Sensors Mag

March R&D Round Up

March 1, 2013 By: Melanie Martella, Sensors

E-mail Melanie Martella

This month we have sensor fusion used to markedly improve GPS precision, better sealing for electronics operating in extreme environments, and a new visualization tool for firefighters.

Urban GPS Readings Get a Boost
GPS receivers rely on their ability to receive a signal from multiple satellites to provide location information; and that's all fine and good while you're on the open road, or tooling across the plains, but it's a lot harder to achieve in the urban canyons of cities where pesky things like tall buildings impede reception and the GPS's idea of where your car actually is can be off by a rather large margin. Spanish researchers from the Universidad Carlos III de Madrid (UC3M) in the Applied Artificial Intelligence Group (GIAA—Grupo de Inteligencia Aplicada Artificial) and the Systems Intelligence Laboratory (LSI—Laboratorio de Sistemas Inteligentes) have developed a system that can boost the location precision of a GPS system by 90% by using inertial sensors, GPS data, (and data fusion). The news article, "A system that improves the precision of GPS in cities by 90 percent," explains the project, as well as the next step, which is to apply the same kind of data fusion approach but using the GPS and sensor suite in a smartphone. I can't wait!

Sealing Sensors
The sensor that tells you whether your computer is overheating is not the same as the sensor providing the temperature down an oil well; for starters they experience wildly different environments. Those users who need sensors capable of operating in conditions that are hostile to electronics rely on carefully designed housings and effective seals to protect the sensing element and electronics within. For example, MEMS temperature, pressure, and vibration sensors intended for use in such environments are typically hermetically sealed in a stout metal casing, sealed in with solder. Researchers at Singapore's A*STAR Institute of Microelectroncis exploring cheaper and more durable alternatives to the metal solders typically used to seal the devices have discovered an aluminum-germanium alloy that is compatible with MEMS manufacturing processes and results in a very robust seal. The researchers alternated extremely thin wafers of the two metals, heated them up to bond the layers, then bumped the temperature up to 475°C to melt the mixture; when cooled the resulting seal could withstand a shear of 46 MPa, was impermeable to water, and could withstand long exposures to 300°C without losing much of its strength. Not bad! For more details, read the news article, "Microelectronics: A tougher seal for rugged environments".

Seeing Through the Smoke
One of the many things that the producers of TV Series Rescue Me did well was to convey just how disorienting and difficult navigating through a house fire can be. It's one thing to know intellectually that the smoke will be thick and choking, it's another to understand what that means in practical terms. Thermal imagers can give firefighters some information, where the sensitive detectors can distinguish between warm bodies and cooler backgrounds. If they're trying to see through flames, the flames act as a too-potent source of IR and the detectors can be overwhelmed. Italian researchers at the Consiglio Nazionale delle Ricerche (CNR) Istituto Nazionale di Ottica have developed a lens-free imaging system that uses IR holography to enable IR imaging through smoke and flames this and the Optical Society article, "Infrared Digital Holography Allows Firefighters to See Through Flames, Image Moving People" is a must-read, with excellent illustrations and explanations. Briefly, what the researchers have done is to send a beam of IR laser light into a room where it can pass through any smoke and flames unhindered. However, the light will be reflected by any objects (walls, furniture, people) in the room and this reflected light is recorded by a holographic imager. The imager then converts that data into a live, 3D movie of the area.

About the Author: Melanie Martella

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