists to utilize the unique physical, chemical, mechanical, and optical properties of materials that naturally occur at that scale. Nanomaterials fall under the field of nanotechnology and the events that occur at the nanoscale level are
7、 based on quantum effects and physical effects such as expanded surface area.How Are Nanomaterials Made?Nanomaterials is a term that includes all nanosized materials, including engineered nanoparticles, incidental nanoparticles, and nano-objects like those that exist in nature. Nanomaterials exist i
8、n nature in the form of biological materials or a byproduct of human activities. For instance, hemoglobin is 5.5 nanometers in diameter and biological ion channels can be as small as a few tenths of a nanometer. Natural nanomaterials such as smoke from fire and sea spray exist in the air around us.
9、Manmade nanomaterial byproducts include automobile exhaust and welding fumes. Scientists have already copied the nanostructure of several natural items including the lotus leave to create water repellent surfaces beings used to make stain proof clothing and spider silk, which is naturally reinforced
10、 with Nanoscale crystals.Nanomaterials can also be engineered and are made through a process called nanomanufacturing. Nanomanufacturing has two basic approaches. Bottom-up builds products by building them up from atomic- and molecular-scale components. The process involves manipulation or synthetic
11、 methods of biochemistry in direct assembling subnanoscale building blocks, such as atomic molecular and supramolecular elements into required nanoscale patterns. It can be a very time consuming process and is therefore better for biomedical, chemical and physical sensors than large scale molecular
12、electronics and computer parts. The fabricaion strategy must occur in parallel or in arrays to self-form groups of atoms fast enough to produce useful structures of macroscopic size. Further research is being done to create self-assembling structures that will put themselves together and reduce the
13、waste of top-down approaches. Currently, the best bottom-up approach is nano-manipulation which allows for precise control over single atoms and nanoscale particles for the formation of nanostructures. Top-down reduces large pieces of materials to the Nanoscale level. The process has evolved from li
14、thographic techniques, requiring larger amounts of materials which can lead to waste from the discarding of excess material. Another difference from the bottom up approach is that in the top-down approach, the parts or chips are both patterned and built in place so that no assembly step is needed. I
15、t is a very useful process for the evolution of the electronics, computer, photonic, and microsystem industries. Combined bottom-up and top-down approaches will soon be the standard practice. Within the top-down and bottom-up categories of nanomanufacturing, there are a growing number of new process
16、es that enable nanomanufacturing. Among these are: Chemical vapor deposition （CVD） is a process in which chemicals react to produce very pure, high-performance films. CVD involves flowing a precursor gas or gasses into a chamber containing one or more heated objects to be coated. A chemical reaction occurs on or near the heated surfaces, resulting in the depos
