Acoustic Sensor Single-End-Wall Transducer Layout
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Solution Overview
Problem
Existing gas sensors with disc-shaped acoustic cavities face challenges in manufacturing complexity and cost due to the need for separate transmitter and receiver components on opposing end walls, which complicates electrical connections and increases production steps.
Innovation Solution
A sensor design where the transmitter and receiver are positioned on a single end wall, mechanically isolated by rigid structures or thin flexible membranes, allowing for simpler construction and reduced manufacturing steps, with a disc-shaped cavity having a circular or elliptical cross-section that facilitates efficient acoustic oscillations and signal generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the transmitter and receiver are positioned on opposing end walls of the disc-shaped cavity, then the acoustic impedance matching and spatial matching between the transducers and the fluid pressure oscillation are optimized, but the device complexity and manufacturing cost increase due to the need for separate positioning and electrical connections
Solution Approach 1:
The patent combines both the transmitter and receiver on a single end wall of the disc-shaped cavity, eliminating the need for separate positioning on opposing walls. This merging approach maintains the acoustic performance by using a single end wall configuration while reducing device complexity and simplifying electrical connections, as both transducers share the same mounting surface and electrical interface layer.
Solution Approach 2:
The single end wall serves multiple functions by accommodating both the transmitter and receiver transducers, as well as providing a common mounting surface for electrical connections. This multi-functional design eliminates the need for separate structural support and electrical interface layers that would be required if transducers were positioned on opposing walls.
2Measurement precision
If the transmitter and receiver are positioned on opposing end walls, then the acoustic performance is optimized, but the manufacturing cost and production steps increase
Solution Approach 1:
The patent merges the positioning of both transmitter and receiver on a single end wall, which simplifies the manufacturing process by reducing the number of assembly steps. This approach maintains acoustic performance while lowering manufacturing cost through simplified production and reduced handling of small parts during assembly.
Solution Approach 2:
The patent segments the transducer array into two groups (transmitter and receiver) that are both positioned on the same end wall, allowing for batch fabrication using common layers of material. This segmentation approach enables parallel production of multiple devices from a single wafer, reducing manufacturing cost while maintaining acoustic performance.
3Measurement precision
If the transmitter and receiver are positioned on opposing end walls, then the acoustic impedance matching is optimized, but the electrical connection complexity increases
Solution Approach 1:
The patent combines the electrical connection points for both transmitter and receiver on a single end wall, allowing both transducers to be electrically interfaced through the same layer or substrate. This merging of electrical connections eliminates the need for separate connection paths through the cavity, thereby reducing electrical connection complexity while maintaining acoustic impedance matching.
4Loss of time
If small size MEMS devices are manufactured in batch process, then the response time is reduced and production efficiency is improved, but the device complexity increases when positioning transducers on opposing walls
Solution Approach 1:
The patent combines both transducers on a single end wall, which simplifies the batch fabrication process for small MEMS devices. This merging approach maintains the rapid response time characteristics of small-sized devices while reducing device complexity, making the batch manufacturing process more efficient and easier to implement.
Solution Approach 2:
The patent segments the transducer configuration into a single-end-wall arrangement that can be fabricated using common layers of material in a batch process. This segmentation enables parallel production of multiple small MEMS devices while maintaining simplified construction, thereby achieving fast response time without increasing device complexity.
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 manufacturing complexity and cost while maintaining high performance, enabling accurate measurement of fluid properties by optimizing the geometry for efficient acoustic resonance and signal generation, with improved response time and suitability for portable applications.
Implementation Method 1
the transmitter causes oscillatory motion of the region of the end wall operatively associated with the transmitter, in a direction substantially perpendicular to the plane of the end walls; such that the perpendicular oscillations of the end walls drive substantially in-plane oscillations of the fluid pressure in the cavity
Implementation Method 2
the substantially in-plane oscillations in the pressure of the fluid drive substantially perpendicular oscillatory motion of the region of the end wall operatively associated with the receiver, resulting in an electrical signal from the receiver
Implementation Method 3
transmitter(s) and receiver(s) are mechanically isolated from one another by means of rigid support structure(s) positioned on the first end wall between the transmitter(s) and receiver(s) or by means of a thin flexible membrane bridging gap(s) in the first end wall between the transmitter(s) and receiver(s)
Data Source
Figure 1A~1C
Figure 2~3C
Figure 4A~4D
AI summary
An acoustic sensor comprises a side wall closed at each end by an end wall to form a cavity which, in use, contains a fluid. At least one transmitter and at least one receiver are operatively associated with one of the end walls. A maximum half width, a, of the cavity and a height, h, of the cavity satisfies the following inequality: a/h is greater than 1.2. In use, the transmitter causes oscillatory motion of the region of the end wall operatively associated with the transmitter, in a direction substantially perpendicular to the plane of the end walls such that the perpendicular oscillations of the end walls drive substantially in-plane oscillations of the fluid pressure in the cavity. The substantially in-plane oscillations in the pressure of the fluid drive substantially perpendicular oscillatory motion of the region of the end wall operatively associated with the receiver, resulting in an electrical signal from the receiver.