RT&L FOCUS AREA(S): General Warfighting Requirements (GWR) TECHNOLOGY AREA(S): Sensors, Materials The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with section 3.5 of the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws. OBJECTIVE: To vastly improve logistics in Multi-Domain Operations (MDO) through a low-cost phosphine sensor which can be integrated onto existing storage containers housing Red Phosphorus (RP)-related materiel. DESCRIPTION: MDO in contested EW (electronic warfare) environments require technologies and weapon systems capable of delivering payloads on target and on time. EM (electromagnetic) attenuating aerosols play a crucial role in protecting the Warfighter MDO by decreasing or modifying electromagnetic signatures detectable by various sensors, seekers, trackers, targeting and optical enhancement devices, and the human eye. RP remains the highest performing fielded visible obscurant, capable of generating the highest-yielding aerosol on a volume and weight basis. Leveraging the exceptional performance of RP is critical when considering payload and load-out constrained systems, such as a rocket warheads. While efforts are underway to modify RP to be less reactive to water, stockpile material is still subject to degradation resulting in the release of highly toxic phosphine gas within the storage containers of RP munitions (Pepelko 2004). Of particular interest, the PA150 (NSN: 8140-01-451-7538) / PA154 (NSN: 8140 01 380 5857) / PA157 (NSN: 8140 01 354 0766) could be outfitted with these sensors. Existing commercially-available sensors are very expensive and not easily integrated onto munition containers, their use would require breaking the seal of storage containers, thereby potentially exposing those involved to the toxic phosphine (Brabec 2019). The goal of this program would be a sensor that would not break the seal of either the inner or outer packs of the container. State-of-the-art sensor technologies are frequently based upon electrochemical or semiconductor sensing media that can directly interact with an analyte, has been p- or n-modified, or has been functionalized by an inorganic or organic moiety capable of direct analyte interaction. Several state-of the-art approaches include: monolayer materials, such as Al2C (Rahimi 2021), self-assembled monolayers (Xia 2013); reduced graphene oxide (Furue 2017), nitrogenated graphene (Yar 2019) which can provide significant signal response enabled by very thin monolayers while providing very high surface areas for analyte interaction; nanoporous and nanostructured silicon (Ozdemir 2010), providing both high surface areas due to nanoporosity and the ability to tune conduction through charge carrier modification or nanostructure growth; and, organic sensing media functionalized with specific moieties (Kim 2020). Sensors based upon these sensing media may function by measuring changes in conductivity induced by variations in charge carriers (electron and hole) when analytes sorb or desorb from the surface, or cause displacement of previously adsorbed species, such as oxygen. Although considered state-of-the-art, these approaches require direct contact of the sensing media and their electronic circuits with the analyte of interest, such as phosphine. Using these sensor technologies with munitions could create significant hazards in the presence of corrosive environments, causing corrosion of circuits and potentially leading to local heating, sparking, or other unintended initiation sources for phosphine, di-phosphine, or the payload. This topic seeks to develop technologies able to monitor phosphine concentrations within munition containers while eliminating any potential for unintended ignition of gases generated by degradative processes, or munition payloads. This low-cost sensor could be fitted upon all existing storage containers to provide an immediate and reliable on-demand read-out of phosphine concentration relative to action level, vastly improving logistics in MDOs. PHASE I: Develop and fabricate a sensor that incorporates all necessary components to function, including both the non-electronic (interior), interface, sensor components (breadboard scale), self-calibration and zeroing, and reliably measures low-level concentrations of phosphine 0.01 ppm 0.02 ppm (an order of magnitude below the OSHA TWA) and high-level concentrations of phosphine to 100 ppm ( 2 ppm). Successful proposals will include any assumptions, along with the expected sensitivity and specificity of the proposed approach. While phosphine is the only pnictogen hydride anticipated to be present as a degradation byproduct, proposed solutions should indicate if the approach will show sensitivity toward phosphine over other pnictogen hydrides. Proposed designs should avoid the use of microheaters that could contribute to unintended ignition. This sensor shall be integrated onto existing munition containers with little to no modification to said containers. At most, two adjacent small sampling holes would be permitted, provided they do not compromise the form, fit or function of the container. Offeror shall coordinate their proposed integration locations and design with the technical points of contact to ensure proper form, fit and function is retained. All components and technological approaches shall be selected in a way to ensure a minimum 15-year uninterrupted service life, and the device shall be serviceable to extend the service life by an additional 15 years, assuming intermittent on-demand usage. Sensor shall incorporate features to maintain calibration, prevent signal drift as a function of time or phosphine saturation. Design approach shall incorporate features to prevent fouling or saturation by other substances, and reliably function when the phosphine saturation limit is reached. Paper study to ensure capability of being miniaturized and cost no more than $15 per unit, assuming 10,000 units of production. Given the low cost of simple circuitry (e.g. dollar store calculators) it is assumed that the cost of the integrated sensor should not exceed the specified per-unit cost at production quantities. Approaches exist to potentially lower manufacturing costs (Prajesh 2015), however awareness of Ph II requirements should be taken to ensure the prototype, once miniaturized, will meet environment/vibrational requirements (ruggedness), as well as any industry and regulatory standards for sensors of toxic materials. Efforts should be made to ensure recovery, reusability, and refurbishment of sensors. Presumed components and parts list, along with shelf and use lifespans shall be provided as a deliverable to Phase I. PHASE II: Miniaturize according to Ph I paper study. Demonstrate the required per-unit cost can be achieved by direct in-house fabrication or through partnerships with commercial electronics fabricators. Must meet all ruggedness (cold and hot conditioning, logistic vibration, drop testing) parameters for the munitions containing RP (MIL-STD-810H, others) while installed on an operationally relevant container. Budget should include all components necessary to meet the requirements, including operationally relevant containers. All production hardware required to produce 10,000 units per year, such as dies, molds, etc., shall be produced and made available during Ph II. All molds, dies, tooling, software, and components shall be a Phase II deliverable. All enclosures and components shall withstand storage and field conditions for a minimum of 30 years. Any seals (e.g. elastomers) incorporated into the design shall withstand storage and field conditions without leakage or other failure for a minimum of 30 years or a minimum of 15 years if the seals are serviceable. Sensor shall retain full functionality and meet all performance requirements for a minimum of 30 years. All energy sources shall provide enough power for full operation for a minimum of 30 years, or shall provide enough power for full operation for a minimum of 15 years and shall be serviceable to extend the service life by an additional 15 years. Full technical data package describing the production unit, components, sourcing, repair protocols, and replacement parts shall be a Phase II deliverable. PHASE III DUAL USE APPLICATIONS: Produce no less than 10,000 units and in integrate into existing RP munition storage containers. Lotting will be in accordance with MIL-STD-1168. REFERENCES: MIL-DTL-211 Revision F, Phosphorus, Red, Technical Detail Specification MIL-STD-810H Pepelko, Seckar, Harp, Kim, Gray, Anderson; Worker Exposure Standard for Phosphine Gas; Society for Risk Analysis; 2004; p1201-13. Davies, N; Red Phosphorus for Use in Screening Smoke Compositions; DTIC ADA372367; 1999 Griffiths, T.; Charslety, E.; Goodall, S.; Barnes, P.; Stability Studies of Red Phosphorus using Heat Flow Microcalorimetry; CPIAC-2002-06570; 2002 Furue, R.; Koveke, P.; Sugimoto, S.; Shudo, Y.; Hayami, S.; Ohira, S-I.; Toda, K. Arsine gas sensor based on gold-modified reduce graphene oxide. Sensors and Actuators B. 2017, 240, pp 657-663. Ozdemir, S.; Gole, J. A phosphine detection matrix using nanostructure modified porous silicon gas sensors. Sensors and Actuators B. 2010, 151, pp 274-280. Brabec, D.; Campbell, J.; Arthur, F.; Casada, M.; Tilley, D.; Bantas, S. Evaluation of Wireless Phosphine Sensors for Monitoring Fumigation Gas in Wheat Stored in Farm Bins. Insects. 2019, 10, pp 121. Rahimi, R.; Solimannejad, M. Sensing ability of 2D Al2C monolayer toward toxic pnictogen hydrides: A first-principles perspective. Sensors and Actuators A. 2021, 331, pp 113000. Prajesh, R.; Jain, N.; Agarwal, A. Low cost packaging for gas sensors. Microsyst. Technol. 2015, 21, pp 2265-2269. Yar, M.; Hashmi, M.; Ayub, K. Nitrogenated holey graphene (C2N) surface as highly selective electrochemical sensor for ammonia. Journal of Molecular Liquids. 2019, 296, pp 111929. Kim, C-Y.; Lee, H-H. Phosphine Electrochemical Sensor Using Gold-Deposited Polytetrafluoroethylene Membrane. Journal of Nanoscience and Nanotechnology. 2020, 20, pp 5654-5657. Xia, N.; Ma, F.; Zhao, F.; He, Q.; Du, J.; Li, S.; Chen, J.; Liu, L. Comparing the performances of electrochemical sensors using p-aminophenol redox cycling by different reductants on gold electrodes modified with self-assembled monolayers. Electrochimica Acta. 2013, 109, pp 348-354. KEYWORDS: RP, Phosphine, Detection, Spectroscopy, MOPP, Obscurant
