Electromagnetically Actuated MEMS Switch Overcoming Stiction
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Solution Overview
Problem
MEMS switches actuated solely by electrostatic force often suffer from stiction issues and material softening, leading to failure in opening the switch after extended periods in a closed state due to creep force, which affects their reliability.
Innovation Solution
The use of an electromagnetic force, generated by a coil positioned under the cantilevered beam, to selectively repel the beam away from the contact, ensuring the switch can be turned off even if stuck or deformed, combined with electrostatic actuation for closing and opening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the beam remains in closed state for extended periods, then the switch maintains connection, but material softening and creep force cause the beam to fail returning to open position
Solution Approach 1:
The electromagnetic actuator applies a preliminary opposing force to counteract the creep force and material softening effects that develop during extended closed state operation. By providing this anti-action force, the system prevents the beam from becoming permanently deformed and ensures it can return to the open position when required.
2Reliability
If electromagnetic coil is added to the MEMS switch, then the switch can be reliably opened by overcoming stiction, but the device complexity increases
Solution Approach 1:
The electromagnetic coil structure is merged with the existing electrostatic actuator components, allowing the same structural elements to serve dual purposes. The coil is positioned to generate electromagnetic force while sharing space and structural support with the electrostatic actuator, thereby reducing the overall increase in device 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 approach ensures reliable switching by overcoming stiction and creep force issues, allowing the switch to maintain proper operation even after extended periods in a closed state, enhancing the reliability and durability of MEMS switches.
Implementation Method 1
An microelectromechanical switch uses electrostatic attraction to draw a beam toward a contact
Implementation Method 2
The electromagnetic repulsion is generated between the beam and a magnetic coil positioned on the same side of the beam as the contact. The magnetic coil produces a magnetic field, which induces a current in the beam that repels the magnetic coil.
Data Source
AI summary
An microelectromechanical switch uses electrostatic attraction to draw a beam toward a contact and electromagnetic repulsion to disengage and repel the beam from the contact. The electrostatic attraction is generated by a gate electrode. The electromagnetic repulsion is generated between the beam and a magnetic coil positioned on the same side of the beam as the contact. The magnetic coil produces a magnetic field, which induces a current in the beam that repels the magnetic coil. The gate electrode and the magnetic coil may be co-planar or in different planes. A circuit may also operate a coil-shaped structure act as the gate electrode and the magnetic coil, depending on the configuration.