Enormous Potential in Very Small Things

What Is Nanoscience?

Image of mouse embryonic stem cells cultured on a silicon nanowire array substrate

A nanometer is a unit of measure, just like a meter or inches, only it represents one-billionth of a meter. Naturally, it is used to measure matter that is extraordinarily small. For example, a hair and a sheet of paper are each about 100,000 nanometers thick.

A typical germ measures about 1,000 nanometers, a water molecule is less than one nanometer.

Nanoscience involves the study, manipulation and control of chemical and biological matter on this very small or "nanoscale"—matter ranging from 1-100 nanometers.

Strange Things Happen at Very Small Sizes

Why study material that is so incredibly small? It turns about ordinary chemical or biological material, like lead or proteins, may behave one way when in comparatively large amounts (called "bulk") and very differently when reduced to the nanoscale. For instance, the National Science Foundation discussed the nature of carbon, "the fourth most abundant element in the universe by weight," without which, "there would be no life on earth."

Depending on its crystal structure--how its atoms bond together--carbon can form several different substances, ranging from sooty coal to glittering diamonds to slippery-smooth graphite.

Slice a chunk of graphite into a flat, single-atom thick sheet, and you get another form of carbon: graphene. Take a sheet of graphene and roll it up like a newspaper, and you get a carbon nanotube (CNT).

CNTs are nanoscale molecules made up of large numbers of carbon atoms, each bonded to three other atoms in a hexagonal (six-sided) pattern, resembling a roll of chicken wire. The pattern can be aligned with the tube's central axis, or it can be twisted. Although a CNT may reach a few centimeters in length, the entire tube is only a few nanometers across, or about 100,000 times thinner than a human hair. At this size, it behaves as if it were one-dimensional.

Promising Properties
So much for the what. But why are CNTs making headlines in fields as diverse as aerospace, opto-electronics and bio-medicine? In a word, properties. Because of their superior structural, chemical, optical and electrical properties, carbon nanotubes are among the most promising candidates for use in tomorrow's ever-shrinking technology.

Mechanically, CNTs are five to 50 times stronger than steel, even though they are incredibly small and light. They also conduct heat extremely well. But it's their optical and electrical characteristics that have many scientists and engineers proposing applications ranging from flexible electronics and photovoltaics, to sensing and fluorescent markers in life sciences.

"CNTs have potential for complementing or replacing many current technologies," said Oscar O. Bernal, NSF program director for condensed matter physics. "For instance, they could one day become the main components in lighting devices and consumer electronics. They could represent savings in energy usage and would have the advantage of being very small, allowing miniaturization beyond current limits."

Fig. 1	Fig. 2	Fig. 3

When carbon-based graphite, which in bulk, looks like the image in Fig 1 is sliced into nanoscale sheets, it becomes graphene (Fig. 2), a form of carbon whose existence was thought to be impossible until it was actually made in 2004. Roll graphene into tubes (called “nanotubes,” [Fig. 3]) and new technological possibilities arise as a result of nanoscience.

What Is Nanotechnology?

Nanoscience involves research and discovery of new principles and materials. Nanotechnology is the application of that research and those discoveries; it is the application of scientific and engineering principles to make and utilize materials at the nanoscale.

For instance, computer processor chips are currently made on a 45 nanometer process. This means that about 1000 of the tiny switches that comprise the processor chip can fit across the width of a single hair. Nanotechnology makes this possible. The circuits that run our cell phones, onboard automobile computers, iPods and almost all electronic devices are equally dependent on nanotechnology and the nanomaterials it creates. Far from exotic, today’s nanomaterials have become integral to our work, our health and our play.

Nanotechnology is being used to increase the efficiency and economic viability of solar cells.

Nanomaterials are used to add strength to composite materials used to make lightweight tennis rackets, baseball bats, and bicycles. Nanostructured catalysts are used to make chemical manufacturing processes more efficient, saving energy and reducing the waste products. A few pharmaceutical products have been reformulated with nanosized particles to improve their absorption and make them easier to administer. Opticians apply nanocoatings to eyeglasses to make them easier to keep clean and harder to scratch. Nanomaterials are applied as coatings on fabrics to make clothing stain resistant and easy to care for. Several companies make nanostructured products using space-saving insulators that are useful when size and weight is at a premium—for example, when insulating long pipelines in remote places, or trying to reduce heating losses in a leaky old house. Nanoceramics are used in some dental implants, or to fill holes in bones after removing a bone tumor, because their mechanical and chemical properties can be tuned to match those of the surrounding tissue.