Electrostatic Actuator With Tapered Comb Fingers for Low Voltage
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Solution Overview
Problem
Existing microelectromechanical (MEMS) electrostatic actuators require high actuation voltages due to the design of comb structures, necessitating a solution to reduce this requirement.
Innovation Solution
The use of tapered comb fingers in a vertical alignment, where one set is fixed and the other is movable, increases electrostatic force, allowing for lower actuation voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional comb structure is used, then the actuator can generate force in z-direction, but large actuation voltage is required
Solution Approach 1:
The comb fingers are designed with tapered geometry where the width varies along the vertical direction. Specifically, the stator comb fingers have a first width at the bottom and a second width at the top that is smaller than the first width. This local variation in dimensions creates regions of different electrostatic field strength, increasing the overall electrostatic force while reducing the required actuation voltage.
Solution Approach 2:
The invention transitions from a conventional two-dimensional comb structure to a three-dimensional tapered structure by introducing width variation along the vertical dimension. This dimensional change allows the comb fingers to generate enhanced electrostatic force through the tapered geometry, enabling lower actuation voltages while maintaining effective actuation capability.
2Ease of operation
If large actuation voltage is applied, then the moving structure can be actuated, but energy consumption increases
Solution Approach 1:
The tapered comb fingers create localized regions of enhanced electrostatic field strength, particularly near the narrower sections. This local concentration of electric field energy increases the electrostatic force efficiency, allowing the actuator to achieve the required actuation capability with lower overall energy input and reduced voltage requirements.
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
Tapered comb fingers enhance electrostatic force, enabling lower actuation voltages and larger displacement, thus improving the efficiency of MEMS electrostatic actuators.
Implementation Method 1
The strain is induced in fixed portion to partially deform it into cavity followed by applying a voltage between portions, the moving portion moves towards the deformed fixed portion
Implementation Method 2
the comb fingers of at least one set are tapered in the vertical direction... the electrostatic force between comb fingers is increased
Data Source
Figure 1a~1b
Figure 1c
Figure 2a~2b
AI summary
The disclosure relates to microelectromechanical electrostatic actuator comprising a first layer and a second layer, a first set of comb fingers in the first layer aligned with a second set of comb finger in the second layer, wherein the x-direction width of the comb fingers of the first set is tapered along the vertical direction. An advantage of this arrangement is that the electrostatic force between comb fingers is increased by tapering and, therefore, lower actuation voltage is required.