Composite humidity sensitive material used for capacitive humidity sensor and sensor preparation method

Abstract

The present invention provides a composite humidity sensitive material used for a capacitive humidity sensor and a sensor preparation method, the formula of the composite humidity sensitive material is as follows: mixing titanium oxide or barium titanate with barium strontium titanate in the mass ratio of 1:1-1:3 to obtain an initial functional ceramic material, mixing polyamide or polytetrafluoroethylene with the initial functional ceramic material in the mass ratio of 0.3wt%-0.5wt% to obtain a mixture; and mixing an inert metal with the mixture in the mass ratio of 15wt%-25wt%. A composite humidity sensitive film is prepared by an aerosol deposition technology from the composite humidity sensitive material, and the capacitive humidity sensor is prepared from the film by a semiconductor processing technology. The sensor has high precision, high stability, heat resistance, pollution prevention and high reliability.

Description

technical field [0001] The invention relates to a composite moisture-sensitive material used for a capacitive humidity sensor and a sensor preparation method. Background technique [0002] The advantages of capacitive humidity sensors are fast response, small size, good linearity, and stability, but most of the products that achieve the above performance are foreign brands, and the prices are very expensive. Some low-priced capacitive humidity sensors sold in the domestic market often fail to reach the above level, and their linearity, consistency and repeatability are not ideal. Below 30% RH, the humidity sensing section above 80% RH is seriously deformed. And regardless of the high-grade or low-grade capacitive humidity sensor, the long-term stability is not ideal. After long-term use, there will be a certain delay in the process of moisture absorption and dehumidification, which will reduce the accuracy of humidity measurement. Moreover, most capacitive humidity sensors ...

AI Technical Summary

Problems solved by technology

Traditional ceramic-based moisture-sensitive materials have many problems to be solved, such as degradation of hysteresis characteristics in complex environments, detection drift under high temperature and high humidity, and detection sensitivity due to pore structure, pore size irregularity, and distribution defects Problems such as poor detection accuracy of drop and low humidity

[0003] At present, the sol-gel method is commonly used to manufacture composite moisture-sensitive materials. The composite moisture-sensitive materials prepared by the sol-gel method can obtain the required homogeneous multi-component system by mixing different materials. The synthesis temperature is low, and the sol or The rheological properties of the gel are conducive to the preparation of the desired humidity sensor moisture-sensing film by the spin-coating technique commonly used in semiconductor micro-nano processing, but during the processing process, it is found that there are some problems to be solved in this technology: first, the preparation method is cumbersome , it is necessary to use a variety of equipment for solution configuration and multiple heating and other complex processing processes, resulting in a long time for the entire sol-gel process, ranging from a few days to a few weeks; second, the configured The gel cannot be stored stably for a long time, and its properties are easily changed, which leads to deviations in the uniformity of the material and the composition ratio of the ingredients; third, multiple heat treatments during the operation are not conducive to maintaining the performance of the polymer material in the mixed material. Stable; fourth, the required raw material (metal alkoxide) is expensive and the recovery technology of alcohol is difficult, which virtually increases the investment in equipment and operation in the preparation process, and it is difficult to realize industrialization because of its high equipment cost

How to improve the sensitivity and reduce the influence of hysteresis characteristics is a difficult point in the research of humidity sensors, and there has been no effective method

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