Chained Iron Microparticles for Directionally Controlled Actuation of Soft Robots

Abstract

Magnetic field-directed self-assembly of magnetic particles in chains is useful for developing directionally responsive materials for applications in soft robotics. Using materials with greater complexity allows advanced functions, while still using simple device architectures. Elastomer films containing chained magnetic microparticles were prepared through solvent casting and formed into magnetically actuated lifters, accordions, valves, and pumps. Chaining both enhances actuation and imparts a directional response. Cantilevers used as lifters were able to lift up to 50 times the mass of the polymer film. We introduce the "specific torque", the torque per field per mass of magnetic particles, as a figure of merit for assessing and comparing the performance of lifters and related devices. Devices in this work generated specific torques of 68 Nm/kgT, which is significantly higher than in previously reported actuators. Applying magnetic fields to folded accordion structures caused extension and compression, depending on the accordion's orientation. In peristaltic pumps comprised of composite tubes containing embedded chains, magnetic fields caused a section of the tube to pinch closed where the field was applied. These results will facilitate both the further development of soft robots based on chained magnetic particles and efforts to engineer materials with higher specific torque.

Flexible Ferrofluids: Design and Applications

“…d) Optical images of magnetic elastomer films employed in accordions, lifters, and peristaltic pumps. Reproduced with permission . Copyright 2017, American Chemical Society.…”

“…It was found that these helical micromotors could display rotation and corkscrew motion responding to a clockwise and 3D rotary magnetic field, respectively. Besides, Schmauch et al embedded chained ferromagnetic nanoparticles into thin elastomer films via solvent casting . The resultant films were then formed into accordions, lifters, and peristaltic pumps and showed excellent magnetic response (Figure d).…”

“…Combining the advantages of field responsive ferrofluids and curable soft materials, magnetically responsive soft robots with different shapes could be fabricated and widely used, [60] such as cilia-like, [61,62] columnar, [63][64][65] helical, [26,[66][67][68][69] film-shaped, [70][71][72][73] mesh-like, [74] etc. [75,76] They have found various applications in drug delivery, wettability manipulation, anti-icing, water purification, and optical transmission.…”

A Multifunctional Nanocomposite Hydrogel for Endoscopic Tracking and Manipulation

“…To introduce additional functionalities, magnetic‐responsive IONPs are combined to the optically responsive G@UCNPs hydrogel to produce a multifunctional hydrogel, using the magnetic self‐assembly of IONPs in hydrogel to introduce anisotropy at the meso‐ and nanoscale . The G@UCNPs were printed with an empty inner portion, which acts as assembly chamber for the magnetic nanoparticles (Figure ).…”

“…To introduce additional functionalities, magnetic-responsive IONPs are combined to the optically responsive G@UCNPs www.advancedsciencenews.com www.advintellsyst.com hydrogel to produce a multifunctional hydrogel, using the magnetic self-assembly of IONPs in hydrogel to introduce anisotropy at the meso-and nanoscale. [4,30,41] The G@UCNPs were printed with an empty inner portion, which acts as assembly chamber for the magnetic nanoparticles (Figure 1). The outer cases composed of G@UCNPs, which is solid at T < 37 C, was filled up with a solution of PEGDA monomer (liquid), the photoinitiator Irgacure 2959 (3 mg mL À1 ), and IONPs (%2.5 mg mL À1 ).…”