Pneumatic Syringe Flow Control for Precise Small-Volume Delivery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing systems struggle to accurately control the flow rate of small volumes of cellular suspensions into low-volume containers, leading to potential contamination and inefficiencies in processing and delivery.
Innovation Solution
A method and system utilizing a programmable controller and pneumatic syringe with proportional-integral-derivative control logic to manage the movement of a piston, incorporating sensors and valves to achieve precise control of the flow rate, including break pressure targeting, glide control, and vent control phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pneumatic syringe is used to deliver small volumes of cellular suspensions, then the delivery precision is improved, but the control of flow rate becomes difficult due to pressure variations and piston movement inconsistencies
Solution Approach 1:
The system employs a feedback control mechanism where a sensor detects the actual volume delivered by the pneumatic syringe and compares it to the target volume. The controller adjusts the pump speed based on the volumetric error (V_error = V_target - V_current) to maintain precise flow rate control despite pressure variations and piston movement inconsistencies.
Solution Approach 2:
The system dynamically adjusts the pump speed during operation. The pump operates at a first speed initially, then the controller decreases the speed linearly to achieve a nominal break pressure, and subsequently increases speed based on detected piston movement and volumetric error, allowing adaptive control of the flow rate throughout the delivery process.
2Productivity
If the pump speed is increased to improve delivery speed, then productivity is improved, but the flow rate control precision deteriorates due to pressure fluctuations
Solution Approach 1:
The system uses periodic monitoring of the piston position and volumetric error, with the controller continuously adjusting pump speed in cycles. The pump operates in phases: initially at high speed for rapid delivery, then speed is modulated periodically based on feedback to maintain precision during different stages of the delivery process.
Solution Approach 2:
The system changes the operating parameters of the pump dynamically. The pump speed is adjusted as a variable parameter based on the delivery stage and volumetric error. The pressure is also controlled as a parameter, with the system targeting a nominal break pressure and adjusting pump speed accordingly to balance delivery speed and control precision.
3Quantity of substance
If intermediate large volume containers are used for storage, then the processing capacity is improved, but the risk of contamination increases and the suitability for single-dose quantities deteriorates
Solution Approach 1:
The system extracts and eliminates the intermediate large volume storage container from the processing workflow. The pneumatic syringe is configured to deliver small volumes directly from processing to final delivery containers, removing the contamination risk associated with intermediate storage while maintaining processing capacity through direct delivery capability.
4Productivity
If the pump operates continuously at high speed, then productivity is improved, but the ability to achieve precise break pressure and control piston movement deteriorates
Solution Approach 1:
The system performs preliminary action by operating the pump at a first speed to initially pressurize the system and achieve the nominal break pressure before the main delivery phase. This preliminary pressurization ensures the piston is ready for controlled movement, and only after this preliminary action is complete does the system transition to the precision control phase.
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
Ensures precise and contamination-free delivery of small volumes of cellular suspensions into low-volume containers, enhancing processing efficiency and reducing the risk of contamination.
Implementation Method 1
a pump for introducing pressurized air/vacuum into the syringe to act on a first side of the piston
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
A method for controlling the flow rate of a pneumatic syringe in a system that includes a disposable fluid circuit and reusable hardware configured to accept the disposable fluid circuit. The disposable fluid circuit includes one or more syringes, while the reusable hardware includes a syringe pump for each syringe of the disposable fluid circuit and a controller. The syringe pump includes a vacuum/pressure source for moving the piston within the syringe and a position detector for indicating the position of the piston within the syringe. The method controls several distinct phases of the process: break pressure targeting, glide control and vent control, and the method is the same regardless of whether a positive pressure or a vacuum is applied to the piston of the syringe. Preferably, a proportional-integral-derivative ("PID") feedback loop is used for controlling the movement of the piston in the syringe.