Spatial Zoom Ion Accumulation in Trapped Ion Mobility Spectrometry
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Solution Overview
Problem
Current ion mobility spectrometers face challenges in achieving high utility rates of ions generated in an ion source, with limitations in adaptability of ion mobilities, mobility separation time, and mobility resolution for specific analytical tasks.
Innovation Solution
The implementation of a 'spatial zoom' method using a long and flat electric field ramp in the ion mobility scanning tunnel, where ions of a selected mobility range are accumulated and scanned, with adjustable voltages to extend the flat field ramp almost the complete length of the tunnel, reducing space charge effects and allowing for high mobility resolution and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a standard electric field ramp is used in the ion mobility scanning tunnel, then the device structure remains simple, but ions of a limited mobility range can be accumulated and space charge effects are significant causing ion losses
Solution Approach 1:
The patent applies local quality by creating a non-uniform electric field ramp with different slopes in different spatial regions of the scanning tunnel. A flatter ramp section is implemented specifically in the region where ions of interest accumulate, reducing space charge effects locally without requiring changes to the entire device structure. This allows selective optimization of the accumulation region while maintaining overall device simplicity.
Solution Approach 2:
The patent implements dynamics by making the electric field ramp adjustable and reconfigurable. The ramp shape can be dynamically modified by controlling the voltages applied to segmented electrodes, allowing the system to adapt the field distribution to match the specific mobility range and intensity of ion packets being analyzed. This dynamic control enables optimization of both accumulation capacity and space charge mitigation.
2Adaptability or versatility
If the mobility range is extended to cover all ion mobilities, then the analytical versatility is improved, but the mobility resolution for specific ion groups decreases
Solution Approach 1:
The patent applies segmentation by dividing the mobility spectrum into multiple selectable ranges or windows. The electric field ramp is configured with different slope regions that correspond to different mobility ranges. Users can select and focus on specific mobility windows of interest, achieving high resolution for those selected ranges while maintaining the capability to analyze the full mobility spectrum by switching between different ramp configurations.
Solution Approach 2:
The patent introduces an additional dimensional control through the spatial distribution of the electric field ramp slopes. By varying the ramp slope as a function of position along the scanning tunnel, the system creates a mapping between spatial position and mobility resolution enhancement. This allows simultaneous coverage of broad mobility ranges while providing focused high-resolution analysis in specific mobility windows through the spatially varying field configuration.
3Productivity
If the scan speed is increased to reduce analysis time, then the productivity is improved, but the mobility resolution deteriorates
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the electric field ramp slope during the scanning process. Steeper ramp sections are used when analyzing ions with mobilities requiring higher resolution, while flatter sections are employed when broader coverage or faster scanning is needed. This parameter modulation allows the system to optimize the trade-off between scan speed and resolution based on the specific analytical requirements of different ion groups.
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 enables the collection of more ions of interest with reduced losses due to space charge, achieving higher mobility resolution and detecting more ions in mass-mobility maps, while maintaining high sensitivity and adaptability to analytical requirements.
Implementation Method 1
separation of ions according to their mobilities is based upon a gas flow in the tunnel, driving the ions in an accumulation phase against a ramp of an electric DC counter-field barrier
Implementation Method 2
separation of ions according to their mobilities is based upon a gas flow in the tunnel, driving the ions
Implementation Method 3
The cylindrical ion mobility scanning tunnel comprises a quadrupolar RF field keeping the ions near the axis
Implementation Method 4
a scan phase starts, in which the field barrier is steadily decreased. Ions are driven in this scan phase by the gas flow over the decreasing top of the field barrier, thereby releasing successively ions from low mobilities to higher and higher mobilities
Data Source
AI summary
The invention relates to the operation of ion mobility spectrometers based on gases pushing the ions over electrical field barriers, preferably in combination with mass spectrometers, and relates to trapped ion mobility spectrometers (“TIMS”). The invention proposes to accumulate and to scan the ions of a selected range of mobilities by using a long and flat electric field ramp created by additional voltages. By a voltage supplied at the beginning of the flat ramp, the lowest mobility of the mobility range of ions to be collected can be selected. By the difference of the voltages at the beginning and the end, the width of the mobility range is determined. The spatial zoom advantageously can collect considerable more ions of interest than a temporal zoom without severe losses by space charge effects, and more ions can be detected in the mass-mobility map.