Quantum dots lined up in a stripy nanorod using strain forces. Nice pictures of some very small but very pretty stuff in this one from 19 July 2007:
Striped nanorods feel the strain
Stripy nanorods containing evenly spaced quantum dots have been prepared thanks to strain forces, report US nanochemists.
This is the first time that strain has been used to construct a '1D superlattice' of this sort without the need to fix the particles to a solid surface, said lead author Paul Alivisatos at the University of California at Berkeley. The free-standing colloidal particles 'can go where particles on a substrate can't go,' explained Alivisatos, opening up a host of biological and other applications.
Read the full story hereAll the colours of the rainbow from magnetic photonic crystals, 13 July 2007:
Colourful Colloids
A simple mixture of iron oxide, a polymer and water can take on any colour simply by applying a magnetic field, US researchers report.
Team leader Yadong Yin of the University of California, Riverside, said that the photonic crystals, closely packed arrays of magnetic colloids, could provide a low-cost route to materials for display screens.
Read more here
I've written about two devices for dispensing tiny drops of liquid. One is capable of injecting miniscule volumes into individual cells, while the other (the world's smallest) can be used to watch the 'dance' of atoms as they crystallise:
Attosyringe shows potential (from 10 July 2007)
US electrochemists have given hope to biologists who want to inject precise and tiny volumes of fluids into living cells. They have developed a syringe that delivers attolitre (10-18 l) volumes.
Michael Mirkin of Queens College, City University of New York, used electrochemistry to control flow into and out of a glass 'needle'. The technique was used to inject fluids into living cellsread more about the attosyringe here
Smallest pipette delivers zeptolitre volumes (from 16 April 2007)
The world's smallest pipette has been developed by US scientists. It is capable of dispensing drops of a molten gold-germanium alloy with a volume of a few zeptolitres, that is, a billionth of a trillionth of a litre. Watching these tiny drops led Eli and Peter Sutter of the Brookhaven National Laboratory, New York to make observations that challenge the classical theory of crystallisation.
Read more about the zeptopipette here
It's all very well making devices that are millions of times thinner than a human hair,
but how much do they weigh? I hear you ask! The scientists behind this story from 29 January 2007 can tell you:
Nanocantilever sets new mass detection record
US scientists have built a device capable of detecting masses as small as 1 attogram (1 x 10-18 g) at ambient temperature and pressure. This sets a new record for detection under these conditions, they claim. Previous devices have required high vacuum and low temperature in order to achieve comparable sensitivity.
The tiny cantilever a few hundred nanometres across vibrates like a diving board. When an object rests on the 'diving board' the frequency at which it vibrates changes in proportion to the mass of the object.
Physicists are getting very excited about graphene, a one-atom thick sheet of graphite. It has some amazing properties but when you make it into a nano-drum, I get excited too (from 25 Jan 2007):
Graphene resonator drums up interest
Drum roll please. US scientists have created a one-atom-thick membrane that resonates like a drumskin. Paul McEuen and co-workers at Cornell University, New York, US, stretched a single sheet of graphene - the hexagonal layer of carbon atoms found in graphite and carbon nanotubes - over a trench etched into a silicon dioxide surface.
No sign of a nano-drumstick though: the researchers 'beat' the drum with a voltage or a laser matched to the natural resonant frequency of the graphene sheet. The resonators are ideally suited for mass, force and charge sensing,Read more about the nano-drumskin here
All these things are mind-bendingly small, but I think being able to actually see them is even more incredible. Check out the UKs most powerful microscope, launched 20 Oct 2007. I was there. I saw atoms. Wow.
UK researchers unveil country's most powerful microscope
For the first time in the UK, researchers will be able to ‘see’ atoms and the bonds between them, thanks to the country’s most powerful commercially available electron microscope. The London Centre for Nanotechnology, this week unveiled its brand new monochromated scanning transmission electron microscope (STEM) at Imperial College, London, UK. It is the only Monochromated electron microscope in the UK, and there are only a handful in the world.
The Titan will be used in a range of projects, including an investigation of bone structure. ‘It came as revelation to me that on the atomic scale, bone is not well understood,’ said David McComb, reader at the department of materials at Imperial, who has overseen the installation of the £3 million facility. McComb hopes this will be ‘a good starting point’ from which to understand how osteoporosis develops.
Need a battery for your nanobot? This flexible source of electricity could be harnessed to drive molecular devices (from 11 Aug 2006):
Nanomachines power up with piezoelectricityNanomachines sound like a great idea, but where is the nanobattery to power them? The problem could be solved with piezolelectric nanowires (NWs), tiny strips of matter a few atoms wide that give out electricity when they are flexed.
US researchers have caused a series of zinc oxide (ZnO) NWs to bend by dragging the tip of an atomic force microscope (AFM) over a vertical array of NWs on a conducting surface. The strained NWs gave out an electric current which could be detected by the AFM. Once the tip passed over the wires and they sprung back to their upright position, the current returned to zero.
read more hereAnd finally, you can't get a switch much smaller than a single molecule (from 8 August 2006):
Single molecule makes electronic switch
A single molecule, trapped between two electrodes, acts as a switch and has a ‘memory’ of the type used in data storage, Swiss and US researchers have found.
Heike Riel of IBM’s research labs in Zurich says this is ‘a step along the way’ to making nanoscale electronic components a reality.
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