Double Diaphragm Gas Sensor for Precision Measurement
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Solution Overview
Problem
Existing gas sensors that measure gas concentrations based on resistive principles face challenges in precision due to variations in ambient temperature, humidity, and aging effects, leading to complex evaluation electronics and larger sensor dimensions.
Innovation Solution
A compact gas sensor design featuring a double diaphragm chip with a reference volume and a measuring volume, where both volumes are manufactured jointly, allowing for compensation of manufacturing-related variations and direct exposure to temperature and moisture changes, reducing the need for complex evaluation electronics and minimizing sensor size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a gas sensor uses a single diaphragm design with heating elements, then the sensor structure is simple, but manufacturing variations and environmental changes cause measurement imprecision
Solution Approach 1:
The sensor is divided into two separate diaphragms: a first diaphragm with an analysis heating element for measuring gas concentration, and a second diaphragm with a reference heating element for reference measurements. This segmentation allows independent optimization of each diaphragm's function while compensating for manufacturing variations through differential measurement
Solution Approach 2:
A base substrate is introduced as an intermediary component to support both diaphragms and define the measuring and reference volumes. This base substrate serves as a common reference plane that enables precise positioning and spacing, thereby improving measurement precision without requiring complex alignment mechanisms
2Reliability
If additional temperature sensors and complex evaluation electronics are added to compensate for environmental changes, then measurement reliability improves, but sensor dimensions and complexity increase
Solution Approach 1:
The reference heating element on the second diaphragm serves as a self-regulating reference that automatically compensates for environmental changes. By comparing the resistance change of the analysis heating element against the reference heating element, the system achieves reliable measurements without requiring external temperature sensors or complex evaluation algorithms
Solution Approach 2:
The system uses electrical resistance as a measurable parameter that inherently reflects both gas concentration effects and environmental temperature changes. By measuring resistance changes of both heating elements and computing their difference, the system extracts gas concentration information while automatically compensating for environmental parameter variations
3Measurement precision
If a larger sensor structure is used to accommodate separate reference and measuring chambers, then measurement accuracy improves, but sensor compactness deteriorates
Solution Approach 1:
The measuring volume and reference volume are nested within the same sensor substrate thickness, with each diaphragm forming a volume between itself and the base substrate. This nesting approach allows both measurement chambers to coexist in a compact three-dimensional arrangement rather than requiring lateral expansion
Solution Approach 2:
The sensor design transitions from a planar two-dimensional layout to a three-dimensional structure by utilizing the vertical dimension between the base substrate and diaphragms to define measurement volumes. This enables both reference and measuring chambers to be positioned in different vertical planes, achieving compact integration
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 enables precise gas concentration measurements regardless of external conditions and aging effects, resulting in a more compact and reliable gas sensor with reproducible results.
Implementation Method 1
at least one analysis heating element situated on a first diaphragm for heating the analysis gas, a reference heating element situated on a second diaphragm for heating a reference gas
Implementation Method 2
the temperature of the heating element thus drops due to the higher thermal conductivity of the hydrogen and a greater heat dissipation accompanying this
Data Source
AI summary
A gas sensor is described for measuring a concentration of an analysis gas based on a thermal conductivity principle, including at least one analysis heating element situated on a first diaphragm for heating the analysis gas, a reference heating element situated on a second diaphragm for heating a reference gas, at least one evaluation electronics unit for measuring a resistance change of the analysis heating element caused by the analysis gas in relation to an electrical resistance of the reference heating element, the first diaphragm and the second diaphragm being situated adjacent to one another in a sensor substrate, due to a base substrate situated on one side on the sensor substrate, a measuring volume is formable between the first diaphragm and the base substrate and a reference volume is formable between the second diaphragm and the base substrate.