Bio-Inspired Magnetically Controlled Reversibly Actuating Multimaterial Fibers

Abstract

Movements in plants, such as the coiling of tendrils in climbing plants, have been studied as inspiration for coiling actuators in robotics. A promising approach to mimic this behavior is the use of multimaterial systems that show different elastic moduli. Here, we report on the development of magnetically controllable/triggerable multimaterial fibers (MMFs) as artificial tendrils, which can reversibly coil and uncoil on stimulation from an alternating magnetic field. These MMFs are based on deformed shape-memory fibers with poly[ethylene-co-(vinyl acetate)] (PEVA) as their core and a silicone-based soft elastomeric magnetic nanocomposite shell. The core fiber provides a temperature-dependent expansion/contraction that propagates the coiling of the MMF, while the shell enables inductive heating to actuate the movements in these MMFs. Composites with mNP weight content ≥ 15 wt% were required to achieve heating suitable to initiate movement. The MMFs coil upon application of the magnetic field, in which a degree of coiling N = 0.8 ± 0.2 was achieved. Cooling upon switching OFF the magnetic field reversed some of the coiling, giving a reversible change in coiling ∆n = 2 ± 0.5. These MMFs allow magnetically controlled remote and reversible actuation in artificial (soft) plant-like tendrils, and are envisioned as fiber actuators in future robotics applications.

Soft Robot Design, Manufacturing, and Operation Challenges: A Review

“…Bio-inspired manipulator designs have gained significant acceptance due to their ability to accommodate various biomotion modes [66]. Such naturally driven principles are commonly employed in various disciplines, including soft robotics [67][68][69][70], composite materials [71,72], path planning [73,74], energy optimization [75], etc. Soft robots inspired by earthworms [8,76,77], snakes [78,79], snails [80,81], insects [82,83], and caterpillars [84,85] have experienced a notable surge in research activities in recent years.…”

“…Soft robots that are made of multifunctional soft materials may be able to demonstrate various biomotions shown in Figure 4, such as shortening or elongation [167,168], twisting or untwisting [130,169], wrapping or unwrapping [112,170], bending or unbending [48,163,165,171], and contraction or expansion [112,168]. These soft matter biomotions can be triggered by common stimuli, such as magnetism [2,31,32,61,67,78,[107][108][109][110][111][112][113]116,172], electricity [33][34][35][36]51,131,134,173], temperature [18,85,111,112,116,122,173], tactility [51,121,145,[158]…”