Integrated MEMS Magnetometer Accelerometer via Lorentz Force
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Solution Overview
Problem
Existing MEMS devices lack the capability to integrate both magnetometer and accelerometer functionalities within a single compact device, often requiring separate components and high-temperature fabrication steps, which complicates integration with CMOS electronics and increases costs.
Innovation Solution
A microelectromechanical (MEMS) device is designed with a structural member acting as both a current-carrying element for magnetometer operation and a proof mass for accelerometer functionality, utilizing a low-temperature fabrication process to enable concurrent magnetometer and accelerometer measurements, allowing for 2D in-plane magnetic field measurement and 1D out-of-plane acceleration detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate magnetometer and accelerometer components are used, then each sensor can be optimized for its specific function, but the device footprint, assembly complexity, and cost increase
Solution Approach 1:
The patent combines magnetometer and accelerometer functionalities into a single integrated MEMS device. The structural member serves dual purposes: as a current-carrying element for magnetometer operation and as a proof mass for accelerometer functionality. This merging eliminates the need for separate components, reducing device footprint and assembly complexity while maintaining measurement precision for both sensor types.
Solution Approach 2:
The structural member in the integrated device performs multiple functions simultaneously. It acts as both the current-carrying element for detecting magnetic fields (magnetometer function) and the proof mass for detecting acceleration (accelerometer function). This multi-functionality allows a single component to replace what would traditionally require two separate sensors, achieving space savings without compromising measurement capabilities.
2Strength
If high-temperature fabrication processes are used for MEMS devices, then certain material properties and structural integrity are achieved, but integration with CMOS electronics becomes difficult and costs increase
Solution Approach 1:
The patent employs low-temperature fabrication processes for manufacturing the integrated MEMS device, deliberately changing the temperature parameter from conventional high-temperature processes. This parameter change enables compatibility with CMOS electronics fabrication, allowing the device to be manufactured using standard semiconductor manufacturing techniques without requiring high-temperature steps that would damage or complicate integration with CMOS circuits, while still achieving sufficient structural integrity for sensor operation.
3Measurement precision
If multiple separate sensors are integrated into a system, then each sensor can operate independently with optimized performance, but power consumption and parasitic noise increase
Solution Approach 1:
By merging magnetometer and accelerometer functionalities into a single integrated device with shared structural components and electronics, the patent reduces the total power consumption compared to operating two separate sensors. The shared infrastructure eliminates redundant power requirements and reduces parasitic noise through common grounding and signal processing pathways, while maintaining independent measurement capabilities for both sensor types.
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
The solution enables a compact, cost-effective integration of magnetometer and accelerometer functions in a single device, supporting static operation at atmospheric pressure and enhanced sensitivity when packaged under vacuum, with reduced power consumption and parasitic noise.
Implementation Method 1
the structural member acts as a current carrying element for a magnetometer
Implementation Method 2
the structural member acts as a proof mass for an accelerometer
Implementation Method 3
capacitive sensing constitutes a very important means of monitoring
Data Source
AI summary
Considerations for selecting capacitive sensors include accuracy, repeatability, long-term stability, ease of calibration, resistance to chemical and physical contaminants, size, packaging, integration options with other sensors and/or electronics, and cost effectiveness. It is beneficial if such sensors are amenable to above-IC integration with associated control/readout circuitry for reduced parasitics and reduced footprint through area sharing. The inventors have established a combined Lorentz force based magnetometer and accelerometer MEMS sensor exploiting a low temperature, above-IC-compatible fabrication process operating without requiring vacuum packaging. By switching an electrical current between two perpendicular directions on the device structure a 2D in-plane magnetic field measurement can be achieved while concurrently, the device serves as a 1D accelerometer for out-of-plane acceleration, by switching the current off and by monitoring the structure's capacitive change in response to acceleration. The design can thus separate magnetic and inertial force measurements, utilizing a single compact device.