Differential Flow Sensor for Dialysis Fluid Balancing
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Solution Overview
Problem
Existing balancing devices for dialysis fluid in extracorporeal blood treatments face challenges in accurately measuring fluid balance, particularly due to high manufacturing tolerances and the need for complex calibration of volume or mass flow sensors, which can be impractical for disposable devices used in mobile or home dialysis systems.
Innovation Solution
A differential flow measuring unit, such as a differential flow sensor, is used to directly measure the flow difference between two paths without separate measurements, allowing for relative calibration and integration into the extracorporeal circuit, enabling accurate liquid balance with reduced production costs and minimizing protein contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If volume or mass flow sensors are used to measure inflow and outflow volumes separately, then measurement precision is improved, but device complexity and calibration requirements increase
Solution Approach 1:
The patent combines two separate flow measurement functions into a single differential flow sensor that directly measures the flow difference between inflow and outflow paths. This merging eliminates the need for separate volume or mass flow sensors and their complex individual calibrations, while maintaining measurement precision through direct differential measurement.
Solution Approach 2:
The patent extracts only the essential measurement function needed for fluid balance - the differential flow between inflow and outflow - rather than measuring each flow separately. This extraction simplifies the measurement system by focusing only on the net flow difference, eliminating unnecessary calibration complexity while preserving measurement accuracy.
2Measurement precision
If balancing chambers with volume-rigid construction are used to ensure identical liquid amounts, then measurement precision is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent replaces the mechanical balancing chamber system with a differential flow sensor that uses flow measurement principles instead of rigid volume containment. This substitution eliminates the need for precisely manufactured volume-rigid chambers, as the measurement is achieved through sensor-based flow detection rather than mechanical volume equivalence.
3Ease of manufacture
If flow sensors are used in disposable dialysis devices, then ease of manufacture is improved, but measurement precision deteriorates due to calibration requirements
Solution Approach 1:
The patent implements a differential flow sensor designed for disposable use in dialysis devices. The sensor is manufactured as a single-use component that does not require complex calibration, enabling easy manufacture and disposal while maintaining adequate measurement precision for clinical fluid balance monitoring through its simplified differential measurement principle.
4Measurement precision
If separate flow measurements are taken in first and second flow paths, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent merges the measurement of inflow and outflow into a single differential flow sensor that directly measures the flow difference. This combining of measurement functions into one integrated sensor reduces device complexity by eliminating separate sensors and their associated signal processing, while maintaining measurement precision through direct differential detection.
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 solution provides a simple, cost-effective, and accurate method for balancing dialysis fluid, reducing the need for frequent recalibration and minimizing errors in fluid balance measurement, especially suitable for portable and home dialysis systems.
Implementation Method 1
The flow measuring cells work according to the magnetic-inductive principle in which both flow measuring cells are exposed to a common magnetic field, so that variations in the magnetic field strength affect both flow measuring cells equally.
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
The invention relates to a balancing method and a balancing device (100, 101, 200, 201, 301, 303) for determining a liquid balance between a flow quantity in a first flow path (FW1) and a flow quantity in a second flow path (FW2). The disclosed balancing device (100, 101, 200, 201, 301, 303) comprises the following elements: a differential flow measuring unit (D) for measuring the differential flow between a flow in the first flow path (FW1) and a flow in the second flow path (FW2); a branch from one of the two flow paths (FW1, FW2) for branching liquid from the one of the two flow paths into another flow path (W); a device for adjusting the flow quantity (P11, P12) in the other flow path, said device being controllable such that the measured differential flow satisfies a specified condition; and a device (K) for ascertaining the flow quantity in the other flow path as a measurement of the liquid balance.