APS News

Microbe-Based Sensors Can Improve Security

Physicists are finding new ways to improve security with astronomically inspired scanners and microbe-based sensors.

Jeffrey Brinker of the University of New Mexico and Sandia National Labs reported at the March Meeting a way to make microbe-based sensors that could be used for security applications. The project originally started when DARPA wanted to develop “insect reconnaissance.” They approached Brinker, asking him to develop tiny biocompatible sensors that could be attached to the backs of bees or other insects.

The insect reconnaissance project never worked out, but the research did lead Brinker to develop a way to build tiny biocompatible nanostructures. Living calls can integrate themselves into those structures, which nurture and protect them. The living cells can be engineered to glow in the presence of chemicals or pathogens, and thus can be used as sensors for security applications.

Brinker makes these structures by mixing up a solution of lipids and silica and living cells. As the solution dries into an ordered solid film, living cells such as yeast and bacteria can integrate themselves into the silica film, and can even direct the formation of the tiny structures that serve as protective houses for the microbes. Brinker calls the development a “new approach to engineering with life.”

The structures protect the cells, and the lipids provide nutrients and keep the cells from drying out. The cells stay alive for weeks to months, even in harsh environments where they would not normally survive, such as in a vacuum or under an electron microscope.

Many of the tiny cells can be printed onto a surface to make arrays of sensors on tiny chips, he said.

The cells can be engineered to fluoresce in the presence of toxic chemicals, explosives or pathogens.

They can be used to detect just about anything, Brinker said.  They could test water or air for chemical or biological weapons. They could also be used to study disease, for instance as a platform to study the onset of dormant diseases like tuberculosis, suggested Brinker.

In another security-related development, Panu Helisto, of VTT Technical Research Center of Finalnd, is working on developing terahertz radiation detectors that could be used for security scanners in airports or other places. The scanner, based on instruments long used in astronomy, would detect terahertz radiation people naturally emit.

It measures radiation using an array of superconducting microbolometers, niobium wires that heat up when they absorb radiation emitted by the subject. Most clothing materials are transparent up to about 1 THz, so a good THz detector could see through clothing to spot concealed weapons.  These sensors could detect concealed weapons up to 100 meters away, so the technology could be used to scan people without their knowledge, said Helisto.

The scanners would not have high enough resolution to reveal anatomical details, making the technology appealing to both the public and the authorities. Images are similar to those created by infrared sensors, said Helisto. Unlike x-ray scanners, the sensors don’t subject the person being scanned to any radiation, and so do not present any health issues, said Helisto.