Parallel Ion Drift Tubes for IMS Throughput
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Solution Overview
Problem
Classical time-of-flight ion mobility spectrometers (IMS) have limitations such as low ion throughput, requiring only a small portion of product ions for detection, and needing to switch polarity to measure both positive and negative ions, leading to inefficient detection and larger, unwieldy devices.
Innovation Solution
A method and device that allows simultaneous detection of both positive and negative product ions in parallel, using a common inlet system and separate drift tubes with controlled electrode arrangements to separate and accelerate ions efficiently, eliminating the need for a switching grid and enabling 100% ion injection into drift spaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a switching grid is used to introduce product ions into the drift space, then ions can be directed into the drift tube, but only a small portion (typically 1%) of product ions pass through the grid and enter the drift tube, resulting in low ion throughput
Solution Approach 1:
The invention extracts and eliminates the switching grid component from the ion mobility spectrometer. By removing this component, 100% of product ions can enter the drift space without being blocked or lost at a grid interface, thereby maximizing ion throughput and detection efficiency simultaneously
Solution Approach 2:
The invention segments the ion path into distinct regions (ionization region, drift space, detection region) with clear spatial separation. Product ions are formed in the ionization region and directly transported through the drift space without encountering blocking structures, enabling complete ion transmission while maintaining functional separation
2Adaptability or versatility
If polarity switching is implemented to measure both positive and negative ions, then both ion types can be detected, but the measurement process becomes sequential rather than simultaneous, increasing measurement time
Solution Approach 1:
The invention introduces a spatial dimension solution by providing separate drift spaces for positive and negative ions. Instead of switching polarity in time (sequential measurement), the system measures both ion types simultaneously in parallel spatial paths, eliminating measurement time loss while maintaining versatility
Solution Approach 2:
The drift region is segmented into separate drift spaces for positive and negative ions. This spatial segmentation allows independent simultaneous measurement of both ion types without polarity switching, resolving the contradiction between versatility and measurement time
3Device complexity
If a single drift tube is used for both positive and negative ions with polarity switching, then device complexity is reduced, but ion throughput is limited to 1% due to grid switching requirements
Solution Approach 1:
The invention merges the ionization region and drift spaces into an integrated structure where product ions are formed and directly transported without intermediate blocking components. This merging eliminates the need for switching grids while enabling 100% ion transmission, resolving the contradiction between device simplicity and ion throughput
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 increases ion throughput, improves detection efficiency, and reduces device size by allowing concurrent measurement of both ion polarities, enhancing the detection limit and operational efficiency of IMS systems.
Implementation Method 1
The target compounds are hereby continuously ionized in an ion source either by using radioactive radiation, photo ionization or corona discharges
Implementation Method 2
The target compounds are hereby continuously ionized in an ion source either by using radioactive radiation, photo ionization or corona discharges
Implementation Method 3
The introduced product ions are continuously accelerated by the electric field and continuously decelerated as a result of collisions with the neutral molecules in the drift gas
Implementation Method 4
The drift velocity of the product ions vd depends linearly on the field strength at a small field strength E, e.g. E=200 V/cm. The mobility K of the product ions is at these small field strengths then independent of the field strength
Implementation Method 5
The introduced product ions are continuously accelerated by the electric field and continuously decelerated as a result of collisions with the neutral molecules in the drift gas. The introduced ions diffuse broadly due to the collisions with the molecules of the ambient air
Implementation Method 6
From the different times-of-flight of the product ions through the drift tube, which are typically in the range 5 to 30 milliseconds, conclusions can be drawn with respect to the different examined chemical compounds
Data Source
AI summary
The invention relates to a method for identifying gases, which are ionized and the drift times of the positive and negative product ions through drift spaces are measured and the measured drift times are evaluated, wherein for measuring the drift times the product ions are accelerated to drift velocities by a resulting electrical field. It is provided that the positive and negative product ions move synchronously and in parallel in the same direction.The invention further relates to a device for identifying gases, which includes at least two drift tubes, wherein each of the drift tubes has at least one respective detector for detecting product ions. For this purpose, at least two drift tubes are arranged in parallel next to each other and are delimited, on one hand, by a common inlet system and, on the other hand, by at least one detector.