Nondestructive inspection and imaging of magnetic hydrogel using the alternating magnetic field infrared thermography

Magnetic hydrogel has great potential application in various fields, such as soft robots, drug delivery and biomedical engineering. We report a testing method, i.e., the infrared thermograph method based on alternating magnetic field excitation for the detection of magnetic hydrogel. We verify the feasibility of concentration evaluation of magnetic nanoparticles in magnetic hydrogels using this method and analyze the relationship between the surface temperature rise rate of the magnetic hydrogel and the nanoparticle concentration. Then, we use this method to inspect and image the distribution of magnetic particles. Besides, we validate that this method is effective for detecting bubble defects in magnetic hydrogel and imaging the three-dimensional distribution of the fibers added in the hydrogel, and metal fibers are mainly concerned. This work provides a clear insight into a nondestructive inspection and imaging method to magnetic hydrogel, and this method can be efficient to detect multiple types of information.