No abstract

Magneto-mechano-electric (MME) composite devices have been used in energy harvesting and magnetic field sensing applications due to their advantages including their high-performance, simple structure, and stable properties. Recently developed MME devices can convert stray magnetic fields into electric signals, thus generating an output power of over 50 mW and detecting ultra-tiny magnetic fields below pT. These inherent outstanding properties of MME devices can enable the development of not only self-powered energy harvesters for internet of thing (IoT) systems but also ultra-sensitive magnetic field sensors for diagnosis of human bio-magnetism or others. This manuscript provides a brief overview of recently reported high-performance MME devices for energy harvesting and magnetic sensing applications.

In this study, we demonstrate a hybrid multimodal soft magnetic composite (SMC) comprising gas-atomized spherical amorphous powder (AP) and carbonyl-iron powder (CIP), and present its enhanced electromagnetic properties. CIP is selectively incorporated into voids between AP, and deforms during compression, effectively reducing the pores, resulting in high packing density of the core, where CIP magnetically bridges AP and helps magnetic domain rotation much efficiently. The hybrid SMC with the addition of 20 wt.% CIP showed constant effective permeability of 57 up to 1 MHz, a remarkable 63% increase compared with the AP core, while DC bias superimposing retention level of 61% was secured with the help of high magnetization of CIP. In addition, the effect of SiO2 surface insulation, prepared by the sol-gel process, on the high-frequency magnetic properties of hybrid SMCs, was also evaluated. It is thus revealed that the high-frequency dynamic loss of the hybrid core, originating from intra-particle eddy current loss and anomalous loss component, and inter-particle eddy currents are negligibly small. We believe that our approach using AP/CIP multimodal hybrid SMCs is an effective way of achieving high permeability as well as high DC bias characteristics at high frequencies. This process will be highly beneficial for the miniaturization of power inductors.

The performance of MME generators was investigated under magnetic flux concentrators (MFC) and confirms the MFC with higher permeability focuses more magnetic flux to the MME generator, which can have incited an added harvested electrical power.

Micron-scale powdered amorphous soft magnetic materials are highly pursued for miniaturised and high-efficiency power inductors working at high frequencies due to their excellent soft magnetic properties such as extremely low coercivity and high electrical resistivity originated from the disordered atomic structures and zero magnetocrystalline anisotropy. However, the limited glass-forming ability (GFA) of amorphous soft magnetic alloys has hindered the preparation of amorphous soft magnetic powders through gas atomisation. Here, we present the development of amorphous soft magnetic alloys based on Mo-containing alloys with abnormal GFA, and demonstrate preparation of fully amorphous soft magnetic powders fabricated through the conventional medium-coolingrate gas atomisation process. Our Mo-containing Fe 73 Si 9−x B 10 P 5 C 3 Mo x alloy showed fully amorphous state in a ribbon form with thickness up to 179 μm. Gas atomisation performed using the alloy produced fully amorphous powder with diameter up to 75 μm, while possessing high saturation magnetisation of 1.25 T.