Electrostatic Actuator Spacer Electrode Prevents Stiction
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Solution Overview
Problem
Conventional electrostatic actuators experience stiction due to charge accumulation on insulating films when electrodes come into contact, leading to adhesion issues.
Innovation Solution
Incorporating a spacer with a spacer electrode portion that maintains the same potential as the electrodes, forming a prescribed air gap between them, preventing charge accumulation and ensuring non-conductive potential control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the movable electrode and fixed electrode come into contact via an insulating film in the approaching state, then the electrostatic actuator can achieve a compact structure with minimal air gap, but charge accumulation on the insulating film causes stiction
Solution Approach 1:
The spacer electrode portion is configured to have the same potential as the movable electrode (both connected to ground potential), eliminating potential difference and preventing charge accumulation on the insulating film between them. This resolves the stiction problem while maintaining minimal air gap for compact structure.
Solution Approach 2:
The spacer acts as an intermediary structure between the movable electrode and fixed electrode. It provides mechanical support to maintain the prescribed air gap while its electrode portion creates an equipotential region that prevents charge accumulation, mediating between the need for contact and the need to prevent stiction.
2Device complexity
If a simple spacer structure is used to form an air gap, then the configuration is simplified, but charge accumulation on the spacer itself causes stiction
Solution Approach 1:
By configuring the spacer to include an electrode portion connected to ground potential, the spacer is transformed from a simple insulator into an equipotential structure. This prevents charge accumulation on the spacer surface while maintaining structural simplicity, resolving the contradiction between simplicity and reliability.
3Reliability
If the spacer electrode portion has the same potential as the movable electrode, then charge accumulation is prevented, but additional potential control mechanisms are required
Solution Approach 1:
The spacer electrode portion automatically maintains the same potential as the movable electrode by both being connected to ground potential. This self-service mechanism eliminates the need for additional active potential control systems, resolving the contradiction between charge prevention and control 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
Prevents stiction by eliminating charge accumulation on the spacer and electrodes, simplifying potential control and enhancing the safety and reliability of variable capacitance capacitors and electric switches.
Implementation Method 1
a movable electrode that is disposed so as to face the fixed electrode and approaches the fixed electrode with an electrostatic force generated between the movable electrode and the fixed electrode
Data Source
AI summary
An electrostatic actuator includes: a fixed driving electrode that is disposed on a silicon substrate; a movable driving electrode that is disposed so as to face the fixed driving electrode and approaches the fixed driving electrode with an electrostatic force generated between the movable driving electrode and the fixed driving electrode; and a pair of spacers that comes in contact with the movable driving electrode in an approaching state in which the fixed driving electrode and the movable driving electrode approach each other and forms a prescribed air gap between the fixed driving electrode and the movable driving electrode, wherein each of the spacers has a spacer electrode portion that comes in contact with the movable driving electrode via an insulator and has the same potential as one of the electrodes at least in the approaching state.