Isolated Sensor Pedestal Design for Thermal Uniformity
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Solution Overview
Problem
Conventional sensors, such as metal oxide semiconductor (MOS) gas sensors, face challenges in maintaining thermal uniformity and are prone to stress due to heat sinking and thermal expansion mismatches, leading to reduced sensitivity and increased power usage.
Innovation Solution
A thermally and stress-isolated sensor design featuring a mounting portion connected to a sensor portion via pedestals, with an insulating gap between the planar portion and the sensor, minimizing heat conduction and structural stress, and a method involving wafer processing to form mesas and pedestals for isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the sensor is mounted to a substrate or header with electrical connections and leads, then electrical connectivity and structural support are achieved, but heat is sunk away from the sensor decreasing thermal uniformity
Solution Approach 1:
The sensor assembly is divided into distinct functional portions: a mounting portion for structural support and electrical connections, a sensor portion for sensing, and intermediate pedestals for thermal isolation. This segmentation allows the mounting structure to provide mechanical support while the pedestals prevent heat conduction paths, maintaining thermal uniformity across the sensor.
Solution Approach 2:
Pedestals serve as intermediary elements between the mounting portion and the sensor portion. These pedestals provide mechanical support and electrical connectivity while having low thermal conductivity, acting as thermal barriers that prevent heat sinking to the mounting structure, thereby maintaining thermal uniformity.
2Reliability
If the sensor operates at relatively high temperatures, then sensing performance is improved, but strains occur in the sensor material due to thermal expansion mismatch
Solution Approach 1:
The assembly is segmented into portions that can be made of different materials optimized for their specific functions. The sensor portion can use materials with appropriate thermal expansion characteristics for high-temperature operation, while the mounting portion uses different materials, with pedestals providing isolation to prevent stress transmission.
Solution Approach 2:
The pedestals act as intermediary elements that decouple the thermal expansion of the mounting structure from the sensor portion. This isolation prevents thermal stress and strain in the sensor material during high-temperature operation, allowing the sensor to maintain reliability.
3Use of energy by stationary object
If conventional sensor structures are used with mounting structures and leads, then structural support and electrical connectivity are provided, but power usage increases due to heat losses
Solution Approach 1:
The pedestals, which might appear as unnecessary structural elements, actually serve the beneficial function of thermal isolation. By introducing these low-conductivity intermediaries, the design converts what would be heat loss paths into thermal barriers, reducing the power required to maintain sensor temperature.
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 solution achieves improved temperature uniformity and reduced power consumption by minimizing heat loss and stress on the sensor, enhancing its operational efficiency and accuracy.
Implementation Method 1
at least one pedestal connecting a mounting portion edge to a sensor portion edge... minimizing heat conduction
Implementation Method 2
at least one insulating gap disposed between the planar portion and the sensor portion
Data Source
AI summary
An isolated sensor and method of isolating a sensor are provided. The isolated sensor includes a mounting portion, a sensor portion disposed adjacent to the mounting portion, and at least one pedestal connecting a mounting portion to a sensor portion.