Hydrogel pH-Responsive Gas Sensor for PPM Food Freshness Detection

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Solution Overview

Problem

Current gas sensors face limitations in measurement sensitivity, struggling to selectively detect specific gases at ppm levels due to cross-talk phenomena and lower resolution compared to the human olfactory system.

Innovation Solution

A gas sensor incorporating a hydrogel support with pH-responsive dyes, such as anthocyanin-based natural dyes, that changes color in response to target gases like volatile organic acids or bases, enhancing selectivity and resolution by using a crosslinked structure and a porous membrane for improved gas collection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If semiconductor-type or electrochemical gas sensors are used, then measurement capability is provided, but cross-talk phenomenon occurs and measurement sensitivity is limited

Engineering Contradiction:

Improvemeasurement sensitivityVSAvoidselectivity

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent uses pH-sensitive dyes that change color in response to pH variations caused by target gas reactions. This color change mechanism enables selective and sensitive detection of specific gases (such as ammonia or carbon dioxide) by converting chemical reactions into visible optical signals, thereby resolving the cross-talk problem and enhancing measurement sensitivity to ppm levels.

Inventive Principle:

Principle #32Color changes

Solution Approach 2:

The invention employs composite hydrogel structures containing multiple functional components: pH-sensitive dyes, hydrogel matrices, and optionally fluorescent materials. This composite approach combines the selectivity of pH-responsive dyes with the sensitivity enhancement of fluorescent materials, achieving both high selectivity and measurement precision simultaneously.

Inventive Principle:

Principle #40Composite materials

2Measurement precision

If current gas sensors are used, then basic gas detection is provided, but resolution is lower than human olfactory organ and cannot detect ppm level gases

Engineering Contradiction:

Improvedetection resolutionVSAvoidsensor structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent utilizes changes in optical parameters (color, fluorescence intensity) in response to pH variations caused by gas absorption. By monitoring these optical parameter changes, the sensor achieves human-olfactory-level resolution for detecting ppm level gases, transforming chemical concentration detection into highly sensitive optical signal detection.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The hydrogel acts as an intermediary medium that absorbs target gases and translates gas concentration into pH changes, which are then detected through color or fluorescence changes. This intermediary mechanism amplifies the detection signal, enabling ppm-level detection without requiring complex sensor structures.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If hydrogel with pH-responsive dye is used, then selectivity and resolution are improved, but device complexity increases

Engineering Contradiction:

Improveselectivity and resolutionVSAvoidsensor structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The hydrogel-dye composite structure performs self-detection through intrinsic pH-responsive color or fluorescence changes. The system is self-sufficient, requiring no external power source or complex electronics for the sensing mechanism itself, thereby achieving high measurement precision with relatively simple device structure.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The invention replaces complex electronic sensing mechanisms with simple optical detection based on pH-responsive color or fluorescence changes. This substitution of mechanical/electronic systems with optical phenomena simplifies the overall device structure while maintaining or enhancing measurement precision and selectivity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 gas sensor achieves high selectivity and resolution, enabling accurate detection of specific gases at ppm levels, effectively determining the freshness, maturity, or fermentation state of foods, and can be integrated into electronic products like refrigerators for temperature control based on gas concentration.

Implementation Method 1

dye provided to be discolored in response to a pH change upon reaction with a target gas

Methodology Applied

Scientific EffectpH change:

Implementation Method 2

hydrogel support discolored through reaction with the target gas

Methodology Applied

Scientific EffectColor change:

Implementation Method 3

a specific gas is dissolved in hydrogel

Methodology Applied

Scientific EffectDissolution: Solvation

Implementation Method 4

the hydrogel support may have a crosslinked structure formed by a cross linking agent including a divalent cation

Methodology Applied

Scientific EffectCrosslinking:

Data Source

PatentUS9983141B2Gas sensor, refrigerator having the gas sensor and method of controlling the refrigerator

Publication Date: 2018.05.29 SAMSUNG ELECTRONICS CO LTD

AI summary

A gas sensor configured to be discolored in response to a pH change upon reaction with a target gas, a refrigerator including the gas sensor, and a method of controlling the refrigerator includes a hydrogel support discolored through reaction with the target gas, and the hydrogel support includes dye provided to be discolored in response to a pH change upon reaction with the target gas.