Flinders' University Nanotechnology Visit.
On September 9, 2005 the SA Microprocessor Group and the SA PIC Users' Group visited the Nanotechnology group of Flinders University's School of Chemistry, Physics and Earth Sciences at its magnificant location on the slopes of the Adelaide Hills overlooking the southern Adelaide suburbs and St Vincent Gulf, only 10 Km from the Adelaide CBD. On the eve of our 30th year it was our biggest meeting for at least 20 years.
Flinders University was the first university in the world to offer courses in this exciting new field of Nanotechnology, by commencing a four year honours program in 2000. This year the Australian Government recognized their work and their promising future by awarding them the biggest grant ever made to an Australian university.
In such a fresh new field a lot of the work is pure research, but there are some industrial applications just starting to emerge, even at this early stage.
The visit was hosted by Dr Jamie Quinton and a team of volunteer research students who were:
- Paul Felici - researching organic surface treatments to reduce corrosion
- Ian MacDonald - researching carbon nanotube applications such as increasing the durability of car tyres
- Rachel Lowe - researching silicon wafers     used to identify surface features of proteins, cells, bacteria, and viruses
- Ben Flavel - researching self-assembly of materials such as polystyrene balls to help manufacture semiconductors in air at room temperature with low energy, low cost and short production times.
- Andrew Hook - researching the uses of STM and AFM microscopes    to produce images of surfaces at atomic levels.
The team first showed us through their many labs       dealing with both chemical and organic nanotech research using both wet and dry processes.
Paul was doing research to see how some organic surface treatments of metals can dramatically reduce corrosion at potentially much lower cost than using conventional plating or paints with possibly more effect than any present rust-proofing and with lower toxicity than, say, using chromates.
Nanotubes are a form of carbon (other forms are graphite and diamond) that are about 10 to 100 nanometers long, are about 100 times stronger than steel and about 1/20 of the weight. They are currently the strongest known substance. Because of the incredible strength of nanotubes, Ian is investigating their use as an additive to rubber to produce highly durable car tyres. Nanotubes are made by either electrical or chemical means. A special feature of nanotubes is their very high conductivity approaching that of superconductors that makes them attractive for semiconductor manufacture and conductive plastics. The cost of making carbon nanotubes has dropped dramatically lately to about $200 per gram, making them likely to be common-place quite soon.
In another lab Ben was researching "self assembly" of materials. He has been using polystyrene nanoparticles that self-align to form a single layer of polystyrene balls all in touch with one another allowing metal to fill the voids between them. The polystyrene is dissolved away to leave a specially textured surface. This demonstrates the possibility of using low temperature, low energy, quick, cheap alternative methods for the production of electronic integrated circuits in future.
Rachael was looking at surface treatments of silicon wafers aimed at providing a very sensitive means of quickly and cheaply detecting and identifying drugs and biological substances such as proteins, antibodies, hormones, bacteria, etc. The conductivity of the surfaces change when they are exposed to even very low concentrations of these organic substances. Wafers like these are already used to detect the early signs of cancer and other diseases.
In any area of scientific research you need to observe, measure and compare results. The Flinders University's nanotechnology school have 2 particularly interesting classes of research tools that they have built on campus as well as purchased from commercial sources. These are the STM (Scanning Tunneling Microscopes) and ultra high vacuum chambers.
Most of us have seen those amazing atomic and molecular images of materials produced with STM or the closely related AFM (Atomic Force Microscope) microscopes. IBM researchers in Germany were awarded a Nobel Prize for the STM's invention.
This image is a "quantum corral" that was made by positioning xenon atoms on nickel using the tip of a tungten probe. You can even see the standing wave patterns produced by the electron density inside the corral. Positioning atoms in this manner is known as "scanning probe lithography".
The incredibly fine tipped tungsten probes used by STM microscopes have only one atom at the tip. The tips are mechanically scanned using piezo-electric devices fitted to the probe. The probe's scanning is controlled to scan by either constant current or constant potential. Currents in the order of picoamps produced by electron tunneling produce an image as the probe scans just above the surface of the specimen. The substate needs to be an electrical conductor. Surprisingly, STMs can operate in air. The Flinders' Nanotech labs perform STM experiments in ultra high vaccuum, in special atmospheres and in air.
I was surprised how the STM was small enough and tolerant enough to vibration and temperature changes to be used on an ordinary desk top (although vibrations and temperature stability are a problem and is the reason why the STMs are located in the basement and were standing on a slab of granite). The latest STMs use built-in mechanical stabilization in their base.
If you do a Google or Vivisimo search on "STM microscopes" you will turn up many references including some fantastic images. You will also see advertisements for STMs typically costing hundreds of thousands of dollars. However, among them I found a project to produce one for under $100 at http://geocities.com/spm_stm!
Dr Jamie Quinton's special interest is the surface physics of atoms and molecules on surfaces, particularly in high vacuum chambers. Flinders have several.    .
To reach the ultra high vacuum needed for nanotech research there are at least 3 pump types used in 3 stages in sequence. The first pump is a rotary vane oil pump that reaches about 10e-7 of an atmosphere. The next stage uses a turbo molecular pump to reach about 10e-9 to 10e-10 atmospheres. The last stage uses either an electro-magnetic pump and/or a cryo-pump to reach about 10e-12. This last stage is about 4 orders of magnitude lower density than the vacuum in the space between the earth and the moon. Also, the vacuum in a TV picture tube is only about 10e-3 of an atmosphere.
Jamie said high vacuum labs are expensive with vacuum chambers easily costing ~ $million or more. Flinders have two. Jamie inherited one that was not working and he and the Flinders' workshops have successfully produced a high performance machine from it.
Special features of the high vacuum chambers are the transfer chamber, or interlock chamber, and the sample transfer arm. The interlock chamber enables samples to be placed inside with relatively little air getting in so that pumping the chamber down to 10e-8 atmospheres takes only 10 minutes compared to 2 days that opening the whole chamber would need. The other feature, the transfer arm, looks a bit like the slide on a slide trombone. It uses magnetic coupling to the outside world that enables samples to be moved around inside the vacuum chamber using external magnets interacting with magnets in the sample transfer arms.
Other features of the vacuum chambers include an electron multiplier for making measurements and an ion gun for bombarding surfaces with gases such as argon to clean or prepare some surfaces.
Jamie's particular interest at the moment is using a mass spectrometer inside the chamber to measure how strongly bound some atoms and molecules are to various surfaces while the surfaces gets heated.
After our lab tour we assembled in a lecture theatre where Dr Jamie Quinton gave us an excellent overview of nanotechnology using a dazzling Power Point presentation to fill in some more detail of what we had been looking at in the labs.
Jamie made the point that nanotechnology is largely based on the understanding, control and manipulation of surfaces at the atomic level. This often means having to deal with observations and measurements at or near one atom in diameter (or about 0.1 nanometers) making STM and AFM microscopes essential tools. In many instances there is a need for extremely high vacuum to properly study surfaces without gaseous interference or at other times use special atmospheres at various pressures.
Also, at the tiny dimensions where nanotechnology is studied, quantum physics predominates and things get very strange.
A lot of immunology and cancer research deals with the surfaces of cells, viruses, bacteria and proteins. This is another area where nanotechnology is helping. Rachael's work on silicon wafers is an example.
Jamie next described two structures presently of special interest to nanotechnologists. One is the carbon C60 molecule, better known as the Bucky Ball or Buckminster Fullerene (looks like one of Buckminster Fuller's geodesic domes, or even a soccer ball). Then there are the closely related carbon nanotubes where the carbon atoms are linked together into long molecules in single or multi-walled versions.
Dr Quinton said one possible use for Bucky Balls presently under investigation is to capture atoms such as highly toxic mercury inside the Bucky Ball structure to render the mercury atoms inert in the environment.
Carbon nanotubes have a lot of potential. Based on their very high conductivity, they may be used to make a new class of field effect transistor (FET) in future.
One of the most successful commercial Australian nanotechnology-based products that Dr Quinton told us about was zinc oxide. For some time zinc oxide has been used in sun screens to shield our skin from the damaging effects of UV rays but the problem was that it was originally highly visible (naturally white, but often with added pigments). Nanotechnology researchers have developed a method of manufacturing zinc oxide nanoparticles in sizes smaller than the wavelength of visible light (ie. less than 500 nm in diameter) so they appear transparent, yet still absorb UV rays.
Other applications being exploited commercially are scratch resistant surfaces to protect cars from getting scratched, water resistant (hydrophilic) surfaces, and photo-chromic sun glasses that darken in strong sun light. A fast acting variation of photo-chromic lenses could protect the wearer from lasers in future.
Following his talk, Dr Quinton got a lot of good questions from the audience. Some questions suggested to me that some members in the audience had been doing a bit of homework in advance of the visit - always a good idea.
I wish to take this opportunity to thank Dr Quinton and his team for generously giving up so much of their time to prepare and conduct our descent into the fascinating, wonderful, tiny world of nanotechnology that is bound to have such a strong influence in our lives in future. I can assure them that it was greatly appreciated by both our groups. I wish them and the Flinders University Nanotechnology school continued success now and into the future. Thanks also to David Warren-Smith for the photos used throughout this report.
. . . Rick Matthews