Photoionization detector having improved gain and reduced humidity sensitivity

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Solution Overview

Problem

Photoionization detectors (PIDs) face issues with high system and background noise due to the use of transimpedance amplifiers and are sensitive to humidity, which affects their accuracy and sensitivity, especially in uncontrolled environments.

Innovation Solution

A photoionization detector sensor with unique electrode patterns, including a negative electrical potential pattern, an electron collecting electrode pattern, and a grounded potential conductive pattern, designed to minimize humidity sensitivity and enhance detection signal strength by concentrating the electric field on ionized molecules, reducing the need for transimpedance amplifiers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If transimpedance amplifiers are used to increase detector sensitivity, then the detection sensitivity is improved, but system and background noise increases

Engineering Contradiction:

Improvedetection sensitivityVSAvoidsystem and background noise

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent removes the transimpedance amplifier from the detection system entirely. Instead of using an amplifier to boost the signal, the design relies on a direct electron collection mechanism where electrons generated by photoionization are collected by a biased electrode and measured as current, eliminating the noise introduced by amplification while maintaining detection sensitivity

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the electronic amplification system (transimpedance amplifier) with a direct electrical measurement system. By using a biased electrode to collect electrons and measuring the resulting current directly, the system substitutes complex electronic signal processing with a simpler electrical measurement approach that inherently has lower noise

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Power

If electrode spacing is reduced to increase signal strength, then detection signal strength is improved, but humidity sensitivity increases due to galvanic currents

Engineering Contradiction:

Improvedetection signal strengthVSAvoidhumidity sensitivity

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a third electrode (electrode C) that is biased at a potential intermediate between electrode A and electrode B. This intermediate electrode acts as a mediator that collects electrons before they can travel across the full voltage differential, thereby reducing the electric field strength and minimizing galvanic current formation in humid conditions while still providing sufficient signal for detection

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the voltage distribution parameters by introducing an intermediate bias potential. Instead of having a single large voltage differential between two electrodes, the system uses three electrodes with progressively changing potentials, effectively dividing the voltage parameter to reduce both signal strength and humidity-induced galvanic currents in a controlled manner

Inventive Principle:

Principle #35Parameter changes

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 improved electrode geometry enhances signal-to-noise performance and accuracy, allowing PIDs to function effectively in humid environments by minimizing noise and humidity-induced errors.

Implementation Method 1

a gas discharge lamp that ionizes molecules of interest to create ionized molecules and electrons

Methodology Applied

Scientific EffectPhotoionization: Photoionisation

Implementation Method 2

designed to minimize humidity sensitivity and enhance detection signal strength by concentrating the electric field on ionized molecules

Methodology Applied

Scientific EffectElectric field: Electric Field

Implementation Method 3

measuring the generated electrons

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS12455261B2Photoionization detector having improved gain and reduced humidity sensitivity

Publication Date: 2025.10.28 MODERN CONTROLS INC

AI summary

A photoionization detector comprised of a gas discharge lamp that ionizes molecules of interest to create ionized molecules and electrons and a sensor having at least one opening for UV light to pass through and electrically conductive patterns on at least one of the top and bottom surfaces of the plate, including at least a negative electrical potential pattern and an electron collecting electrode pattern. The ionized molecules are collectable by a bias electrode and electrons are collectable by a collector electrode. The negative electrical potential pattern includes a linear portion and a polarization plate. The electron collecting electrode pattern includes a wire suspended across the at least one opening and a linear portion on the surface opposite the wire. The electrically conductive patterns can further include a grounded potential conductive pattern having a first portion on the top surface and a second portion on the bottom surface.