Micro-Relay Closed Magnetic Circuit Design
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Solution Overview
Problem
Existing micro-relays face challenges in efficiently coupling magnetic fields due to high magnetic reluctance, leading to inconsistent operating characteristics and high power consumption, particularly in vertically actuated designs, and difficulties in integrating practical electromagnetic coils for laterally actuated relays.
Innovation Solution
A microfabricated micro-relay with a monolithically integrated planar coil and switch, forming a closed magnetic circuit with ferromagnetic cores, allowing efficient magnetic field channeling and reducing the magnetic field strength required, and utilizing multiple coils to generate high field strength with relaxed design parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If vertically actuated micro-relays are used with conventional MEMS-based planar processing, then the movable structure can be created straightforwardly, but adding an efficient magnetic circuit with compact magnetic path and large cross section area is challenging
Solution Approach 1:
The patent transitions from planar 2D magnetic circuits to 3D vertically stacked magnetic circuits. Multiple magnetic layers are stacked above each other with magnetic vias connecting them, creating a three-dimensional magnetic path that achieves compact footprint while maintaining large effective cross-sectional area for efficient magnetic coupling.
2Ease of manufacture
If thin-film layers are used for movable magnetic elements, then micro-relays can be fabricated using standard MEMS processes, but the operating characteristics vary significantly depending on deposition conditions
Solution Approach 1:
The patent changes the geometric parameters of the magnetic circuit elements (increasing cross-sectional area, optimizing path length) to compensate for variations in thin-film material properties. This allows the magnetic circuit to maintain consistent operating characteristics despite variations in deposition conditions, as the geometry becomes the dominant factor rather than material property variations.
3Reliability
If laterally actuated micro-relays are used with tethers, then operating characteristics are decoupled from thin-film properties, but integrating practical electromagnetic coils within the device is difficult
Solution Approach 1:
The patent merges the electromagnetic coil structure with the magnetic circuit elements. The coil is formed as an integrated component surrounding or adjacent to the magnetic path, combining the actuation mechanism and magnetic circuit into a single unified structure that simplifies integration while maintaining performance.
4Reliability
If high magnetic field strength is required for actuation, then reliable switching can be achieved, but power consumption increases
Solution Approach 1:
The patent converts the high magnetic reluctance (harmful factor) into a design opportunity by creating a optimized magnetic circuit geometry that minimizes reluctance. The vertically stacked structure with magnetic vias creates low-reluctance paths that reduce the magnetic field strength required for actuation, thereby reducing power consumption while maintaining reliable switching.
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 enhances the coupling efficiency of magnetic fields, reduces power consumption, and improves the reliability and consistency of micro-relay operating characteristics, while enabling practical integration of electromagnetic coils within a compact footprint.
Implementation Method 1
an electromagnetic coil for generating a magnetic field based on the flow of the first current
Implementation Method 2
a readily magnetized or 'soft' ferromagnetic material may be employed in the magnetic path
Implementation Method 3
The force exerted on the relay contacts due to the magnetic field produced by the electromagnetic coil
Data Source
AI summary
A micro-relay that overcomes some of the limitations and drawbacks of the prior art is disclosed. The micro-relay comprising: (1) a first substrate comprising one or more monolithically integrated planar coils for generating a magnetic field; and (2) a second substrate comprising a magnetically actuated switch having a moving contact that selectively moves in a plane parallel to its substrate. The first and second substrate are aligned and bonded to collectively provide a closed magnetic circuit that efficiently channels the generated magnetic field through the switch.