Magnetic Sensor Using Acoustically Driven Ferromagnetic Resonance
- Technology Benefits
- Devices that operate with very low power, yet provide high tunability.
- Technology Application
- Medical imaging (Magnetoencephalography, Magnetocardiography, MRI) Metal detection and sensing (sensors for autonomous vehicles, metal detectors, military applications) Low-frequency antenna at very small size (detection of low-frequency RF signals) Navigation, gyroscopes, orientation finding, (measuring Earth's magnetic field) Bug finding / circuit detection (measuring weak RF and DC magnetic fields produced by circuitry) Geological / magnetic anomaly detection
- Detailed Technology Description
- None
- Application No.
- WO2018111769
- Others
-
Additional Technologies by these Inventors
Tech ID/UC Case
27130/2017-055-0
Related Cases
2017-055-0
- *Abstract
-
Ferromagnetic resonance (FMR) measures magnetic properties of materials by
detecting the precessional motion in of the magnetization in a ferromagnetic sample.
Different types of FMR include externally-driven FMR and current-driven FMR. FMR can
be excited using a variety of techniques, like cavity excitation, stripline excitation, spin
transfer torque, and spin orbit torque, among others These applications are typically not
compatible with device applications. They require large cavities, high power drive and use
large sample volume in order to be effective.
However, FMR has some attractive characteristics. These includes the ability to
modulate material permeability and electromagnetic absorption as a function of magnetic
applied field.
UC investigators have developed a surface acoustic wave (SAW) delay line on a piezoelectric lithium niobate substrate. The delay line consists of a pair of interdigitated transducers (IDTs) – one used to generate a SAW, and the other used to detect the SAW once it has travelled across the gap between the two IDTs. A magnetostrictive ferromagnetic material (in our case nickel) is deposited between these two IDTs, and the strain generated by the SAW is transferred into the film. This generates a time-varying internal magnetic field within the magnetostrictive film. The delay line is operated in the GHz range. By appropriately biasing the magnetic film with an external magnetic field, the magnet can be driven into FMR. In this regime, the magnet
beings to strongly absorb the travelling SAW. Thus, by measuring the absorption of the SAW (by comparing the input power incident on the generating IDT to the power measured on the detection IDT), it can be determined whether the magnet has entered FMR. This interaction also substantially alters the phase of the travelling wave – and measurements of this phase
difference can also be used to detect FMR. This effect can be used as an extremely sensitive magnetic field sensor by biasing the magnetic film so that it is very close to entering FMR and then measuring the absorption or phase of the SAW as a function of applied magnetic field. In this regime, very small changes in the external magnetic field can cause substantial and easily
measurable changes in the output power and output phase measured on the detection IDT. By using industry-standard generation and detection techniques and an input power of 20 mW, these devices should be able to measure magnetic fields on the order of ~100 femtoTesla at room temperature, beating comparable state of the art devices by several orders of magnitude when considering relevant SWaP metrics.
- *IP Issue Date
- Jun 21, 2018
- *Principal Investigator
-
Name: Dominic Labanowski
Department:
Name: Sayeef Salahuddin
Department:
- Country/Region
- USA
