Low-humidity capacitive sensor and method of making same

By loading hygroscopic salt materials into porous alumina thin films and combining this with nanoporous structure design, the problem of low detection sensitivity of porous alumina-based humidity sensors in low-humidity environments was solved, and a low-humidity capacitive sensor with high sensitivity and stability was fabricated.

CN122109222APending Publication Date: 2026-05-29SOUTHEAST UNIV
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
SOUTHEAST UNIV
Filing Date
2026-04-24
Publication Date
2026-05-29

AI Technical Summary

Technical Problem

Existing porous alumina-based humidity sensors have low detection sensitivity in low humidity environments, making it difficult to achieve highly sensitive detection of trace amounts of moisture, and their fabrication process is complex.

Method used

By employing a structural design that combines a porous anodic aluminum oxide thin film layer with hygroscopic salt and an electrode layer, the hygroscopic salt material is loaded into nanopores. This enhances the adsorption of water molecules and amplifies the capacitance response signal by utilizing its strong hygroscopic capacity and the spatial confinement effect of the nanopore structure.

Benefits of technology

This improved the sensor's detection sensitivity and stability in low-humidity environments, enabling highly sensitive detection in such environments while simplifying the fabrication process.

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Abstract

The application discloses a low-humidity capacitive sensor and a preparation method thereof. The low-humidity capacitive sensor comprises an aluminum substrate, a porous anodic aluminum oxide film layer, a hygroscopic salt and an electrode layer. The porous anodic aluminum oxide film layer is arranged on the surface of the aluminum substrate. The hygroscopic salt is loaded in the nanopore channel of the porous anodic aluminum oxide film layer and on the pore wall surface. The electrode layer is arranged on the surface of the porous anodic aluminum oxide film layer. The preparation method comprises the following steps: performing surface cleaning and pretreatment on the aluminum substrate; forming the porous anodic aluminum oxide film layer on the surface of the aluminum substrate through an anodic oxidation method; immersing the obtained product in a hygroscopic salt solution, so that the hygroscopic salt enters the nanopore channel of the porous anodic aluminum oxide film layer and is loaded on the pore wall surface; drying; and preparing the electrode layer on the surface of the porous anodic aluminum oxide film layer, so that the electrode layer and the aluminum substrate form a capacitive structure. The application improves the adsorption capacity of the sensor to water molecules, significantly improves the capacitive sensitivity, and adopts inorganic materials with strong stability.
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