Temperature indicator for culinary article
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Solution Overview
Problem
Thermochromic semiconductor materials used as temperature indicators are not compatible with oils or lipids when hot, leading to reduction and loss of thermochromic properties, and react with certain compounds like polytetrafluoroethylene (PTFE), resulting in non-functional coatings.
Innovation Solution
A core-shell particle structure is developed, where the core comprises a thermochromic semiconductor and the shell has multiple layers of mineral or hybrid organo-mineral materials, providing protection from external environments and maintaining thermochromic properties even in the presence of oils or high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thermochromic semiconductor materials are used as temperature indicators, then color change visibility and thermochromic accuracy are improved, but compatibility with oils and lipids deteriorates when hot
Solution Approach 1:
A silica-based intermediate layer is introduced between the thermochromic semiconductor core and the external oil/lipid environment. This intermediary layer prevents direct contact and chemical reaction between the semiconductor and reducing agents in oils, while allowing thermal energy to pass through for thermochromic function. The silica layer acts as a protective barrier that maintains both thermochromic accuracy and oil compatibility.
Solution Approach 2:
The temperature indicator uses a composite particle structure consisting of a thermochromic semiconductor core surrounded by a silica-based shell. This composite structure combines the thermochromic properties of the semiconductor with the chemical stability and oil resistance of silica, achieving both measurement precision and reliability in culinary applications.
2Adaptability or versatility
If thermochromic semiconductors are combined with PTFE, then non-stick properties are improved, but thermochromic properties are lost due to chemical reaction
Solution Approach 1:
The coating system is segmented into distinct functional layers: a PTFE-based non-stick layer and a separate thermochromic indicator layer. The thermochromic particles are encapsulated in silica shells that prevent chemical interaction with PTFE, allowing both non-stick properties and thermochromic functionality to coexist without mutual interference.
Solution Approach 2:
The silica shell surrounding the thermochromic semiconductor acts as an intermediary barrier that prevents direct chemical reaction between the semiconductor and PTFE. This intermediary layer allows the thermochromic material to maintain its properties while being incorporated into a PTFE-based non-stick coating system.
3Ease of operation
If thermochromic semiconductors are exposed to hot oils, then temperature indication function is improved, but reduction reaction occurs and thermochromic properties are lost
Solution Approach 1:
A silica-based protective layer is introduced as an intermediary between the thermochromic semiconductor and hot oils. This layer allows thermal energy to pass through for temperature indication while blocking chemical reducing agents in the oil from reaching and reducing the semiconductor, thereby maintaining both functionality and compositional stability.
Solution Approach 2:
The temperature indicator employs a composite particle structure with a thermochromic semiconductor core and a silica-based shell. This composite design provides chemical stability against reduction by hot oils while preserving the thermochromic temperature indication function during culinary use.
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 core-shell particles maintain reversible thermochromic properties and thermal stability up to 800°C, are resistant to acid degradation, and do not react with PTFE, ensuring visibility and durability in culinary applications.
Implementation Method 1
thermochromic semiconductor materials whose properties allow for the possibility of a progressive and reversible change of color as the temperature rises
Implementation Method 2
the shell comprises at least two layers: an inner layer in contact with the core and comprising a mineral material or a hybrid organo-mineral material; and an outer layer comprising a mineral material or a hybrid organo-mineral material that is different from that of the inner layer
Implementation Method 3
semiconducting metal oxides are easily reduced with heat when in contact with oil or lipids, and the compounds formed after such a reduction reaction are no longer thermochromic. For example, Bi2O3 is reduced to metallic bismuth (Bi(m))
Data Source
AI summary
The invention relates to a particle with a core-shell structure, the core of which comprises at least one thermochromic semiconductor and the shell comprises at least two layers—an inner layer in contact with the core and comprising a mineral material or an organo-mineral hybrid material; and—an outer layer comprising a mineral material or an organo-mineral hybrid material, different from that of the inner layer. The invention also relates to a method for producing this particle, and the use thereof as a temperature indicator, in particular in a culinary article, such as a pan.