Porous Membrane Sampling for In Situ Microfluidic Mass Spectrometry
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Solution Overview
Problem
Current mass spectrometry methods are unable to analyze dynamic, living systems in situ without destroying or altering them, limiting their application in biochemical, pharmaceutical, and medical research.
Innovation Solution
A method involving a sample fluid conduit with a membrane and a surface sampling capture probe that establishes a pressure differential to draw sample liquid through the membrane, combining it with a solvent composition for analysis, allowing for in situ mass spectrometry of liquid samples without damaging the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mass spectrometry is used to analyze liquid samples, then chemical analysis capability is improved, but the system being analyzed is destroyed or altered
Solution Approach 1:
The system is divided into separate components: a microfluidic device containing the living system, a porous membrane for sampling, and a mass spectrometry analysis system. This segmentation allows analysis of a small sample portion without destroying the entire system.
Solution Approach 2:
A small volume of liquid is extracted from the microfluidic device through the porous membrane using a capture probe. This extraction enables mass spectrometry analysis of the extracted sample while the majority of the living system remains intact and continues to function.
2Loss of information
If in situ mass spectrometry is performed on stable samples, then chemical information is obtained, but dynamic living systems cannot be analyzed
Solution Approach 1:
The system enables continuous sampling and analysis of dynamic microfluidic devices. The porous membrane allows ongoing extraction of liquid samples while the living system continues to function, providing continuous chemical information rather than single-point measurements.
Solution Approach 2:
The porous membrane acts as an intermediary between the living system and the mass spectrometry analysis system. It enables selective passage of small molecules while retaining larger components, facilitating analysis of dynamic systems without direct contact that would cause destruction.
3Productivity
If sample liquid is drawn through membrane pores, then sampling efficiency is improved, but surface tension may prevent solvent flow
Solution Approach 1:
The system controls pressure parameters to overcome surface tension forces. By applying appropriate pressure differentials across the porous membrane, the system enables sample liquid to be drawn through the pores despite the surface tension barrier that would otherwise prevent solvent flow.
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 continuous, non-destructive chemical analysis of dynamic fluid systems, allowing for real-time characterization of small volumes of liquid directly from microfluidic devices without significantly altering the system's state, facilitating repeated measurements and chemical imaging.
Implementation Method 1
The surface tension of the solvent composition when in a liquid junction with the membrane having a junction fluid diameter can prevent expansion of the junction fluid diameter beyond two times the diameter of the distal end of the capture probe. The surface tension of the solvent composition does not permit the solvent to flow through the pores of the membrane at the second pressure.
Implementation Method 2
A second pressure is established within the liquid junction at the membrane. The second pressure can be lower than the first pressure. Sample liquid is drawn through the pores of the membrane by the second pressure at the liquid junction
Implementation Method 3
A surface sampling capture probe with a distal end is provided. The capture probe includes a solvent supply conduit with an open end and a solvent exhaust conduit with an open end. A solvent composition is flowed at the distal end of the capture probe from the open end of the solvent supply conduit to the open end of the exhaust conduit and establishes a liquid junction with the membrane and establishes a second pressure within the liquid junction at the membrane.
Implementation Method 4
A solvent composition is flowed at the distal end of the capture probe from the open end of the solvent supply conduit to the open end of the exhaust conduit and establishes a liquid junction with the membrane
Implementation Method 5
The method can further include the step of conducting mass spectrometry on the extracted sample liquid
Data Source
AI summary
A system for sampling a liquid includes a sample fluid conduit including a membrane having pores. The membrane prevents the passage of the sample liquid through the pores at a first pressure of the sample liquid in the sample fluid conduit. A surface sampling capture probe has a distal end. The capture probe includes a solvent supply conduit and a solvent exhaust conduit. A solvent composition flowing at the distal end of the capture probe establishes a liquid junction with the membrane and establishes a second pressure within the liquid junction at the membrane. The second pressure is lower than the first pressure. Sample liquid will be drawn through the pores of the membrane by the second pressure at the liquid junction. A method for sampling a liquid and for performing chemical analysis on a liquid are also disclosed.