TOWARDS ELECTRICALLY ACTIVATING SMA-BASED COMPRESSION KNITS

Abstract

Compression devices are widely used in fields such as astronautics, cosmetics, and medical therapy for treatment of various diseases such as Postural orthostatic tachycardia syndrome (POTS) and Orthostatic Hypotension (OH). Unlike traditional compression devices that apply static pressure on the body, there have been some efforts to integrate smart materials such as shape memory alloys (SMAs) to make compression garments active and controllable. SMA-based compression systems can be made in tourniquet (band) and knit (larger area) forms. SMA Knits are typically activated through direct heating approaches that may not be accessible in real-life applications. Unlike other forms of SMA actuators, due to the complexity of SMA wire interconnections in the knit, Joule heating has not been investigated yet. Hence, this paper presents an experimental protocol to electrically activate the SMA-knits through Joule heating. The designed protocol, include measurement of generated force, electrical properties, and temperature in a displacement control condition. The results of this study indicate that connecting the power leads to the middle of a knitted SMA sample along the course direction, can contribute to a better wide-reaching electrical pathway, and subsequently achieves better force generation through Joule heating.