Machine Design

Cell phones defend against terrorism

Radiological dirty bombs pose a considerable threat, especially in metropolitan areas with dense populations.

Julie Kalista
Online Editor

Researchers at Purdue University hope to minimize the threat with a network of cell phones equipped with sensors that can detect and track radiation.

Cell phones already have global positioning locators, so a phone network could serve as a tracking system. "The network of sensors will be small, portable, and cheap, eventually will be built into laptops, personal digital assistants, and cell phones," says Ephraim Fischbach, physics professor at Purdue.

Tiny solid-state radiation sensors are already commercially available. "Cell phones would just require additional circuitry which wouldn't add much bulk," according to Fischbach.

Cell phones today also function as Internet computers that can report their locations to towers in real time. This network would use the same process to send an extra signal to a data center. Software can evaluate the radiation levels and pinpoint its location. The network would send signals to the data center, and it would send information to authorities without even alerting the people carrying the phones.

Researchers tested the system last year and found that it can detect weak radiation sources 15 ft. from the sensors. A test source was set up on campus and people randomly walked around carrying the detectors. The radiation source was weak and sealed, much weaker than you would see in a radiological dirty bomb.

The system can be trained to ignore know radiation sources like hospitals and certain common items like bananas, that contain radioactive potassium. The system would be sensitive enough to detect tiny levels of radiation, but smart enough to discern which sources posed threats or were harmless.

Researchers are asking the public to push for this, as the more people walking around with cell phones and PDAs, the easier it would be to detect and catch perpetrators. Please email Karen White, senior technology manager at Purdue, for more information.

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