Closed-Loop Ion Guide for Compact IMS
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Solution Overview
Problem
Conventional ion mobility spectrometers face challenges in achieving high-resolution separation of ions while maintaining a compact design, especially when multiple stages of separation and manipulation (such as unfolding or fragmentation) are required, leading to instrument length and complexity issues.
Innovation Solution
A closed-loop ion guide with a curved, labyrinthine path and a combination of DC and RF voltage systems allows ions to make multiple circuits, using transient DC potentials to propel and confine ions, enabling high-resolution ion mobility separation and flexibility for both simple and complex experiments without excessive size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional ion mobility spectrometers use multiple stages of separation and manipulation to achieve high-resolution separation, then the separation resolution is improved, but the instrument length and complexity increase
Solution Approach 1:
The patent implements a nested configuration where the ion mobility drift tube is positioned inside the mass spectrometer vacuum chamber. The drift tube operates at atmospheric pressure while the mass spectrometer operates under vacuum, with the drift tube passing through a window or aperture in the vacuum chamber wall. This nesting allows both separation stages to occur in sequence within a compact footprint, avoiding the need for separate, lengthy instrument sections.
Solution Approach 2:
The patent transitions from a linear, sequential arrangement of separation stages to a compact configuration by utilizing spatial dimensionality - placing the atmospheric pressure drift tube inside the vacuum chamber of the mass spectrometer. This dimensional reorganization allows the ion mobility separation to occur concentrically within the mass analysis region, dramatically reducing the overall instrument length while maintaining both separation functions.
2Measurement precision
If conventional ion mobility spectrometers use multiple stages of separation and manipulation to achieve high-resolution separation, then the separation resolution is improved, but the device complexity increases
Solution Approach 1:
The patent creates a multi-functional system where the ion mobility drift tube serves multiple purposes: it provides the separation medium for ion mobility analysis, maintains atmospheric pressure conditions optimal for ion mobility, and acts as the interface region between atmospheric pressure ionization and vacuum-based mass analysis. The same physical structure supports both the drift tube operation and the mass spectrometer function, reducing the need for separate specialized components.
Solution Approach 2:
The patent merges the ion mobility separation system and the mass spectrometer into a single integrated instrument. The drift tube is positioned within the mass spectrometer vacuum chamber, and ions are transferred directly from the drift tube outlet to the mass analyzer through a shared interface region. This merging eliminates the need for separate instrument sections and complex transfer mechanisms, simplifying the overall device architecture while enabling multi-stage separation and analysis.
3Measurement precision
If a closed-loop ion guide with curved labyrinthine path is used to enable multiple ion circuits, then the ion mobility separation resolution is enhanced, but the device complexity increases
Solution Approach 1:
The patent employs a curved or labyrinthine ion guide path within the drift tube instead of a straight linear path. Ions traverse the drift tube in a curved trajectory, increasing the effective path length and number of circuits through the separation region without proportionally increasing the physical instrument length. This curvature enhances separation resolution by allowing more interaction length between ions and the buffer gas while maintaining a compact device footprint.
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 design enhances ion mobility separation resolution, allows for efficient ion manipulation, and maintains a compact instrument size, capable of handling complex experiments without performance compromise.
Implementation Method 1
The application of the AC or RF voltage to the electrodes results in radial confinement of ions passing through the ion mobility spectrometer
Implementation Method 2
An ion mobility spectrometer is known comprising a drift tube or cell wherein an axial electric field is maintained along the length of the drift tube... Ions having a relatively high ion mobility pass relatively quickly along the ion mobility spectrometer whereas ions having a relatively low ion mobility pass more slowly
Implementation Method 3
Ions are therefore temporally separated according to their ion mobility
Data Source
Figure 1~2
Figure 3A~3B
Figure 4A~4E
AI summary
A closed-loop ion guide (1) is disclosed comprising a plurality of electrodes having apertures through which ions are transmitted in use. Ions are injected into the closed- loop ion guide (1) and may make several circuits of the closed- loop ion guide (1) before being ejected from the ion guide (1). In a mode of operation the ion guide (1) may be arranged to separate ions temporally according to their ion mobility.