Encapsulated Magnetoelectric Composites for Wirelessly Powered Brain Implantable Devices

Abstract

Magnetoelectric devices are readily employed as sensors, actuators, and antennas, but typically exhibit low power output. This paper presents considerations for the viability of magnetoelectric composites for wireless power transfer in neural implantation. This is accomplished herein by studying different types of biocompatible encapsulants for magnetoelectric devices, their impact on the output voltage of the composites, and the rigidity of the materials in the context of tissue damage. Simulation results indicate that a polymer encapsulant, rather than creating a substrate clamping effect, increases the voltage output of the magnetoelectric, which can be further improved by careful polymer selection. These attributes are modelled using the finite element method (FEM) with COMSOL Multiphysics. The addition of a 0.2 mm poly(ethyl acrylate) encapsulating layer increases the piezoelectric voltage to 3.77 V AC output at a magnetic field strength of 200 Oe, as the magnetostrictive layer deforms inside the flexible outer polymer. Comparing voltage conditioning circuits, the output is sufficient for low-voltage neuronal stimulation when employing a simple bridge rectifier which boasts minimal charging time and ripple voltage lower than 1 mV.

Magnetically Guided Catheters, Micro- and Nanorobots for Spinal Cord Stimulation

“…To be considered for neurostimulation, micro- and nanorobots must be able to generate an electrical field. Since neuronal stimulation in the brain has already been demonstrated (Yue et al, 2012 ; McGlynn et al, 2020 ; Singer et al, 2020 ; Kozielski et al, 2021 ), this can serve as an intriguing technology for SCS. In micro- and nanorobotic applications, magnetoelectric devices are mostly made from magnetoelectric composites that exhibit coupling between ferromagnetism and ferroelectricity (Spaldin and Fiebig, 2005 ; Wang et al, 2010 ) and consist of a structural combination of magnetostrictive and piezoelectric materials ( Figure 2D ) (Wang et al, 2010 ).…”

Parametric investigations of wireless energy transfer using strain-mediated magnetoelectric transmitter-receiver

“…Thirdly, most of the discussed conventional WET techniques use high-frequency waves or vibrations, which are potential health hazards, potentially posing integration challenges in biomedical applications [34]. ME composites in the millimeter scale, usually operating in a few hundred Hz to tens of kHz range, have been shown to be biocompatible and therefore offer a wider spectrum of applications [35,36]. Notably, the frequency range is dependent on the size, constituent materials, and operating conditions.…”

Enhancing Isolation in Solidly Mounted Resonators for Brain Implantable Microbots

“…neural interfacing devices struggle with the brain tissue reaction to traditional implantation designs [1]. The device activation method and the transmission of power and data are key factors to enable their operation for neurostimulation and recording.…”

“…For that reason, the research about RF acoustic resonators that uses the coupling of magnetoelectric and piezoelectric materials is essential. This kind of resonators enable the actuation of the implantable microbots via magnetic field, as well as a wireless transmission of power and data, causing minimal tissue damage and offering a considerable improvement to brain implantable devices [1], [3]- [5].…”