Stacked Humidity Sensor with Insulating Shielding Layer
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Solution Overview
Problem
Existing humidity sensors face challenges in reducing size and power consumption due to the arrangement of sensor and reference units, which leads to increased parasitic capacitance and higher power consumption.
Innovation Solution
The design includes a substrate with a reference electrode above it, a lower electrode separated from the substrate by an insulating film, and an upper electrode forming a parallel-plate detection capacitor, reducing parasitic capacitance and power consumption by stacking the sensor units and using a shielding layer to confine the electric field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the sensor unit and reference unit are arranged alongside each other on the substrate, then the sensor structure is simple and easy to manufacture, but the sensor size increases and parasitic capacitance becomes large
Solution Approach 1:
The patent transitions from a planar arrangement where sensor and reference units are placed side-by-side on the substrate to a three-dimensional stacked configuration. The lower electrode is positioned above the substrate separated by an insulating film, with the upper electrode above the lower electrode, creating vertical layering. This dimensional change reduces the horizontal area occupied while maintaining the functional separation between sensor and reference units.
2Device complexity
If the lower electrode is disposed on the substrate to function as a capacitance detecting electrode, then the sensor structure is simplified, but parasitic capacitance between the lower electrode and substrate becomes large
Solution Approach 1:
The patent introduces an insulating film as an intermediary layer between the substrate and the lower electrode. This insulating film acts as a mediator that electrically isolates the lower electrode from the substrate, thereby reducing parasitic capacitance formation while still allowing the lower electrode to function as a capacitance detecting electrode. The insulating film enables the lower electrode to be positioned close to the substrate without direct electrical contact.
3Ease of manufacture
If the sensor unit and reference unit are arranged alongside each other on the substrate, then the manufacturing process is straightforward, but power consumption increases due to large parasitic capacitance
Solution Approach 1:
The patent employs vertical stacking of electrodes and insulating layers to reduce the horizontal footprint of the sensor unit and reference unit. By arranging components in multiple vertical layers rather than side-by-side on the substrate, the overall sensor size is reduced, which in turn reduces the total parasitic capacitance and associated power consumption while maintaining manufacturing feasibility through standard thin-film deposition processes.
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
This configuration results in a smaller and more energy-efficient humidity sensor with reduced parasitic capacitance, allowing for accurate humidity measurement while minimizing power consumption.
Implementation Method 1
parasitic capacitance between the capacitance detecting electrode and the substrate becomes large
Implementation Method 2
a humidity sensing film, formed of a polymeric material whose dielectric constant varies depending on the amount of absorbed moisture
Implementation Method 3
the sensor unit and the reference unit are parallel-plate capacitors in which upper and lower electrodes are included
Data Source
AI summary
A sensor includes a substrate, a reference electrode provided above the substrate, a lower electrode provided above the reference electrode via an insulating film, and an upper electrode provided above the lower electrode via a physical quantity detecting film. The upper electrode and the lower electrode form a parallel-plate-type detection capacitor, and the lower electrode and the reference electrode form a parallel-plate-type reference capacitor.