Ion Mobility Spectrometer Shutter with Third Electrode
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Solution Overview
Problem
Conventional ion mobility spectrometers face challenges due to elongate and irregular ion swarms caused by the Tyndall-Powell shutter, requiring lengthy drift spaces and complicating the detection of different ion types, which hinders the miniaturization of these devices and complicates the distinction between different ion swarms.
Innovation Solution
The introduction of a third electrode surface in the shutter system, where the potential between the first and second electrode surfaces is reversed while maintaining a constant potential for the third electrode, allowing only ions between the first and second electrodes to pass through, thereby controlling the length and shape of the ion swarm, and using elongate or grid-like electrode elements to create a uniform electric field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a Tyndall-Powell shutter with two electrode surfaces is used to control ion flow, then the shutter can effectively open and close to emit ion bursts, but the ejected ion swarm becomes elongate and irregular in shape
Solution Approach 1:
The shutter is divided into three separate electrode surfaces (first, second, and third) instead of two, with each surface performing a specific function. The first and second surfaces control the main shutter action, while the third surface specifically shapes the ion swarm, segmenting the control functions to achieve both effective shutter operation and uniform ion swarm shape.
Solution Approach 2:
The third electrode surface acts as an intermediary element between the main shutter mechanism and the ion swarm. By applying a specific potential to this intermediate surface, it mediates the ion flow to create a uniform swarm shape without interfering with the primary shutter opening/closing function.
2Loss of time
If the shutter is briefly opened and closed to emit short bursts of ions, then ion bursts are emitted through the drift space, but a considerable length of drift space (4-20 cm) is required to separate different ion types
Solution Approach 1:
The third electrode surface pre-shapes the ion swarm into a compact, uniform form before the ions enter the drift space. This preliminary action of shaping reduces the initial swarm length, allowing different ion types to be separated more quickly and reducing the required drift space length while maintaining effective ion burst emission timing.
3Measurement precision
If a lengthy drift space (4-20 cm) is used to separate ion swarms, then different ion types can be distinguished, but the housing must comply with highly specific design requirements to obtain a uniform potential difference
Solution Approach 1:
The uniform shaping of the ion swarm by the third electrode surface before entry into the drift space creates more favorable initial conditions for ion separation. This preliminary uniformity reduces the sensitivity to housing design variations, allowing for simpler housing designs while maintaining ion type differentiation capability.
4Productivity
If the irregular stingray-like shape of the ejected ion swarm is used, then ions are emitted through the shutter, but the detection curve becomes erratic and difficult to interpret
Solution Approach 1:
The third electrode surface serves as an intermediary that transforms the irregular ion swarm shape into a uniform one, mediating between the shutter's ion emission function and the detection system's need for interpretable signals. This intermediate shaping action maintains ion emission throughput while producing regular detection curves that are easy to interpret.
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 allows for a shorter ion swarm length, easier separation of different ion types, and a more uniform ion shape, enabling accurate detection with a shorter drift space and improved distinction between ion swarms, facilitating the development of compact and accurate ion mobility spectrometers.
Implementation Method 1
As soon as the potential between the first and second electrode surfaces is reversed, while the potential of the third electrode surface remains the same, the ions between the first electrode surface and the third electrode surface will be attracted to the third electrode surface, while the ions between the first and second electrode surfaces are propelled in the direction of the drift space.
Implementation Method 2
An electric field or drift potential is applied over this drift space between the shutter and the collector plate, whereby the ions will migrate in the direction of the collector plate.
Implementation Method 3
using elongate or grid-like electrode elements to create a uniform electric field
Implementation Method 4
Since different types of ion have a different displacement velocity within the drift potential, this being referred to as ion mobility, a swarm of one type of ions will arrive at the collector plate at a different time from a swarm of another type.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3
AI summary
The invention relates to a shutter for an ion mobility spectrometer (20), the shutter comprising: a first electrode surface (1 1) with a number of first electrode elements arranged in the first plane and at a distance from each other; a second electrode surface (12) arranged parallel to and at a distance from the first electrode surface and having a number of second electrode elements arranged in the second plane and at a distance from each other; means for applying a potential difference between the first electrode elements and the second electrode elements, and a third electrode surface (13) with a number of third electrode elements arranged in the third plane and at a distance from each other, wherein the third electrode surface is arranged parallel to and at a distance from the first electrode surface and wherein the third electrode surface is arranged on the opposite side of the first electrode surface relative to the second electrode surface.