Design and Characterization of an Active Compression Garment for the Upper Extremity

This paper presents the design, development, and testing of an active textile-based wearable compression device that is capable of delivering a controlled pulsatile compression. The device uses low spring index nickel titanium (NiTi) coil actuators to produce an applied dynamic pressure of up to 5.5 kPa. The selected NiTi coil actuators produce pressure when thermally stimulated with Joule heating via an applied current (0.3 A), and generate recoverable strains up to 75% in extension. An optical fiber strain sensor was developed to monitor the textile strain and enable the indirect estimation of the applied pressure. A new approach using a passive NiBR spring (in parallel with the NiTi actuators) was also developed to assist the NiTi coils in recovering the detwinned martensite form after cooling. The pressure distribution around a rigid cylindrical shape was also evaluated, showing higher applied pressures (5.5 kPa) where the NiTi coil actuators were located. The strain sensor exhibits high accuracy compared to a reference commercial sensor (as indicated by the high correlation indexes of up to 0.97 between compression cycle measurements with both solutions).