Pulse Discharge Sensor Hardware Modification for Sodium Poisoning

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Solution Overview

Problem

Current gas sensors using the Pulse Discharge Technique (PDT) face issues with sodium atom poisoning of the Pt electrode due to cross-layer potential and are unable to accurately measure oxygen concentration at low temperatures, limiting concurrent O2 and NOx detection.

Innovation Solution

Modifying the PDT hardware by replacing the single polarity power supply with a floating positive and negative output supply and connecting one heater lead to the reference electrode ground, while adding an electrically isolated additional reference electrode to measure differential signals for accurate oxygen concentration calibration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single polarity power supply is used in PDT, then the sensor charging process is simplified, but cross-layer potential forms causing sodium atom diffusion and Pt electrode poisoning

Engineering Contradiction:

Improvepower supply configurationVSAvoidelectrode performance

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The power supply is segmented into separate positive and negative output channels, allowing independent control of potential applied to different electrodes. This segmentation enables the heater lead to be connected to the reference electrode without creating cross-layer potential, thus preventing sodium diffusion while maintaining simplified hardware architecture.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The reference electrode and heater lead are connected to the same potential (ground), creating an equipotential condition that eliminates the electric field responsible for sodium ion migration. This equipotential connection prevents electrode poisoning while allowing the sensor to function correctly under PDT conditions.

Inventive Principle:

Principle #12Equipotentiality

2Reliability

If the heater lead is connected to the reference electrode to eliminate cross-layer potential, then sodium diffusion is reduced, but sensor charging during PDT is interfered with

Engineering Contradiction:

Improveelectrode performanceVSAvoidsensor charging process

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The power supply outputs are segmented into separate positive and negative channels, allowing the reference electrode to be connected to the heater lead on one channel while the measurement electrode receives controlled potential from the other channel. This segmentation enables simultaneous achievement of equipotential reference and functional charging.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The grounded connection between heater lead and reference electrode acts as an intermediary that establishes a common reference potential, eliminating cross-layer potential without interfering with the measurement electrode charging process. This intermediary connection resolves the conflict between electrode protection and charging functionality.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Use of energy by moving object

If the sensor operates at low temperature, then energy consumption is reduced, but oxygen concentration measurement becomes inaccurate

Engineering Contradiction:

Improvepower consumptionVSAvoidoxygen concentration measurement

Core Design Contradiction:

Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

The reference electrode is prepared in advance by connecting it to the heater lead and grounding it, establishing a stable baseline potential before measurements begin. This preliminary configuration enables accurate differential measurements at low temperatures by compensating for thermal effects and drift, allowing precise oxygen measurement without requiring high operating temperatures.

Inventive Principle:

Principle #10Preliminary action

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 solution reduces sodium atom diffusion and electrode poisoning, enabling concurrent measurements of O2 and NOx concentrations without interfering with the sensor charging, and allows for accurate oxygen concentration determination.

Implementation Method 1

under the influence of electric field generated by the cross-layer potential formed between the Pt heater (11) and the Pt electrode (7)

Methodology Applied

Scientific EffectElectric Field: Electric Field

Implementation Method 2

Sodium atoms are reaching the Pt electrode via electro-diffusion through the Al2O3 substrate layers (2) under the influence of electric field

Methodology Applied

Scientific EffectElectro-diffusion: Diffusion

Implementation Method 3

conditioning a gas sensor through the application of pulse discharges

Methodology Applied

Scientific EffectPulse discharge: Electric Spark

Data Source

PatentUS10837940B1Planar sensor design and pulse discharge technique hardware

Publication Date: 2020.11.17 BJR SENSORS LLC

AI summary

An improvement in the method or technique of conditioning a gas sensor is provided through the application of Pulse Discharge Technique (PDT) in order to condition mixed-potential gas sensors. A modified planar sensor design to minimize sodium atom diffusion and platinum electrode poisoning under conditions of PDT are provided. Modification of the PDT hardware is provided without modification of the sensor design. The improvement method comprises:a) Replace a single polarity power supply with a power supply with floating positive and negative output;b) Connect one of the heater leads with the reference electrode lead and connect it to the ground.