Capacitive Gas Sensor Structure for Room-Temperature Selective Sensing

Solution Overview

Problem

Existing capacitive gas sensors face challenges in operating at room temperature, achieving high response and recovery speeds, selective sensing of specific gases, and reducing noise due to phase differences.

Innovation Solution

A capacitive gas sensor design featuring a sensitive material surrounded by upper and lower electrodes with a porous structure, where capacitance changes with gas adsorption or desorption, and voltage frequency is adjusted to selectively sense methanol, toluene, and acetone gases.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a resistive gas sensor using oxide semiconductor is used to achieve high sensitivity, then sensitivity is improved, but power consumption increases and long-term stability deteriorates due to high temperature operation requiring a heater

Engineering Contradiction:

ImprovesensitivityVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent replaces the thermal field (heater-based resistive sensing) with an electric field-based capacitive sensing system. The sensor operates by measuring capacitance changes in a dielectric layer when target gases are adsorbed, eliminating the need for high-temperature heating and significantly reducing power consumption while maintaining high sensitivity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operating principle from thermal-based resistance measurement to electrical-based capacitance measurement. By using a dielectric layer whose capacitance changes with gas adsorption, the system achieves high sensitivity without requiring high-temperature operation, thus resolving the contradiction between sensitivity and power consumption.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If a resistive gas sensor using oxide semiconductor is used to achieve high sensitivity, then sensitivity is improved, but long-term stability deteriorates due to high temperature operation

Engineering Contradiction:

ImprovesensitivityVSAvoidlong-term stability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent replaces the thermal field (heater-based resistive sensing) with an electric field-based capacitive sensing system. The sensor operates by measuring capacitance changes in a dielectric layer when target gases are adsorbed, eliminating the need for high-temperature heating and significantly reducing power consumption while maintaining high sensitivity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operating principle from thermal-based resistance measurement to electrical-based capacitance measurement. By using a dielectric layer whose capacitance changes with gas adsorption, the system achieves high sensitivity without requiring high-temperature operation, thus resolving the contradiction between sensitivity and power consumption.

Inventive Principle:

Principle #35Parameter changes

3Speed

If a capacitive gas sensor with porous structure is used to improve response speed, then response and recovery speeds are improved, but noise due to phase difference increases

Engineering Contradiction:

Improveresponse speedVSAvoidnoise due to phase difference

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The patent applies different frequencies to different electrode pairs based on their spatial orientation. Horizontal electrode pairs use one frequency while vertical electrode pairs use another frequency, allowing the system to maintain fast response through porous structure while reducing phase difference noise by differentiating the operating frequencies of different measurement channels.

Inventive Principle:

Principle #3Local quality

4Adaptability or versatility

If voltage frequency is adjusted to selectively sense specific gases, then selectivity is improved, but device complexity increases due to frequency control requirements

Engineering Contradiction:

Improvegas selectivityVSAvoidfrequency control complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies different frequencies to different electrode pairs based on their spatial orientation. Horizontal electrode pairs use one frequency while vertical electrode pairs use another frequency, allowing the system to maintain fast response through porous structure while reducing phase difference noise by differentiating the operating frequencies of different measurement channels.

Inventive Principle:

Principle #3Local quality

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 sensor achieves improved response and recovery speeds, reduced noise, and selective sensing of target gases, enabling efficient operation at room temperature with reduced power consumption.

Implementation Method 1

a sensitive material for adsorbing or desorbing a target gas

Methodology Applied

Scientific EffectAdsorption: Adsorption

Data Source

PatentUS12590918B2Capacitive gas sensor and method for manufacturing same

Publication Date: 2026.03.31 IND UNIV COOP FOUND HANYANG UNIV ERICA CAMPUS

AI summary

Provided is a capacitive gas sensor. The capacitive gas sensor comprises a sensitive material for adsorbing and desorbing a target gas, an upper electrode surrounding the sensitive material, a lower electrode facing the upper electrode, and a porous structure disposed between the upper electrode and the lower electrode, wherein the capacitance of the sensitive material changes as the sensitive material adsorbs and desorbs the target gas.