N25A-T027 TITLE: Dynamic Thermal Management Suit

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Advanced Materials;Human-Machine Interfaces

OBJECTIVE: Develop and demonstrate a suit to be worn to protect an individual from thermal exposures in water (28-99°F) diving, capable of maintaining individual at a core body temperature of 95-99°F and maintaining the temperature of diver’s extremities above 53.6°F. Suit shall be designed using new approaches and materials, that can insulate an individual submerged in water from hypo and hyperthermia. The system should work in helmeted or unhelmeted and in tethered and untethered conditions. The system should be capable of functioning in a highly contaminated environment.

DESCRIPTION: Thermal management in an aqueous environment places a significant challenge for human physiology due to the high thermal conductance of water versus air. Most locations in which military divers must dive require thermal protection. There is not currently a rugged, reliable system that can maintain normal physiologic temperature for the diver.

There are several engineering challenges. First in an untethered system the diver must carry any power source. Second, there is a specific requirement to keep the extremities warm enough to maintain manual dexterity. Third a tube suit or other wet suit materials compress at depth resulting in reduced insulation. Prior attempts have resulted in bulky designs that are difficult to both put on, take off and impedes mobility. Fourth and finally, when using a tethered system there may be heat loss/gain due to traversing the length of the tether resulting in reduced cooling or heating for the diver.

Consideration should be given to an innovative dynamic approach (e.g., additive manufacturing, metamaterials, bio-inspired hydrophobic gels) that shields the body from direct contact and allows the diver to maintain a normal body temperature. Innovative solutions that are dynamic and can adjust to cold and hot environments are most desirable. Mobility, and don and doff times should be comparable or better to those of current wetsuits.

PHASE I: Define and develop a design for a thermal-protective diving suit that is capable of use in a great range of water temperatures (28-99°F) and maintains an internal temperature that maintains a healthy core body temperature (95-99°F) and a temperature of > 53.6°F in the extremities for a 10-hour threshold duration. Prepare designs that are sufficiently detailed to specify all materials needed, their availability, how they will be implemented, and the overall thermal suit thickness. Specify how the design buffers the external water temperature to the body and will adapt in changing conditions. The suit material, its seams (both intergarment and at wrists, neck, and feet), and any closing mechanisms must stand up to typical underwater diver activities and approximately 100 dives. The design created in Phase I should lead to plans to build a prototype unit in Phase II.

Human factor and human subject testing are critical in follow-on Phases of this topic. Please carefully review the requirements of approval for proposals that include testing of human subject and compliance with Institutional Review Board (IRB): https://www.nre.navy.mil/work-with-us/how-to-apply/compliance-and-protections/research-protections. IRB approval is needed prior to award of Phase II. Performers must submit a proposal for IRB approval during Phase I.

PHASE II: Develop, fabricate, lab-test (in variable conditions), and provide two suits/systems for form, fit, and function evaluation by operational Navy divers in maritime environments. Within the period of performance, revise the design and refabricate an additional 10 units based on feedback.

PHASE III DUAL USE APPLICATIONS: Assist the Navy in transitioning the technology to operational use, support the Navy for test, validation, and qualification of the system for use by military divers, and develop commercial variants suitable for commercial, scientific, and recreational divers. Create a marketing plan for reaching civilian users and mass production, to bring the per unit cost down to under five hundred dollars.

REFERENCES:

1. Piantadosi, C. A.; Ball, D. J.; Nuckols, M. L. and Thalmann, E. D. "Manned Evaluation of the NCSC Diver Thermal Protection (DTP) Passive System Prototype." US Naval Experimental Diving Unit Technical Report (NEDU-13-79), 1979. http://archive.rubicon-foundation.org/xmlui/bitstream/handle/123456789/3356/NEDU_1979_13.pdf?sequence=1

2. Bardi, Jason S. "How Does Fur Keep Animals Warm in Cold Water?" American Physical Society, College Park, MD, November 23, 2015. https://www.aps.org/units/dfd/pressroom/news/2015/upload/7pr-animals2015.pdf

3. Nuckols, M.L. "Analytical modeling of a diver dry suit enhanced with micro-encapsulated phase change materials." Ocean Engineering, Volume 26, Issue 6, 1999, pp. 547-564.

ISSN 0029-8018, https://doi.org/10.1016/S0029-8018(98)00001-8 https://www.sciencedirect.com/science/article/pii/S0029801898000018

KEYWORDS: Diving, Wetsuit, Drysuit, Hypothermia, Hyperthermia, Personal Protective Equipment, PPE

TPOC 1: Sandra Chapman
Email: [email protected]

TPOC 2: Joy Dierks
Email: [email protected]

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