Sensor apparatus and method for use with gas ionization systems
Inventors
BLACK, MIKE • Hart, Matthew • Somerville, John • Taylor, Alastair • Manasi, Iva • Allsworth, Max
Assignees
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Publication Number
US-9953818-B2
Publication Date
2018-04-24
Expiration Date
Abstract
An ion mobility gas detector apparatus including a detector core, an inlet gas path, an exhaust gas path, a source of diluent gas, and at least one or more sensors for measuring temperature, pressure and humidity of gas streams. Further included is a mixing mechanism adapted to mix at least first and second gas streams in response to one or more sensor measurements. A controller is provided for applying drive signals to the detector core.
Core Innovation
The described invention provides an ion mobility gas detector system in which a first inlet gas stream and a second diluent gas stream are provided to the ion mobility sensor, and at least one of temperature, pressure, and humidity of each gas stream is measured. The inlet and diluent gas streams are mixed at least in part in response to those measurements. This compensates for ambient environmental effects that can otherwise alter detector behavior and analyte characterization.
The system architecture includes a detector core with an inlet gas path and an exhaust gas path, together with a mixing mechanism that mixes inlet and diluent and/or recirculated streams responsively to sensor measurements. Temperature, pressure, and humidity sensors are associated with the gas streams, enabling mixing control based on measured conditions. Recirculating flow, scrubber, filter, heater, and flow controllers are described as part of the architecture to adjust a dilution ratio and control sensor-head humidity.
In the context of Field Asymmetric Ion Mobility Spectrometry (FAIMS), the detector core and related circuitry are used with charge management to address charge buildup in the FAIMS analytical gap and to reduce charge mirroring, with ion polarity selection for operation. Electric-field-assisted detector electrode arrangements are described, including perforations and reflector/EMI shielding, together with RF stability feedback and mode switching between low power chemical-event monitoring and a higher discrimination mode for additional analysis.
Claims Coverage
Independent claim 1 covers a method of mixing gas streams in an ion mobility sensor by measuring at least temperature, pressure, and humidity for each gas stream and mixing in response. The provided claims also specify a detector core with inlet and outlet gas paths, and FAIMS operation including a low power chemical-event mode that switches to a higher discrimination mode. Overall, the inventive coverage centers on sensor-driven responsive mixing control for environmental compensation in an ion mobility/FAIMS detector.
Responsive mixing based on measured temperature, pressure, and humidity
Providing a first inlet gas stream to the ion mobility sensor; providing a second diluent gas stream to the ion mobility sensor; measuring at least one of temperature, pressure and humidity of each first and second gas stream; and mixing at least the first and second gas streams in response to measurement of at least the first and second gas streams.
Detector core with inlet and outlet gas paths
An ion mobility sensor including a detector core plus an inlet gas path and an outlet gas path.
Measuring temperature, pressure, and humidity for each gas stream
Using one or more sensors to measure temperature, pressure, and humidity of each first and second gas stream.
Mixing performed by a mixing mechanism responsive to measured conditions
Using a mixing mechanism to mix at least a first and a second gas stream in response to measuring those gas streams.
FAIMS detector implementation
Implementing the method using an ion mobility sensor that is a Field Asymmetric Ion Mobility (FAIMS) detector.
Low power chemical-event monitoring with mode switching
Configuring the FAIMS detector to run in a low power mode to monitor for a chemical event, and upon detection switching to a higher discrimination mode for additional analysis.
The claims tie responsive gas-stream mixing to measured temperature, pressure, and humidity for each stream to manage environmental effects in an ion mobility sensor. The coverage also specifies a detector core with inlet and outlet gas paths and FAIMS operation including low power chemical-event monitoring with switching to higher discrimination.
Stated Advantages
Compensates ambient environmental effects (temperature, pressure, humidity) that would otherwise degrade results.
Avoids spectral distortion and contamination.
Enables robust spectra through temperature control of filters versus a FAIMS core and controlled recirculation/clean baseline operation.
Simplifies analyte characterization by controlling sensor-head humidity and dilution ratio.
Provides stable operation through charge management to reduce charge buildup and charge mirroring.
Supports efficient monitoring by operating in low power mode for chemical-event detection and switching to higher discrimination mode for additional analysis.
Documented Applications
Chemical-event monitoring in a FAIMS-based ion mobility detector using a low power mode, with switching to higher discrimination mode for additional analysis.
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