Multi-Stable MEMS Switch with Curved Electrodes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
MEMS switches face challenges with soft contact materials due to low hardness, leading to adhesion forces that are larger than necessary contact forces, resulting in decreased reliability and shorter lifetimes, while conventional electrostatic switch designs are inefficient for soft materials due to oversized actuators and high actuation voltages.
Innovation Solution
A multi-stable switch mechanism with electrostatic curved-electrode actuators that utilize a zipper-like actuation mechanism, where the electrode distance increases from the clamped end to the free end, allowing for large deflection at medium actuation voltages and creating maximum force in the end-position, suitable for soft contact materials by actively opening with a large force and passively maintaining contact with spring energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If soft contact materials (e.g., gold) are used to achieve low contact resistance and high thermal conductivity, then electrical contact performance is improved, but adhesion forces increase leading to contact stiction and reduced reliability
Solution Approach 1:
The patent inverts the conventional switch operation mode by using active opening force instead of passive spring-based closing force. The electrostatic actuator actively pulls the contacts open, while the spring passively allows closing, reversing the traditional approach and enabling reliable operation with soft contact materials by overcoming adhesion forces during opening
Solution Approach 2:
The patent changes the force balance parameters by designing the spring constant and electrostatic actuator strength to achieve optimal contact and opening forces. By carefully selecting spring constants (e.g., 0.1-10 mN/m) and actuator dimensions, the system achieves sufficient contact force for electrical connection while generating adequate opening force to overcome adhesion, resolving the contradiction between soft material benefits and stiction risks
2Force
If conventional electrostatic actuators with parallel-plate electrodes are used to achieve active contact closing, then contact force is generated, but the actuator becomes oversized and requires high actuation voltages
Solution Approach 1:
The patent employs curved electrodes instead of parallel-plate electrodes, creating a non-uniform electric field that concentrates force at the contact region. The curved geometry allows the actuator to achieve maximum force output at the tip with smaller overall dimensions and lower actuation voltages, eliminating the need for oversized actuators while maintaining effective contact force
Solution Approach 2:
The patent applies local quality by concentrating the electrostatic field and force generation at the critical contact region through curved electrode geometry. The electrode curvature is optimized to generate high field strength locally at the tip where contact occurs, rather than distributing force uniformly across a large parallel-plate area, thus achieving effective contact force with minimal actuator size
3Reliability
If soft contact materials are used with conventional switch designs, then low contact resistance is achieved, but contact separation force becomes insufficient leading to permanent stiction
Solution Approach 1:
The patent fundamentally inverts the force generation strategy by making the electrostatic actuator responsible for active opening rather than passive closing. This inversion ensures that the full strength of the electrostatic force is available to overcome adhesion during opening, while the spring provides only the minimal force needed for closing, guaranteeing reliable separation of soft contact materials
Solution Approach 2:
The patent applies preliminary action by pre-charging the spring during the closed state, storing elastic energy that assists the electrostatic actuator during opening. The spring is compressed or deflected during contact closure, and this stored energy is released to provide additional opening force, ensuring adequate separation force is available when needed without requiring excessive actuator strength
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 enhances actuation and performance by providing a smaller, more efficient switch design that overcomes adhesion forces and maintains stable contact resistance, suitable for high-volume fabrication and reducing the need for oversized actuators, thus improving reliability and energy efficiency.
Implementation Method 1
The actuator mechanism features active closing by the electrostatic force
Implementation Method 2
passive opening by the spring energy stored in the deflected, i.e. pulled in, structure
Implementation Method 3
The counteracting restoring spring force is directly proportional to d
Implementation Method 4
electrostatic curved-electrode actuators that utilize a zipper-like actuation mechanism, where the electrode distance increases from the clamped end to the free end
Data Source
AI summary
The invention relates to a method, a system and a multi stable arranged to switch the configuration of the signal path for electrical signals comprising a first moving element (12) and a second moving element (14), wherein the first and second element can be arranged into at least two mechanically stable states: a mechanical interlocked state, wherein the first moving element is mechanically interlocked with the second moving element wherein a signal path in the switch is arranged in a closed configuration; and a non interlocked state, wherein the first moving element is separated from the second moving element and the signal path in the switch is arranged in an open configuration; wherein the switch further comprises a fixated electrostatic electrode (10) configured with a first fixated electrode part arranged to actuate and move at least one of the moving elements when an electrical potential difference is applied between the first fixated electrode and at least one of the moving elements, transitioning the moving elements from one state to another.