Usability and Performance Comparison of Active Shape Memory and Passive Stockings for Medical Compression

On-body compressive therapy is an essential treatment for a variety of health conditions. Traditional compression methods like pneumatics and knit stockings offer quality compression, but present issues with user experience (donning/doffing challenges or bulk/mass issues). This paper covers two studies related to active compression stockings, which utilize knitted shape memory alloy (SMA) wire to produce dynamic compression forces on the body. When these SMA knit panels are heated with an at-home heating pad, the knit contracts and creates dynamic compression. The first study characterizes the forces produced on the body by a new iteration of an SMA knit stocking. The second study compares two versions of the SMA knit garment with a commercially available knit compression garment. The results show that SMA knit compression garments are able to produce medical grade compression on the body, but that sizing and material properties can greatly impact the forces produced. In a comparison of different compression stockings, the user experience of the SMA compression garment was preferred over the alternative garments. Overall, the potential of SMA knit compression is further highlighted, with a clear need for further development to ensure consistent medical grade compression.