Magnetoelectric nanoparticles shape modulates their electrical output

Abstract

Core-shell magnetoelectric nanoparticles (MENPs) have recently gained popularity thanks to their capability in inducing a local electric polarization upon an applied magnetic field and vice versa. This work estimates the magnetoelectrical behavior, in terms of magnetoelectric coupling coefficient (αME), via finite element analysis of MENPs with different shapes under either static (DC bias) and time-variant (AC bias) external magnetic fields. With this approach, the dependence of the magnetoelectrical performance on the MENPs geometrical features can be directly derived. Results show that MENPs with a more elongated morphology exhibits a superior αME if compared with spherical nanoparticles of similar volume, under both stimulation conditions analyzed. This response is due to the presence of a larger surface area at the interface between the magnetostrictive core and piezoelectric shell, and to the MENP geometrical orientation along the direction of the magnetic field. These findings pave a new way for the design of novel high-aspect ratio magnetic nanostructures with an improved magnetoelectric behaviour.

Comparative analysis of energy transfer mechanisms for neural implants

“…This involves not only optimizing the materials but also the overall design of the transducer and the tuning of the magnetic field generator and ultrasonic modulation. Engineers and scientists are exploring various transducer geometries and configurations to enhance their energy conversion capabilities, ensuring that the implants receive sufficient power to function effectively ( Iqbal et al, 2022 ; Marrella et al, 2023 ; Sasmal and Arockiarajan, 2023 ).…”

Magnetoelectric Nanoparticles for Wireless Peripheral Nerve Stimulation: A Computational Study

“…Following, the steps are illustrated in detail. Leveraging on the results of our previous works [19,20], the MENPs were modeled as dipolar distributions aligned along the hypothesized direction of the external low-amplitude magnetic field used for eliciting the ME effect. The dipole was modeled as a positive hemisphere of 2.5 mV and a negative hemisphere of -2.5 mV separated by an insulating layer of techotane material (V = 0 mV, σ = 0 S/m, ε = 3.4, and μr = 1).…”

“…Initially, we hypothesized to inject a single MENP to investigate the effects of a highly localized stimulation. The MENP was modeled as a sphere with a diameter of 80nm (Figure 1), in accordance with computational and experimental studies [14,[19][20][21]. Additionally, considering that experimental studies [7] indicate that MENPs tend to agglomerate when injected into biological means, with the size of the agglomerates depending on the injected MENPs concentration, we also included larger MENPs agglomerates of varying size (referred to as 'clusters') in our simulations.…”

Magnetoelectric Nanoparticles for Wireless Peripheral Nerve Stimulation: A Computational Study

“…Leveraging the results of our previous multiphysics studies [18,19], the electric model of the core-shell CoFe 2 O 4 -BaTiO 3 composites consisted of a dipolar distribution aligned along the hypothesized direction of the external low-frequency magnetic field used for eliciting the ME effect. The dipole was modeled as a positive hemisphere of 2.5 mV and a negative hemisphere of −2.5 mV separated by an insulating layer of techotane material (V = 0 mV, σ = 0 S/m, ε = 3.4, and µ r = 1).…”

“…The electromagnetic physical quantities generated by the presence of MENPs and their interactions with the dynamics of the nervous system were quantified by a computational approach. Starting from the results obtained by previous multiphysics models of such nanoparticles [18,19], which included the investigation of the magnetostriction and piezoelectric effect multiphysics coupling, this work presents the modeling of the electric behavior of MENPs when placed into a uniform AC magnetic field at a frequency of 50 Hz and amplitude above magnetic saturation. Furthermore, this study focused on the quantification of the electric field distribution induced by MENPs in the human body, the thresholds needed to elicit action potentials, the impact of pulse shape and the selectivity of axons' activation inside the neuronal fibers, and, finally, the complex interplay between the two [20,21].…”