Microfluidic Fluid Seal Using Thermo-Pneumatic Evaporation Control
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Solution Overview
Problem
Microfluidic systems are susceptible to unwanted evaporation due to their small reaction volumes and large surface-to-volume ratios, which can affect biological and chemical analyses by reducing test volumes, changing reagent concentrations, and introducing air bubbles, thereby skewing results.
Innovation Solution
A fluid analysis system that isolates the analysis chamber from vent ports and open surfaces by introducing an immiscible oil with low saturated vapor pressure into inlet and outlet channels using a thermo-pneumatic seal, where a gas bubble expansion pushes the oil into these channels to prevent evaporation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If microfluidic systems are used to analyze small volumes of fluid, then analysis precision is improved, but evaporation loss increases due to large surface-to-volume ratios
Solution Approach 1:
The patent introduces a sealing fluid as an intermediary substance that forms a barrier between the sample fluid and the environment. This sealing fluid is immiscible with the sample fluid and has low vapor pressure, preventing evaporation while allowing the microfluidic analysis to proceed. The sealing fluid acts as a mediator that protects the small-volume sample from evaporative loss without interfering with the analysis.
Solution Approach 2:
The patent creates an inert environment by filling the microchannel with a sealing fluid that has low vapor pressure and is immiscible with the sample fluid. This inert fluid environment prevents evaporation of the sample fluid while allowing the analysis to proceed. The sealing fluid creates a controlled, non-evaporative atmosphere around the sample.
2Ease of operation
If the analysis chamber is open to allow fluid introduction, then ease of operation is improved, but evaporation from open surfaces increases
Solution Approach 1:
The patent applies preliminary action by introducing the sealing fluid into the microchannel before introducing the sample fluid. This preliminary placement of the sealing fluid creates a barrier that prevents subsequent evaporation during the analysis process. The sealing fluid is positioned in advance to block evaporative pathways while maintaining chamber accessibility for fluid introduction.
3Loss of substance
If mechanical seals are used to prevent evaporation, then evaporation prevention is improved, but device complexity and reliability worsen due to mechanical parts prone to breakdown
Solution Approach 1:
The patent replaces mechanical sealing systems with a fluid-based sealing approach. Instead of using mechanical seals, O-rings, or other moving mechanical parts to prevent evaporation, the system uses an immiscible sealing fluid with low vapor pressure that forms a static barrier. This substitution eliminates mechanical wear and failure modes while effectively preventing evaporation.
Solution Approach 2:
The patent uses a hydraulic approach by introducing a sealing fluid into the microchannel to create a fluid barrier that prevents evaporation. This fluid-based sealing mechanism replaces mechanical sealing systems, utilizing fluid properties (immiscibility and low vapor pressure) rather than mechanical contact to achieve the sealing function.
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 creates an evaporation-free environment for biological or chemical reactions, maintaining reaction volumes and concentrations without mechanical parts prone to breakdown, ensuring accurate results.
Implementation Method 1
a gas bubble expansion pushes the oil into these channels to prevent evaporation
Implementation Method 2
introducing an immiscible oil with low saturated vapor pressure into inlet and outlet channels
Data Source
AI summary
In one example in accordance with the present disclosure, a fluid analysis system is described. The fluid analysis system includes an inlet channel to an analysis chamber. The analysis chamber is to receive a fluid sample to be analyzed. The fluid analysis system also includes a fluid branch having a fluidic junction along the inlet channel and a gas chamber to house a volume of trapped gas, the gas chamber being in fluid communication with the fluid branch. The fluid analysis system also includes a sealing fluid delivery system to fill the fluid branch with a sealing fluid and a heater adjacent the gas chamber to heat the gas chamber such that the trapped gas expands to push the sealing fluid into the inlet channel to seal the analysis chamber.