Thermal Sensor Combining Thermopile and Pyroelectric Elements
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Thermal sensors, particularly thermopile and pyroelectric sensors, face challenges in accuracy, sensitivity, and noise issues, with pyroelectric sensors experiencing leakage and hysteresis that hinder their use in thermal imaging due to image fade and ghosting effects, while thermopile sensors are slow and less sensitive.
Innovation Solution
A microelectronic device combining thermopile and pyroelectric sensors with a thermal isolation membrane and heat sink, where the thermopile elements are thermally coupled to both the heat absorber and sink, and pyroelectric elements are used to stabilize the voltage response, achieving similar temperature response coefficients and improved signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If pyroelectric sensors are used, then sensitivity and speed are improved, but accuracy deteriorates due to leakage and hysteresis
Solution Approach 1:
The patent combines thermopile and pyroelectric sensors into a single integrated device. The thermopile portion provides accurate DC voltage output for steady-state measurements, while the pyroelectric portion provides fast AC voltage output for dynamic changes. By merging these two sensor types, the device achieves both high accuracy (from thermopile) and fast response speed (from pyroelectric) simultaneously.
2Measurement precision
If thermopile sensors are used, then accuracy is improved, but sensitivity and response speed deteriorate
Solution Approach 1:
The patent combines thermopile and pyroelectric sensors into a single integrated device. The thermopile portion provides accurate DC voltage output for steady-state measurements, while the pyroelectric portion provides fast AC voltage output for dynamic changes. By merging these two sensor types, the device achieves both high accuracy (from thermopile) and fast response speed (from pyroelectric) simultaneously.
3Measurement precision
If pyroelectric sensors are used, then sensitivity is improved, but reliability deteriorates due to leakage and hysteresis
Solution Approach 1:
The patent combines thermopile and pyroelectric sensors into a single integrated device. The thermopile portion provides accurate DC voltage output for steady-state measurements, while the pyroelectric portion provides fast AC voltage output for dynamic changes. By merging these two sensor types, the device achieves both high accuracy (from thermopile) and fast response speed (from pyroelectric) simultaneously.
Solution Approach 2:
The patent introduces a floating diffusion node as an intermediary between the pyroelectric sensor and the readout circuitry. This floating diffusion acts as a charge storage node that integrates the fast pyroelectric signal while isolating it from the leakage and hysteresis effects. The floating diffusion mediates between the pyroelectric element and the measurement circuit, preserving signal integrity while maintaining fast response characteristics.
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 retains the sensitivity and speed of pyroelectric sensors while enhancing accuracy and reducing noise, resulting in a higher signal-to-noise ratio and stable temperature measurements.
Implementation Method 1
Thermal sensors operate by absorbing radiation, such as infrared energy emitted by a hot object, and converting that heat into an electric signal
Implementation Method 2
Thermopiles are composed of thermocouples that convert thermal energy into electrical energy. The Seebeck effect causes a voltage proportional to the temperature difference to appear across thermopiles
Implementation Method 3
Pyroelectric sensors based on pyro-electricity concept. Certain pyroelectric minerals and crystals create electric charge when they are subject to temperature change
Implementation Method 4
A first end of each one of the thermopile elements is thermally coupled to the heat absorbing layer and thermally isolated from the heat sink by the thermal isolation membrane
Data Source
AI summary
A thermal sensor device using a combination of thermopile and pyroelectric sensors is disclosed. The combination is achieved in a process flow that includes ferroelectric materials, which may be used as a pyroelectric sensor, and p-poly/n-poly for thermopiles. The combination retains the sensitivity and accuracy of the thermopile sensor and speed of pyroelectric sensors. The combination provides lower noise than individual thermopile sensors and results in a higher signal-to-noise ratio.