Segmented RF Ion Guide with Protruding Electrodes
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Solution Overview
Problem
Existing ion guides face challenges in efficiently transferring ions between high-pressure and low-pressure regions in mass spectrometry, with multipole ion guides performing poorly at high pressures and ion funnels performing poorly at lower pressures, and there is a need for a design that combines axially alternating and cross-wise wiring while being easier to fabricate and assemble.
Innovation Solution
A radio frequency ion guide design featuring a plurality of electrodes with protruding elements forming a row of segmented aperture members, where the dimension of the aperture contour changes along the row to form an ion funnel, simplifying manufacturing and improving robustness, and allowing for simultaneous cross-wise and axially alternating electrical wiring, reducing ion trapping and enhancing ion transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multipole ion guides are used to transport ions through vacuum stages, then ion confinement and transfer are achieved, but performance deteriorates at high pressures (100-10000 Pascal range)
Solution Approach 1:
The ion guide is segmented into multiple ring electrodes stacked along the axis, with each ring capable of receiving independent electrical potentials. This segmentation allows the creation of localized electric field regions that can effectively guide ions at high pressures where traditional multipole guides fail, while maintaining overall ion transport functionality across pressure ranges.
Solution Approach 2:
The system changes electrical parameters by applying different potentials to adjacent rings in an alternating pattern, creating a moving potential well that propels ions axially. This dynamic parameter manipulation enables effective ion guidance at high pressures and adapts to different pressure conditions, resolving the adaptability issue.
2Reliability
If stacked ring electrodes are wired with axially alternating phases, then ion guidance is achieved, but the design becomes complex and difficult to manufacture
Solution Approach 1:
Multiple ring electrodes are merged into a single integrated component where adjacent rings are electrically connected through conductive pathways within the same structure. This merging eliminates the need for separate wiring of individual rings, simplifying manufacturing while maintaining the axially alternating phase configuration necessary for ion guidance.
Solution Approach 2:
The stacked ring electrode structure serves multiple functions simultaneously: it provides mechanical support, creates the necessary electric field configuration for ion guidance, and incorporates internal conductive pathways for electrical connection. This multi-functionality reduces assembly steps and manufacturing complexity while maintaining guidance performance.
3Reliability
If ion funnels are used at near atmospheric pressures, then ion transfer is improved, but performance deteriorates at lower pressures
Solution Approach 1:
The ion guide employs dynamic electrical control by alternating potentials between adjacent rings to create a moving potential well that actively propels ions forward. This dynamic mechanism maintains effective ion transfer at near atmospheric pressures while also performing adequately at lower pressures, unlike static ion funnel designs.
Solution Approach 2:
The system dynamically changes electrical parameters along the axial direction by applying alternating potentials to adjacent rings, creating regions of high and low potential that move ions forward. This parameter variation enables effective operation across a broad pressure range, including both near atmospheric and lower pressures.
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 design effectively transfers ions from an ion source to a mass analyzer, improving ion transmission efficiency and reducing manufacturing complexity and costs, while maintaining robustness and reliability.
Implementation Method 1
The function of the ion guides is to confine and transfer the ion beam throughout the intermediate vacuum stages via a radio frequency (RF) field generated by the guide itself
Implementation Method 2
a direct current (DC) electrical gradient is created using a power supply and a resistor chain to supply the desired and sufficient voltage to each ring to create a driving force for ions to be transported through the funnel
Implementation Method 3
ions may be formed by electron ionization (EI) or chemical ionization (CI) of the gas phase sample molecules
Implementation Method 4
In one of the more widely used methods known as electrospray ionization (ESI), analyte is dissolved in a liquid solution and sprayed from a needle. The spray is induced by the application of a potential difference between the needle and a counter electrode
Data Source
AI summary
An ion guide that transports ions from an ion source at generally a high-pressure level to a mass analyzer at generally a low-pressure level has a plurality of identical electrodes fabricated with protruding elements that forming an ion tunnel or an ion funnel, when the electrodes are assembled around a common longitudinal axis. The protruding elements allow the generation of the radio frequency field necessary to radially confine ions. Each electrode may be machined from a solid block of conductive material, such as metal. The disclosed arrangement greatly simplifies the manufacturing process, reducing cost, and improving robustness and reliability of the ion guide itself.