Magnetoelectric Neural Stimulator Circuit for Deep-Tissue Power and Data
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Solution Overview
Problem
Existing technologies face challenges in delivering power and data wirelessly to miniature neural stimulators inside the body, as conventional methods suffer from absorption by the body, impedance mismatches, and limitations in frequency ranges, leading to bulky devices and failure points.
Innovation Solution
The use of magnetoelectric materials to convert alternating magnetic fields into high-frequency electrical signals, enabling efficient wireless power and data transfer through magnetoelectric films and CMOS circuits, allowing for miniaturized neural stimulators that operate at clinically relevant frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional wireless power transmission methods (electromagnetic or ultrasound waves) are used, then power can be transmitted wirelessly to implanted devices, but the body absorbs the waves and impedance mismatches occur at interfaces between air, bone, and tissue
Solution Approach 1:
The patent changes the operating frequency parameter to low frequencies (below 1 MHz, specifically 10-500 kHz) where magnetic fields experience minimal absorption by biological tissues and no impedance mismatch at tissue-bone-air interfaces. This frequency selection resolves the contradiction by operating in a regime where wireless power transmission is efficient without significant energy loss.
Solution Approach 2:
The patent replaces conventional electromagnetic induction or ultrasound-based wireless power transmission with magnetoelectric material-based power transfer. The magnetoelectric material directly converts the low-frequency magnetic field into electrical energy through the magnetoelectric effect, bypassing the need for electromagnetic resonance or acoustic wave transmission that suffer from tissue absorption and impedance issues.
2Ease of operation
If magnetically-powered stimulators based on induction or magnetothermal effects are used, then wireless power transmission is achieved, but they do not operate in clinical high-frequency ranges above 20 Hz due to fundamental limitations
Solution Approach 1:
The patent employs composite magnetoelectric materials consisting of magnetostrictive layers (e.g., Metglas, permalloy) bonded to piezoelectric layers (e.g., PVDF, PZT). The magnetostrictive layer converts the magnetic field into mechanical strain, which the piezoelectric layer then converts into electrical voltage. This composite structure enables direct conversion of low-frequency magnetic fields into high-frequency electrical stimulation signals, overcoming the frequency limitations of pure inductive or magnetothermal approaches.
Solution Approach 2:
The magnetoelectric material exploits mechanical vibration and resonance at the material level. The magnetostrictive layer vibrates in response to the magnetic field, inducing strain in the piezoelectric layer which generates electrical signals. This mechanical coupling mechanism allows the system to respond to low-frequency magnetic fields while generating high-frequency electrical outputs suitable for clinical neural stimulation applications.
3Volume of moving object
If wireless neural stimulators are miniaturized, then device size is reduced for better implantability, but power transmission efficiency and reliability are compromised
Solution Approach 1:
The magnetoelectric material acts as a self-powered energy converter within the implant. It directly harvests energy from the externally applied magnetic field and converts it into electrical power without requiring an internal battery or complex power management circuitry. This self-service capability allows the device to be miniaturized while maintaining reliable power transmission, as the power generation is distributed at the material level rather than requiring a centralized power source.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables miniature, wireless neural stimulators that can safely and reliably deliver power and data deep into tissue, overcoming absorption and impedance issues, and supports therapeutic neural stimulation with tunable waveforms.
Implementation Method 1
magnetoelectric materials that provide miniature energy harvesting from magnetic fields for neural stimulation or to power electronic devices
Implementation Method 2
The film (a laminate of piezoelectric and magnetoelectric materials) can transform the magnetic field into a high frequency, high voltage electrical signal
Data Source
AI summary
The disclosure describes new apparatus, systems and methods utilizing magnetoelectric neural stimulators with tunable amplitude and waveform. Specific embodiments of the present disclosure include a magnetoelectric film, a magnetic field generator and an electrical circuit coupled to the magnetoelectric film, in particular embodiments, the electrical circuit comprises components configured modify an electrical output signal produced by the magnetoelectric film. In certain embodiments, the electrical circuit is configured to modify the electric signal to charge a charge storage element, to transmit data to an implantable wireless neural stimulator, and to provide a stimulation output to electrodes.