Gas-Retaining Ion Guide With Axial RF-DC Ion Acceleration
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Solution Overview
Problem
Existing lens-free collision cells in mass spectrometry and ion mobility spectrometry require precise control of gas pressure to optimize ion collisions, which can be challenging due to the need for accurate alignment and gas retention mechanisms.
Innovation Solution
A gas retaining ion guide with RF and DC electrodes is introduced, where RF electrodes generate an electric field to contain ions, and DC electrodes provide axial acceleration by changing their radial distance from the central axis, enhancing ion containment and acceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If gas pressure is increased in the collision cell to enhance ion collisions, then collision efficiency is improved, but gas retention becomes more difficult and requires more complex sealing mechanisms
Solution Approach 1:
The patent combines the gas seal function with the ion guiding function by integrating DC electrodes into the RF electrode structure. The DC electrodes serve dual purposes: providing radial gas sealing and generating axial electric field for ion acceleration, thereby reducing the need for separate complex sealing mechanisms while maintaining high collision efficiency
Solution Approach 2:
The DC electrodes are designed to perform multiple functions simultaneously: they act as gas seals to prevent gas leakage from the high-pressure collision region, generate axial electric fields for ion acceleration, and maintain the RF field configuration for ion containment. This multi-functionality reduces device complexity while improving collision efficiency
2Device complexity
If lens-free collision cell design is used to simplify structure, then device complexity is reduced, but ion focusing capability deteriorates
Solution Approach 1:
The patent replaces mechanical ion focusing lenses with an electric field-based focusing mechanism. By applying axial acceleration through DC electrodes within the RF quadrupole field, ions are focused and directed without requiring additional mechanical lenses or apertures, thus maintaining simplicity while achieving proper ion focusing
Solution Approach 2:
The patent uses electric field parameter variations (axial acceleration through DC voltage applied to RF electrodes) to achieve ion focusing instead of mechanical parameter changes. By adjusting the axial electric field strength, ion trajectories are controlled and focused without adding mechanical focusing components
3Speed
If axial ion acceleration is added to improve ion transport, then ion velocity is increased, but device complexity increases due to additional electrodes
Solution Approach 1:
The patent merges the ion acceleration function with the existing RF electrode structure by applying DC voltage to the same electrodes that generate the RF field. This eliminates the need for separate acceleration electrodes, as the RF electrodes perform both RF confinement and DC acceleration functions simultaneously
Solution Approach 2:
The RF electrodes are designed to serve dual purposes: generating the RF field for radial ion confinement and providing axial ion acceleration through applied DC voltage. This multi-functionality increases ion velocity without requiring additional dedicated acceleration electrodes, thus avoiding increased device complexity
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
The gas retaining ion guide effectively contains ions and accelerates them axially, improving collision efficiency and maintaining a compact, cost-effective design suitable for various applications in mass spectrometry and ion mobility spectrometry.
Implementation Method 1
when different phases, most often opposite phases, of a predetermined RF voltage are applied to adjacent electrodes, an RF electric field is generated that provides containment of ions in the ion region
Implementation Method 2
In order to provide an axial DC electric field component, at least some of the conductive surfaces of the DC electrodes have a radial distance from the central axis that changes between the entrance and exit of the ion guide
Data Source
AI summary
A gas retaining ion guide has RF electrodes distributed about an ion region that provide an RF confinement field for ions therein. DC electrodes are also provided that extend from an entrance of the ion guide to an exit, and provide a DC electric field. The DC electrodes are further from the central axis than the RF electrodes, and each provides a gas seal between two adjacent RF electrodes. Conductive surfaces of the DC electrodes establish the DC electric field through gaps between adjacent RF electrodes, and the conductive surfaces have a distance from the central axis that changes over the length of the ion guide so as to provide an axial DC field component. The size of the DC electrode conductive surfaces and a width of the gaps between RF electrodes may be selected to ensure that ions escaping confinement through the gaps are discharged on the conductive surfaces.