Table 3.

SMA actuators used in exoskeletons.

Reference/Year	Main SMA Element	Location/Purpose	Weight	Force/Torque
Villoslada et al. Universidad Carlos III de Madrid [168]/2015	Wire (0.5 mm dia.)	Wrist	300 g	35 N
Hadi et al. (Univ. of Tehran) [171]/2018	Wire (0.25 mm dia.)	Hand rehabilitation	-	10 N each finger (40 N grasping)
Jeong et al. (Korea advanced institute of technology) [172]/2019	Spring (150 mm max. deformed length)	Wrist motion	151 g	1.32 Nm
Yang et al. (Northeastern University, China) [173]/2021	Spring (113 mm max. deformed length)	Hand rehabilitation	-	2.7 N
Zhang et al. (Dalian Univ. of Technology) [174]/2021	Wire (2 wires supported by bias spring)	Knee		40 N
Xie et al. (Univ. of Shanghai, China) [167]/2023	Springs with composite structure	Hand	120 g	6.4 N (max. for one finger)
Xie et al. Univ. of Shanghai, China) [175]/2023	Spring (4 springs)	Elbow	230 g wearable (877 g total)	100 N