Ganesh Tamadapu

Gelatin-based magnetic hydrogels are composed of gelatin polymer, water, and magnetic nanoparticles. The properties of embedded nano-particles, such as coercivity and remanent magnetization, play an essential role while designing hydrogels for specific applications such as soft robotic tentacles, which can be used in minimally invasive surgery (e.g., catheters and endoscopes). The effective properties of the magnetic hydrogels can be tuned by combining various soft and hard magnetic nanoparticles. In the present work, carbonyl iron and strontium hexaferrite are used to prepare the hybrid hydrogels. The magnetization response (m-h curve) of the hydrogels is experimentally obtained, and the results confirm that the hydrogels’ effective properties are dependent on the embedded particles. Furthermore, experimental compression tests confirm that the stiffness of the hybrid hydrogels (75 kPa) is higher than the pure hydrogels (16.5 kPa). Subsequently, the strain developed in the hydrogels under the magnetic field is measured using the digital image correlation (DIC) method. Thus, the present study provides useful insights into synthesizing soft and hard magnetic hydrogels with customized magnetic and mechanical properties.

A unique approach to synthesize novel hard magnetic soft hydrogels with higher water content is proposed. The hard magnetic soft hydrogel contains cross-linked macromolecules of gelatin and water with embedded strontium hexaferrite (SFO) particles. First, SFO nanoparticles are synthesized using the auto-combustion method. Subsequently, the particles prepared are added to the hydrogels with three different weight fractions. The hydrogels are subjected to mechanical and magnetic loadings to investigate the mechanical, and actuation behavior, respectively. In addition, the hydrogels are also subjected to cyclic magnetic loading in transverse and antiparallel directions. Based on the experiments, it is observed that the deflections of the hydrogels can be controlled remotely by varying magnetic fields. Moreover, this study can be utilized to design a hydrogel beam with variable particle concentrations that can form complex shapes.