Harvesting Energy from the Sun
Rising oil prices and the threat of global warming have rekindled the search for alternative sources of energy. While we reported this year on the growing acceptance of nuclear power as a source of clean energy, we also described several advances in nanotechnology that may pave the way for more practical solar power. Konarka of Lowell, MA, has pushed forward its “roll-to-roll” solar cell technology, which is based on nanoparticles embedded in a film. While its cells aren’t as efficient as conventional ones, they are made using an inexpensive process. The lower price tag, combined with the cells’ flexibility, could make solar power available in more places, including the windows of buildings and fabrics for tents, handbags, and other items. We also reported on the use of nanowires for capturing the energy of the sun, which could lead to higher efficiency from inexpensive cells.

The Lithium Economy
Light lithium-based batteries can pack quite a punch – so much so that they’ve been too dangerous to group together in high-power applications, such as cordless drills and hybrid cars. Now, thanks to computer modeling that identifies promising new battery materials, this is no longer the case. This year we saw the introduction of lithium ion battery packs in cordless tools, and 2006 will bring more such applications, as well as a move toward lighter, more powerful hybrid cars. Eventually, materials monitoring could lead to batteries with enough power and energy density to make electric cars practical – and a pleasure to drive. Because lithium batteries don’t have the distribution problems inherent in hydrogen, batteries could beat out fuel cells in the cars of the future.

Toward Self-Assembling Devices
A nanotech dream is the “one-pot” synthesis: combine raw materials, mix, bake – and out comes a working device made from nanoscale parts. Such a synthesis technique wouldn’t require as much energy as the high-temperature reactions in the semiconductor industry today. It would also dramatically cut down on the use of dangerous solvents and the production of waste materials. And it would also be cheap. Angela Belcher at MIT is directing the evolution of viruses and yeasts to make such self-assembly possible. Others hope to use diatoms as templates for nanodevices. In our current Technology Review magazine (Dec. 2005/Jan. 2006) we describe a nanomachine that could help assemble single-molecule memory devices.

Nanomedicine
This year saw the advance of fantastically sensitive nanosensors capable of detecting disease at its earliest stages – when it can still be treated. Charles Lieber and Xiaowei Zhuang, chemistry professors at Harvard, demonstrated that nanowires could be used to detect a single viral particle. An array of such detectors might be able to screen almost instantly for as many as one hundred different viruses at once – a boon for doctors diagnosing disease or a country defending against biological attacks.

Nanosensors might also sniff out cancer earlier and with more precision than current tests. High sensitivity means only a small blood sample is needed – comparable to the fingerprick used by diabetics to monitor glucose levels. Such a test could be invaluable for people with a family history of disease, for example, either to quickly identify the need for treatment or to set their minds at ease that they are healthy. The tests themselves might be inexpensive and so easy to use that they could be bought over the counter at a drugstore. We reported on the work of Charles Lieber at Harvard and James Heath, a physical chemist at the California Institute of Technology, developing such sensors.

Nanoscale particles could also be used as a core delivery device for the detection, imaging, and targeted and personalized treatment of cancer. This has the potential of transforming cancer treatment, killing more tumors, while at the same time eliminating the usual side effects of chemotherapy or radiation therapy. James Baker, a physician and professor at the University of Michigan, has developed a delivery system that could make it into human trials next year.

Universal Memory
While self-assembly might one day transform computer manufacturing, more near-term applications are likely to come from hybrid solutions that combine new nanoparticles and existing fabrication techniques. This path is being followed by Nantero, a company that has created a process for making so-called universal memory. This type of computer memory could store information without a continuous source of power, similar to the flash card in a digital camera, yet access it very quickly, like the memory inside a PC. Nantero’s technique incorporates nanotubes into traditional semiconductor fabrication processes. The company says partners using the nanotube technology will make announcements about actual products in 2006.

Nano and the Environment
Nanotechnology is leaping technical hurdles – but ultimately its success will depend on winning over consumers. And that will mean assuring the public that nano-scale materials are safe. The very aspects that make nanotechnology so exciting – novel properties emerging at this scale and the ability to subtly and precisely modify these properties, with such dramatic results – raise questions about how these new substances will behave in the environment, including the human body. This year there have been growing efforts to discover the environmental and health effects of nanomaterials. Now many nanotech proponents say that the coming year will be a critical window of opportunity for demonstrating that researchers and industry take safety concerns seriously. It will be a time to find and deal with any existing problems – before they become dire-sounding headlines. However, whether 2006 will also bring the increased organization, cooperation, and funding needed to make this oversight happen remains an open question.