Review of NiTi Shape Memory Alloy Applications in Robotics

This review provides a structured overview of nickel–titanium (NiTi) shape memory alloy applications in contemporary robotic systems. Due to their shape memory effect, superelasticity, and high energy density, NiTi alloys are widely employed as compact and lightweight actuators in robotics. This paper first reviews NiTi actuators and drive mechanisms, including linear, rotary, bending, self-sensing, and superelastic configurations, along with their performance limitations related to speed, efficiency, and thermal management. Subsequently, the use of NiTi-based actuation in robotic grippers is discussed, emphasizing compliant grasping, adaptability, compact actuation, and structural integration. The review further examines applications of NiTi alloys in soft robotics, where material compliance enables bio-inspired motion. Hybrid soft robotic systems integrating NiTi actuators with elastomeric structures are highlighted. In addition, recent advances in microrobotics employing NiTi-based microactuators and shape-transformable microrobots are summarized. Finally, current challenges and future research directions for NiTi alloy applications in robotics are outlined. Unlike actuator-centered reviews of shape memory alloys in robotics, this work adopts an application and system-oriented perspective focused specifically on NiTi, considering its use not only as a thermally activated actuator but also as a superelastic, structural, self-sensing, and multifunctional robotic element.