Integrated Capacitive Detector for Ion Mobility Spectrometers

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Solution Overview

Problem

Ion mobility spectrometers face challenges in accurately detecting and identifying substances due to low ion current signals, which require amplification to measure time-of-flight effectively, and existing detectors may introduce noise or have limited bandwidth.

Innovation Solution

An integrated capacitive detector with a capacitive transimpedance amplifier circuit is implemented, utilizing a collector and capacitive plate as a capacitor to amplify ion current signals, and includes a reset mechanism to manage charge accumulation and reduce noise, allowing for precise detection of ions in spectrometers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional detectors are used to detect ion current signals, then the detection system is simple, but the detection sensitivity is insufficient and noise is high

Engineering Contradiction:
Improvedetection sensitivityVSAvoiddetector structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines the collector, amplifier, and capacitor into a single integrated detector structure. The collector collects ions and generates current signals, which are directly amplified by the integrated amplifier, and the capacitor integrates the amplified signals to produce measurable voltage outputs. This merging of functions into one compact detector resolves the contradiction by achieving high detection sensitivity through integration while maintaining structural simplicity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent introduces an integrated capacitor as an intermediary element between the ion collection and signal measurement processes. The capacitor integrates the current signals from the collector over time, converting them into voltage signals that can be measured. This intermediary component enables high detection sensitivity by accumulating weak ion current signals without requiring complex external amplification circuits.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If signal amplification is increased to detect low ion current signals, then detection sensitivity improves, but noise and bandwidth limitations increase

Engineering Contradiction:
Improvesignal detection capabilityVSAvoidnoise
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent employs periodic resetting of the integrator capacitor to manage noise accumulation. The reset mechanism periodically discharges the capacitor, preventing saturation and reducing low-frequency noise while maintaining the ability to detect transient ion current signals. This periodic action resolves the contradiction by enabling continuous sensitive detection without noise buildup.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The integrated detector uses feedback mechanisms where the output voltage from the capacitor is fed back to control the amplification and integration process. This feedback stabilizes the detection system, preventing noise amplification while maintaining high sensitivity for detecting weak ion current signals. The feedback loop adjusts the system response to optimize signal-to-noise ratio.

Inventive Principle:
Principle #23Feedback

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

The solution enhances the detection sensitivity and reduces noise, enabling accurate identification of ions by converting low ion current to a measurable voltage with improved bandwidth and noise reduction, effectively addressing the limitations of existing detectors.

Implementation Method 1

An integrated capacitive detector with a capacitive transimpedance amplifier circuit is implemented, utilizing a collector and capacitive plate as a capacitor to amplify ion current signals

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 2

capacitive transimpedance amplifier circuit is implemented, utilizing a collector and capacitive plate as a capacitor to amplify ion current signals

Methodology Applied
Scientific EffectTransimpedance amplification:

Implementation Method 3

includes a reset mechanism to manage charge accumulation and reduce noise

Methodology Applied
Scientific EffectCharge accumulation: Electrical Accumulator

Implementation Method 4

By measuring the time of flight along the cell it is possible to identify the ion

Methodology Applied
Scientific EffectTime of flight: Time of Flight

Data Source

PatentEP2856140B1Spectrometer comprising amplifier and integrated capacitor
Publication Date: 2019.10.16 SMITHS DETECTION WATFORD LTD
  • EP2856140B1 patent drawingFigure 1
  • EP2856140B1 patent drawingFigure 2
  • EP2856140B1 patent drawingFigure 3~4

AI summary

Spectrometers including integrated capacitive detectors are described. An integrated capacitive detector integrates ion current from the collector into a changing voltage. The detector includes a collector configured to receive ions in the spectrometer, a dielectric, and a plate arranged in an overlapping configuration with collector on an opposite side of the dielectric. The detector also includes an amplifier.