Curved Ion Drift Region for Compact Mobility Spectrometer
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Solution Overview
Problem
Conventional ion mobility spectrometers are bulky due to long drift regions, which limits their compactness and mobility resolution, especially when trying to maintain high-resolution measurements.
Innovation Solution
Drift regions are bent into curved shapes that extend into the third dimension, allowing ions to balance path lengths through alternating curvatures and using RF focusing to keep ions on axis, reducing the overall device length without compromising mobility resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the drift region is made long to improve mobility resolution, then the device becomes bulky and loses compactness
Solution Approach 1:
The drift region is configured in a three-dimensional curved path (e.g., helical or serpentine) instead of a straight line, allowing the ion trajectory to extend through additional spatial dimensions. This enables a longer effective drift path to be achieved within a compact device footprint, resolving the contradiction between mobility resolution and device volume.
Solution Approach 2:
The drift region employs curved geometries (helical, serpentine, or circular paths) to extend the ion trajectory length without increasing the linear dimensions of the device. The curved path allows ions to traverse a longer distance through the drift gas while maintaining a compact overall device structure, thereby achieving high mobility resolution without bulkiness.
2Volume of moving object
If the drift region is curved to reduce device length, then ions may diffuse away from the central axis
Solution Approach 1:
Radio frequency (RF) voltages are applied to electrodes surrounding the curved drift region, creating oscillating electric fields that generate radial focusing forces. These forces continuously steer diffusing ions back toward the central axis of the curved path, preventing ion loss and maintaining mobility resolution despite the curved geometry.
Solution Approach 2:
Instead of using purely geometric constraints to maintain ion trajectories, the invention employs electromagnetic fields (RF voltages on electrodes) to dynamically focus ions along the curved path. This substitution of mechanical/geometric focusing with electromagnetic field control enables effective ion confinement in curved geometries.
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 enables a compact, high-resolution ion mobility spectrometer design that maintains mobility resolution while significantly reducing the device's footprint, allowing for more versatile laboratory applications.
Implementation Method 1
In a further refinement of the invention, the drifting ions are radially focused onto the axis of the curved shape by means of an RF field which generates a pseudopotential
Implementation Method 2
Ions which have moved away from the axis by diffusion processes can balance out different path lengths
Implementation Method 3
The ions of the substance under investigation are usually pulled through the stationary gas by means of an electric field. The large number of collisions with the gas molecules leads to a constant drift velocity vd for every ionic species which is proportional to the electric field strength E: vd=M×E.
Data Source
AI summary
The invention relates to devices for measuring the mobility of ions in gases at pressures of a few hectopascal. To make the device more compact, drift regions are bent into curved shapes, which extend into the third dimension. Parts of the drift region may lie above others. Alternating directions of curvature in the curved shapes balance out different path lengths by passing through approximately equal drift distances on outer and inner trajectories. Ions are held near the axis of the curved drift region by sectional or permanent focusing. One possible shape is a double loop in the shape of a figure eight. The shape extends perpendicular to its plane of projection so that several double loops lie on top of each other. RF ion funnels or ion tunnels can keep the ions near the axis. Axial focusing may use a pseudopotential radial to the axis of the curved shape.