Integrated MEMS Actuator and Capacitive Sensor for Keyboard Feedback
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Solution Overview
Problem
There is a need for MEMS actuators that can function as both actuators and sensors, capable of sensing parameters such as position or force applied, to enable feedback loops and indicate changes in state, particularly in applications like computer keyboards.
Innovation Solution
The integration of electrostatic MEMS actuators with capacitive sensors allows for the determination of capacitance changes, which indicate the state or position of the actuator, enabling the actuator to function as both a sensor and a force effector, such as a key press in a keyboard, through the use of cascaded electrostatic actuators with alternating layers and polysilicon hinges for enhanced travel and force capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate sensor is integrated with the MEMS actuator, then sensing capability is improved, but device complexity increases
Solution Approach 1:
The patent combines the sensor and actuator into a single integrated device. The capacitive sensor shares the same structure as the electrostatic actuator, using the movable electrode and fixed electrode configuration for both actuation and sensing functions simultaneously, thereby reducing device complexity while maintaining sensing capability
Solution Approach 2:
The electrostatic MEMS actuator structure serves dual purposes: it functions as an actuator when voltage is applied and as a capacitive sensor when capacitance is measured. This multi-functionality eliminates the need for separate sensor components while preserving both actuation and sensing capabilities
2Ease of manufacture
If the MEMS actuator structure is simplified, then ease of manufacture is improved, but sensing precision deteriorates
Solution Approach 1:
The same electrostatic MEMS structure with movable and fixed electrodes is used for both actuation and sensing without modification. This universal design simplifies manufacturing by eliminating the need for separate sensor structures while maintaining sufficient sensing precision through capacitance measurement of the existing electrode configuration
3Adaptability or versatility
If separate actuator and sensor components are used, then functional versatility is improved, but device complexity increases
Solution Approach 1:
The integrated electrostatic MEMS device provides both actuation and sensing functions within a single structure. The movable electrode can be actuated by applied voltage and simultaneously serves as one plate of a capacitor for position sensing, achieving functional versatility without increasing device complexity
Solution Approach 2:
The patent merges the actuator and sensor functions into a single integrated component. The electrostatic actuator structure with its movable and fixed electrodes inherently provides capacitive sensing capability, eliminating the need for separate components and reducing overall 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 solution enables MEMS actuators to provide tactile feedback and accurately sense key presses in keyboards, offering improved control and resistance profiles, enhancing user interaction and system responsiveness.
Implementation Method 1
A capacitive sensor can be configured to determine a capacitance of the electrostatic MEMS actuator. The capacitance of the electrostatic MEMS actuator can depend upon the position or state of the electrostatic MEMS actuator.
Implementation Method 2
Electrostatic microelectromechanical systems (MEMS) actuators are well known. Such MEMS actuators are used in a verity of applications.
Data Source
AI summary
A device can have an electrostatic MEMS actuator and a capacitive sensor in electrical communication with the electrostatic MEMS actuator. The capacitive sensor can be configured to determine a capacitance of the electrostatic MEMS actuator while a force is being applied to the electrostatic MEMS actuator as the electrostatic MEMS actuator is being actuated. The device can be used to construct a keyboard having tactile feedback, for example.