Detection of Genuine and Hoax Biological and Non-biological Contaminants on Various Media
Since the terrorist attacks on 9/11 there has been a need to develop a mail processing facility to screen irradiated mail for contaminants. Currently, no integrated system applications exist for mail sorter apparatus. Commercial off-the-shelf triggers cannot be used directly in fluctuating mail room environments. Current threat detection methodologies are very labor intensive and are not automated. Finally, no central control application and remote monitoring functions are available.
Researchers at the Johns Hopkins Applied Physics Laboratory were tasked with developing a system to eliminate the possibility of contaminated mail from being delivered to members and staff of the U.S. Senate. A secondary objective was to detect letters containing either hoax material or biological threats that had been killed by irradiation.
This invention works in combination with existing mechanical pinch roller mechanisms on high speed automated sorting machines which have been shown to effectively eject particulate material from envelopes during routine mail processing applications.
The system initially cuts off the corner of an envelope and the envelope is then jogged to liberate particulate matter from the cut corner. A particle counter triggers an alarm if a predefined threshold value is exceeded and a Dry Filter Unit (DFU) captures any aerosolized particles ejected during jogging. Overall, the system provides air handling and filtration for improved worker protection when particles are released during the sorting process and incorporates innovative methods for improved collection of particulate matter as it is ejected from envelopes. Features of this invention which offer a significant improvement over current technology are:
· Improves particulate extraction by perforating/serrating the envelope prior to the pinch roller mechanism.
· Filters air within the mail sorter apparatus with a HEPA filter and optional charcoal filter elements to minimize the likelihood of escape (and subsequent worker exposure) for potential threat materials.
· Rapidly evacuates particulate matter ejected by the pinch roller mechanism during sorting through use of a particulate collection nozzle with relatively high air evacuation flow rate.
· Includes sampling chamber for extending dwell time of particulate cloud and matching to off-the-shelf sensor cycle times.
· Incorporates algorithms for monitoring background particulate levels and adjusting threat trigger level accordingly for improving the likelihood of detection and reducing false alarm rates.
· Incorporates letter counting and a circular image buffer for post threat alarm identification of letters with potential threat or hoax materials.
· Incorporates a system control application which monitors air handler status, shuts down sorter operations during air handler faults, and halts the sorter when potential threats are detected.
· Provides for multisensor correlation which allows for improved threat detection and false alarm rejection through knowledge-based integration of data from multiple sensor technologies. Examples include visible domain imaging in combination with particulate counters, infrared imaging techniques, florescence, and mass spectroscopy.
· Provides for remote system interrogation and trend reporting/tracking.
Patent Status: U.S. patent(s) 7458248 issued.