— Tooth decay often goes undetected until too late. Early signs of damage are usually hidden from sight and it is unhealthy to take too many X-rays.
Now researchers working for the National Institutes of Health (NIH) in the US have discovered that infrared light with a wavelength of 1310 nanometres - can pass straight through a tooth, providing a safe and simple way to probe for hidden decay.
Most light frequencies bounce off enamel, meaning they cannot probe below the surface. But the NIH research found that, for a narrow band of infrared, reflection is 30 times less than normal.
An infrared diode shines light through a tooth and a Charge-Coupled Device (CCD) sensor on the other side measures the light that passes through. Any decay inside the tooth creates small pores that scatter the infrared light, causing a dark shadow to appear in the resulting image.
The image quality could be further improved by polarising the infrared light before sending it through a tooth, the researchers suggest. This is because any hidden pores should also depolarise this light, making for better image contrast.
Tests show that an infrared diode can shine light through 5 millimetres of enamel, providing an image as clear as an X-ray, but without exposing the patient to harmful radiation.
Read the full tooth decay probe patent application.
Full body freshener
Imagine stepping off a long-haul flight feeling clean and refreshed rather than grubby and exhausted.
Four German inventors working for Airbus Deutschland have filed an application for a "refreshment cell" that would spruce up economy travellers as well as privileged, first class ones. Instead of making passengers wet with water, as in a shower, the Airbus system would freshen them up with dry air.
Earlier this year, Boeing filed a patent for an in-flight shower that bathes passengers in water mist (see Mile-high showers. But the Airbus system promises to be easier to use, as passengers would not need to undress.
A small chamber, like a toilet, would have a chair on a slow-moving turntable, surrounded by several air jets. A passenger could sit in the chair and press a touch-screen panel to start it turning while each jet blast out a stream of high pressure air.
The air temperature could cycle between warm and cool, with the passenger's choice of added scents. Loudspeakers might also play the sound of breaking waves while ambient lights also slowly change colour, the inventors suggest.
Read the full full body freshener patent application.
Flying surveillance 'skeets'
Political demonstrators and unruly sports crowds beware. Roke Manor, the high-tech UK research lab owned by Siemens of Germany, is developing a simple surveillance system that could be quickly deployed to monitor their movements.
It involves launching compact, saucer-shaped sensor systems into a crowd from the back of a truck. These surveillance "skeets" are moulded from tough plastics and contain a range of covert surveillance tools from fish eye cameras and microphones to a GPS receiver that pinpoints its location. Antennas, stowed for flight, quickly pop-up when one hits the ground.
Cellphone sensors could also use signals broadcast by ordinary cellphone masts to monitor objects in a similar way to radar (see Cellphone 'radar' tracks traffic flow). By monitoring subtle changes in the strength of these cellphone signals, the devices could together monitor the movements of a crowd, the inventors claim.
Each sensor system would send collected data back to a police station or security centre via a cellphone network. The saucers would be camouflaged and, if someone tampers with one, the unexpected motion should trigger an alarm back at base. The systems could perhaps even be used to look for survivors in disaster zones, the inventors say.
Read the full flying surveillance 'skeets' patent application.
For more than 30 years, Barry Fox has trawled through the world's weird and wonderful patent applications, uncovering the most exciting, bizarre or even terrifying new ideas. Read previous Invention columns, including:
Laser healing, throwable game controllers, Microwave oven gun, Smart-card DVDs, Smart night scope, laser microphone, triple-standard DVD, ultimate body armour, Long-range stunner, tongue-o-vision, jellyfish injections, Flesh-burn sensor, fire-escape tubes, VoIP mangling, in-flight rearming, sense that fat, Designer speakers, throw-away parachutes, password-protected bullets, spinning touchdown, palmtop Feng Shui, Origami gadgets, mile-high showers, Hydrogen fuel balls, human cannonballs, the riot slimer, the bomb jammer, Apple's all-seeing screen, the TV-advert enforcer, the wing-sprouting drone, the drink-driver arm scanner, laser spark plugs, remote-controlled implants,the "I've been shot" gun, the snore zapper, the guitar phone, explosive-eating fungus, viper vision, exploding ink, the moody media player, the spy-diver killer, preventing in-flight interference, the inkjet-printer pen, sonic watermarks, the McDownload, hot-air plane, landmine arrows, soldiers obeying odours, coffee beer, wall-beating bugging, eyeball electronics, phone jolts, personal crash alarm, talking tooth, shark shocker, midnight call-foiler, burning bullets, a music lover's dream, magic wand for gamers, the phantom car, phone-bomb hijacking, shocking airport scans, old tyres to printer ink and eye-tracking displays.