Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Sensor could detect concealed weapons without X-rays

02.08.2005


A new sensor being patented by Ohio State University could be used to detect concealed weapons or help pilots see better through rain and fog.



Unlike X-ray machines or radar instruments, the sensor doesn’t have to generate a signal to detect objects – it spots them based on how brightly they reflect the natural radiation that is all around us every day.

There is always a certain amount of radiation – light, heat, and even microwaves – in the environment. Every object – the human body, a gun or knife, or an asphalt runway – reflects this ambient radiation differently.


Paul Berger, professor of electrical and computer engineering and physics at Ohio State and head of the team that is developing the sensor, likened this reflection to the way glossy and satin-finish paints reflect light differently to the eye.

Once the sensor is further developed, it could be used to scan people or luggage without subjecting them to X-rays or other radiation. And if the sensor were embedded in an airplane nose, it might help pilots see a runway during bad weather.

The Ohio State sensor isn’t the only ambient radiation sensor under development, but it is the only one Berger knows of that is compatible with silicon – a feature that makes it relatively inexpensive and easy to work with.

Berger describes the sensor in the current issue of the journal IEEE Electron Device Letters. His coauthors include Niu Jin, who performed this work for his doctorate at Ohio State and is now at the University of Illinois at Urbana-Champaign; Ronghua Yu and Sung-Yong Chung, both graduate students at Ohio State; Phillip E. Thompson of the Naval Research Laboratory; and Patrick Fay of the University of Notre Dame.

Berger said that the new sensor grew out of his team’s recent invention of a device called a tunnel diode that transmits large amounts of electricity through silicon.

He was reading about another team’s ambient radiation sensor when he realized that their device worked like one of his diodes -- only in reverse.

“It’s basically just a really bad tunnel diode,” he explained. “I thought, heck, we can make a bad diode! We made lots of them back when we were figuring out how to make good ones.”

As it turns out, a really bad tunnel diode can be a really good sensor.

Diodes are one-way conductors that typically power amplifiers for devices such as stereo speakers. Berger’s diode is unique because it is compatible with mainstream silicon, so computer chip makers could manufacture it cheaply and integrate it with existing technology easily.

The new sensor is essentially one of these tunnel diodes with a strong short circuit running backwards and very little tunneling current running forwards.

Thompson prepared the films of layered semiconductor material, and the Ohio State team fabricated and tested the sensors.

The way engineers measure the effectiveness of such sensors is to draw a line graph charting the amount of current passing through them. Then they measure the curvature of the line at the point where the current is zero. A steep curve indicates that a sensor is working well, so the higher this so-called “curvature coefficient” is, the better.

In the laboratory, prototypes of the Ohio State sensor averaged a curvature coefficient of 31. While one other research team has produced a sensor with a coefficient of 39, that sensor is made of antimony – an exotic metal that is hard to work with and not directly compatible with the silicon circuit that surrounds the sensor element, Berger pointed out.

“So our raw sensor performance isn’t quite as good, but our ultimate performance should be superior because you could integrate our device directly with any conventional microchip readout circuitry that you wanted to build,” he said.

The team that is making the antimonide sensor has succeeded in combining it with a camera system; the pictures look a lot like X-ray images, with bodies and clothing appearing as dim outlines and metal objects such as guns standing out in sharp relief.

That camera system has performance issues that Berger thinks could be solved with his silicon-compatible design. Still, the image has inspired him to think big about where his work could go in the future. Combat pilots, for instance, could potentially use this technology to stealthily identify other aircraft as friend or foe.

“If you got a fast enough response and a high-resolution image, I wonder if you might be able tell one kind of aircraft from another without revealing your location to the enemy,” he said.

The National Science Foundation and the Office of Naval Research funded this work.

Paul Berger | EurekAlert!
Further information:
http://www.osu.edu

More articles from Power and Electrical Engineering:

nachricht Neuron and synapse-mimetic spintronics devices developed
17.04.2019 | Tohoku University

nachricht New discovery makes fast-charging, better performing lithium-ion batteries possible
16.04.2019 | Rensselaer Polytechnic Institute

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Quantum gas turns supersolid

Researchers led by Francesca Ferlaino from the University of Innsbruck and the Austrian Academy of Sciences report in Physical Review X on the observation of supersolid behavior in dipolar quantum gases of erbium and dysprosium. In the dysprosium gas these properties are unprecedentedly long-lived. This sets the stage for future investigations into the nature of this exotic phase of matter.

Supersolidity is a paradoxical state where the matter is both crystallized and superfluid. Predicted 50 years ago, such a counter-intuitive phase, featuring...

Im Focus: Explosion on Jupiter-sized star 10 times more powerful than ever seen on our sun

A stellar flare 10 times more powerful than anything seen on our sun has burst from an ultracool star almost the same size as Jupiter

  • Coolest and smallest star to produce a superflare found
  • Star is a tenth of the radius of our Sun
  • Researchers led by University of Warwick could only see...

Im Focus: Quantum simulation more stable than expected

A localization phenomenon boosts the accuracy of solving quantum many-body problems with quantum computers which are otherwise challenging for conventional computers. This brings such digital quantum simulation within reach on quantum devices available today.

Quantum computers promise to solve certain computational problems exponentially faster than any classical machine. “A particularly promising application is the...

Im Focus: Largest, fastest array of microscopic 'traffic cops' for optical communications

The technology could revolutionize how information travels through data centers and artificial intelligence networks

Engineers at the University of California, Berkeley have built a new photonic switch that can control the direction of light passing through optical fibers...

Im Focus: A long-distance relationship in femtoseconds

Physicists observe how electron-hole pairs drift apart at ultrafast speed, but still remain strongly bound.

Modern electronics relies on ultrafast charge motion on ever shorter length scales. Physicists from Regensburg and Gothenburg have now succeeded in resolving a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

First dust conference in the Central Asian part of the earth’s dust belt

15.04.2019 | Event News

Fraunhofer FHR at the IEEE Radar Conference 2019 in Boston, USA

09.04.2019 | Event News

 
Latest News

Marine Skin dives deeper for better monitoring

23.04.2019 | Information Technology

Geomagnetic jerks finally reproduced and explained

23.04.2019 | Earth Sciences

Overlooked molecular machine in cell nucleus may hold key to treating aggressive leukemia

23.04.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>