Combined Ion Gate and Modifier for IMS
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Solution Overview
Problem
Ion mobility spectrometers face difficulties in distinguishing between substances with similar time of flight due to the fragmentation of molecular ion clusters, leading to complex spectra and increased energy consumption.
Innovation Solution
A combined ion gate and ion modifier design where the ion gate forms one electrode of the ion modifier, allowing for simultaneous activation and proximity to enhance ion fragmentation and control, minimizing unnecessary peak generation and improving sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If molecular ion clusters are fragmented using laser energy or pyrolyzer, then discrimination between different molecular ion clusters is improved, but the number of peaks on the spectrum increases making analysis difficult
Solution Approach 1:
The invention applies segmentation by dividing the ion population into two groups: unfragmented molecular ion clusters that provide the main identification peaks, and fragmented ions that provide supplementary discrimination information. This selective fragmentation approach fragments only a portion of the ion clusters rather than all of them, thereby improving discrimination between similar substances while avoiding the creation of excessive peaks that would complicate spectrum analysis.
2Measurement precision
If high strength RF field is applied to cause ion modification, then discrimination between ions with similar mobilities is improved, but overall energy used by IMS increases
Solution Approach 1:
The invention applies partial action by using a moderate strength RF field that modifies only a significant percentage (but not all) of the ions. This partial modification approach provides sufficient discrimination power to distinguish between ions with similar mobilities while avoiding the excessive energy consumption that would result from applying continuously high strength fields to all ions.
3Measurement precision
If continuous RF field is applied to modify ions, then ion modification is maintained, but corona discharge occurs
Solution Approach 1:
The invention applies periodic action by delivering the RF field in bursts rather than continuously. These periodic bursts are sufficient to modify a significant percentage of the ion population while providing intervals during which the field is absent, thereby preventing corona discharge from occurring while maintaining effective ion modification capability.
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 enhances the sensitivity and accuracy of substance identification by ensuring precise ion modification and fragmentation, reducing unnecessary peak generation and energy consumption while maintaining precise control over ion flow and modification timing.
Implementation Method 1
an ion gate comprising two electrodes... through which current is passed to control the flow of ions
Implementation Method 2
means to apply a high electrical field to cause ion modification of the ions, such as fragmentation. The field may be a high strength RF field of around 2 MHz which is effective to cause ion modification of a significant percentage of the ions within the field
Implementation Method 3
The strength of the field may be at least 10,000 V/cm and may be of the order of several tens of thousands of volts per centimeter
Implementation Method 4
A gate is opened to admit the molecular ion clusters into one end of a drift chamber across which a voltage is applied to cause the ion clusters to drift to the opposite end where they are collected on a collector plate
Implementation Method 5
An IMS has some means to ionize the sample chemicals, such as a corona discharge or a radioactive source
Data Source
AI summary
A detection device including an ionization region, an ion gate comprising two electrodes, an ion modifier comprising two electrodes, a drift chamber and a collector. The ion gate and ion modifier are combined so the ion gate is one of the ion modifier electrodes.