Capacitive Pressure Transducer Eliminating Physical Electrode Connections
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Solution Overview
Problem
Existing capacitive pressure transducers face challenges in manufacturing complexity and durability due to the need for precise rotational alignment and the use of materials like solder or conductive epoxies for electrode connections, which can lead to failure modes and stray capacitance errors.
Innovation Solution
A capacitive pressure transducer design featuring a substrate with a sensing electrode and a coupling electrode, where a spacer creates a fixed and dynamic capacitive gap, allowing for capacitive coupling without physical electrical contact, reducing signal amplitude loss and simplifying assembly by eliminating rotational alignment requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If physical electrical contact is used to connect electrodes, then electrical connection is achieved, but manufacturing complexity and durability are reduced due to precise rotational alignment requirements and material failure modes
Solution Approach 1:
The patent replaces the mechanical electrical connection system (solder joints, conductive epoxies requiring precise alignment) with a capacitive coupling system. The source electrode and diaphragm electrode form a capacitor that couples electrical signals without physical contact, eliminating mechanical connection complexities and improving reliability.
Solution Approach 2:
The patent introduces an electrical field as an intermediary between the source electrode and diaphragm electrode. This electrical field mediates the signal transmission, allowing electrical coupling without direct physical contact, thereby avoiding the reliability issues of physical connections while maintaining electrical functionality.
2Reliability
If physical connections are used for electrode attachment, then electrical connectivity is established, but stray capacitance errors and failure modes are introduced
Solution Approach 1:
The patent replaces physical electrical connections with capacitive coupling, eliminating the sources of stray capacitance errors associated with solder joints and conductive epoxies. The capacitive coupling method inherently avoids the parasitic effects introduced by physical connection materials and geometries.
3Manufacturing precision
If rotational alignment is required for electrode assembly, then precise electrical connection is achieved, but manufacturing ease and assembly simplicity are reduced
Solution Approach 1:
The patent replaces the mechanical alignment system with a capacitive coupling system that is inherently alignment-tolerant. The capacitive coupling effect occurs over an area between electrodes rather than at a specific point contact, eliminating the need for precise rotational alignment during assembly.
Solution Approach 2:
The capacitive coupling mechanism serves multiple functions: it provides electrical signal coupling, inherently filters high-frequency noise, and tolerates misalignment, replacing multiple separate requirements that would otherwise need to be satisfied by a mechanical connection system.
4Loss of energy
If signal amplitude loss is reduced through direct connection, then signal strength is maintained, but physical connection requirements increase complexity
Solution Approach 1:
The patent replaces physical signal transmission through connection materials with capacitive signal coupling. The capacitive coupling efficiently transfers signal energy without the losses and complexities associated with physical connections, achieving low signal loss without requiring complex connection structures.
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 capacitive coupling design enhances manufacturing ease, durability, and reliability by eliminating the need for physical connections and reducing signal loss, while maintaining equivalent capacitance values, thus improving the overall performance and longevity of the pressure transducer.
Implementation Method 1
The coupling electrode and the diaphragm electrode together define a coupling capacitance... The coupling electrode, diaphragm electrode, and sensing electrode together form a circuit that can be modeled as two capacitors in series
Implementation Method 2
Pressure changes induce flexion in the diaphragm, which change the distance between the parallel offset conductive plates, causing a measureable change in capacitance
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
A capacitive pressure transducer of an embodiment of the present invention capacitively couples two electrodes on a substrate with a diaphragm electrode to form a transducing circuit without the need for a physical connection between the electrodes. Embodiments of the present invention have a substrate (220) with a coupling electrode (250) and a sensing electrode and an attached diaphragm with a diaphragm electrode. A spacer positioned between the substrate and the diaphragm (210) provides for a cavity that defines a gap between the sensing electrode and the diaphragm electrode. A dielectric spacer(230) may be positioned over the coupling electrode to increase the capacitance between the coupling electrode and the diaphragm electrode. The capacitive pressure transducer has similar electrical characteristics as existing capacitive pressure transducers, is easier to manufacture, and has long-term reliability and durability improvements brought about by the elimination of mechanical interconnects and additional conductive materials.