Ion Mobility Gas Recirculation for High-Resolution Separation
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Solution Overview
Problem
Existing ion mobility separation techniques face limitations in gas flow management, leading to inefficient separation efficiency, excessive pumping requirements, and space charge effects, especially at reduced pressures, which restrict ion throughput and resolution.
Innovation Solution
A gas recirculation arrangement supplies at least 50% of the gas flow within the ion separation region, directing it transversely to the major ion travel direction, using a combination of electric fields and gas dynamics to trap ions axially based on their mobility, enabling high separation efficiency without excessive pumping capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gas flow is increased to improve separation efficiency, then separation resolution is improved, but pumping requirements become excessive
Solution Approach 1:
The patent implements a recirculating gas flow system where buffer gas is continuously circulated through the drift tube and returned to the inlet, creating a continuous useful action that maintains high gas flow velocity for improved separation resolution without requiring proportionally increased pumping capacity. The gas flow path forms a closed loop that maximizes the utility of each unit of gas flow.
Solution Approach 2:
The patent introduces a flow splitter and flow combiner as intermediary components that enable the gas flow to serve dual purposes: providing separation medium in the drift tube and being recirculated back to the inlet. These intermediaries facilitate the transition from linear gas consumption to cyclic gas utilization, reducing the burden on the vacuum pumping system.
2Measurement precision
If gas flow velocity is increased to improve separation efficiency, then ion throughput is limited by space charge effects
Solution Approach 1:
The patent applies different flow conditions to different regions of the ion mobility cell. The recirculating gas flow is concentrated in the drift tube region where separation occurs, providing high local gas flow velocity for improved separation efficiency. Meanwhile, the overall system maintains manageable gas load through the recirculation architecture, allowing higher ion throughput without excessive space charge effects.
3Measurement precision
If long drift tube is employed to achieve high resolution at low pressures, then separation resolution is improved, but device complexity and length increase
Solution Approach 1:
The patent employs dynamic gas flow recirculation to enhance the effective path length for ion separation without physically extending the drift tube. By recirculating the gas flow multiple times through the drift tube, ions experience extended interaction with the separation medium, achieving high resolution in a compact device. The dynamic recirculation creates an effective path length much greater than the physical tube length.
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
Enhances separation efficiency and resolution while reducing the need for large vacuum pumps, allowing higher ion throughput and improved gas flow management, thus overcoming the limitations of conventional methods.
Implementation Method 1
Ion mobility separation utilizes the transport of analyte ions through a gas in the presence of an electric field to temporally or spatially separate the ions according to their mobility cross-sections
Implementation Method 2
ion velocity is proportional to electric field E: v = K*E wherein K is the ion mobility
Data Source
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AI summary
An ion mobility analyser is disclosed having a gas flow directed along the ion travel axis and a set of electrodes to which DC voltages are applied to establish a DC field. The opposing forces of the gas flow and DC field cause ions to be trapped within a separation region in axial regions determined by their ion mobilities. A gas recirculator, having inlet and outlet ends respectively located downstream and upstream of the separation region, supplies at least fifty percent of the gas flow within the separation region, thereby reducing vacuum pumping requirements.