Description
Objective: This topic seeks disruptive technologies applied to the development of physically semi-porous flexible coupons (e.g. paper or polymer with plasmonic nanoparticles) to sample from a range of smooth and rough or abrasive surfaces found in operational environments using Surface Enhanced Raman Spectroscopy (SERS). Ideally, these tickets would be designed with multiple SERS substrates (either mixed or located in specific separate regions of the coupon) to target multiple classes of chemical and biological (CB) hazards (e.g., toxins, fentanyl analogs). Such coupons would greatly expand the capabilities of fielded hand-held Raman spectrometers from bulk detection and identification to detection of trace/residue amounts of hazard and potentially improving the selectivity against impurities co-present in the sample. Coupons would ideally be compatible with any fielded Raman device and with wavelengths of 785nm, 830nm and 1064 nm. Description: The Department of Defense has fielded several handheld Raman detectors over the past 15 years to support specialized chemical, biological, radiological, and nuclear (CBRN) units across the services and Special Operations forces. These detectors typically contain very large libraries (in the thousands) of solid and liquid chemicals (including toxins, as chemicals of biological origin) that are identifiable with the device. However, these devices typically require a “bulk” amount of liquid or solid sample (grams or milliliter amounts) and have difficulty in identification of chemicals in mixtures of materials. SERS is a technique that offers the potential to greatly enhance the sensitivity and selectivity of current and future handheld Raman detectors. SERS coupons are typically inexpensive with very low size and weight and require no additional power or sample preparation, making them a highly attractive option for soldiers already heavily physically burdened. However, SERS signals can vary significantly between different substrates and even within the same substrate, making it difficult to establish consistent measurements. Factors including substrate fabrication, material homogeneity, and analyte adsorption all contribute to this variability. This topic seeks approaches to overcoming these challenges with application to the range of threat chemicals that could be encountered on the battlefield in liquid or solid form. These include but are not limited to nerve agents, blister agents, arsenicals, pharmaceutical based agents, and toxins. Proposals should provide an innovative solution to the specified need. They should address a science-based approach to how promising substrates are identified and patterned on a coupon (either as a patterned mixture of substrates, separate spots of different substrates, or other). Consideration of consistency in substrate materials and patterning should be addressed. Please include science-based analysis of predicted selectivity and sensitivity enhancements spanning representative members of several previously noted classes of compounds. Preliminary data is preferred to supplement modeling, simulation and analysis, and surrogate chemicals may be used in place of highly regulated target chemicals. Keywords: SERS, Raman, chemical, toxin, substrate, CBRN, CB