Thermographic Sensor With Thermo-Couple-Driven Transistors for Low Crosstalk
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing thermographic sensors face challenges in achieving high sensitivity, low response time, and limited thermal cross-talk, which affects their performance and hinders their use in consumer applications, especially in mobile devices.
Innovation Solution
A thermographic sensor is designed by combining thermal transistors with thermo-couples, where each thermo-couple provides a sensing voltage based on the temperature difference between its hot and cold joints, and the transistors are driven by these voltages to generate a sensing electrical signal, with the sensor being integrated on a semiconductor-on-insulator body and utilizing suspended membranes for improved thermal insulation and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thermographic sensors use uncooled TMOS transistors or thermo-piles, then the sensors can operate at room temperature without complex cooling equipment, but the sensitivity and response time are insufficient for high-performance applications
Solution Approach 1:
The patent combines two previously separate sensing mechanisms (TMOS transistors and thermo-couples) into a single integrated sensing element. The thermo-couple drives the TMOS transistor, creating a cascaded sensing system where the thermal voltage from the thermo-couple modulates the transistor's channel, multiplying the output signal and significantly improving sensitivity while maintaining room temperature operation
Solution Approach 2:
The sensing element uses composite material structures including suspended membranes with specific thermal conductivities, layered configurations of different materials (semiconductor layers, insulator layers, metal contacts) to optimize both thermal isolation for sensitivity and electrical performance for signal output
2Measurement precision
If thermographic sensors use traditional structures, then manufacturing is relatively straightforward, but thermal cross-talk between adjacent sensing elements increases, reducing measurement precision
Solution Approach 1:
The sensor array divides the substrate into discrete, isolated sensing elements using suspended membranes. Each sensing element is thermally isolated from its neighbors by air gaps created through release holes in the sacrificial layer, preventing thermal cross-talk while maintaining precise temperature measurements for each pixel
Solution Approach 2:
The suspended membrane structure acts as a thin film that thermally isolates the sensing elements from the substrate and from each other. The membrane's thin profile minimizes thermal conduction paths, reducing thermal cross-talk between adjacent elements while maintaining mechanical integrity
3Speed
If thermographic sensors use conventional designs, then the device structure is simpler, but the response time is slower and sensitivity is reduced
Solution Approach 1:
The sensing structure employs dynamic thermal isolation through suspended membranes that can rapidly respond to temperature changes. The lightweight membrane structure has low thermal mass, enabling fast thermal response time, while the TMOS transistor provides rapid electrical signal modulation in response to thermal input
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 combination enhances sensitivity and reduces response time, improving the sensor's performance in terms of noise equivalent temperature difference (NETD), making it suitable for consumer applications, including mobile devices.
Implementation Method 1
Each thermo-couple converts a temperature gradient between a hot and a cold junction (generated by the thermal radiation) into electrical energy (measuring its amplitude) according to the Seebeck effect.
Data Source
AI summary
A thermographic sensor is proposed. The thermographic sensor includes one or more thermo-couples, each for providing a sensing voltage depending on a difference between a temperature of a hot joint and a temperature of a cold joint of the thermo-couple; the thermographic sensor further comprises one or more sensing transistors, each driven according to the sensing voltages of one or more corresponding thermo-couples for providing a sensing electrical signal depending on its temperature and on the corresponding sensing voltages. A thermographic device including the thermographic sensor and a corresponding signal processing circuit, and a system including one or more thermographic devices are also proposed.