Compression garments are worn articles of clothing commonly used in astronautics to provide therapeutic, mechanical manipulation of body fluids to maintain health during and subsequent to exposure to extreme environments (i.e. space). Orthostatic intolerance garments (OIG), like the anti-gravity suit (AGS), are compression garments used to prevent crew from experiencing orthostatic intolerance (OI) and consequential syncope and blackouts while performing reentry, landing, and egress tasks.
Mobility is a critical factor and current limitation to AGS design stemming predominantly from the fact that they are inflated and therefore stiff. Efforts have been made to revise current gas-pressurized systems and replace them with undersized knit compression garments, which are garments designed using passive, elastic materials, such as knits (fabrics made of interlooping stretch yarns). However, undersized compression garments are difficult to don/doff and are not able to exert dynamic or controllable pressure on the body. The literature sites 83% of astronauts who return from long-duration missions lasting over one month experience a range of cardiovascular changes while in microgravity conditions that can put them at risk for experiencing OI; therefore, cardiovascular health will become increasingly important to advance missions outside of low earth orbit (LEO) (e.g. The Journey to Mars).
This research addresses the OIG technology gap by advancing SMA knitting technology for wearable, on-body applications. Active textiles are an emerging area of research that could advance the capabilities of aerospace compression garment design by contracting on command. Shape memory alloys (SMA), for example, are active materials with pseudoelastic properties and can be engineered to "remember" prescribed forms through an annealing process. Traditional weft knit architectures can be engineered to produce contraction if individual yarns incorporate SMA wire, causing large, dynamic displacements and contractive forces across the fabric surface that can be turned on/off or achieve various compression levels. The expected outcome of this research endeavor is to generate active material designs that could be used in the design of controllable, mobile, and untethered compression garments (e.g. OIG) that create (or relieve) compression on the user. Leveraging SMA knit technology in compression garment design has a huge potential for improving aerospace OIGs, which are critical for astronaut health and wellbeing as we transition to a new era in human space exploration.
Patent: ACTIVE KNIT COMPRESSION GARMENTS Granberry, R., Abel, J., Holschuh, B. "Active Knit Compression Stockings," US Application No. 62532638. Filed 14 July, 2017.
- Granberry, R., Eschen, K., Holschuh, B., & Abel, J. (2019). Functionally Graded Knitted Actuators with NiTi‐Based Shape Memory Alloys for Topographically Self‐Fitting Wearables. Advanced Materials Technologies.
- Eschen, K., Abel, J., Granberry, R., & Holschuh, B. (2018, September). Active-Contracting Variable-Stiffness Fabrics for Self-Fitting Wearables. In ASME 2018 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers.
- Granberry, R., Abel, J., & Holschuh, B. (2017, September). Active knit compression stockings for the treatment of orthostatic hypotension. In Proceedings of the 2017 ACM International Symposium on Wearable Computers (pp. 186-191). ACM.
- Granberry, R., Dunne, L., & Holschuh, B. (2017, July). Effects of Anthropometric Variability and Dimensional Change Due to Posture on Orthostatic Intolerance Garments. 47th International Conference on Environmental Systems.