Flexible PCB Matching Layer for Low-Loss Ultrasonic Transducers
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Solution Overview
Problem
Existing ultrasonic transducers for measuring fluid flow in pipes face challenges in achieving accurate measurement due to high energy losses and complex manufacturing processes, leading to increased costs and reduced reproducibility, especially when measuring gases with low acoustic impedance.
Innovation Solution
The ultrasonic transducer incorporates a flexible printed circuit board as both a matching and protective layer, simplifying manufacturing by eliminating the need for a separate protective layer and reducing the number of components, while providing improved impedance matching and electrical contact through a conductive layer divided into partial planes for individual element control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate protective layer is added to protect the matching layer from mechanical damage or contamination, then the protection of the matching layer is improved, but the impedance matching deteriorates
Solution Approach 1:
The patent combines the protective layer and matching layer into a single integrated layer. This layer is designed to simultaneously provide mechanical protection against damage and contamination while maintaining the acoustic impedance matching properties between the piezoelectric element and the fluid, thereby resolving the contradiction between protection and impedance matching performance
Solution Approach 2:
The integrated layer serves multiple functions: it acts as both a protective barrier against mechanical damage and contamination, and as an acoustic impedance matching layer for efficient ultrasonic wave transmission. This multi-functionality eliminates the need for separate protective and matching layers
2Reliability
If multiple separate layers (backing layer, matching layer, protective layer) are used in the ultrasonic transducer, then the protection and impedance matching are improved, but the manufacturing complexity and costs increase
Solution Approach 1:
The patent merges the protective layer and matching layer into a single integrated structure, reducing the total number of layers from three (backing, matching, protective) to two (backing, integrated protective-matching). This simplification reduces manufacturing complexity and costs while maintaining the necessary protection and impedance matching functions
Solution Approach 2:
The integrated layer performs multiple functions simultaneously - providing mechanical protection, preventing contamination, and ensuring acoustic impedance matching. This multi-functional design eliminates the need for multiple separate components, thereby reducing device complexity
3Loss of energy
If the matching layer is exposed to the fluid for measurement, then the ultrasonic wave coupling into the gas is improved, but the matching layer becomes vulnerable to mechanical damage or contamination
Solution Approach 1:
The patent combines the protective and matching functions into a single layer that is exposed to the fluid. This integrated layer allows ultrasonic waves to couple efficiently into the gas while simultaneously providing protection against mechanical damage and contamination, resolving the contradiction between coupling efficiency and vulnerability
4Manufacturing precision
If separate process steps are used for producing layers with thicknesses in the range of 100 to 500 μm, then the manufacturing precision of each layer is improved, but the production costs and effort increase significantly
Solution Approach 1:
The patent combines the protective layer and matching layer into a single layer with a total thickness in the range of 100 to 500 μm. This integrated approach allows for simplified manufacturing with fewer process steps while maintaining precise thickness control, thereby reducing production effort and costs
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 reduces production costs, enhances measurement accuracy by minimizing energy loss, and ensures reproducibility by simplifying the manufacturing process and improving mechanical rigidity, making it suitable for industrial-scale production.
Implementation Method 1
a piezo element coupled to the first electrode and used to generate an ultrasound wave to be emitted
Implementation Method 2
a matching layer, which is arranged on the second electrode and enables impedance matching between the piezo element and the fluid, e.g. gas, in order to couple the generated ultrasound into the gas or out of the gas
Data Source
AI summary
The invention relates to an ultrasonic transducer (1) for transmitting and/or for receiving ultrasonic waves, comprising a backing layer (2), a matching layer (A) for impedance matching to the fluid (F), a piezoelectric element (4) arranged between the backing layer (2) and the matching layer (A), a first electrode (3a) between the support layer (2) and the piezo element (4) providing a first electrical contact (K1) of the piezo element (4), wherein the matching layer (A) is formed by a flexible printed circuit board (Lp) and the flexible printed circuit board (Lp) provides a second electrical contact (K2) of the piezo element (4).