CMOS Humidity Sensor Arrays With Built-In Heaters and Vertical Plates
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional CMOS integrated humidity sensors face issues with non-uniform heat distribution, limited sensitivity due to restricted exposure of the moisture-sensitive dielectric layer, lack of redundancy, and limited utility due to the use of a single dielectric material.
Innovation Solution
A CMOS integrated humidity sensor design featuring a substrate with multiple unit sensors, each comprising a resistive heating structure and capacitive humidity sensors with interdigitated vertical metal plates separated by a moisture-sensitive dielectric, allowing for individual control and varying dielectric materials across sensors to enhance sensitivity and redundancy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single dielectric material is used in conventional CMOS humidity sensors, then the device complexity is reduced, but the sensitivity and detection range are limited
Solution Approach 1:
The sensor is divided into multiple unit humidity sensors, each containing capacitive humidity sensors with different dielectric materials. This segmentation allows each unit to detect different humidity ranges with optimized sensitivity, while the overall system benefits from the combined detection capability across multiple units.
Solution Approach 2:
Different dielectric materials are assigned to different capacitive humidity sensors within the unit sensors based on their specific detection requirements. Each dielectric material is strategically placed to optimize sensitivity for particular humidity ranges, creating local quality variations that enhance overall measurement precision.
2Measurement precision
If the moisture-sensitive dielectric layer is extensively exposed to enhance sensitivity, then the sensitivity increases, but the heat distribution becomes non-uniform
Solution Approach 1:
The sensor surface is segmented into multiple unit humidity sensors with capacitive sensors distributed across different locations. This segmentation allows the dielectric layer to be exposed at multiple discrete points rather than as a single large area, enhancing sensitivity while distributing the thermal load more uniformly across the sensor surface.
Solution Approach 2:
The capacitive humidity sensors are arranged in a three-dimensional configuration with metal plates extending in vertical directions. This dimensional arrangement increases the effective exposure area of the dielectric layer without requiring a large planar footprint, thereby improving sensitivity while maintaining better heat distribution through the vertical structure.
3Reliability
If multiple unit humidity sensors are integrated with individual control, then redundancy and sensitivity are improved, but the device complexity increases
Solution Approach 1:
The humidity sensor is segmented into multiple independent unit humidity sensors, each capable of individual control and measurement. This segmentation provides redundancy as each unit can operate independently or in combination with others, improving reliability while the modular structure manages complexity through standardized repeating units.
Solution Approach 2:
Multiple unit humidity sensors are merged into a single integrated device with shared control circuitry and readout electronics. This merging approach provides redundancy through multiple sensing elements while minimizing the increase in device complexity by consolidating control functions rather than providing separate control for each unit.
4Measurement precision
If the dielectric layer is extensively exposed to increase sensitivity, then the sensitivity improves, but the manufacturing precision requirements increase
Solution Approach 1:
The capacitive humidity sensors utilize vertical metal plates extending in the vertical direction rather than relying solely on planar exposure. This dimensional transition increases the effective surface area of the dielectric layer exposed to moisture while maintaining compact lateral dimensions, thereby improving sensitivity without proportionally increasing manufacturing precision requirements for large-area patterning.
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 design achieves improved heat distribution, increased sensitivity, and redundancy by allowing for individual sensor control and use of diverse dielectric materials, enhancing detection range and accuracy.
Implementation Method 1
each unit humidity sensor comprises a resistive heating structure disposed above the substrate
Implementation Method 2
The dielectric is a material with the property that the dielectric constant will change as the moisture content within the dielectric changes
Implementation Method 3
each unit humidity sensor having a top surface that at least a portion of which is water-permeable
Data Source
AI summary
A complementary metal oxide semiconductor (CMOS) integrated humidity sensor with built-in heater is disclosed. In an aspect, a capacitive humidity sensor comprises a substrate and a plurality of unit humidity sensors disposed above the substrate. Each unit humidity sensor comprises a resistive heating structure disposed above the substrate, a plurality of capacitive humidity sensors disposed above the resistive heating structure and set apart from each other in a vertical direction, and a top surface at least a portion of which is water-permeable. Each capacitive humidity sensor comprises a pair of interdigitated vertical metal plates extending in a first direction, set apart from each other in a second direction orthogonal to the first direction, and separated from each other by a moisture-sensitive dielectric disposed between the pair of interdigitated vertical metal plates. At least one capacitive humidity sensor uses a different moisture-sensitive dielectric than another capacitive humidity sensor.