Ultra Violet (UV) induced fluorescence remains a core technique for the real time detection of biological aerosols. With this approach, the detection of an aerosolized biological event is based on the fluorescent and scattering signals observed from biological particles when exposed to one or more UV sources. In 2004, the Edgewood Chemical Biological Center (ECBC) initiated an effort to develop a low cost, small, lightweight, low power biological agent detector, identified as the TAC-BIO, based on this principle. Unlike previous laser based detectors, this program has capitalized on Semiconductor UV Optical Sources (SUVOS) being developed by the Defense Advanced Research Projects Agency (DARPA). Compared to the existing UV lasers, these SUVOS devices and their commercial counter-parts offered a means of achieving small, low cost, low power UV excitation sources. A general design philosophy of incorporating these devices with other low cost components has allowed ECBC to develop a detector that provides a credible degree of performance while maintaining the target size weight and power attributes. This paper presents an overview of the TAC-BIO and some of the findings to date.
Ultra-violet fluorescence remains a cornerstone technique for the detection of biological agent aerosols. Historically, these UV based detectors have employed relatively costly and power demanding lasers that have influenced the exploitation of the technology to wider use. Recent advancements from the Defense Advanced Research Project Agency's (DARPA) Solid-state Ultra Violet Optical Sources (SUVOS) program have changed this. The UV light emitting diode (LED) devices based on Gallium Nitride offer a unique opportunity to produce small, low power, and inexpensive detectors. It may, in fact, be possible to extend the SUVOS technology into detectors that are potentially disposable. This report will present ongoing efforts to explore this possibility. It will present the Tactical Biological (TAC-BIO) detector as such a solution for low cost, low power, lightweight device for biological agent detection.
A number of strategies to meet the need for a small and inexpensive biosensor that mitigates military and civilian vulnerabilities to biological weapons are currently being pursued. Among them is UV induced biological fluorescence. UV induced biofluorescence is a potentially successful strategy because it involves no chemical consumables and it is an "on-line" detection method where particles can be interrogated without impaction onto a substrate or into a liquid. Indeed, there are already existing fluorescence based sensors already in place, yet these are limited by the cost and power consumption of the laser based UV excitation sources. Fortunately, inexpensive and low power solid state UV sources arising from the Defense Advanced Research Projects Agency's (DARPA) Semiconductor UV Optical Sources (SUVOS) project have become commercially available in wavelengths capable of exciting aromatic amino acids (e.g. tryptophan) and metabolic products (e.g. NADH). The TAC-Bio Sensor is capable of exploiting either source wavelength and will ultimately include both source wavelengths within a single sensor.
Initial work with the deep UV sources involves the correct optical filtering for the devices. The primary emission from both the 280 nm and 340 nm devices occurs at the design wavelength and is about 20 nm FWHM, however, there is a tail extending to the longer wavelengths that interferes with the fluorescence signal. A system of optical filters that sufficiently removes the long wavelength component from the UV source is designed and tested for the deep UV sources. Ongoing work with the sensor has confirmed that sensitivity to small biological particles is enhanced with the deeper wavelengths. When the 340 nm sources are placed in the TAC-Bio, it is capable of detecting 4 micron diameter Bacillus globigii (BG, Dugway, washed 4X) spore agglomerates. The deep UV sources show an improvement in signal to noise of 2, permitting the detection of 3 micron diameter BG agglomerates.
Ultra-violet fluorescence remains a corner stone technique for the detection of biological agent aerosols. Historically, these UV based detectors have employed relatively costly and power demanding lasers that have influenced the exploitation of the technology to wider use. Recent advancements from the Defense Advanced Research Project Agency's (DARPA) Solid-state Ultra Violet Optical Sources (SUVOS) program has changed this. The UV light emitting diode (LED) devices based on Gallium Nitride offer a unique opportunity to produce small, low power, and inexpensive detectors. It may, in fact, be possible to extend the SUVOS technology into detectors that are potentially disposable. This report will present ongoing efforts to explore this possibility. It will present candidate UV fluorescence based detector designs along with the biological aerosol responses obtained from these designs.
In light of the current state of detection technologies designed to meet the current threat from biological agents, the need for a low-cost and lightweight sensor is clear. Such a sensor based on optical detection, with real time responses and no consumables, is possible. Devices arising from the Defense Advanced Research Projects Agency's (DARPA) Semiconductor UV Optical Sources (SUVOS) are the enabling technology. These sources are capable of emitting UV wavelengths known to excite fluorescence from biological agent particles while costing a few dollars apiece and consuming low power. These devices are exploited in the TAC-Bio Sensor. A unique optical design is used to collect the usable portion of the LED emission and focus it into the probing region of the sensor. To compensate for the low UV power density relative to UV lasers, the TAC-Bio utilizes a unique opposed flow configuration to increase the interaction between particles and the UV beam. The current TAC-Bio sensor testbed is capable of detecting fluorescence Bacillus globigii (BG, an anthrax simulant) spore agglomerates down to 5 microns in diameter. Ongoing work is focusing on increasing signal to noise so that smaller particles, possibly single spores, can be detected, as well as on including additional data channels, such as light scattering, to increase selectivity of the sensor.
A lightweight, tactical biological agent detection network offers the potential for a detect-to-warn capability against biological aerosol attacks. Ideally, this capability can be achieved by deploying the sensors upwind from the protected assets. The further the distance upwind, the greater the warning time. The technological challenge to this concept is the biological detection technology. Here, cost, size and power are major factors in selecting acceptable technologies. This is in part due to the increased field densities needed to cover the upwind area and the fact that the sensors, when deployed forward, must operate autonomously for long periods of time with little or no long-term logistical support. The Defense Advanced Research Project Agency’s (DARPA) Solid-state Ultraviolet Optical Source (SUVOS) program offers an enabling technology to achieving a detector compatible with this mission. As an optical source, these devices emit excitation wavelengths known to be useful in the detection of biological aerosols. The wavelength band is absorbed by the biological aerosol and results in visible fluorescence. Detection of a biological aerosol is based on the observed intensity of this fluorescence signal compared to a background reference. Historically this has been accomplished with emission sources that are outside the boundaries for low cost, low power sensors. The SUVOS technology, on the other hand, provides the same basic wavelengths needed for the detection process in a small, low power package. ECBC has initiated an effort to develop a network array based on micro UV detectors that utilize the SUVOS technology. This paper presents an overview of the micro UV detector and some of the findings to date. This includes the overall design philosophy, fluid flow calculations to maximize presentation of aerosol particles to the sources, and the fluorescence measurements.
A lightweight, tactical biological agent detection network offers the potential for a detect-to-warn capability against biological aerosol attacks. Ideally, this capability can be achieved by deploying the sensors upwind from the protected assets. The further the distance upwind, the greater the warning time. The technological challenge to this concept is the biological detection technology. Here, cost, size and power are major factors in selecting acceptable technologies. This is in part due to the increased field densities needed to cover the upwind area and the fact that the sensors, when deployed forward, must operate autonomously for long periods of time with little or no long-term logistical support. The Defense Advanced Research Project Agency’s (DARPA) Solid-state Ultraviolet Optical Source (SUVOS) program offers an enabling technology to achieving a detector compatible with this mission. As an optical source, these devices emit excitation wavelengths known to be useful in the detection of biological aerosols. The wavelength band is absorbed by the biological aerosol and results in visible fluorescence. Detection of a biological aerosol is based on the observed intensity of this fluorescence signal compared to a background reference. Historically this has been accomplished with emission sources that are outside the boundaries for low cost, low power sensors. The SUVOS technology, on the other hand, provides the same basic wavelengths needed for the detection process in a small, low power package. ECBC has initiated an effort to develop a network array based on micro UV detectors that utilize the SUVOS technology. This paper presents an overview of the micro UV detector and some of the findings to date. This includes the overall design philosophy, fluid flow calculations to maximize presentation of aerosol particles to the sources, and the fluorescence measurements.
Improved situational awareness is a primary goal for the Objective Force. Knowing where the enemy is and what are the threats to his troops provides the commander with the information he needs to plan his mission and provide his forces with maximum protection from the variety of threats that are present on the battlefield.
Sensors play an important role in providing critical information to enhance situational awareness. The sensors that are used on the battlefield include, among others, seismic, acoustic, and cameras in different spectral ranges of the electro-magnetic spectrum. These sensors help track enemy movement and serve as part of an intrusion detection system. Characteristically these sensors are relatively cheap and easy to deploy.
Chemical and biological agent detection is currently relegated to sensors that are specifically designed to detect these agents. Many of these sensors are collocated with the troops. By the time alarm is sounded the troops have already been exposed to the agent. In addition, battlefield contaminants frequently interfere with the performance of these sensors and result in false alarms. Since operating in a contaminated environment requires the troops to don protective garments that interfere with their performance we need to reduce false alarms to an absolute minimum.
The Edgewood Chemical and Biological Center (ECBC) is currently conducting a study to examine the possibility of detecting chemical and biological weapons as soon as they are deployed. For that purpose we conducted a field test in which the acoustic, seismic and electro-magnetic signatures of conventional and simulated chemical / biological artillery 155mm artillery shells were recorded by an array of corresponding sensors. Initial examination of the data shows a distinct differences in the signatures of these weapons.
In this paper we will provide detailed description of the test procedures. We will describe the various sensors used and describe the differences in the signatures generated by the conventional and the (simulated) chemical rounds. This paper will be followed by other papers that will provide more details information gained by the various sensors and describe how fusing the data enhance the reliability of the CB detection process.
In support of the Disparate Sensor Integration (DSI) Program a number of imaging sensors were fielded to determine the feasibility of using information from these systems to discriminate between chemical simulant and high explosives munitions. The imaging systems recorded video from 160 training and 100 blind munitions detonation events. Two types of munitions were used; 155 mm high explosives rounds and 155 mm chemical simulant rounds. In addition two different modes of detonation were used with these two classes of munitions; detonation on impact (point detonation) and detonation prior to impact (airblasts). The imaging sensors fielded included two visible wavelength cameras, a near infrared camera, a mid wavelength infrared camera system and a long wavelength infrared camera system.
Our work to date has concentrated on using the data from one of the visible wavelength camera systems and the long wavelength infrared camera system. The results provided in this paper clearly show the potential for discriminating between the two types of munitions and the two detonation modes using these camera data. It is expected that improved classification robustness will be achieved when the camera data described in this paper is combined with results and discriminating features generated from some of the other camera systems as well as the acoustic and seismic sensors also fielded in support of the DSI Program.
The paper will provide a brief description of the camera systems and provide still imagery that show the four classes of explosives events at the same point in the munitions detonation sequence in both the visible and long wavelength infrared camera data. Next the methods used to identify frames of interest from the overall video sequence will be described in detail. This will be followed by descriptions of the features that are extracted from the frames of interest. A description of the system that is currently used for performing classification with the extracted features and the results attained on the blind test data set are next described. The work performed to date to fuse information from the visible and long wavelength infrared imaging sensors including the benefits realized are next described. The paper concludes with a description of our ongoing work to fuse imaging sensor data.
Currently, the detection of Chemical and Biological agents on the battlefiedl is limited to the response from point and standoff C/B agent detectors. Speculation has been raised, however, that non-C/B sensors could assist in the detection process. Data from unattended ground sensors, infrared imagers, and radar may provide useful information to support a deteciton and may actually provide some warning capability. Ideally, these devices would provide this informiaotn while providign the core Force Protection functions assigned to them. Over the last years, the Soldier and Biological Chemical Command has conducted ouitdoor testing to collect seismic, acoustic, infrared, and radar signatures from conventional and non-conventional events to determine if tehse events can be separated. Preliminary results using several high resolution-laboratory grade seismic, acoustic and IR sensors would indicate that these sensors provide useful discrimination information.
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