Magnetic Tunnel Junction Accelerometer EMI Resistance
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Solution Overview
Problem
Current accelerometers face challenges in achieving high density and resistance to ElectroMagnetic Interference (EMI) while maintaining a small and lightweight form factor, particularly in applications requiring unique environmental performance such as space and flight applications.
Innovation Solution
The use of Magnetic Tunnel Junction (MTJ) based sensor devices with two MTJs, each comprising a free layer, tunnel barrier, and pinned layer, connected to encapsulated reservoirs containing conductive particles, which detect acceleration by comparing output voltages through the Tunneling Magneto-Resistance effect, offering enhanced integration and resistance to EMI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If piezoelectric displacement transducers are used to detect acceleration, then the device can measure acceleration, but the device size and weight increase
Solution Approach 1:
The patent replaces the mechanical piezoelectric displacement transducer system with a magnetic field-based detection system using magnetic tunnel junctions and magnetic particle reservoirs. This substitution eliminates the need for heavy mechanical components while maintaining acceleration detection capability through magnetic field interactions, directly resolving the contradiction between measurement accuracy and device weight.
Solution Approach 2:
The patent changes the detection parameter from mechanical displacement to magnetic field strength. By measuring changes in magnetic field strength caused by accelerating magnetic particles rather than mechanical displacement, the system achieves accurate acceleration measurement with significantly reduced device mass, as magnetic sensing components are much lighter than piezoelectric transducers.
2Measurement precision
If piezoelectric displacement transducers are used to detect acceleration, then the device can measure acceleration, but the device becomes susceptible to ElectroMagnetic Interference (EMI)
Solution Approach 1:
The patent replaces the piezoelectric system with a magnetic-based system that is inherently more resistant to EMI. The magnetic tunnel junction sensors and magnetic particle reservoirs operate based on magnetic field interactions rather than electrical signals, making the system less susceptible to electromagnetic interference while maintaining accurate acceleration measurement.
Solution Approach 2:
The patent employs composite material structures including magnetic tunnel junctions with pinned layers, free layers, and tunnel barriers, combined with magnetic particle reservoirs. These composite magnetic structures provide EMI resistance while enabling precise acceleration detection through their magnetic field response characteristics.
3Productivity
If traditional accelerometer designs are used, then the device can detect acceleration, but the integration density is low
Solution Approach 1:
The patent merges the sensor structure with memory cell architecture by integrating magnetic tunnel junction sensing elements with magnetic particle reservoirs in a unified structure. This merging enables high integration density similar to MRAM technology while the standardized cell design simplifies manufacturing, resolving the contradiction between integration density and device complexity.
Solution Approach 2:
The magnetic tunnel junction structure serves multiple functions: it acts as both the sensing element for acceleration detection and is compatible with MRAM memory cell designs. This multi-functionality allows the same basic structure to be used for both sensing and memory applications, dramatically increasing integration density without proportionally increasing structural complexity.
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 solution enables more compact, lightweight, and resilient acceleration sensors with improved integration and EMI resistance, suitable for demanding environments like space and flight applications, while supporting compatibility with MRAM technology and other sensing devices.
Implementation Method 1
comparing output voltages through the Tunneling Magneto-Resistance effect
Data Source
AI summary
A magnetic tunnel junction (MTJ) based sensor device includes a first MTJ element, a first reservoir, a second MTJ element, a second reservoir, and processing circuitry. The first reservoir includes first particles configured to move within the first reservoir during acceleration. A first portion of the first reservoir is electrically coupled to a free layer of the first MTJ element. The second reservoir includes second particles configured to move within the second reservoir during acceleration. A first portion of the second reservoir is electrically coupled to a free layer of the second MTJ element. The processing circuitry is configured to determine an acceleration based on a first output voltage at a pinned layer at the first MTJ element and a second output voltage at a pinned layer at the second MTJ element.