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 Waste from paper and pulp industry supplies raw material for development of new redox flow batteries
12.10.2017 | Johannes Gutenberg-Universität Mainz

nachricht Low-cost battery from waste graphite
11.10.2017 | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt

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: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Ocean atmosphere rife with microbes

17.10.2017 | Life Sciences

Neutrons observe vitamin B6-dependent enzyme activity useful for drug development

17.10.2017 | Life Sciences

NASA finds newly formed tropical storm lan over open waters

17.10.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>