could make it possible for us to wear all kinds of smart gear. But such things always need a source of power, and that's usually batteries. If the battery doesn't stretch then there's a problem. A team at Northwestern University are on track to solve that problem with a battery that can stretch to 3 times its size without a loss in performance, and also be charged by induction.

The battery, which resembles a sticking plaster, uses islands of energy-storing materials dotted on a stretchy polymer. The wires that connect the pockets of power are looped into S shapes, so they straighten out as the material stretches. Unfortunately the prototype only runs through 20 charge and discharge cycles, so there's a bit of development yet to do. Get ready to wear your smartphone.

HIGH-FLYING PLASTIC: Flying a single engine Cessna from Sydney to London is quite a feat, but Jeremy Rowsell will be doing it on his own, and using an unconventional and untested fuel. Rather than standard aviation fuel, he'll be using a fuel that's made only from recycled plastic waste. His purpose is to raise awareness about this type of fuel, along with breaking a record or two. If all that waste plastic can be turned into something useful then why aren't we doing it already?


MORE LIGHT AND HEAT: Supermarkets use nearly 10 times as much energy as a normal household. They need to keep food frozen or just cool, shoppers pleasantly warm and the store well-lit. Fraunhofer Institute has developed ways to cut the power bills by 25%, mainly through clever systems for dealing with heating, cooling and light. A combined central refrigeration system takes waste heat from freezers and uses it to warm the store. Surplus heat is turned into cool air through a geothermal heat pump and used to reduce the power required for chillers. Meanwhile, to reduce the energy needed for lighting they had the novel idea of installing windows in the roof. They did fit the skylights out though with microscreens that allow only indirect light to pass through. I bet shoppers spend more under natural light too.

A NEW LIGHT: Retinitis pigmentosa and other diseases cause the eye's photoreceptors to degenerate and eventually die, which means the person goes blind. Retina Implant, a German company, has developed an artificial retina that may restore some vision. The artificial retina is a 3 millimeter square chip that contains 1,500 photodiodes. Light strikes the diodes which then give off a weak electrical signal. That signal's boosted to allow the wearer to see. A battery behind the ear provides the power. In a study most patients had some limited vision restored, being able to see cutlery, letters, their own hands or the faces of family members. Presumably more diodes means better vision.

A SOUND SUIT: The SpiderSense suit from the University of Illinois uses ultrasonic reflections to alert the wearer to nearby objects or people. The suit has microphones embedded, so when the ultrasound detects someone approaching small robotic arms in the suit exert a growing pressure on the body. The wearer can then feel the pressure and avoid the approaching object. In tests wearers were able to detect someone approaching 95% of the time. With more sensors the suit could have a higher resolution. The creators believe a device like this could be useful for cyclists or for blind people. Is that other 5% you have to worry about.

Miraz Jordan,