Linearized Micromechanical Sensor Leverage Electrostatic Actuation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Micromechanical sensors face significant non-linearity issues in measuring physical quantities like acceleration and atmospheric pressure, particularly at larger deflections, where the relationship between the sensed quantity and capacitance becomes highly non-linear, limiting their accuracy and sensitivity over an enlarged measuring range.
Innovation Solution
A micromechanical sensor design featuring a substrate with a cavity and a flexible diaphragm, a lever element, and two capacitive sensors with electrodes positioned to oppose each other, along with an electrostatic actuator that applies a force to improve linearity by adjusting the pivot angle of the lever element, allowing for better signal linearization and enhanced sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple capacitive sensors are used to improve linearity, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The lever element is divided into multiple sections (first end section, center section, second end section) with separate joint elements, allowing independent capacitive sensing at different locations. This segmentation enables linearization through differential measurement while maintaining a relatively simple overall structure.
Solution Approach 2:
The invention transitions from a single capacitive sensor measuring vertical displacement to multiple sensors measuring both vertical and rotational dimensions. By adding the rotational degree of freedom through the lever element, the system achieves linearization across a broader measurement range without proportionally increasing complexity.
2Measurement precision
If the measuring range is enlarged, then sensitivity is improved, but linearity deteriorates due to large deflections
Solution Approach 1:
The lever element is designed to pivot dynamically in response to diaphragm deflection, transforming the measurement from pure vertical displacement to a combination of vertical and rotational movement. This dynamic response allows the sensor to maintain linearity across larger deflection ranges by distributing the measurement across different motion modes.
Solution Approach 2:
The lever element acts as an intermediary mechanism between the diaphragm and the capacitive sensors. It converts the non-linear vertical deflection of the diaphragm into a more linear rotational movement that can be measured by the capacitive sensors, thereby improving linearity over an extended measuring range.
3Measurement precision
If electrostatic actuator is added to improve linearity, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The electrostatic actuator serves multiple functions: it pre-positions the lever element to optimize the measurement range, compensates for non-linearities, and can potentially serve as part of the sensing mechanism itself. This multi-functionality reduces the need for additional dedicated components for linearization.
Solution Approach 2:
The electrostatic actuator changes the operational parameters of the sensor system by applying controlled forces to adjust the lever element's position and orientation. This dynamic parameter adjustment allows the system to maintain optimal linearity across different measurement conditions without requiring a fundamentally different sensor architecture.
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 significantly improves the linearity and accuracy of the sensor's signal over a larger measuring range, reducing fluctuations and enabling precise measurement of physical quantities by effectively linearizing the relationship between the physical quantity and the sensor's signal.
Implementation Method 1
the actuator operates on the basis of an electrostatic attractive force. If a control voltage is applied to the electrodes, then the electrodes are attracted to each other electrostatically.
Implementation Method 2
A capacitance of the sensor is dependent on a relative spacing of the electrodes, so that the physical quantity may be determined on the basis of the capacitance of the sensor.
Data Source
AI summary
A micromechanical sensor includes a substrate having a cavity; a flexible diaphragm spanning the cavity; and a lever element that spans the diaphragm and has a first and second end section on opposite sides of a center section. A first joint element is between the first end section and the substrate and a second joint element is between the center section and the diaphragm. The lever element can be pivoted due to a deflection of the diaphragm. Two capacitive sensors are provided, each having two electrodes, one electrode of each sensor being mounted at one of the end sections of the lever element, and the other being mounted on the substrate. The electrodes are disposed so that distances between the electrodes of different sensors are influenced oppositely when the lever element is pivoted. Also, an actuator is provided for applying an actuating force between the lever element and the substrate.