Acoustic Ferromagnetic Resonance Sensor for Low-Power Field Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing ferromagnetic resonance (FMR) techniques are not compatible with device applications due to their requirement for large cavities, high power, and large sample volumes, limiting their practicality and efficiency.
Innovation Solution
Acoustically driven ferromagnetic resonance (ADFMR) devices using surface acoustic waves (SAWs) and film or high-tone bulk acoustic resonators (FBAR/HBAR) that operate with low power and are suitable for low-power applications, utilizing piezoelectric elements and interdigitated transducers to excite ferromagnetic resonance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional FMR techniques are used, then magnetic field sensing capability is achieved, but device size becomes large and power consumption increases
Solution Approach 1:
The patent replaces conventional mechanical/electromagnetic excitation systems with acoustically driven ferromagnetic resonance. Surface acoustic waves (SAWs) are used to excite the ferromagnetic resonance in a thin film, eliminating the need for large cavities and high-power electromagnetic drive systems. This substitution of the excitation mechanism directly reduces device size while maintaining magnetic field sensing capability.
Solution Approach 2:
The patent changes the operating parameters by using acoustic wave frequencies and leveraging the magnetostrictive effect in thin films. By operating at acoustic frequencies and utilizing the coupling between acoustic strain and magnetic moment, the system achieves resonance in a compact geometry, thereby reducing device size while preserving measurement precision.
2Measurement precision
If conventional FMR techniques are used, then magnetic field sensing capability is achieved, but power consumption becomes high
Solution Approach 1:
The patent replaces high-power electromagnetic excitation with low-power acoustic wave excitation. Surface acoustic waves can be generated with much lower power requirements compared to conventional cavity or stripline excitation methods, directly addressing the power consumption issue while maintaining the ability to detect magnetic fields with high precision.
Solution Approach 2:
By changing to acoustic frequency operation and utilizing the efficient coupling between acoustic strain and magnetic moment through magnetostriction, the system achieves effective magnetic resonance excitation at lower power levels, thereby reducing power consumption while maintaining measurement precision.
3Measurement precision
If conventional FMR techniques are used, then magnetic field sensing capability is achieved, but device complexity increases
Solution Approach 1:
The patent replaces complex electromagnetic cavity structures and high-power drive electronics with simpler acoustic wave generation and detection systems. Surface acoustic wave devices can be fabricated using standard piezoelectric and ferromagnetic thin film deposition techniques, significantly reducing device complexity while maintaining high magnetic field sensing capability.
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
ADFMR devices achieve highly sensitive magnetic field sensing, capable of measuring fields on the order of 100 femtoTesla with low power consumption, outperforming conventional methods by several orders of magnitude.
Implementation Method 1
The acoustic drive portion generates an acoustic wave that excites the magnetostrictive element into ferromagnetic resonance through acoustic-magnetic coupling
Implementation Method 2
utilizing piezoelectric elements and interdigitated transducers to excite ferromagnetic resonance
Implementation Method 3
Ferromagnetic resonance (FMR) measures magnetic properties of materials by detecting the precessional motion in of the magnetization in a ferromagnetic sample
Data Source
AI summary
An acoustically driven ferromagnetic resonance (ADFMR) device has a piezoelectric element comprised of piezoelectric material, first and second electrodes arranged in a vertical stack with the piezoelectric element to activate the piezoelectric element to generate an acoustic wave, a radio frequency voltage source electrically connected to the first electrode, a magnet comprised of a magnetostrictive material to receive the acoustic wave, the magnet being in the vertical stack with the first and second electrodes and the piezoelectric element, wherein the acoustic wave resonates at a ferromagnetic resonance of the magnetostrictive material, and a readout circuit to detect a change in the acoustic wave by detecting g one of an output voltage amplitude, a change in impedance or a reflection of the acoustic wave in the magnet to measure an unknown magnetic field in which the ADFMR device resides and as experienced at the magnetostrictive element.