Peristaltic Pump Valve Speed Control for Hemolysis Prevention
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Solution Overview
Problem
Current fluid infusion systems in medical settings face challenges in accurately monitoring and controlling fluid flow, leading to issues such as occlusions, air presence, and inefficient fluid delivery, which can impact patient care.
Innovation Solution
A pump system incorporating a tube platen, plunger, bias member, inlet and outlet valves, actuator mechanism, position sensor, and processor to detect anomalies and occlusions, with optional ultrasonic sensors for air detection, ensuring precise fluid delivery and monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high flow rates are delivered using traditional constant speed syringe pumps, then productivity is improved, but fluid shear stress increases causing hemolysis and protein denaturation
Solution Approach 1:
The pump system transitions from constant speed operation to variable speed operation, dynamically adjusting the plunger actuation speed based on the prescribed flow rate requirements. This allows high flow rates to be achieved while maintaining plunger speeds below the threshold that causes hemolysis, thereby resolving the contradiction between productivity and harmful fluid shear stress
Solution Approach 2:
The system changes the operational parameters by limiting plunger speed to remain below a predetermined threshold while achieving desired flow rates through coordinated valve timing and cam profile optimization. This parameter change allows high productivity without exceeding the shear stress threshold that causes hemolysis
2Productivity
If high flow rates are delivered using traditional peristaltic pumps, then productivity is improved, but fluid shear stress and stasis increase causing hemolysis
Solution Approach 1:
The peristaltic pump implements dynamic control of roller compression timing and duration, adjusting the peristaltic action to achieve high flow rates while preventing excessive shear stress and fluid stasis that cause hemolysis, thereby resolving the contradiction between productivity and harmful effects on blood cells
3Productivity
If fast-acting valves are used to achieve high flow rates, then productivity is improved, but valve slamming and water hammer effects increase causing inaccurate dosing
Solution Approach 1:
The system applies preliminary anti-action by limiting the rise speed of valves and plunger to predetermined maximums before problematic pressures and flows can develop. This prevents valve slamming and water hammer effects that would compromise dosing accuracy, while still allowing sufficiently high flow rates for productivity
Solution Approach 2:
The system changes operational parameters by imposing speed limits on valve actuation and plunger movement, transforming the approach from fast-acting components to controlled-speed operation. This parameter change eliminates valve slamming and water hammer effects while maintaining adequate productivity through optimized timing coordination
4Productivity
If traditional pump designs are used to achieve high flow rates, then productivity is improved, but fluid shear stress increases causing inaccurate dosing
Solution Approach 1:
The pump system implements dynamic control where plunger speed is continuously adjusted to remain below thresholds that cause hemolysis and dosing errors, while productivity is maintained through coordinated valve timing that optimizes flow delivery. This dynamic approach resolves the contradiction between high flow rate and dosing 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
The system effectively detects and manages occlusions and air presence, ensuring consistent and accurate fluid delivery, enhancing the reliability and efficiency of fluid infusion processes.
Implementation Method 1
a peristaltic pump comprising: a tube platen; a plunger configured for actuation toward and away from the tube platen
Implementation Method 2
a cam shaft configured to actuate the plunger, the inlet valve and the outlet valve
Data Source
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AI summary
There is described a pump for pumping fluid, the pump comprising: a tube platen; a plunger configured for actuation toward and away from the tube platen when the tube platen is disposed opposite to the plunger; an inlet valve upstream of the plunger configured for actuation between an occluding position and a non-occluding position; an outlet valve downstream of the plunger configured for actuation between an occluding position and a non-occluding position; a cam shaft configured to actuate the plunger, the inlet valve and the outlet valve; a motor operatively coupled to the cam shaft; and a processor operatively coupled to the motor and configured to control the motor, wherein the processor is configured to limit at least one of a rise of the inlet valve, a rise of the outlet valve, and a rise of the plunger to below a predetermined speed. There is also described a method of operating a peristaltic pump.