Span Element Temperature Sensor for Fast Fluid Parameter Measurement
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Solution Overview
Problem
Existing sensor devices for measuring fluid parameters, such as thermal conductivity and gas temperature, often suffer from inaccuracies due to the slow response of substrate temperature sensors, which can be several minutes after changes in fluid temperature, leading to delayed thermal equilibrium and compromised measurement accuracy, especially in applications like medical respiratory devices.
Innovation Solution
A sensor device with a span element and at least two span element temperature sensors that quickly reach thermal equilibrium with the fluid, allowing for the derivation of an absolute fluid temperature, enabling precise measurement of parameters like thermal conductivity, thermal diffusivity, and volumetric specific heat by decoupling the span element from the substrate, thereby providing a fast and accurate fluid temperature measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If substrate temperature sensors are used to measure fluid temperature, then the measurement structure is simple and integrated, but the response time is slow (minutes) due to thermal equilibrium delays
Solution Approach 1:
The device segments the temperature sensing function by introducing a separate span element with its own temperature sensors (span element temperature sensors) that are thermally coupled to the fluid but independent from the substrate temperature sensors. This segmentation allows the span element to respond quickly to fluid temperature changes without being constrained by the substrate's thermal mass and slow equilibrium time.
Solution Approach 2:
The span element acts as an intermediary between the fluid and the measurement system. It is thermally coupled to the fluid through the recess opening, allowing it to rapidly equilibrate with fluid temperature, while its temperature sensors provide the measurement interface. This intermediary structure decouples the fast thermal response from the substrate's slow response.
2Measurement precision
If substrate temperature sensors are used, then device structure is simplified, but measurement accuracy deteriorates due to substrate temperature lag
Solution Approach 1:
The device segments the temperature sensing function by introducing a separate span element with its own temperature sensors (span element temperature sensors) that are thermally coupled to the fluid but independent from the substrate temperature sensors. This segmentation allows the span element to respond quickly to fluid temperature changes without being constrained by the substrate's thermal mass and slow equilibrium time.
Solution Approach 2:
The invention changes the thermal parameters of the sensing system by using a span element with different thermal properties than the substrate. The span element has lower thermal mass and is thermally isolated from the substrate, enabling faster thermal response. The system utilizes both substrate temperature and span element temperature measurements, combining different thermal parameter responses to achieve accurate fluid parameter determination.
3Speed
If absolute substrate temperature is used as fluid temperature measure, then thermal equilibrium provides stable baseline, but fast changing fluid temperatures (millisecond to second scale) cannot be tracked
Solution Approach 1:
The invention introduces dynamic responsiveness by using the span element temperature sensors that can rapidly track fluid temperature changes. The span element's thermal design allows it to dynamically follow fast-changing fluid temperatures, while the system maintains reliability by using the substrate temperature as a stable reference baseline for calibration and compensation.
Solution Approach 2:
The system uses feedback from both substrate temperature sensors and span element temperature sensors. The span element temperature provides real-time feedback on fluid temperature changes, while the substrate temperature provides feedback on the stable baseline. The control system combines these feedback signals to maintain measurement accuracy during fast transient conditions.
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 approach allows for more accurate and rapid determination of fluid parameters by using the absolute span element temperature as a measure for the fluid temperature, reducing measurement errors caused by substrate temperature lag and enabling precise corrections or compensations, thus improving the accuracy of fluid parameter measurements.
Implementation Method 1
at least two span element temperature sensors arranged to provide a span element temperature signal; deriving, from said span element temperature signal, an absolute span element temperature
Implementation Method 2
determining at least one parameter of a fluid by means of a sensor device, the sensor device being in particular a thermal flow sensor device... wherein said parameter is a thermal conductivity of said fluid, a thermal diffusivity of said fluid, a volumetric specific heat of said fluid
Data Source
Figure 1~2
AI summary
A method of using a sensor device for measuring a parameter and comprising: a substrate with a recess, a span element spanning said recess, a span element temperature sensor (4;5;6) and a heater element. The method comprises the steps of operating said sensor device (1) such as to measure, by the span element temperature sensor (4;5;6), a span element temperature signal (sm), and to derive, from the span element temperature signal (sm), an absolute span element temperature (Tm); and using, by said sensor device (1), said absolute span element temperature (Tm) as a measure for an absolute temperature (Tg) of said fluid (g) for determining said parameter of said fluid (g). The present invention also relates to a sensor device configured to carry out the method according to invention.