Dual Mesh Ion Gate for Fast IMS Throughput
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Solution Overview
Problem
Ion mobility spectrometry (IMS) and IMS-time-of-flight (TOF) systems face limitations in charge throughput, dynamic range, and speed when combined with fast separation methods, leading to signal losses and mismatched gas pressures and ion cloud sizes, which restrict their analytical capabilities.
Innovation Solution
The implementation of a dual mesh gate with an RF signal applied between meshes to form an RF barrier for ions at varying gas pressures, allowing for the formation of short, spatially uniform ion packets, which can be pulsed or released using a ramped DC field, resulting in a shorter IMS spectrometer and higher throughput, dynamic range, and speed, compatible with rapid chromatography and mass spectrometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional IMS with Tyndal gate is used, then ion separation is achieved, but signal loss occurs due to low duty cycle (∼1%) and mismatch in gas pressures and ion cloud size
Solution Approach 1:
The patent changes the gate structure from a single Tyndal gate to a dual mesh gate system with RF signal application. This parameter change in gate configuration and operating mode (RF barrier formation) enables continuous ion transmission while maintaining separation efficiency, resolving the duty cycle limitation of conventional single-gate systems.
2Reliability
If ion packets are trapped between gate pulses to improve sensitivity, then detection limit is enhanced, but ion packet duration increases to 200-400 μs which slows down IMS speed
Solution Approach 1:
The patent employs periodic RF signal application to the dual mesh gate, creating a dynamic RF barrier that can be rapidly switched. This periodic action allows for fast ion packet formation and release cycles, achieving both high sensitivity through controlled trapping and high speed through rapid gate modulation, overcoming the speed-sensitivity tradeoff.
3Reliability
If ion packets are spread to 200-400 μs for confinement, then ion trapping is improved, but drift separation time increases to 20-40 ms requiring long (1 m) drift tubes
Solution Approach 1:
The patent introduces dynamic control of the dual mesh gate system with independently controllable RF and DC components. This dynamic capability allows real-time adjustment of ion packet duration and confinement strength, enabling short drift times with compact drift tubes while maintaining effective ion confinement through adaptive gate modulation.
4Stability of the object's composition
If space charge capacity is limited to 1E+7 charges per pulse, then ion trap stability is maintained, but charge throughput and dynamic range are restricted
Solution Approach 1:
The patent segments the ion gate into two independent meshes that can be controlled separately. This segmentation allows one mesh to manage ion admission while the other controls ion release, enabling continuous ion flow and significantly increased charge throughput while maintaining ion trap stability through distributed charge management.
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 configuration enables faster IMS operation with improved charge throughput and dynamic range, allowing for rapid surface analysis and in-source reaction tracking, and is compatible with high-speed GC×GC analysis, achieving 1-2 ms cycles and higher resolution.
Implementation Method 1
A gate is disclosed comprising a dual mesh with an RF signal applied between meshes, thus forming an RF barrier for ions at gas pressures from 1 to 100mBar
Implementation Method 2
ions can be either pulsed ejected to form 10-20us packets, or released in a mass-dependent fashion by a ramped DC field
Data Source
AI summary
A method and apparatus are disclosed for improving ion mobility spectrometry by using a fast and spatially wide ion gate based on local RF field barrier opposed to a switching DC field. The improvement accelerates the ion mobility analysis and improves charge throughput and dynamic range of the IMS. The invention is particularly suited for rapid dual gas chromatography. In one important embodiment, the accelerated IMS is coupled to a multi-reflecting time-of-flight mass spectrometer with a fast encoded orthogonal acceleration. There are described methods of comprehensive and orthogonal separation in multiple analytical dimensions.