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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.

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 sensitive chemical aerosol Raman detector (CARD) has been developed for the trace detection and identification of chemical particles in the ambient atmosphere. CARD includes an improved aerosol concentrator with a concentration factor of about 40 and a CCD camera for improved detection sensitivity. Aerosolized isovanillin, which is relatively safe, has been used to characterize the performance of the CARD. The limit of detection (SNR = 10) for isovanillin in 15 s has been determined to be 1.6 pg/cm, which corresponds to 6.3 × 10 molecules/cm or 0.26 ppb. While less sensitive, CARD can also detect gases. This paper provides a more detailed description of the CARD hardware and detection algorithm than has previously been published.

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