Pressure-Driven Fluidic Injection for Electrophoresis Microchips

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional microfluidic methods for electrospray ionization face challenges with injection bias and ionization suppression due to electrokinetic flow, which limits the effectiveness of sample focusing and separation in mass spectrometry analysis.

Innovation Solution

The implementation of pressure-driven injection methods that allow for precise control of sample volume and elimination of electrokinetic injection bias by using a microfluidic device with pressure-driven sample injection and electrophoretic separation, enabling the use of on-device sample focusing techniques like transient isotachophoresis without the need for voltage differentials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If electrokinetic flow is used for sample injection, then sample can be introduced into the separation channel, but injection bias occurs and ionization suppression is caused

Engineering Contradiction:

Improvesample injectionVSAvoidionization efficiency

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent replaces the electrokinetic injection mechanism (electrical field-driven) with a pressure-driven mechanical injection system. This substitution eliminates the injection bias and ionization suppression caused by electrokinetic flow while maintaining effective sample introduction into the separation channel.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts and removes the problematic electrokinetic injection step from the system, keeping only the pressure-driven injection mechanism. This extraction eliminates the harmful effects of electrokinetic flow (injection bias and ionization suppression) while preserving the essential function of sample introduction.

Inventive Principle:

Principle #2Taking out (Extraction)

2Manufacturing precision

If voltage differentials are applied for sample injection, then sample can be focused, but on-device sample focusing methods cannot be effectively used

Engineering Contradiction:

Improvesample focusingVSAvoidsample focusing method compatibility

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The patent replaces voltage differential-based electrokinetic focusing with pressure-driven mechanical focusing. This allows on-device sample focusing methods like transient isotachophoresis to be effectively implemented without the limitations of electrokinetic injection, enhancing both precision and method compatibility.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If conventional electrokinetic injection is used, then sample can be introduced, but injection bias cannot be eliminated

Engineering Contradiction:

Improvesample introductionVSAvoidinjection accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent substitutes pressure-driven mechanical injection for electrokinetic injection, thereby introducing samples accurately without the injection bias inherent in voltage-driven methods. This improves measurement precision while maintaining ease of operation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 reduces injection bias, enhances ionization efficiency, and allows for effective separation and analysis of samples with varying electrical conductivity and viscosity, improving the accuracy and reliability of mass spectrometry results.

Implementation Method 1

injecting a fluid sample from the sample reservoir into the separation channel downstream of the BGE reservoir by concurrently applying a defined pressure to the BGE reservoir and a defined pressure to the sample reservoir

Methodology Applied

Scientific EffectPressure-driven flow: Pressure Gradient

Implementation Method 2

electrophoretically separating the delivered sample in the separation channel by applying voltage to the BGE reservoir and a downstream location of the separation channel

Methodology Applied

Scientific EffectElectrophoresis: Electrophoresis

Implementation Method 3

electrospray ionization involves the use of electric fields to disperse a sample solution into charged droplets

Methodology Applied

Scientific EffectElectrospray ionization: Electrohydrodynamics

Implementation Method 4

Through subsequent evaporation of the droplets, analyte ions contained in the droplet are either field emitted from the droplet surface or the ions are desolvated resulting in gas phase analyte ions

Methodology Applied

Scientific EffectEvaporation: Evaporation

Data Source

PatentUS10734216B2Pressure driven fluidic injection for chemical separations by electrophoresis

Publication Date: 2020.08.04 THE UNIV OF NORTH CAROLINA AT CHAPEL HILL

AI summary

A pneumatic method, and associated apparatus, for injecting a discrete sample plug into the separation channel of an electrophoresis microchip (100) is disclosed. In a first step, pressurized gas (90) is applied to the sample (30) and background electrolyte (20) reservoirs such that the pressure is higher there than at the sample waste reservoir (35) to create a focused sample stream at the junction between the sample and separation channels. In a second step, the pressure at the sample reservoir (30) is reduced in order to pneumatically inject the sample plug into the separation channel. The waste reservoir (35) may be connected to a pressure reducing device (91). The methods, systems and devices are particularly suitable for use with a mass spectrometer (200i).