While nanotechnology has been around for many years, there continues to be more revolutionary developments using nanoscale breakthroughs. Some of the most promising innovations include new techniques in nano-based manufacturing of both devices and nanoparticles, nano-based textiles that have potential in military and battery technology applications, and new technologies that can replace traditional electronics devices with smaller, more cost-efficient options.

Nano-Based Manufacturing

Emory Chan of Berkeley Lab directs WANDA, a nanocrystal-making robot, to perform complex work-flows that traditionally require extensive chemistry experience. (Roy Kaltschmidt, Berkeley Lab)
IBM scientists have created a 3D map of the Earth so small that 1,000 of them could fit on one grain of salt. The scientists accomplished this through a new technique that uses a tiny, silicon tip with a sharp apex — 100,000 times smaller than a sharpened pencil — to create patterns and structures as small as 15 nanometers at greatly reduced cost and complexity. This patterning technique opens new prospects for developing nano-sized objects in fields such as electronics, chip technology, medicine, life sciences, and optoelectronics.

The tip, similar to the kind used in atomic force microscopes, is attached to a bendable cantilever that controllably scans the surface of the substrate material with the accuracy of one nanometer. By applying heat and force, the nano-sized tip can remove substrate material based on predefined patterns, thus operating like a “nano-milling” machine with ultra-high precision. Similar to using a milling machine, more material can be removed to create complex 3D structures with nanometer precision by modulating the force or by re-addressing individual spots.

The new technique achieves resolutions as high as 15 nanometers, with a potential of going even smaller. Using existing methods such as e-beam lithography, it is becoming increasingly challenging to fabricate patterns at resolutions below 30 nanometers, where the technical limitations of that method are reached.

Compared to expensive e-beam-lithography tools that require several processing steps and equipment that can easily fill a laboratory, the tool created by IBM scientists — which can sit on a tabletop — promises improved and extended capabilities at very high resolutions, but at one-fifth to one-tenth of the cost and with far less complexity.

Potential applications range from the fast prototyping of nano-sized devices for future computer chips, to the production of well-defined, micron-sized optical elements like aspheric lenses and lens arrays for optoelectronics and on-chip optical communication.

This 3D rendered image shows a heated nanoscale silicon tip, borrowed from atomic force microscopy, that is chiseling away material from a substrate to create a nanoscale 3D map of the world. At this size, 1,000 world maps could fit on a grain of salt. (Image courtesy of Advanced Materials).
Advances in nano-manufacturing are critical in order to mass-produce, at a cost-effective level, nano materials for a myriad of uses. Scientists at Lawrence Berkeley National Laboratory (Berkeley, CA) have taken nano-manufacturing to the ultimate automated level. They have established a revolutionary nanocrystal-making robot capable of producing nanocrystals with staggering precision. This one-of-a-kind robot provides colloidal nanocrystals with custom-made properties for electronics, biological labeling, and luminescent devices.

This robotic engineer is named WANDA (Workstation for Automated Nanomaterial Discovery and Analysis), and was developed in collaboration with Symyx Technologies at the Molecular Foundry, a U.S. Department of Energy user facility at Berkeley Lab. By automating the synthesis of these nanocrystals, WANDA circumvents the issues facing traditional techniques, which can be laborious and are difficult to reproduce from one laboratory to the next. WANDA’s synthetic prowess can help researchers sift through a large, diverse pool of materials for specific applications.

WANDA’s liquid-handling robotics prepare and initiate reactions by injecting nanocrystal precursor chemicals into an array of reactors. After a series of reactions is complete, the structural and optical properties of these nanocrystals can be screened rapidly, also using automated methods. WANDA is housed inside a nitrogen-filled chamber designed to keep oxygen and water from interacting with reactive precursor chemicals and freshly formed nanocrystals. Since the robot is controlled by software protocols, novice users can direct WANDA to perform complex workflows that traditionally require extensive chemistry experience.

WANDA has produced nanomaterials under conditions analogous to those used in traditional flask-based chemistry. Starting with nanomaterials such as cadmium selenide quantum dots, whose size can be adjusted to emit different colors of visible light, the team showed how WANDA can optimize the size, crystal structure, and luminescence properties of different nanocrystals.

“This technology will change the way nanoscience research is performed,” said Emory Chan, a senior scientific engineering associate at the Molecular Foundry. “Not only does WANDA enable the optimization and mass production of nanoparticles our users need, but this robot also facilitates experiments that give us a deeper understanding into the chemistry and physics of nanoscale materials.”

Nano-Based Technology to Replace Semiconductors

The nanotechnology-based plastic switch developed by Tel Aviv University’s Dr. Koby Scheuer for use in fiber-optic cables.
Nano-based technology created by Dr. Koby Scheuer of Tel Aviv University’s School of Electrical Engineering may make computers and the Internet hundreds of times faster — a communications technology enabler that could be in use in as little as five or ten years from now. The plastic-based technology is designed for the nanophotonics market for optical devices and components. The plastic-based “filter” is made from nanometer-sized grooves embedded into the plastic. When used in fiber-optic cable switches, the device will make communication devices smaller, more flexible, and more powerful.

Every optical device used in today’s communication tools has a filter. Whether it’s the drive reader in a laptop or the cable that brings long-distance phone calls, each system uses filters to clean up the signal and interpret different messages. In the next decade, fiber-optic cables that now run from city to city will feed directly into each individual home. When that technology comes to light, the new plastic-based switches could revolutionize communications.

The new filter uses a plastic-based switch, replacing hard-to-fabricate and expensive semiconductors, which can take days or months to manufacture. The plastic polymer switches come in a liquid solution. Using a method called “stamping,” almost any lab can make optical devices out of the silicon rubber mold, which is scored with nano-sized grooves, invisible to the eye and each less than a millionth of a meter in width. A plastic solution can be poured over the mold to replicate the optical switch in minutes. When in place in a fiber-optic network, the grooves on the switch modulate light coming in through the cables, and the data is filtered and encoded into usable information.

The device can also be used in airplane, ship, and rocket gyros; inserted into cell phones; and made a part of flexible virtual reality gloves so doctors can “operate” on computer networks over large distances.

Making the Common T-Shirt a Super-Textile

A simple cotton T-shirt may one day be converted into tougher, more comfortable body armor for soldiers or police officers thanks to a development by researchers at the University of South Carolina. They have increased the toughness of a T-shirt by combining the carbon in the shirt’s cotton with boron. The result is a lightweight shirt reinforced with boron carbide, the same material used to protect tanks.

Stanford University’s recipe for conductive textiles: Dip cloth in nanotube ink, dry in oven for 10 minutes at 120 °C.
The scientists started with plain, white T-shirts that were cut into thin strips and dipped into a boron solution. The strips were later removed from the solution and heated in an oven. The heat changes the cotton fibers into carbon fibers, which react with the boron solution and produce boron carbide. The result is a fabric that’s lightweight, tougher and stiffer than the original T-shirt, yet flexible enough that it can be bent. That flexibility is an improvement over the heavy boron-carbide plates used in bulletproof vests and body armor.

The boron-carbide bulk material currently in use is brittle. In contrast, the boron-carbide nanowires synthesized by the scientists keep the same strength and stiffness of the bulk boron carbide, but have super-elasticity. Much tougher body armors could be fabricated using this new technique. It could also be used to produce lightweight, fuel-efficient cars and aircraft. The resulting boron-carbide fabric can also block almost all ultraviolet rays.

Stanford University researchers also are working with the common T-shirt, creating batteries and simple capacitors from ordinary textiles dipped in nanoparticle-infused ink. The conductive textiles, called “eTextiles,” represent a new class of integrated energy storage device, born from the synthesis of prehistoric technology with cutting-edge materials science.

While conventional batteries are made by coating metallic foil in a particle slurry and rolling it into compact form, the new eTextiles were manufactured using a simple dipping and drying procedure, in which a strip of fabric is coated with a special ink formula and dehydrated in the oven. The procedure works for manufacturing batteries or supercapacitors, depending on the contents of the ink: oxide particles such as LiCoO2 for batteries, and conductive carbon molecules (single-walled carbon nanotubes) for supercapacitors.

The lightweight, flexible, and porous character of natural and synthetic fibers has proven to be an ideal platform for absorbing conductive ink particles. That helps explain why treated textiles make such efficient energy storage devices. A piece of eTextile weighing about 10 ounces (the approximate weight of a T-shirt) could hold up to three times more energy than a cell phone battery.

The potential applications of wearable power range from health monitoring to moving-display apparel. Large companies have expressed an interest in developing reactive, high-performance sportswear using the new technology, and the U.S. military is looking at integrating energy textiles into its battle array, a move that may one day lighten a soldier’s carrying load.


NASA Tech Briefs Magazine

This article first appeared in the June, 2010 issue of NASA Tech Briefs Magazine.

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