Fabrication and electromagnetic properties of bio-based helical soft-core particles by way of Ni–Fe alloy electroplating

Ni–Fe alloy electroplating was used as a bio-limited forming process to fabricate bio-based helical soft-core ferromagnetic particles, and a low frequency vibration device was applied to the cathode to avoid microorganism (Spirulina platens) cells adhesion to the copper net during the course of plating. The morphologies and ingredients of the coated Spirulina cells were characterized using scanning electron microscopy and energy dispersive spectrometer. The complex permittivity and permeability of the samples containing the coated Spirulina cells before and after heat treatment were measured and investigated by a vector network analyzer. The results show that the Spirulina cells after plating keep their initial helical shape, and applying low frequency vibration to the copper net cathode in the plating process can effectively prevent agglomeration and intertwinement of the Spirulina cells. The microwave absorbing and electromagnetic properties of the samples containing the coated Spirulina cells particles with heat treatment are superior to those samples containing the coated Spirulina cells particles without heat treatment.

► We used the microorganism cells as forming template to fabricate the bio-based helical soft-core ferromagnetic particles.
► Microorganism selected as forming templates was Spirulina platens, which are of natural helical shape and have high aspect ratio.
► Coated Spirulina cells were a kind lightweight ferromagnetic particle.