INTRODUCTION: Compression garments tend to be difficult to don/doff, due to their intentional function of squeezing the wearer. This is especially true for compression garments used for space medicine and for extravehicular activity (EVA). We present an innovative solution to this problem by integrating shape changing materials - NiTi shape memory alloy (SMA) coil actuators formed into modular, 3D-printed cartridges - into compression garments to produce garments capable of constricting on command. METHODS: A parameterized, 2-spring analytic counterpressure model based on 12 garment and material inputs was developed to inform garment design. A methodology was developed for producing novel SMA cartridge systems to enable active compression garment construction. Five active compression sleeve prototypes were manufactured and tested: each sleeve was placed on a rigid cylindrical object and counterpressure was measured as a function of spatial location and time before, during, and after the application of a step voltage input. RESULTS: Controllable active counterpressures were measured up to 34.3 kPa, exceeding the requirement for EVA life support (29.6 kPa). Prototypes which incorporated fabrics with linear properties closely matched analytic model predictions (4.1%/2 10.5% error in passive/active pressure predictions); prototypes using nonlinear fabrics did not match model predictions (errors. 100%). Pressure non-uniformities were observed due to friction and the rigid SMA cartridge structure. DISCUSSION: To our knowledge this is the first demonstration of controllable compression technology incorporating active materials, a novel contribution to the field of compression garment design. This technology could lead to easy-to-don compression garments with widespread space and terrestrial applications.
Bibliographical noteFunding Information:
The authors would like to thank our colleagues at NASA Johnson Space Center, NASA Langley Research Center, NASA Jet Propulsion Laboratory, U.S. Army Natick Soldier Systems Center, and MIT for their support and collaboration. Th is work was supported by a NASA OCT Space Technology Research Fellowship (NASA Grant NNX11AM62H) as well as the MIT Portugal Program.
© by the Aerospace Medical Association, Alexandria, VA.
- Extravehicular activity
- Mechanical counterpressure space suit
- Orthostatic intolerance
- Shape memory alloys
- Wearable technology