Membrane Pump Conductivity Detection for Cartridge Reuse
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Solution Overview
Problem
The re-use of disposable cartridges in hemodialysis machines, either deliberate or accidental, leads to reduced efficacy and potential damage to the machine due to membrane deformation, and existing systems lack effective methods to detect such re-use.
Innovation Solution
A membrane pump usage condition detection system using a measuring device to determine electrical characteristics across a valve in the flow path, with a comparator and signal generator to provide an output signal indicative of the cartridge's usage condition, preventing further use when thresholds are exceeded.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a disposable cartridge is designed for single-use with a flexible membrane, then the reliability of hemodialysis treatment is improved, but the device complexity increases due to the need for usage detection systems
Solution Approach 1:
The cartridge itself serves as the detection element through its flexible membrane that deforms under compression. The membrane's physical response to compression forces directly indicates usage status, eliminating the need for separate electronic sensors or complex detection circuits. The system uses the cartridge's own mechanical properties for self-diagnosis.
Solution Approach 2:
A simple compression member acts as an intermediary between the cartridge and the detection system. This compression member applies controlled compression to the cartridge and translates the membrane's deformation into a detectable signal, serving as a mechanical mediator that simplifies the overall detection architecture.
2Reliability
If valve leak detection systems are installed to detect improper valve closing, then the reliability is improved, but the device complexity increases due to additional conductivity electrodes and measurement circuits
Solution Approach 1:
The valve leak detection function is merged with the usage condition detection function. The same compression member and membrane deformation mechanism that indicate cartridge usage also detect valve leakage. By combining these detection functions into a single mechanical system, the patent eliminates the need for separate conductivity electrodes and measurement circuits while maintaining both detection capabilities.
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
The system effectively detects membrane pump usage conditions, preventing re-use and ensuring the integrity of the cartridge, thereby maintaining the efficacy of hemodialysis treatments.
Implementation Method 1
A conductivity measurement is taken across the electrodes when the valve is closed. For a normally functioning valve, a low conductivity, or indeed no conductivity should be detected when the valve is closed.
Data Source
AI summary
A membrane pump usage condition detection system and a method of determining a membrane pump usage condition. The membrane pump usage condition detection system comprises a membrane pump defining a flow path arranged to be opened and dosed by at least one valve, a measuring device; a comparator; and a signal generator. The measuring device is configured to determine an electrical characteristic between two points on the flow path of the membrane pump, one point arranged upstream of the at least one valve and the other point arranged downstream of the at least one valve. The measuring device measures the electrical characteristic when the at least one valve is closed. The comparator is configured to monitor the electrical characteristic. The signal generator is arranged to provide an output signal when the electrical characteristic is indicative of a membrane pump usage condition.