Microfluidic Liquid Delivery via Gas Pressure Control
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Solution Overview
Problem
Current microfluidic systems face challenges in delivering precise volumes of liquids, particularly in bioindustries, due to mechanical stresses and cross-contamination issues with existing pumps, and the high cost and calibration requirements of gas pressure controllers and fluid flow rate sensors.
Innovation Solution
A device comprising a microfluidic channel with a gas mass flowmeter and pressure control unit, allowing precise measurement of gas mass to calculate liquid volume, using an equation of state to achieve accurate liquid delivery with minimal mechanical stress and reduced cross-contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If precision volumetric pumps are used to deliver accurate fluid volumes, then volume delivery accuracy is improved, but mechanical stresses damage the fluid and its components
Solution Approach 1:
The patent replaces mechanical volumetric pumps with a gas pressure-based delivery system. Gas is introduced into a chamber containing the liquid, and the gas pressure controls liquid displacement through a flexible membrane or piston. This substitution eliminates direct mechanical contact between pump components and the liquid, thereby reducing mechanical stresses and damage to fluid components while maintaining volume delivery accuracy through pressure control.
Solution Approach 2:
The patent introduces gas as an intermediary medium between the control system and the liquid. The gas pressure serves as a mediator that transmits control signals to the liquid without direct mechanical contact. The gas chamber acts as an intermediary volume that converts pressure control into liquid displacement, eliminating the need for direct mechanical pumping action on the liquid.
2Productivity
If gas pressure controllers with flow rate sensors are used for reactive flow rate control, then flow rate control accuracy and reactivity are improved, but system cost and complexity increase
Solution Approach 1:
The patent extracts and removes the expensive and complex flow rate sensor from the system. Instead of using a flow rate sensor to measure and control liquid flow, the system uses gas pressure control to indirectly control liquid displacement. The gas pressure controller alone suffices to provide reactive flow rate control, eliminating the need for additional sensors and complex feedback mechanisms.
Solution Approach 2:
The patent employs a disposable flexible membrane or piston chamber that can be easily replaced. This simple, low-cost component replaces expensive, calibration-required flow rate sensors. The disposable nature of the membrane/piston eliminates calibration needs and reduces long-term system complexity and cost.
3Measurement precision
If flow rate sensors are used for closed loop control, then volume delivery accuracy is improved, but cross-contamination risk increases due to direct fluid contact
Solution Approach 1:
The patent replaces the mechanical flow rate sensor that requires direct liquid contact with a gas pressure-based measurement system. Gas pressure sensors can measure pressure differential across the flexible membrane without requiring direct contact with the liquid, thereby eliminating cross-contamination risk while maintaining volume delivery accuracy through pressure-controlled displacement.
Solution Approach 2:
The patent uses gas pressure as an intermediary measurement parameter instead of direct liquid flow measurement. The gas pressure differential across the flexible membrane serves as a proxy for liquid flow rate, allowing accurate measurement without direct liquid contact. This intermediary approach eliminates cross-contamination while preserving measurement accuracy.
4Measurement precision
If calibration procedures are implemented for pressure controllers, then volume delivery accuracy is improved, but time consumption and operational complexity increase
Solution Approach 1:
The patent implements a self-calibrating system where the gas pressure controller automatically compensates for variations in chamber volume, membrane elasticity, and other parameters through real-time pressure measurements. The system uses the pressure differential across the flexible membrane as a direct indicator of liquid displacement, eliminating the need for manual calibration procedures while maintaining high accuracy.
Solution Approach 2:
The patent employs continuous feedback through pressure sensing that automatically adjusts gas pressure to maintain accurate liquid delivery. The pressure sensor provides real-time feedback on the actual displacement, and the controller makes automatic corrections, eliminating the need for time-consuming manual calibration procedures and ensuring consistent 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
Enables precise liquid delivery with accuracy below 10 μL, minimizing mechanical stress and cross-contamination, while reducing the need for expensive flow rate sensors and their calibration.
Implementation Method 1
a high-resolution differential pressure sensor that measures pressure difference between both ends of calibrated hydraulic resistance
Implementation Method 2
a pressure control unit (4) suitable to control pressure inside said channel by flowing gas through said gas mass flowmeter
Implementation Method 3
Using equation of state of the gas, it is possible to measure very precisely the volume occupied by gas introduced, which corresponds to volume of liquid displaced in the channel
Data Source
AI summary
A liquid delivery device that includes a channel having an inner section lower than 9 mm2 and inner volume lower than 50 mL, a gas mass flowmeter connected to the inlet of the channel, and a pressure control unit suitable to control pressure inside the channel by flowing gas through the gas flowmeter.