Waveguide Pressure Sensor for Continuous Force Distribution
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Solution Overview
Problem
Existing pressure sensors are inadequate for accurately and efficiently measuring mechanical stresses, particularly in elastomeric bodies, as they either require discontinuous measurements, are expensive, or can only record average stresses, and are not suitable for large strains or flexible applications.
Innovation Solution
A pressure sensor system utilizing a waveguide with an asymmetrical stripline design, comprising a compressible dielectric layer and a control unit that determines forces by measuring the change in reflection coefficient using inverse Fourier transformation or stored characteristic maps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If piezoresistive transducers are used to measure normal stress distributions continuously and electronically, then measurement precision is improved, but device complexity and cost increase significantly
Solution Approach 1:
The force application area is divided into multiple segments along the waveguide length, with each segment contributing to the reflection coefficient at specific frequency ranges. By analyzing the frequency spectrum of the reflection coefficient, the control unit can determine the position and magnitude of forces in different segments, enabling spatially resolved force distribution measurement without requiring individual sensors at each location.
Solution Approach 2:
The patent replaces the mechanical/electrical measurement system (piezoresistive transducers with individual wiring) with an electromagnetic waveguide system. The waveguide uses electromagnetic wave propagation and reflection characteristics to detect force distribution, substituting complex electrical measurement infrastructure with a simpler electromagnetic field-based approach that provides both spatial and force magnitude information through frequency analysis.
2Device complexity
If a single resonator is used to measure normal forces in elastomeric components, then device simplicity is improved, but measurement precision deteriorates as only average normal stress can be recorded
Solution Approach 1:
The patent adds a frequency dimension to the measurement by using a continuous band of frequencies rather than a single resonant frequency. The waveguide's reflection coefficient is analyzed across a frequency spectrum, where different frequency components correspond to different positions along the waveguide length. This frequency-domain approach enables spatially resolved measurements while maintaining a single, simple sensor structure.
3Measurement precision
If conventional pressure-measuring foils with multiple resistors are used, then measurement precision is improved, but ease of operation deteriorates due to significant wiring and electronics requirements
Solution Approach 1:
The patent merges multiple measurement functions into a single waveguide structure. Instead of requiring separate resistors and their individual wiring connections, the waveguide integrates force magnitude detection and spatial position detection into one component. The reflection coefficient analysis simultaneously provides information about force size and location, eliminating the need for complex wiring infrastructure and simplifying system operation.
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
Enables continuous, accurate measurement of forces over large areas, allowing for precise determination of stress distribution and application points, suitable for elastomeric components and flexible applications.
Implementation Method 1
measuring the change in reflection coefficient
Implementation Method 2
A pressure sensor system utilizing a waveguide with an asymmetrical stripline design
Implementation Method 3
compressible dielectric layer
Implementation Method 4
compressible dielectric layer
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The present invention relates to a pressure sensor system with at least one pressure sensor (1) in the form of a waveguide (1) with, in this order, a first ground plane (10), an incompressible dielectric (11), a signal plane (12), a compressible dielectric (13) and a second ground plane (14), wherein the waveguide (1) is configured such that a force (F) acting on the waveguide (1) can change the frequency-dependent reflection coefficient of the waveguide (1), and with at least one control unit, which is configured and set up to excite the waveguide (1), preferably by means of a microwave transmitter/receiver unit (2), with a frequency-variable signal, to detect the reflected component, preferably by means of a directional coupler (3), and to derive from the emitted frequency-variable signal and its reflected component, preferably by means of an evaluation unit (4),to determine the reflection coefficient as a function of frequency, and to determine the acting force (F) from the difference between a predetermined reflection coefficient and the determined reflection coefficient.