Sealed Sensor Device Seal Failure Detection
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Solution Overview
Problem
Existing thermal sensor devices face performance degradation due to out-gassing and out-diffusion of gas molecules, making it difficult to detect imperfect hermetic seals during manufacturing and in the field, leading to increased costs and potential device failures.
Innovation Solution
A sealed sensor device with a gas-filled internal atmosphere at a predetermined pressure below atmospheric pressure, equipped with a thermopile and membrane structure that includes a heating element, allowing for detection of seal failures by measuring responsivity changes, and a method for manufacturing this device using glass-frit wafer bonding techniques without requiring additional processing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the device is hermetically sealed to maintain stable internal pressure, then device reliability is improved, but detection of imperfect seals becomes difficult
Solution Approach 1:
The patent converts the harmful effect of out-gassing (which masks seal defects) into a beneficial detection mechanism. By designing the device to be sensitive to pressure changes caused by out-gassing, the very process that previously hidden seal imperfections now serves as the detection signal. The thermopile-based pressure sensing capability allows detection of even minor pressure drift that indicates seal failures.
Solution Approach 2:
The patent implements feedback by continuously monitoring internal pressure through the thermopile structure. The pressure changes caused by out-gassing or seal failures are detected and fed back to the measurement circuit, which compares actual pressure against expected values. This feedback mechanism enables real-time detection of seal imperfections without requiring external vacuum chamber testing.
2Measurement precision
If vacuum chamber testing is used to detect seal failures, then detection accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The patent enables the device to test itself without external testing equipment. The built-in thermopile pressure sensing capability allows the device to autonomously detect seal failures by monitoring its own internal pressure changes during normal operation or simple pressure equalization tests. This self-testing capability eliminates the need for expensive vacuum chamber testing while maintaining high detection accuracy.
Solution Approach 2:
The patent replaces the mechanical vacuum chamber testing system with an electronic sensing system. Instead of using physical vacuum chambers and complex mechanical testing apparatus, the invention uses electronic pressure sensing through the thermopile structure to detect seal failures. This substitution dramatically reduces manufacturing costs while maintaining or improving detection capability.
3Difficulty of detecting and measuring
If additional testing steps are added to detect seal failures, then detection capability is improved, but device complexity increases
Solution Approach 1:
The patent merges the seal detection function with the existing thermal sensing structure. The thermopile that is already used for thermal measurements also serves as the pressure sensing element for seal detection. This merging of functions eliminates the need for separate detection systems or complex additional testing procedures, as the same structural elements perform multiple functions.
Solution Approach 2:
The patent makes the thermopile structure universal by enabling it to perform both thermal sensing and pressure sensing functions. The same membrane and thermopile assembly that detects thermal radiation also detects pressure changes indicative of seal failures. This multi-functionality reduces overall device complexity while enhancing detection capabilities without requiring additional specialized 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
Enables reliable detection of imperfect hermetic seals both during and after manufacturing, maintaining stable internal pressure and reducing manufacturing costs, while allowing for the use of existing processes and materials, thus minimizing the risk of device failure and improving accuracy in seal detection.
Implementation Method 1
the membrane structure also comprises a heating element... allowing for detection of seal failures by measuring responsivity changes
Implementation Method 2
A sealed sensor device with a gas-filled internal atmosphere at a predetermined pressure below atmospheric pressure, equipped with a thermopile and membrane structure
Data Source
AI summary
A sealed sensor device (104) comprising: an internal atmosphere comprising a gas pressurised to a predetermined pressure, the predetermined pressure being below atmospheric pressure when the internal atmosphere is hermetically sealed from ambient. A sensor cavity (214) is also provided having a periphery and is in fluid communication with the internal atmosphere, thereby comprising the gas and the gas having a mean free path at the predetermined pressure associated therewith. A thermopile (256) is disposed in the sensor cavity (214) for detecting a change in pressure of the internal atmosphere and detecting failure of the hermetic seal. A membrane structure (234) disposed within the cavity comprises the thermopile (256). The membrane structure (234) also comprises a heating element, and a shortest distance from substantially any point on the membrane structure (234) to the periphery of the sensor cavity (214) is less than the mean free path of the gas at the predetermined pressure.