Differential Capacitive Pressure Sensor for Wide-Range Precision
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Solution Overview
Problem
Conventional electrostatic capacitive pressure sensors face challenges in achieving high measurement accuracy, high resolution, wide dynamic range, and miniaturization due to limitations in diaphragm size and inter-electrode gap, which affect flexibility and pressure detection capabilities.
Innovation Solution
The sensor employs a configuration with a fixed and movable electrode, a reference chamber, and a measurement chamber, applying sequential potentials to the movable electrode to generate difference signals, and includes an insulating layer to enhance accuracy and reduce noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the diaphragm size is increased to improve measurement accuracy, then measurement precision is improved, but device size increases and miniaturization is hindered
Solution Approach 1:
The patent divides the sensor into two separate chambers: a measurement chamber for pressure detection and a reference chamber for reference pressure. This segmentation allows the measurement diaphragm to be small for miniaturization while the reference chamber provides a stable reference point, resolving the contradiction between small size and measurement accuracy.
Solution Approach 2:
The patent introduces a reference chamber dimension that is separate from the measurement chamber, adding a spatial dimension for reference pressure. This allows the measurement diaphragm to remain small while the reference system provides adequate measurement baseline, enabling both miniaturization and accurate measurement.
2Measurement precision
If the inter-electrode gap is reduced to improve resolution, then measurement resolution is improved, but flexibility decreases and dynamic range is narrowed
Solution Approach 1:
By separating the measurement and reference functions into different chambers, the patent allows the measurement electrode gap to be optimized for high resolution while the reference chamber provides a stable baseline, enabling both high resolution and wide dynamic range without compromise.
Solution Approach 2:
The patent changes the operational parameters by introducing differential pressure measurement between two chambers, allowing the use of smaller electrode gaps for higher resolution while the differential measurement approach maintains flexibility and extends the measurable pressure range.
3Measurement precision
If sequential potentials are applied to the movable electrode to generate difference signals, then noise interference is reduced, but device complexity increases
Solution Approach 1:
The patent applies sequential potentials to the movable electrode in a periodic manner, switching between connection to the measurement chamber and reference chamber. This periodic switching generates differential signals that cancel noise, improving signal-to-noise ratio while using a relatively simple switching mechanism.
Solution Approach 2:
The patent uses the output from the reference chamber as feedback to compensate for common-mode noise and drift in the measurement. By comparing the measurement chamber output with the reference chamber output, the system eliminates noise without requiring complex additional circuitry.
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 design enables high-precision pressure detection with a wide dynamic range and miniaturization, allowing for accurate fluid pressure measurement in both static and dynamic states, while reducing noise interference.
Implementation Method 1
The central portion of the second electrode 404 (diaphragm) is deflected in response to a pressure change of the fluid
Implementation Method 2
The displacement movement of the surface of the second electrode 404 due to this deflection changes a gap d between the electrodes. An electrical signal is applied to the first electrode 403 (the movable second electrode 404 is typically grounded) such that a change in capacitance between the first electrode 403 and the second electrode 404 is sensed and associated with the pressure of the fluid filling the second chamber 402
Data Source
AI summary
An electrostatic capacitive pressure sensor including a reference chamber provided between a fixed electrode and a movable electrode that deflects in accordance with fluid pressure, a measurement chamber filled with a fluid for causing deflection of the movable electrode, a means for sequentially applying a first potential and a second potential to the fixed electrode and generating a first output signal corresponding to the first potential and a second output signal corresponding to the second potential, and a means for generating a difference signal between the first output signal and the second output signal.