System and method for an acoustically driven ferromagnetic resonance sensor device
Inventors
Labanowski, Dominic • Salahuddin, Sayeef
Assignees
Publication Number
US-11740192-B2
Publication Date
2023-08-29
Expiration Date
2040-12-14
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Abstract
A system and method for design and operation an acoustically driven ferromagnetic resonance (ADFMR) based sensor for measuring electromagnetic fields that includes: a power source providing an electrical signal to an ADFMR circuit, sensitive to electromagnetic fields, wherein the ADFMR circuit comprises an ADFMR device. The system detect and measure external electromagnetic (EM) fields by measuring a perturbation of the electrical signal through the ADFMR circuit due to the EM fields. The system and method may function to facilitate the design and operation of a chip-scale ADFMR device usable to measure EM fields.
Core Innovation
The invention describes a system and method for an acoustically driven ferromagnetic resonance (ADFMR) sensor device designed to measure electromagnetic (EM) fields. The system includes a power source producing an electrical signal delivered to an ADFMR circuit containing an ADFMR device sensitive to electromagnetic fields. The device converts the electrical signal into an acoustic wave that propagates along a magnetic material, typically a ferromagnet, where the wave is absorbed or perturbed by the magnetic resonance effect. This perturbation alters the signal, which is then converted back into an electrical signal and detected to determine the magnitude or gradient of the EM field.
The system is intended to facilitate the design and operation of compact, chip-scale ADFMR devices, in contrast to conventional ferromagnetic resonance techniques that require bulky, high-power laboratory setups using large sample volumes and cavities. The disclosed system enables integration into circuits, such as printed circuit boards, and supports CMOS-compatible processing for scalable and cost-effective production. Additionally, the system supports configurations including interferometers and gradiometers to improve sensitivity and multidimensional field measurements.
The background section identifies several shortcomings in current magnetic field sensing technologies. Traditional ferromagnetic resonance methods are not suitable for compact, production-ready systems due to size, power, and integration constraints. Other magnetic sensors such as SERF and SQUID offer high sensitivity but suffer from complexity and integration difficulties, while smaller sensors like Hall effect and magnetoresistive sensors sacrifice sensitivity. Thus, there is an unmet need for a compact, sensitive, low power, and integratable magnetic field sensor such as that provided by the acoustically driven ferromagnetic resonance sensor device.
Claims Coverage
The patent includes multiple independent claims broadly covering systems for acoustically driven ferromagnetic resonance (ADFMR) sensor devices, detailing variants of ADFMR circuits, interferometer and gradiometer configurations, and associated signal processing subcomponents.
Integrated ADFMR sensor system with power splitting and combining
A system comprising a power source with an electronic oscillator delivering an electrical signal to at least one circuit including an ADFMR circuit and a parallel reference circuit; a power splitter upstream to split the signal into test and reference signals; a power combiner downstream to combine the signals; and a detector circuit to measure electromagnetic fields from perturbations in the electrical signal.
Interferometer circuit formed by ADFMR and reference circuits
The combination of a first ADFMR circuit and a first reference circuit situated in parallel, forming an interferometer circuit for electromagnetic field measurement through signal interference.
Inclusion of advanced signal processing circuits
The system further includes circuits such as a vector modulator parallel to the ADFMR circuit for noise reduction, an IQ mixer upstream of the detector for amplitude and phase measurement, and a linearization circuit comprising an external EM field source, comparator, and logic circuit configured to operate in a setup mode to optimize measurement regimes.
ADFMR circuit with matching networks, attenuators, and phase shifters
ADFMR circuits that include upstream and downstream matching networks for impedance matching, attenuators for signal power adjustment, and phase shifters to enable constructive or destructive interference and optimize measurement sensitivity.
Parallel configuration of multiple ADFMR circuits for multidimensional sensing and gradient measurements
Systems comprising multiple ADFMR circuits connected in parallel, each with one or more ADFMR devices possibly having distinct sensing orientations, with power splitters and combiners enabling gradiometer functionality to measure spatial gradients of EM fields.
ADFMR device implemented as surface acoustic wave (SAW) devices
The use of surface acoustic wave devices as ADFMR devices where input and output interdigital transducers on a piezoelectric substrate convert electrical signals to acoustic waves and vice versa with a magnetic film between them to enable resonance-based EM sensing.
The claims encompass various configurations of ADFMR-based sensor systems, including single or multiple ADFMR circuits, integration with reference circuits to form interferometers, gradiometer setups for gradient measurement, and inclusion of signal processing components like vector modulators, IQ mixers, and linearization circuits. The inventive features focus on compact, low power, and sensitive electromagnetic field sensing using acoustic excitation of ferromagnetic resonance with specialized circuit architectures.
Stated Advantages
Provides a compact, chip-scale magnetic field sensor enabling integration not possible with conventional large-scale FMR systems.
Enables CMOS-compatible processing for scalable and cost-effective production of magnetic sensors.
Offers enhanced sensitivity to electromagnetic fields over a broad frequency spectrum (0-10 GHz).
Facilitates multidimensional and gradient measurements of EM fields through multiple ADFMR circuits.
Operates at low power consumption, thereby reducing heat generation and enabling use in temperature-sensitive environments.
Documented Applications
Mechanical sensor devices requiring magnetic field measurement.
Magnetic imaging technologies.
Replacement for SQUID devices for magnetic sensing.
Magnetoencephalography systems for detecting brain activity.
General field measurements where small size, low power, and high dynamic range are desirable.
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