Smart implants may alleviate neurological conditions

SMART implants in the brains of people with neurological disorders could eventually help develop treatments for people with Parkinson's disease, depression and obsessive compulsive disorder.

Last week, a team from Medtronic of Minneapolis, Minnesota, reported on their design for a neurostimulator at the Engineering in Medicine and Biology Society meeting in Minneapolis. The devices use electrodes to deliver deep stimulation to specific parts of the brain.

Neurostimulators are already approved to treat conditions such as Parkinson's disease, essential tremor, and dystonia, as well as obsessive compulsive disorder. But existing devices deliver stimulation on a set schedule, not in response to abnormal brain activity. The Medtronic researchers think a device that reacts to brain signals could be more effective, plus the battery would last longer, an important consideration for implantable devices.

Tim Denison, a Medtronic engineer working on the device, says that the neurostimulator will initially be useful for studying brain signals as patients go about their day. Eventually, the data collected will show whether the sensors would be useful for detecting and preventing attacks.

Human trials are years away, but elsewhere, NeuroPace a start-up firm in Mountain View, California, is finishing clinical trials using its RNS smart implant device in 240 people with epilepsy, the results of which will be available in December, says Martha Morrell, chief medical officer at NeuroPace. An earlier feasibility study on 65 patients provided preliminary evidence that the devices did reduce seizures.

The NeuroPace device is implanted within the skull where it monitors electrical activity via electrodes implanted deep in the brain. If it spots the "signature" of a seizure, it will deliver brief and mild electrical stimulation to suppress it. Mark George, a neurologist at the Medical University of South Carolina in Charleston, says heart pacemakers developed in a similar way, as researchers learned to make them detect and react to signals from the heart. "I think it's absolutely inevitable that we'll develop a smarter, more intelligent way to figure out how and when to stimulate," George says.

Find out if we can cool the planet

OUR profligate greenhouse emissions are creating problems of planetary proportions for our descendants. Even in the best-case scenario, if we make drastic cuts in emissions soon, sea levels will rise by anything from 10 metres to 25 metres over the next few thousand years.

Faced by the loss of so much precious coastal land, it seems quite plausible that our descendants will resort to some kind of mega-project to cool the planet and stop the ice sheets melting. If so, why not do it sooner rather than later? It might save countless lives, not to mention the myriad species otherwise doomed to extinction.

There is no shortage of grand ideas for geoengineering. We could pump cooling sulphur into the atmosphere to disperse incoming sunlight, or generate reflective clouds by spraying seawater heavenwards from special ships. We might even launch an almighty flotilla of parasols into space to shade our planet from the sun.

The problem with all of these schemes is that we have little clue whether they would work. Some of the best evidence so far comes from the cataclysmic eruption of Mount Pinatubo in 1991, which obligingly conducted a large-scale experiment for us on the effect of injecting sulphur into the upper atmosphere. From a global cooling perspective, the results were encouraging: temperatures sank temporarily by up to 0.5 °C. It remains unclear, however, whether the effects of sulphur on global weather patterns can be predicted or controlled. The dangers include triggering severe regional droughts, and even destroying the ozone layer.

Faced with such dangers, it would be foolhardy to do anything yet. What we need is a concerted global research drive into the potential and pitfalls of geoengineering. It will take decades to establish which of the possibilities are feasible, effective and safe, what their costs would be, and for whom. Such a programme - encompassing modelling and small-scale experiments, as well as research into the international legal implications of such schemes - need not be expensive, says Steve Rayner of the University of Oxford. It would be small change compared with, say, what is needed to develop alternative energy technologies.

Despite that, resistance to geoengineering is considerable, and with good reason. In some quarters, geoengineering is already being promoted as an alternative to reducing greenhouse gas levels, rather than as a temporary measure for curbing warming while we get emissions under control. Cooling the planet without curbing carbon dioxide levels won't prevent ocean acidification, whose effects will include the loss of protective coral reefs as erosion outstrips reef-building.

What's more, by deploying geoengineering without also cutting emissions, we could land ourselves in a terrible trap. The higher levels of greenhouse gases rise, the more geoengineering would be required to counteract their warming effect and the longer it would have to go on for. We could suffer unexpected and disastrous side effects from geoengineering but be unable to stop for fear of worse consequences from rapid warming if we did.

That is just the kind of thing a coherent plan of research into geoengineering should investigate. Given the possibility that researchers have underestimated the scale and speed of climate change, and with emissions rising faster than ever, it would be foolish not to investigate what geoengineering might achieve. Is it our best bet for ensuring that Earth remains a benign home to future generations, or a dangerous delusion? We need to find out.

Giant crystals and spherical flames: science in microgravity

In the absence of gravity, surface tension dominates the physics of fluids. Here, in an image taken on the International Space Station, it causes water to extend from a metal loop as if it were stirred by an invisible spoon.

This stirring effect was created by using a flashlight to unevenly heat the water. The resulting temperature difference induced an imbalance in the surface tension, causing the fluid to rotate.

Such surface-tension-triggered movement, called Marangoni convection, is less obvious on Earth, but can be seen in environments such as cooling puddles of molten steel.

Extreme steel 'Velcro' takes a 35-tonne load

For all its usefulness, Velcro hardly inspires excitement. But German engineers have taken inspiration from the mild-mannered fastener to create a version of the hook-and-loop concept with enough steely strength for extreme loads and environments.

A square metre of the new fastener, called Metaklett, is capable of supporting 35 tonnes at temperatures up to 800 ºC, claim Josef Mair and colleagues at the Technical University of Munich, Germany. And just like everyday Velcro it can be opened up without specialised tools and used again.

Conventional hook-and-loop fasteners are used for everything from bandages to cable boots in aircraft and securing prosthetic limbs. Mair thinks his spring-steel fastener is tough enough to be used for building facades or car assembly. "A car parked in direct sunlight can reach temperatures of 80 °C, and temperatures of several hundred °C can arise around the exhaust manifold," he says, but Metaklett should be able to shrug off such extremes.

The fastening is made from perforated steel strips 0.2 millimetres thick, one kind bristling with springy steel brushes and the other sporting jagged spikes.

Metaklett can support maximum weight when pulled on in the plane of the strips, and a square metre can hold a perpendicular load of 7 tonnes, says Mair.