Contactless Manipulation of Soft Robots

Abstract

In recent years, jointless soft robots have demonstrated various curvilinear motions unlike conventional robotic systems requiring complex mechanical joints and electrical design principles. The materials employed to construct soft robots are mainly programmable anisotropic polymeric materials to achieve contactless manipulation of miniaturized and lightweight soft robots through their anisotropic strain responsivity to external stimuli. Although reviews on soft actuators are extensive, those on untethered soft robots are scant. In this study, we focus on the recent progress in the manipulation of untethered soft robots upon receiving external stimuli such as magnetic fields, light, humidity, and organic solvents. For each external stimulus, we provide an overview of the working principles along with the characteristics of programmable anisotropic materials and polymeric composites used in soft robotic systems. In addition, potential applications for untethered soft robots are discussed based on the physicochemical properties of programmable anisotropic materials for the given external stimuli.

Efficient Chain Formation of Magnetic Particles in Elastomers with Limited Space

“…Magnetic elastomers are a type of stimuli-responsive soft material [1][2][3][4][5] and its physical properties alter in response to magnetic fields. The magnetic response for a magnetic elastomer is in general drastic; therefore, the material attracts considerable attention as actuators in the next generation of materials [6][7][8]. Magnetic elastomers consist of polymeric matrices, such as polyurethane, and magnetic particles with nano or micron sizes in diameter.…”

A Soft Transporter Robot Fueled by Light

“…Scientific fascination for nature's machineries has fueled an expanding field of research focused on mimicking these essential functions of natural systems into synthetic soft robots with untethered control. [1][2][3][4][5][6] Responsive materials [7][8][9][10][11] with actuation triggered by heat, light, and humidity are of special interest for soft robotics to eliminate the need for wiring or tubing connectivity between the device and the external controllers, allowing for lighter, autonomous, and more versatile soft robots. [1,12] Current developments in soft microrobotics aspire toward systems with locomotive freedom as well as the ability to perform useful tasks, such as cargo handling.…”

Photo-Mechanical Response Dynamics of Liquid Crystal Elastomer Linear Actuators

“…Engineering the molecular alignment led to demonstration of a 5 mm diameter rotary motor that uses a travelling deformation in a ring-shaped rotor, frictionally coupled to the stator-similar to the piezo motors used in autofocus camera lenses [24]. LCE actuators are among the promising candidates for actuators in small scale mechanics and robotics [25]-they can be remotely controlled with spatially and/or temporarily modulated light beams and, due to their soft nature and elasticity, can be used directly to realize various concepts of soft, untethered robots [26]. Furthermore, the material itself can be programmed to respond differently in different situations, e.g., selectively interacting with objects having certain optical properties [27].…”

“…LCE actuators are among the promising candidates for actuators in small scale mechanics and robotics [ 25 ]—they can be remotely controlled with spatially and/or temporarily modulated light beams and, due to their soft nature and elasticity, can be used directly to realize various concepts of soft, untethered robots [ 26 ]. Furthermore, the material itself can be programmed to respond differently in different situations, e.g., selectively interacting with objects having certain optical properties [ 27 ].…”