VARIABLE DEPENDIENTE

With so many achievements already realised, it is perhaps pertinent to ask “Where is nanotechnology heading”? It is envisaged that nanotechnology will lead to tiny robotic devices, utilizing nanoelectronics, sensors and MEMS/NEMS for in-vivo monitoring and diagnosis of electro-optic deficiencies and malfunctions of human systems. Yet, the current applications of nanotechnology are much more mundane: stain-resistant trousers, better sun creams, tennis rackets reinforced with carbon nanotubes! There is a huge gap between what nanotechnology is believed to have promised and what it has actually delivered so far.

In his book, Engines of Creation: The Coming Era of Nanotechnology, published in 1986, Drexler imagined sophisticated nanoscale machines that could operate with atomic precision. He envisaged a particular way of achieving nanotechnology, which involved using hard materials like diamond to fabricate complex nanoscale structures by moving reactive molecular fragments into position. His approach was essentially mechanical, whereby tiny gears and bearings are integrated to make tiny robot factories, probes and vehicles.

Drexler postulated that since nanoscale machines are expected to be extensively employed in biological systems and would be synthesized in significantly large quantities under ambient conditions, it should be possible to discover the growth conditions to synthesize them for a variety of other applications as well. The beauty of nanotechnology is that it is truly multi- disciplinary, re-unifying the common threads between science, engineering and technology. It is so vivid, with possibilities left only to the constraint of perhaps human imagination. With a little exaggeration, it seems possible that materials with any desired physical, chemical or electronic properties can be tailor-made by playing with the nano-dimensions.

The next generation is going to be directly or indirectly exposed to a variety of nano-products ranging from cosmetics to sports, from medical to industrial, and also space applications. With the advent of any new revolutionary technology with enormous potential for applications, it is perhaps even more pertinent to assess the risks and challenges accompanying them. The effect of nanoparticles on biological and ecological systems in large is a subject to be studied with the highest priority. A new field, nano-toxicology, has evolved in order to probe this field. It is important to qualify the application of nanomaterials for industrial and large-scale societal applications, not only based on their properties but also based on their possible long-term side effects.

SUMMARY

• The unique properties of nanomaterials are due to the presence of a high concentration of defects.

• The word ‘nano’ refers to a Greek prefix meaning dwarf or something very small. It depicts one billionth (10–9_{) of a unit.}

• Nanomaterials refer to the class of materials with at least one of their dimensions in the nanometric range. They can be metals, ceramics, polymers or composites.

• Nanomaterials exhibit uniquely different physical, chemical and mechanical properties compared to bulk materials.

• A number of characterizing tools have been developed over the past three decades and have helped in understanding the behaviour of nanomaterials and nanostructures. • Nanostructured materials may occur in several different geometric configurations

including wires, tubes, rods, horns, shells, pores, etc.

• Over millions of years, a multitude of nanoparticles and devices have been perfected by nature through the process of evolution.

• The cell membranes, and several other functional organelles within the biological cell of living beings are in fact of nanometric size.

• It is envisaged that nanotechnology will lead to tiny robotic devices, utilizing nano- electronics, sensors and MEMS for invivo monitoring and diagnosis of deficiencies and malfunctions of human systems.

Norio Taniguchi (1912–99) of Tokyo Science University coined the term nanotechnology in 1974 to describe semiconductor processes such as thin film deposition and ion beam milling, which exhibit control on the order of a nanometre. He defined nanotechnology as that which consists of the “processing of separation, consolidation, and deformation of materials by one atom or one molecule”. The early work of Prof. Taniguchi was on abrasive mechanisms during high precision machining of hard and brittle materials. At Tokyo Science University, he pioneered the application of energy beam techniques to ultra precision materials processing, which included electro discharge, microwave, electron beam, photon (laser) and ion beams. Professor Taniguchi received Euspen’s 1st _{Lifetime Achievement} Award in 1999. The citation on Prof. Taniguchi’s award reads: “In recognition of his unique and outstanding contributions to research and development in the ultra precision materials processing technologies and in 1974, being the first to formulate and use the term Nanotechnology. Through his vision, writings and example of total dedication to his field of endeavour he has stimulated the development of what will be one of the dominant technologies of the 21st Century.”

Richard P Feynman (1918–88) was one of the greatest theoretical physicists of the twentieth century. This quote of his is regarded as the ‘start’ of nanotechnology, “The principles of physics, as far as I can see, do not speak against the possibility of maneuvering things atom by atom. It is not an attempt to violate any laws; it is something, in principle, that can be done; but in practice, it has not been done because we are too big.”

Sumio Iijima discovered carbon nanotubes in 1991. He has been a Senior Research Fellow at NEC Corporation since 1987 and a Professor of Materials Science at Meijo University in Nagoya. He has the leading role in the International Cooperative Research Project ‘Nanotubulites’ of Japan Science and Technology Corporation (ICORP/JST). He is also the Director of the Research Center for Advanced Carbon Materials of National Institute of Advanced Industrial Science and Technology (AIST).

CNR Rao is the President and Linus Pauling Research Professor of the Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore. He steers the Nano Science and Technology Initiative (NSTI) of the Department of Science and Technology, Government of India. Although Prof. Rao started his career working on spectra and structure of molecules, his research interests have slowly moved towards the synthezis and characterization of designer solids with novel structures and properties. Several nanoparticles and nanoparticle assemblies, open framework structures and porous solids have been synthesised by him exhibiting fascinating scientific behaviour. He has authored nearly 1400 research papers and edited or written 40 books in materials chemistry. The Einstein Gold Medal of UNESCO, Hughes Medal of the Royal Society, and Somiya Award of the International Union of Materials Research Societies (IUMRS), Dan David Prize for materials research from Israel and the first India Science Prize are among the recognitions that he has received.

K Eric Drexler is the pioneer of productive nanosystems. He has authored the book Engines of Creation: The Coming Era of Nanotechnology, which is possibly the first book in this field. He has also written another book Nanosystems: Molecular Machinery, Manufacturing, and Computation, which has also become very popular. He is currently Chief Technical Advisor of Nanorex, which is engaged in developing software for the design and simulation of molecular machine systems. He received his doctoral degree in the field of molecular nanotechnology from MIT in 1991, which is the first PhD degree in this field.

Prominent individuals in nanoscience and technology

Richard P Feynman: First mentioned the concept of ‘nano’ in a 1959 lecture

Norio Taniguchi: Defined the term ‘nanotechnology’

K Eric Drexler: Promoted technological significance

Sumio Iijima: Discovered nanotubes

Don Eigler: Studied manipulation of surface atoms and the effects on electron density of states

Richard Smalley: Co-discoverer of buckminsterfullerene

Harry Kroto: Co-discoverer of buckminsterfullerene

Erwin Müller: Invented the field ion microscope and the atom probe

Gerd Binnig: Co-inventor of the scanning tunnelling microscope

Heinrich Rohrer: Co-inventor of the scanning tunnelling microscope

Phaedon Avouris: Made the first electronic devices made of carbon nanotubes

Alex Zettl: Built the first molecular motor based on carbon nanotubes

PM Ajayan: Pioneer in nanotubes research

CNR Rao: Most prominent researcher and promoter of nanomaterials research in India

H Gleiter: First produced nanostrctured materials by inert gas condensation