Ion Guide Exit Transmission Control for Mass Spectrometry

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Solution Overview

Problem

Conventional orthogonal acceleration Time of Flight mass spectrometers face challenges in handling high ion arrival rates, leading to detector saturation and reduced dynamic range, due to limitations in commercial analogue to digital recording systems and electron multipliers, which result in mass to charge ratio and charge state discrimination effects during ion beam attenuation.

Innovation Solution

An ion guide with a confinement region and an attenuation device that differentially ejects or deflects ions based on their spatial positions, allowing only ions within a specific cross-sectional profile to pass through, thereby attenuating the ion beam without significant mass to charge ratio or charge state dependency, using a combination of RF and DC voltages to confine and control ion distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If ion beam attenuation is performed using conventional methods, then the ion population is reduced to prevent detector saturation, but mass to charge ratio and charge state discrimination effects occur

Engineering Contradiction:

Improvedetector saturation preventionVSAvoidmass to charge ratio accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent applies local quality by creating a spatially non-uniform electric field through the lens electrode arrangement that selectively affects ions at different radial positions. The field strength varies with radial distance, causing ions at different positions to experience different deflection forces, thereby achieving position-dependent attenuation without mass-to-charge discrimination.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent transitions from conventional uniform attenuation methods to a spatially-resolved attenuation approach by introducing radial position as an additional dimension for ion selection. The lens system creates a two-dimensional ion distribution pattern where attenuation can be controlled independently at different radial positions, eliminating the need for mass-to-charge dependent calibration.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Productivity

If high ion arrival rates are maintained for improved sensitivity, then detector saturation occurs, but reducing ion population decreases dynamic range

Engineering Contradiction:

Improveion arrival rateVSAvoiddetector linear dynamic range

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent implements dynamic control of ion transmission by varying the lens electrode voltages in real-time or between acquisition cycles. This allows the system to adapt the degree of attenuation based on the actual ion population and detector response, enabling operation at high ion arrival rates while maintaining the detector within its linear dynamic range through active feedback or predetermined voltage settings.

Inventive Principle:

Principle #15Dynamics

3Reliability

If uniform ion beam attenuation is applied, then detector saturation is prevented, but overall dynamic range is reduced

Engineering Contradiction:

Improvedetector saturation preventionVSAvoiddynamic range

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs partial action by allowing different portions of the ion beam to pass through to the detector based on their radial position. Rather than uniformly attenuating the entire beam, the system permits ions from certain radial regions to contribute to the signal while attenuating others, thereby preserving more of the ion population and maintaining greater dynamic range while still preventing saturation.

Inventive Principle:

Principle #16Partial or excessive action

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 allows for controlled attenuation of ion beams, increasing the dynamic range of downstream detection systems by reducing saturation effects and simplifying calibration routines, while maintaining the homogeneity of ion distributions and minimizing stratification, thus enhancing the overall performance of mass spectrometry.

Implementation Method 1

using a combination of RF and DC voltages to confine and control ion distribution

Methodology Applied

Scientific EffectElectrostatic field: Electric Field

Implementation Method 2

an attenuation device arranged and adapted to eject or deflect ions having spatial positions which fall outside of a second cross-sectional profile

Methodology Applied

Scientific EffectElectrostatic force: Electric Field

Data Source

PatentUS11282690B2Ion guide exit transmission control

Publication Date: 2022.03.22 MICROMASS UK LTD

AI summary

An ion guide (40) is disclosed that comprises an ion confinement region having a first cross-sectional profile with a first cross-sectional area A1 in a plane orthogonal to a direction of ion transmission. An attenuation device ejects or deflects ions having spatial positions which fall outside of a second cross-sectional profile having a second cross-sectional area A2, wherein A2<A1.