Crowdsourcing ideas

What if you could use a lensless, portable microscope to detect microbes in the air? This did not occur to the designers of the apparatus, which cost hundreds of thousands of pounds to develop but was lying unused in a storeroom at Oxford University. But it did occur to James Dash, a 15-year-old pupil at John Hampden Grammar School in High Wycombe, Buckinghamshire. His winning proposal was one of 51 entries in a competition run by Marblar, a website for crowdsourcing ideas.

CyMap, researchers’ name for the device, is one of countless clever gizmos and techniques mothballed as solutions in search of a problem. An estimated 95% of all technologies coming out of universities never make it to the real world. Marblar, which was launched in September by a bunch of PhD students in Britain, aims to harness the collective imagination to prevent such waste. Other ongoing competitions invite people to come up with uses for a new kind of foam, a probe inspired by a wasp sting or paint-guns to squirt layers of paint just few molecules across.

The original inventors pay a small fee to post a challenge on Marblar’s website, using videos and slideshows to explain in plain English how their technology works. Geeks of all ages then submit their ideas about what it might be used for. Other users rate these before the inventors themselves pick the winner, who typically receives a cash prize of about £500 ($800). In future, says Daniel Perez, one of Marblar’s co-founders, winners may be invited to partner with the inventors and gain a stake in the commercialisation of their joint intellectual effort.

Marblar will not eliminate all waste. Many inventions have straightforward uses, says Lita Nelsen, director of the (rather busy) technology-licensing office of the Massachusetts Institute of Technology, all they need is better marketing. This is something technology transfer officers, often business-minded boffins who are able both to identify prospective licensees and explain the research to a non-scientist, may be better placed to do.

But Marblar is definitely onto something. IP group, a British venture-capital firm that invests in innovations spun out of universities, has ploughed about $600,000 into the start-up. It is already considering creating a company to commercialise a technology to glue strands of DNA without using an enzyme. In another challenge, a PhD student from Cambridge noticed that this is just the sort of thing he needed in his work on novel methods for drug delivery.

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Image credit: Marblar

A revolution in lens-making

Understanding of optics has changed no end since the world’s oldest known lens was ground nearly 3,000 years ago in modern-day Iraq. Yet its Assyrian maker would instantly recognise today’s lenses, which continue to be made much as they were then: by fashioning a piece of transparent material into a solid with curved surfaces. Just as invariably, the curves introduce optical aberrations whose correction requires tweaking the lens’s geometry in complicated ways. As a consequence, lenses remain bulky, especially by the standards of modern electronics.

Enter Federico Capasso, of Harvard University. He and his colleagues have created a lens that is completely flat and the width of two human hairs. It works because its features, measured in nanometres (billionths of a metre), make it a “metamaterial”, endowed with some weird and useful properties.

According to the laws of quantum mechanics, a particle of light, called a photon, can take literally any possible path between source A and point B. However, those same laws stipulate that the path of least time is the most likely. When a photon is travelling through a uniform medium, like a vacuum, that amounts to a straight line. But although its speed in a vacuum is constant, light travels at different (lower) speeds in different media. For example, it moves more slowly in glass than it does in air. So in a medium composed of both air and glass, light’s most likely path from A to B will depend on the thickness of glass it needs to traverse, as well as the total distance it needs to cover. That means that the light may sometimes prefer to bend. This is the quantum-mechanical basis of refraction.

In order to maximise the probability that photons from A will end up precisely at B, those going in a straight line need to be slowed down relative to those taking a more circuitous route, so that, in effect, all hit B the same time. This can be done by forcing the former to pass through more glass than the latter. The result is a round piece of glass that is thick in the middle, where the straight-line path crosses, and tapers off towards the edge, where the less direct routes do—in other words, a focusing lens, with its focal point at B.

Dr Capasso’s lens, described in Nano Letters, also slows photons down. But instead of using varying thickness of glass to do the job, he and his team created an array of antennae which absorb photons, hold on to them for a short time and then release them. In order for this trick to work, though, the distance between the antennae has to be smaller than the wavelength of the light being focused. In Dr Capasso’s case that means less than 1,550 nanometres, though he thinks that with tweaking it could be made to work with shorter-wavelength visible light, too.

Creating the array involved coating a standard silicon wafer, 250 microns thick, with a 60-nanometre layer of gold. Most of this layer was then stripped away using a technique called electron-beam litography, leaving behind a forest of V-shaped antennae arranged in concentric circles. By fiddling with their precise shape, after much trial and error, antennae lying on different circles could be coaxed into holding on to the photons for slightly different lengths of time, mimicking an ordinary glass lens. The whole fragile system can be sandwiched between two sheets of transparent material to make it more robust.

At present the new-fangled lens only works for monochromatic light and so is unlikely to replace the glass sort in smartphone cameras anytime soon. But it could revolutionise instruments that rely on single-colour lasers, by making further minaturisation possible while eliminating the optical aberrations inherent to glass lenses. Such devices include laser microscopes, which are used to capture high-resolution images of cells, or optical data storage, where a more accurate and smaller lens could help squeeze more information into ever less space.

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  1. Capasso et al., Aberration-Free Ultrathin Flat Lenses and Axicons at Telecom Wavelengths Based on Plasmonic Metasurfaces, Nano Letters2012.
  2. Capasso et al., Light Propagation with Phase Discontinuities: Generalized Laws of Reflection and Refraction, Science2011.

Also appeared in The Economist. Also available in audio here.

Image credit: Francesco Aieta

The evolution of venom: Poison pill

The bite of a rattlesnake can, within minutes, cause paralysis and extensive internal bleeding. If untreated it can kill. It might also hold the key to treating high blood pressure, heart diseases and stroke. In 1998 two drugs to prevent heart attacks, derived from rattlesnake and viper venoms, were approved. Since then a number of other venom components have proved effective against some varieties of cancer and brain disorders like Alzheimer’s or Parkinson’s, but gaining regulatory approval has proved tricky. Part of the reason is that it is difficult to tweak toxins such that they preserve their medicinal effects but lose their nefarious ones, like stanching blood flow or numbing the nervous system.

Now, though, Wolfgang Wüster, of Bangor University, in Britain, and his colleagues have stumbled on an evolutionary mechanism that might make such modifications easier in future. Dr Wüster was investigating venomous snakes and lizards to understand what they had in common. They differ in many respects—most venomous lizards, for instance, have fangs in the lower jaw, whereas snakes have them in the upper jaw. But in 2005 Bryan Fry of Sydney University found that snakes and lizards in fact share venom-making genes, suggesting that both share a venomous reptilian ancestor.

Whereas Dr Fry looked only at selected venom-making genes, Dr Wüster had the luxury of complete genetic data for different snake and lizard species. This allowed him to check if venom-spitting reptiles possess other shared genetic traits, too. As he and his team report in Nature Communications, they do.

These include genes to produce enzymes that perform some basic physiological functions. Intriguingly, some of these housekeeping genes were sitting among venom-producing ones. Venom genes are known to have evolved from more innocuous sorts, but it was thought that all the genes in a particular stretch of DNA assumed the venom-producing function. To find some that did not, therefore, posed a quandary. Were the innocuous genes among the insidious ones simply evolutionary relics? Were they evolved versions of the original innocuous genes that, unlike their venom-producing neighbours, remained innocuous? Or did they in fact evolve from venom genes that had lost their venom-producing prowess?

To help decide the matter, Dr Wüster ran a computer model to trace the genes’ evolutionary histories. This revealed that the third scenario was the most likely. Moreover, it seems that certain housekeeping genes turned into venom-producing ones and back again several times in reptiles’ genetic past. This means that the venom-producing genes and the housekeeping variety nested among them are genetically similar. As such, they produce proteins which are themselves alike in many respects, but not necessarily in their ability to do harm.

Practical applications of this knowledge are not an immediate prospect. But by understanding what makes a venom protein venomous researchers may get a better idea of how to remove the unwanted sting. That is one trick drugmakers would love to be able to pull of.

First published on

Image credit: The Economist