Magnetic Valve Plunger Position Control via Capacitance
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Solution Overview
Problem
Automated liquid handling systems face challenges in maintaining precise and accurate dispensing and aspirating of liquid volumes due to variations caused by manufacturing tolerances, aging, mechanical wear, environmental influences, and operational conditions, leading to inconsistent coefficient of variation (CV) in magnetic valve performance over time.
Innovation Solution
A method for controlling a magnetic valve by applying opening, holding, and closing currents based on capacitance measurements to adjust and calibrate the valve's operation, ensuring precise control of the plunger's position and time, thereby stabilizing the volume of liquid dispensed or aspirated.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If time pressure dispensing is used with magnetic valves, then liquid handling speed is improved, but manufacturing tolerances and mechanical wear cause coefficient of variation to change over time
Solution Approach 1:
The patent adjusts magnetic valve operating parameters (current amplitude, pulse width, duty cycle) to compensate for manufacturing tolerances, aging, and mechanical wear. By dynamically changing these parameters, the system maintains consistent liquid handling performance despite component degradation over time.
Solution Approach 2:
The system measures actual liquid volumes dispensed and uses this feedback to adjust magnetic valve parameters. This closed-loop control compensates for variations caused by manufacturing tolerances and mechanical wear, maintaining reliable coefficient of variation over extended operation periods.
2Reliability
If manufacturing tolerances are reduced to improve valve consistency, then coefficient of variation stability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The system performs self-calibration by measuring its own liquid handling performance and automatically adjusting magnetic valve parameters. This eliminates the need for extremely tight manufacturing tolerances, as the system compensates for its own variations through automated parameter adjustment.
Solution Approach 2:
Instead of relying on precise manufacturing, the system achieves consistency by dynamically adjusting operating parameters (current, pulse width, duty cycle) to compensate for manufacturing variations and component aging.
3Manufacturing precision
If environmental controls are implemented to reduce temperature and humidity effects, then liquid handling accuracy is improved, but device complexity and operational cost increase
Solution Approach 1:
The system measures actual liquid volumes and uses feedback to adjust magnetic valve parameters, compensating for environmental variations without requiring controlled temperature and humidity environments.
Solution Approach 2:
The patent replaces environmental control mechanisms with electrical parameter adjustments. Instead of controlling temperature and humidity physically, the system compensates for their effects by adjusting magnetic valve current and timing parameters.
4Productivity
If valve switching time is reduced to improve dispensing speed, then productivity is improved, but mechanical wear increases causing coefficient of variation to change
Solution Approach 1:
The system adjusts magnetic valve parameters (current amplitude, pulse width) to optimize switching speed while compensating for mechanical wear. By changing these parameters dynamically, the system maintains both high speed and consistent performance despite increased switching frequency.
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 allows for precise and consistent liquid handling by adjusting the magnetic valve's operation parameters, reducing variations in the coefficient of variation and ensuring accurate dispensing and aspirating of predetermined volumes, enhancing the reliability of automated liquid handling systems.
Implementation Method 1
a magnetic valve, comprising a solenoid coil (13) and a mobile anchor forming a plunger (14)
Implementation Method 2
measuring a capacitance at the magnetic valve (3)
Data Source
AI summary
A method for controlling a magnetic valve and particularly a method for dispensing and/or aspirating a volume of liquid as well as a corresponding dispenser/pipetting apparatus is disclosed. The method for controlling a magnetic valve has measuring a capacitance at the magnetic valve and determining a position of a plunger based on the measured capacitance. The method for dispensing or aspirating a volume of liquid has controlling a flow of a system fluid by a magnetic valve located between a pressure source and a dispenser/pipetting tip, dispensing or aspirating a volume of liquid through an exterior opening of the tip dependent on the flow of the system fluid, wherein controlling the flow and determining a flow time in dependence of the volume of liquid to be dispensed or aspirated, and controlling the magnetic valve is held open for the duration of the flow time.