Differential Thermal Anemometer for Dialysis Weight Loss
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Solution Overview
Problem
Current systems for measuring weight loss in haemodialysis treatments lack precision and are costly due to their complexity, which can lead to significant side effects from inaccurate fluid removal.
Innovation Solution
A differential flow-meter based on the thermal anemometer principle, using self-heated resistors and a Wheatstone bridge configuration to directly measure the difference in flow rates between two channels, reducing the need for separate heaters and temperature sensors and minimizing errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional calorimetric flow-meter systems are used with separate heaters and temperature sensors, then measurement coverage is comprehensive, but device complexity and production cost increase significantly
Solution Approach 1:
The patent combines the heater and temperature sensor functions into a single integrated sensor element. The sensor includes a heating element and a temperature sensing element positioned in close proximity, allowing both heating and temperature measurement to be performed by one component rather than separate components. This reduces the number of active elements while maintaining measurement capability.
Solution Approach 2:
The integrated sensor serves multiple functions: it acts as both a heating source and a temperature sensor. The same sensor element that heats the fluid also measures the temperature, eliminating the need for separate dedicated heater and temperature sensor components. This multi-functionality reduces system complexity and production costs.
2Reliability
If multiple separate active elements are used for flow measurement, then measurement capability is comprehensive, but manufacturing cost and system size increase
Solution Approach 1:
The patent merges multiple active elements (heater and temperature sensor) into a single integrated sensor unit. This integration reduces the number of components that need to be manufactured, assembled, and calibrated separately, thereby reducing production costs while maintaining reliable measurement functionality.
Solution Approach 2:
The sensor is designed as a modular integrated unit that can be manufactured as a single component or pre-assembled module. This segmentation allows for standardized production of the sensor unit, reducing manufacturing complexity and cost compared to assembling multiple separate active elements.
3Productivity
If conventional flow measurement systems are used, then system robustness is adequate, but measurement precision for weight loss calculation is insufficient
Solution Approach 1:
The integrated sensor provides direct temperature measurement at the heating location, enabling accurate calculation of heat transfer and flow rate. This feedback mechanism allows the system to precisely determine weight loss by measuring temperature changes caused by fluid flow, improving measurement precision for dialysis treatment monitoring.
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 achieves high sensitivity and precision in measuring fluid flow differences, reducing systematic and random errors, and simplifying the sensor control, leading to more accurate and cost-effective dialysis treatments.
Implementation Method 1
A sensitive element can be found on the separating element arranged between the two channels, said sensitive element containing one or more resistors, self-heated thanks to the Joule effect
Implementation Method 2
the principle of the thermal anemometer, according to which a wire (resistor), specially overheated by the Joule effect, is cooled in proportion to the flow rate of the fluid touching it
Implementation Method 3
A differential flow-meter based on the thermal anemometer principle, using self-heated resistors and a Wheatstone bridge configuration to directly measure the difference in flow rates
Data Source
AI summary
A differential flow-meter for measuring the weight loss in dialysis treatments. The differential flow-meter is of the “thermal anemometer” type.