Recessed Semiconductor Strain Sensor Assembly for Harsh Conditions
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Solution Overview
Problem
Existing strain gauges used in industrial applications face issues with resistance to lubricants, moisture, temperature fluctuations, vibrations, and mechanical stress, leading to damage or disconnection, and semiconductor strain gauges are not commonly used due to sensitivity and accuracy concerns.
Innovation Solution
A strain measuring assembly using a sensor body with semiconductor strain gauges positioned in recessed portions and protuberant contacts, combined with a protective case, to withstand aggressive environments, featuring a printed circuit board with conductive metal structures and temperature sensors for accurate strain and temperature measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If foil resistance strain gauges are used with foil pads, then the sensor can be applied to measure strain, but the foil pad has low resistance to lubricants causing etching and damage
Solution Approach 1:
The patent uses a foil carrier made of composite material (metal foil with polymer coating) that combines the electrical conductivity of metal with the chemical resistance of polymer, providing protection against lubricant etching while maintaining strain gauge functionality
Solution Approach 2:
The foil carrier acts as a flexible protective shell that encloses the strain gauges and conductors, providing mechanical protection and chemical resistance while allowing strain transmission to the sensing elements
2Reliability
If foil pads are used to mount strain gauges, then the sensor can be attached to the measured point, but the foil pad does not provide sufficient protection from moisture, temperature fluctuations, and vibrations
Solution Approach 1:
The patent merges multiple protective functions into the foil carrier structure, which simultaneously provides mechanical support, environmental protection, and electrical connectivity, eliminating the need for separate protective components
Solution Approach 2:
The strain gauges and conductors are nested within the foil carrier structure, which encloses them and provides protection while allowing the entire assembly to function as an integrated unit
3Measurement precision
If semiconductor strain gauges are used, then the sensitivity and measurement accuracy are significantly higher, but they are not commonly used due to concerns about withstanding mechanical and chemical stress
Solution Approach 1:
The foil carrier provides a protective enclosure for the semiconductor strain gauges, shielding them from mechanical damage and chemical exposure while allowing strain transmission through the flexible foil material
Solution Approach 2:
The combination of semiconductor strain gauges with the composite foil carrier creates a hybrid structure that leverages the high sensitivity of semiconductors with the robustness of composite materials, enabling both high precision and high reliability
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 solution provides enhanced accuracy and durability in measuring strain under harsh conditions, allowing for precise strain and temperature compensation, and enables repeated use in demanding industrial settings.
Implementation Method 1
Each said semiconductor strain gauge (3) comprises a semiconductor strain gauge body and two conductive contacts of the strain gauge
Implementation Method 2
The sensor body (2) further comprises at least one temperature sensor
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The invention is a strain sensor (1) and a strain measuring assembly comprising the sensor, which is particularly suitable for measuring strain in industrial applications. The strain sensor (1 ) comprises a sensor body (2) and at least one semiconductor strain gauge (3) comprising a strain gauge body and two conductive contacts of the strain gauge through which the semiconductor strain gauge (3) is attached to the sensor body (2). The sensor body (2) comprises a contact side for attachment to the measured surface and an outer side opposite the contact side. The contact side comprises a protuberant portion for contact with the measured surface and a recessed portion, on which the semiconductor strain gauge (3) is placed, wherein both conductive contacts of the strain gauge are brought to the outer side of the sensor body (2). The sensor body (2) can preferably be a printed circuit board provided on the contact side with recesses (4) for housing the strain gauges. To increase the resistance, the strain sensor (1) can for example be encapsulated by a covering material or provided with a metal case (10).