Magnetic soft silicone elastomers with tunable mechanical properties for magnetically actuated devices

Abstract

Funding informationNatural Sciences and Engineering Research Council of Canada; Fonds de recherche du Québec -Nature et technologies Polydimethylsiloxane (PDMS)/iron oxide magnetic nanoparticle (NP) composites with tailored mechanical properties are prepared for use in magnetically actuated soft devices based on their controlled deformation by the application of an external magnetic field. This investigation reports the synthesis and functionalization of iron oxide NPs, the preparation of the PDMS/NP composites, the evaluation of NP dispersion using scanning electron microscopy (SEM) and optical microscopy, and the mechanical characterization of the composite films. Characterization includes rheological measurements as well as stress-strain curves to obtain the Young modulus and elongation at break. SEM is used to probe individual NP dispersion, whereas optical microscopy provides rapid access to quantitative information about the size and distribution of particle aggregates. Results for nonfunctionalized (nf), oleic acid (OA)coated, and stearic acid (SA)-coated iron oxide NPs and their blends are presented.PDMS elastomers containing both OA-and SA-coated iron oxide NPs are found to have very low Young moduli with substantially higher resistance to failure than neat PDMS. For example, a formulation containing 2.5 wt% OA-coated NPs and 2.5 wt% SA-coated iron oxide NPs has a modulus of 0.15 MPa (compared with 0.24 MPa for neat PDMS), while it can withstand an elongation of about 1.5 times its initial length compared with only 0.3 times for neat PDMS. As a comparison, the modulus of the most commonly used commercial PDMS elastomer (Sylgard 184) is an order of magnitude higher than that of the composites prepared here, whereas maximum elongation is similar for the two. The formulations developed in this work could be used in applications where high deformability is required with limited magnetic field strength and/or NP loading. K E Y W O R D S iron oxide, mechanical properties, polydimethylsiloxane, surface treatment

Enhanced Magnetic Anisotropy for Reprogrammable High‐Force‐Density Microactuators

“…Magnetic fillers widely used in the literature include spherical shaped magnetic particles (such as iron oxide [14,15] and NdFeB [16,17] ) that lack shape anisotropy and thus require a high loading of magnetic material or the use of strong fields to achieve a noticeable response. In order to achieve significant actuation and effective transduction of magnetic field energy into mechanical energy, it is important to have a high remanent magnetic moment.…”

Reconfigurable Flexible Electronics Driven by Origami Magnetic Membranes

“…[ 11–14 ] Another promising driving approach uses magnetic fields, [ 15,16 ] which have the advantages of highest manipulation forces, enabling high speed and reversible operation in small spaces, and biological‐friendly. They can be used to remotely manipulate magnetic membranes that are achieved by embedding discrete magnetic particles such as ferrite, aluminum–iron–nickel (AlFeNi), and neodymium–iron–boron (NdFeB) into soft polymetric matrices based on polydimethylsiloxane (PDMS), [ 17,18 ] Ecoflex, [ 19 ] or polyurethane. [ 20 ] These membranes may not only serve as essential components in energy harvesters, [ 21 ] soft robotics, [ 22–24 ] and medical–surgical devices, [ 25–27 ] but also become the substrates of flexible electronics due to their compatible mechanics.…”

Miniaturized soft centrifugal pumps with magnetic levitation for fluid handling

“…Miniaturization and weight reduction of centrifugal pumps are very challenging when considering their complex structures but are very tempting in terms of their capability to handle large volumes of fluids for wearable applications. Soft materials (20)(21)(22)(23) and flexible electronics (24)(25)(26)(27) may yield mechanical systems with lightweight and excellent compatibility to biotissues (28)(29)(30). Despite lots of demonstrations in skin patches (31)(32)(33), soft robots (34)(35)(36), and implantable devices (37)(38)(39), fabricating conventional mechanical pumps with soft materials has seldomly been achieved, not to mention a rotational flexible structure in a liquid environment for fluid delivery.…”