Syringe Pump Occlusion Detection via Dynamic Baseline
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Solution Overview
Problem
Syringe pump systems face challenges in accurately detecting occlusions in fluid lines due to variations in stiction and force caused by anti-free flow claws, leading to false alarms when relying solely on fluid pressure measurements.
Innovation Solution
A method involving the collection of detected force values within moving time windows, calculation of best-fit line slopes, and comparison of slope differences to determine a baseline force, with a relative force value triggering an alarm if exceeding a pre-defined threshold, while also converting force to pressure for occlusion detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fluid pressure measurements are used to detect occlusions, then occlusion detection capability is provided, but false alarms occur due to variations in stiction and anti-free flow claw force
Solution Approach 1:
The system transitions from using a static pressure threshold to a dynamic baseline that continuously adapts to varying operating conditions. By calculating a moving average baseline from recent pressure readings and comparing current pressure against this dynamic baseline rather than a fixed threshold, the system accounts for real-time variations in stiction and anti-free flow claw force, eliminating false alarms while maintaining occlusion detection accuracy
Solution Approach 2:
The system implements feedback by continuously monitoring pressure readings and using them to update the baseline. The baseline is recalculated based on recent pressure measurements, creating a closed-loop system that adapts to changing conditions. This feedback mechanism allows the system to distinguish between normal pressure variations and actual occlusions, resolving the contradiction between detection capability and false alarm reduction
2Device complexity
If a fixed pressure threshold is used for occlusion detection, then the detection mechanism is simple, but it cannot accommodate variations in stiction and spring force causing false alarms
Solution Approach 1:
The system replaces the static fixed threshold with a dynamic baseline that continuously adapts to varying operating conditions. By calculating a moving average baseline from recent pressure readings and comparing current pressure against this dynamic baseline rather than a fixed threshold, the system accounts for real-time variations in stiction and anti-free flow claw force, eliminating false alarms while maintaining occlusion detection accuracy
Solution Approach 2:
The system changes the reference parameter from a fixed threshold value to a dynamically calculated baseline that represents normal operating pressure at each moment. This parameter transformation allows the detection mechanism to accommodate variations in stiction and spring force without requiring complex adjustments, reducing false alarms while maintaining simplicity
3Measurement precision
If sensitivity for occlusion detection is increased, then detection accuracy improves, but false alarms increase due to normal pressure variations
Solution Approach 1:
The system implements feedback by continuously monitoring pressure readings and using them to update the baseline. The baseline is recalculated based on recent pressure measurements, creating a closed-loop system that adapts to changing conditions. This feedback mechanism allows the system to distinguish between normal pressure variations and actual occlusions, resolving the contradiction between detection capability and false alarm reduction
Solution Approach 2:
The system transitions from using a static pressure threshold to a dynamic baseline that continuously adapts to varying operating conditions. By calculating a moving average baseline from recent pressure readings and comparing current pressure against this dynamic baseline rather than a fixed threshold, the system accounts for real-time variations in stiction and anti-free flow claw force, eliminating false alarms while maintaining occlusion detection accuracy
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 enhances sensitivity and accuracy in occlusion detection, reducing false alarms and ensuring timely intervention by automatically stopping the pump motor when occlusion pressure is reached.
Implementation Method 1
A detected force value caused by pressure inside a fluid line is collected
Implementation Method 2
converting force to pressure for occlusion detection
Data Source
AI summary
A method of monitoring pressure inside a fluid line and a system for implementing the method. The method is applicable to syringe pump systems. The method includes the steps of measuring a force value caused by a pressure inside the fluid line; collecting the measured force values during at least two consecutive moving time windows; calculating a slope of a best-fit line within each time window; calculating a slope difference of the slopes of the best-fit lines; comparing the slope difference with a pre-determined threshold gradient value; defining a baseline force as the detected force value when the slope difference is equal to the threshold gradient value; determining a relative force value by subtracting the baseline force from the detected force value; and, triggering an alarm if the relative force is greater than a pre-defined threshold force.