Ion Mobility Spectrometer Pre-Filter Segmentation
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Solution Overview
Problem
Existing ion mobility spectrometry methods face challenges in achieving precise separation and measurement of ions due to complex constructions and imprecision caused by ions entering from the entire flow area, leading to errors in mobility determination.
Innovation Solution
A simpler method and device for second-order aspiration IMS, where ions are filtered to enter from the central part of the flow cross-section, utilizing a static or slowly changing electric field and a pre-filter with thin metal plates to control ion flow and enhance precision, allowing only central ions to enter the measurement chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ions are allowed to enter from the entire flow cross-section, then the ion flow is simple and construction is easier, but measurement precision deteriorates due to imprecise separation and errors from ions entering at different positions
Solution Approach 1:
The flow cross-section is segmented into multiple regions (central region and peripheral regions) using partition walls. Only ions from the central region are allowed to enter the measurement chamber, while ions from peripheral regions are blocked. This segmentation improves measurement precision by ensuring ions enter from a defined position with consistent flow velocity, without requiring complex external control systems.
Solution Approach 2:
Different regions of the flow cross-section are given different functions: the central region serves as the ion emission source for measurement, while peripheral regions are blocked off. This local differentiation allows the system to achieve high precision measurements from the optimal central flow region without complicating the overall construction.
2Measurement precision
If the sample gas is guided to the centre of the transport-gas flow, then separation precision improves, but construction becomes more complicated due to difficulty in controlling transport gas and sample gas flows
Solution Approach 1:
The flow channel is physically segmented into a central emission channel and peripheral shut-off channels using partition walls. This structural segmentation automatically guides ions from the center without requiring complex flow control mechanisms, as the geometry itself ensures central ion entry.
Solution Approach 2:
The partition wall structure with its specific geometry (width, height, positioning) automatically performs the function of guiding central ions while blocking peripheral ions. The structure serves itself by using its own geometric properties rather than requiring external active control systems to achieve precise ion guidance.
3Measurement precision
If a narrow ion flow is created at the centre of the flow cross-section, then separation precision improves significantly, but construction complexity increases due to the need for precise flow control
Solution Approach 1:
The flow channel is divided into discrete regions using partition walls with specific dimensions. The central emission channel has controlled width and height to produce the desired narrow ion flow, while peripheral channels are blocked. This segmentation achieves precise narrow flow control through simple geometric design rather than complex manufacturing processes.
Solution Approach 2:
The partition wall structure creates a localized narrow flow region at the center while leaving the rest of the system simple and easy to manufacture. The complex precise flow control is confined to a small local area (the emission channel dimensions) rather than requiring complex control throughout the entire system.
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 significantly improves measurement precision by concentrating ion density at the center, reducing errors, and allowing for compact, stable, and efficient ion mobility measurement.
Implementation Method 1
separation of ions with differing ion mobilities with the aid of a transverse electric field
Implementation Method 2
leading of the ionized gas flow through an elongated ion-mobility measuring chamber in its defined flow cross-section, separation of ions with differing ion mobilities with the aid of a transverse electric field
Implementation Method 3
ionization of the sample gas in a gas flow
Data Source
Figure 1~6
Figure 3a~4
Figure 7~8
AI summary
The invention relates to a method and device for measuring gaseous substances, in which the method comprises the stages: - ionization of the sample gas in a gas flow (10), - leading of the ionized gas flow through an elongated ion-mobility measuring chamber (12) in the cross-section defined by it, - filtering out (14) of ions from the ionized gas flow at a distance from the measuring electrodes (ex, e2, e3), permitting the passage of only the ions travelling from the flow cross-section at the selected point, - separation of ions (J1-n) with a different ion mobility, with the aid of a transverse static electric field and at least one measuring-electrode pair (e1, e2, e3) arranged along the wall of the measuring chamber.