Microfluidic Pressure Circuit With Parallel Valves and Damping
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Solution Overview
Problem
Microfluidic devices face challenges in achieving a balance between pressure response dynamics and stability while minimizing air and electrical consumption, as larger solenoid valves improve dynamics but reduce precision, and smaller valves enhance stability but slow response times.
Innovation Solution
A microfluidic device design incorporating an on/off valve in parallel with a proportional valve, allowing for quick pressure changes during transient states and precise control in steady states, along with a damping system to mitigate pressure oscillations, enables both fast response and stable pressure management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a larger solenoid valve is used to improve pressure response dynamics, then the response speed increases, but the precision and stability of pressure control deteriorate
Solution Approach 1:
The pressure control system is segmented into two distinct valve components: an on/off valve for rapid pressure changes and a proportional valve for precise pressure regulation. This segmentation allows each valve to be optimized for its specific function, resolving the contradiction between response speed and precision.
Solution Approach 2:
The system dynamically switches between two valve modes: the on/off valve provides fast dynamic response during transient states, while the proportional valve provides stable precision control during steady states. This dynamic allocation of functions resolves the contradiction across different operational phases.
2Measurement precision
If a smaller solenoid valve is used to improve pressure stability and precision, then the pressure control precision improves, but the pressure response dynamics slow down
Solution Approach 1:
The pressure control system is segmented into two distinct valve components: an on/off valve for rapid pressure changes and a proportional valve for precise pressure regulation. This segmentation allows each valve to be optimized for its specific function, resolving the contradiction between response speed and precision.
Solution Approach 2:
The control system periodically switches between using the on/off valve during transient states for fast response and the proportional valve during steady states for precision control. This periodic action ensures both fast response dynamics and stable precision are achieved at appropriate times.
3Speed
If an on/off valve with large opening area is used to improve response speed, then the response time decreases, but pressure oscillations increase
Solution Approach 1:
A damping system is introduced to cushion the pressure oscillations generated by the on/off valve during rapid opening and closing operations. This beforehand cushioning allows the on/off valve to maintain its fast response capability while the damping system mitigates the harmful oscillations.
Solution Approach 2:
The damping system acts as an intermediary between the on/off valve and the fluid system, absorbing and dissipating the pressure oscillations generated by the valve's rapid actions. This intermediary component allows the valve to operate at high speed without directly transmitting harmful oscillations to the system.
4Measurement precision
If only a proportional valve is used for pressure control, then the precision is maintained, but the response time increases and air consumption increases
Solution Approach 1:
The pressure control system is segmented into two distinct valve components: an on/off valve for rapid pressure changes and a proportional valve for precise pressure regulation. This segmentation allows each valve to be optimized for its specific function, resolving the contradiction between response speed and precision.
Solution Approach 2:
The control system periodically switches between using the on/off valve during transient states for fast response and the proportional valve during steady states for precision control. This periodic action ensures both fast response dynamics and stable precision are achieved at appropriate times.
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 solution achieves improved pressure response dynamics and stability with reduced gas consumption, allowing for precise control of pressure in microchannels across various volumes, enhancing the overall performance of microfluidic devices.
Implementation Method 1
a controlled gas flow into the reservoir can be established. Specifically, the solenoid valve is connected to a control system that regulates its opening based on pressure information from a pressure sensor measuring the gas pressure in the tank. This allows for dynamic control of the gas pressure in the tank and the product flow rate in the microchannel, as this flow rate depends on the pressure exerted by the gas on the product within the tank.
Implementation Method 2
The circuit includes an on/off valve mounted in parallel with a proportional valve. These valves are controllable so as to modify the pressure exerted in the reservoir by the second fluid on the first fluid.
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A microfluidic device comprising a tank (6) supplying a microchannel (2) with a first fluid (S), and a circuit (8) in which a flow of a second fluid can be established without contact with the microchannel (2). The circuit (8) passes through the tank (6) or is connected to the tank (6) by a pipe (30). The circuit (8) comprises a first on/off valve (12) mounted in parallel with a first proportional valve (11), these first valves (11, 12) being controllable in such a way as to modify the pressure applied in the tank (6) by the second fluid to the first fluid (S).