Ultra Miniature Multi-Hole Probe High Frequency Response
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Solution Overview
Problem
Conventional multi-hole pressure probes have limited frequency response due to probe size and static pressure transducer limitations, with remote pressure transducers causing time response delays and P-N junction isolation issues at high temperatures.
Innovation Solution
A miniature multi-hole pressure probe using silicon-on-insulator (SOI) technology with leadless piezoresistive sensors, where each sensor is mounted in its own miniature header, eliminating cavities and thermal mismatch, enabling high-frequency operation and stability across a wide temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional remote pressure transducers are used, then measurement accuracy is improved, but time response is degraded (delayed)
Solution Approach 1:
The patent combines the pressure sensing function and the electronic measurement function into a single integrated transducer assembly. The piezoresistive sensor is directly mounted in the probe body, eliminating the need for separate remote transducers connected via tubing. This integration allows the sensor to be positioned at the optimal measurement location while maintaining high measurement accuracy, thereby resolving the contradiction between measurement accuracy and time response.
2Ease of manufacture
If P-N junction isolation is used in semiconductor transducers, then manufacturing is simplified, but high temperature performance is degraded
Solution Approach 1:
The patent changes the isolation mechanism from P-N junction isolation to oxide layer isolation. This parameter change in the isolation method allows the transducer to operate at high temperatures (up to 300°C or higher) without the leakage and performance degradation associated with P-N junctions, while still maintaining manufacturability through standard semiconductor fabrication processes.
3Quantity of substance
If larger probe size is used, then more measurement locations are available, but frequency response is degraded
Solution Approach 1:
The patent uses multiple miniature transducers, each with its own independent sensing element, allowing multiple measurement locations to be distributed throughout the probe body. Each transducer operates independently with its own high-frequency response characteristics, enabling simultaneous measurements at multiple locations without compromising the frequency response of individual sensors.
4Speed
If smaller probe size is used, then frequency response is improved, but manufacturing complexity increases
Solution Approach 1:
The patent replaces complex mechanical mounting and alignment mechanisms with integrated semiconductor fabrication techniques. The piezoresistive sensor elements are fabricated directly on the transducer substrate using standard semiconductor processes, eliminating the need for precise mechanical assembly and reducing overall device complexity despite the small size and multiple components.
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 probe achieves improved high-frequency response and accuracy while maintaining a small size, capable of measuring flow angles and static pressures with enhanced stability and temperature resistance, allowing for robust and precise measurements in harsh environments.
Implementation Method 1
a plurality of leadless SOI transducers each having an active deflection area associated with a semiconductor substrate, each transducer having a header for supporting the same
Implementation Method 2
the piezoresistive network is isolated from the deflecting material by an oxide layer
Implementation Method 3
the two wafers are fusion bonded together in accordance with the above-noted U.S. Pat. No. 5,286,671. The resulting molecular bond between the two wafers is as strong as the silicon itself
Data Source
AI summary
A pressure probe includes a longitudinal tubular housing symmetrically disposed about a central axis and having an ultra miniature conical front end and an opened back end. A plurality of aperture ports having an opening are disposed about the front end. A plurality of ultra small leadless transducers has a central active deflecting area in a semiconductor substrate, and a layer of oxide on a bottom surface. At least one sensor network is disposed within the active area on the oxide layer. A glass contact wafer is bonded to the non-deflecting portion of sensing network and has a number of apertures surrounding the active area suitable for interconnection with header. A header encloses each transducer and is of a shape and size to be positioned in an associated aperture port of the probe housing. At least one lead is coupled to a header pin extending from bottom of the aperture and directed through the bottom opening into the hollow of the probe housing.