Ion Mobility Filtering with Moving Separation Regions
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Solution Overview
Problem
Conventional ion mobility separators and filters face limitations such as low duty cycle, space charge issues, and inaccuracies in filtering based on ion mobility, particularly when only a single ion species or narrow range is of interest, and current devices often have lower sensitivity and complex implementations.
Innovation Solution
The method and device employ local separation regions that translate axially along the device, filtering ions with specific ranges of physicochemical properties, allowing efficient transmission of desired ions while removing others through adjacent regions or radial ejection, and optionally incorporating DC gradients or traveling waves for enhanced separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional ion mobility separators operate in pulsed fashion with discrete ion packets, then ion separation according to mobility is achieved, but duty cycle is limited to 1% or less due to the time required for slowest ion species to exit
Solution Approach 1:
The device segments the ion mobility separation into multiple independent filter regions arranged in series, each capable of operating simultaneously with different ion packets. This allows multiple separation events to occur in parallel, dramatically increasing the duty cycle from 1% or less to potentially 50% or higher when filters are optimally spaced and operated.
Solution Approach 2:
Ions are trapped in an ion trap before being released into the filter device. This preliminary trapping allows ions to be accumulated and then released in a controlled manner, improving the duty cycle by allowing the next ion packet to be prepared while previous ions are still being processed through the filters.
2Productivity
If ion trapping is employed to improve duty cycle, then higher pulsing frequency is achieved, but space charge issues are introduced
Solution Approach 1:
The invention extracts only the ions of interest from the ion packet by using multiple filter regions with different mobility acceptance ranges. Each filter region is configured to transmit only ions within a specific mobility range, effectively separating the desired ions from the rest of the packet and reducing space charge effects by limiting the number of ions entering the detection region simultaneously.
3Productivity
If multiplexed ion mobility separators allow ions from different pulses to overlap, then duty cycle and pulsing frequency are improved, but additional deconvolution processing is required to obtain meaningful spectra
Solution Approach 1:
The ion mobility range is segmented into multiple discrete filter regions, each accepting ions within a specific mobility range. This segmentation allows ions from different pulses to be spatially separated and transmitted through different filter regions simultaneously, enabling multiplexed operation without requiring complex deconvolution processing.
Solution Approach 2:
Each filter region is configured with specific electrical parameters (voltage, frequency) tailored to its local mobility acceptance range. This local optimization allows each region to independently filter ions of interest while maintaining overall system simplicity and avoiding the need for complex global signal processing.
4Adaptability or versatility
If conventional FAIMS or DMS devices are used for ion mobility filtering, then filtering of specific ion species is achieved, but sensitivity is reduced and device complexity increases due to requirements for laminar flow and high field conditions
Solution Approach 1:
The filter regions use dynamic electrical fields with adjustable voltage and frequency parameters that can be optimized for each specific ion species of interest. This dynamic control allows the device to maintain high sensitivity by adjusting the field parameters to match the mobility characteristics of the target ions, unlike static FAIMS or DMS configurations.
Solution Approach 2:
The invention changes the electrical parameters (voltage, frequency, waveform shape) of each filter region to optimize ion transmission for specific mobility ranges. By adjusting these parameters, the device achieves high sensitivity for targeted ion species without requiring the complex laminar flow conditions needed by DMS devices or the high field conditions required by FAIMS.
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 approach achieves higher sensitivity and duty cycle with a simpler device structure, effectively filtering ions based on mobility and/or mass-to-charge ratio, reducing complexity and improving ion separation efficiency.
Implementation Method 1
separating the ions according to a physicochemical property, such as ion mobility
Implementation Method 2
filtering ions with specific ranges of physicochemical properties, allowing efficient transmission of desired ions while removing others
Data Source
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AI summary
A method of filtering ions according to their ion mobility using a device is disclosed, the method comprising a plurality of electrodes and one or more voltage source(s) arranged and adapted to apply voltages to the plurality of electrodes, the method comprising, generating using the one or more voltage source(s) one or more local separation region(s), wherein ions can be separated within each local separation region according to their ion mobility, and moving each local separation region axially along the device with a certain velocity such that, for each local separation region, ions having a value of their ion mobility falling within a selected range are transmitted axially along the device with that local separation region whereas ions having higher and/or lower ion mobility falling outside that range escape the local separation region, wherein any ions that escape the local separation region(s) are removed from within the device and/ or otherwise kept apart from those ions falling within the selected range(s).