A State-of-the-Art Review on Robots and Medical Devices Using Smart Fluids and Shape Memory Alloys

Abstract

Over the last two decades, smart materials have received significant attention over a broad range of engineering applications because of their unique and inherent characteristics for actuating and sensing aspects. In this review article, recent research works on various robots, medical devices and rehabilitation mechanisms whose main functions are activated by smart materials are introduced and discussed. Among many smart materials, electro-rheological fluids, magneto-rheological fluids, and shape memory alloys are considered since there are mostly appropriate application candidates for the robot and medical devices. Many different types of robots proposed to date, such as parallel planar robots, are investigated focusing on design configuration and operating principles. In addition, specific mechanism and operating principles of medical devices and rehabilitation systems are introduced and commented in terms of practical realization.

Materials as Machines

“…The mechanical output of SMAs has already found widespread implementation in end use. SMAs show particular promise as material actuators and have also been examined in robotics 36. We conclude this discussion of SMAs by describing recent, geometry‐dependent (wire, torsional, and film) implementations of SMAs in functional uses in robotics and related technologies.…”

“…During the phase transformation, the austenite‐start (A s ) temperature demarcates the beginning of this phase transformation, at which point the SMA begins to recover its lattice structure and shape. Once the material reaches the austenite‐finish temperature (A f ), the phase transformation (and mechanical response) is complete 13,36,37…”

“…SMAs in a wire geometry are particularly suited for tensile actuation due to their comparatively higher efficiency (by weight) and uniformity of generated stress over the cross‐sectional area of the device. Numerous wire‐based actuators have been described 36,39–42. For example, Allen et al employ a Nitinol wire embedded with a polycaprolactone (PCL) rod, both of which are encapsulated in a silicone rubber to form a composite actuator ( Figure a) 43.…”

“…Twisted SMA geometries (such as coils and springs) can realize comparatively larger strokes than straight wires, enabling differentiated performance in robotics 36. Twisted SMA configurations (wire coils) have been used by Uchikoba and co‐workers to control a quadruped MEMS microrobot with four‐independent leg locomotors 49.…”

Unstructured Uncertainty Based Modeling and Robust Stability Analysis of Textile-Reinforced Composites with Embedded Shape Memory Alloys

“…The elastic properties of textile reinforced composites require smart actuators which possess adaptability and deformability. Smart materials which include piezoelectric materials, shape memory alloys (SMA), and dielectric elastomers have been used in diverse flexible structures [7][8][9]. Among these smart materials, SMAs have the advantages of simple structure, small size, excellent (i.e., higher) force to weight ratio, large displacement, and high stiffness [10,11].…”