OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Biotechnology OBJECTIVE: Develop sensing capabilities for the detection of airborne biological aerosols. The instrumentation must be capable of rapidly and continuously identifying bioaerosol particles based on the detection of helical structures present in biomolecules and discerning bioaerosols from the larger inorganic and organic background matrix via point detection at the location of the instrument in real time. The final device should be deployable on an unmanned platform such as unmanned aerial vehicle (UAVs) or unmanned ground vehicle (UGVs). DESCRIPTION: A robust chemical-biological defense requires a fast, reliable, specific, and inexpensive biological aerosol threat detection system to prevent deadly contamination of soldiers and the general population. This requirement is critical for urban and/or battlespace settings where the atmosphere contains inorganic, organic, and biological particles with complex physico-chemical characteristics across orders of magnitude in size (0.1 100 microns [ m]). The detection of possible biological threat materials is limited by their small concentration within this ambient matrix containing materials of non-interest and interfering compounds. While sensor technology has improved over the last 20 years, threat detection remains a challenge in operational environments at mission-speed due to the complex and dynamic nature of the surrounding environmental media. A fully operational biothreat detection system comprises trigger, rapid confirmer/identifier, sample collector, and final confirmer/identifier. Early triggers were mainly based on the detection of laser induced fluorescence (LIF) (e.g., BAWS, WIBS, UVAPS) and have become the industry standard, as they provide some level of correlation to the chemical nature of the bioaerosols, while upholding the ability of continuously operating at high throughput. However, despite decades of significant improvements, LIF-based early-warning systems exhibit shortfalls with respect to accuracy due to the existence of similar chromophores in both threat aerosols and innocuous background particles [1,2]. Furthermore, it has been shown that the fluorescence signal of a bioaerosol can be severely altered by changes in environmental conditions [3]. A recent surge in highly infectious diseases, as highlighted by the COVID-19 pandemic and respiratory syncytial virus infection (RSV), revived interest in the early detection and identification of health-threatening bioaerosols and various strategies including optical methods, such as elastic light scattering (ELS) were suggested as potential solutions. Widely used in atmospheric and planetary sciences, ELS generates the physical information useful for a particles' classification (e.g., size, morphology, refractive index) but is unsuitable for unambiguous chemical identification. However, some polarization containing elements of the scattering Mueller Matrix (S12, S34 and S14) enable retrieval of molecular conformation for complex biopolymers, and in limited instances circular intensity differential scattering (CIDS) was used to achieve characterization based on molecular or morphological chirality, without using fluorescent labels [4]. Furthering these capabilities, a recent study by Pan et al. demonstrated that CIDS measurements performed on a single airborne aerosol can distinguish particles with a helical structure (i.e., DNA and RNA) from background particles [5]. An ingenious design used in this work highlights opportunities for the development of a deployable compact device streamlining traditional bulky components, such as polarization modulator, lock-in amplifier, and rotation goniometer. Leveraging these developments, detecting chirality in bioaerosols has the potential to generate an autonomous early-warning capability that could augment the Department of Defense's chem-bio defense effort by distinguishing biological threats from background particles. The sensing capability should overlap with the inhalable particle size and rely on contactless optical methods to sense biological chirality. The system should have a continuous real-time monitoring (tens of thousands particles/sec) capability and, at a minimum, should be able to distinguish biological particles from inorganic or organic background. PHASE I: Phase I entails the design of a concept for a rapid, chirality detecting early-warning biosensor. The study should lead to a laboratory demonstration that outlines major components of the system. The Phase I project should focus on the discrimination of bioaerosols from non-bioaerosols in the 0.1 100 m particle size range, with accuracy >80%. The accompanying architecture required to integrate fast data analysis and machine learning for particle differentiation should also be included. The Phase I should also define a clear path forward for designing a prototype with low size, weight, and power (SWaP) to enable deployment on unmanned vehicles. Biological threats of all classes are of interest for sensing and identification. Examples include biological spores, such as anthrax or simulants thereof (that can be accessed by the small business offeror), and allergens like pollens. The Phase I final report must explain in detail the detection method selected, software concepts, hardware requirements, and identify potential use cases and limitations. PHASE II: Mature the concept into a pre-production portable instrument prototype integrating the capabilities outlined in the concept developed during Phase I. The key deliverable of Phase II will be the demonstration of the system in a relevant environmental setting where the prototype is capable of sampling upwards of 10,000 particles per second and detecting biological particles to within 90% accuracy. Evaluation of the machine-learning particle-detection algorithms will be extended to multiple threat vectors. The system will be benchmarked against standard techniques of aerosol identification. An initial analysis of the commercial applications of the system will be conducted, focusing on the baseline cost of the system and the market space addressed by the technology development. PHASE III DUAL USE APPLICATIONS: PHASE III: The small business will pursue commercialization of the technologies developed in Phase II for potential government and commercial applications. Government applications include rapid early-warning detection of biological threat aerosols. PHASE III DUAL USE APPLICATIONS: The proposed method has the potential to be integrated into ongoing Department of Defense programs including the Nuclear, Biological and Chemical Reconnaissance Vehicle Sensor Suite Upgrade (NBCRV SSU) program and the Joint Biological Tactical Detection System (JBTDS) program. The system could similarly be installed on UAVs and UGVs used by other agencies responsible for early-warning biological threat surveillance such as the Department of Homeland Security (DHS). The successful product can also fulfill air quality environmental applications such as assessing pollutants, or other airborne pathogens driving highly infectious diseases for commercial applications and for use by government agencies including the U.S. Environmental Protection Agency (EPA). REFERENCES: 1. Pinnick, R. G., Hill, S. C., Pan, Y.-L., and Chang, R. K., Fluorescence spectra of atmospheric aerosol at Adelphi, Maryland, USA: Measurement and classification of single particles containing organic carbon , Atmospheric Environment 38, 1657-1672 (2004). ; 2. Pan, Y.-L., Pinnick, R. G., Hill, S. C., Rosen, J. M., and Chang, R. K., Single-particle laser-induced fluorescence spectra of biological and other organic-carbon aerosols in the atmosphere: measurements at New Haven, Connecticut, and Las Cruces, New Mexico , Journal of Geophysical Research, 112(2007). ; 3. Kinahan, S. M.; Tezak, M. S.; Siegrist, C. M.; Lucero, G.; Servantes, B. L.; Santarpia, J. L.; Kalume, A.; Zhang, J.; Felton, M.; Williamson, C. C.; Pan, Y. L., Changes of fluorescence spectra and viability from aging aerosolized E. coli cells under various laboratory-controlled conditions in an advanced rotating drum. Aerosol Sci Tech 53 (11), 1261-1276 (2019). ; 4. A. L. Gratiet, L. Pesce, M. Oneto, R. Marongiu, G. Zanini, P. Bianchini, and A. Diaspro, Circular intensity differential scattering (CIDS) scanning microscopy to image chromatin-DNA nuclear organization, OSA Continuum 1(3), 1068 1078 (2018). 5. Pan, Y.-L.; Kalume; A.; Arnold J.; Beresnev, L.; Wang C.; Rivera, D.; Crown, K. and Santarpia J., Measurement of Circular Intensity Differential Scattering (CIDS) from Single Airborne Aerosol Particles for Bioaerosol Detection and Identification , Optics Express 30 (2), 1442-1451 (2022). KEYWORDS: Biological Threat Detection; sensors; aerosols; environmental sampling; environmental surveillance
