Mapping actuating performance of knitted shape memory alloys and proposing design guidelines for assistive wearable applications

Abstract

The purpose of this study was to map the actuating performance of knitted SMA modules, and propose design guidelines for developing optimal SMA actuators, to be used in wearable assistive devices, suitable to be worn on the human body. To validate the findings of this study in the real world, we adopted an assistive rehabilitation glove for hemiplegic patients as a particular design case. To characterize the bending and contractile properties of knitted SMA modules, we conducted actuating performance tests with 720 knitted SMA samples under various conditions in actuation force, bending angle, contraction, electric power, and surface temperature. Based on the results, we proposed design guidelines by aligning the actuating performance of knitted SMA modules with joint mobility of hemiplegic patients for a smart rehabilitation glove. We anticipate that the outcomes of this study will serve as a practical yardstick for researchers in determining the desired actuating performance of a knitted SMA module that can support and assist the joint motion of the human body, when designing a wearable assistive device.