Capacitive relative humidity sensor based on graphene oxide

Abstract

The invention discloses a capacitive relative humidity sensor based on graphene oxide. The humidity sensor is characterized by comprising a substrate (1), an oxide layer (2), a heating strip (3) and an insulating layer (4) that are successively arranged on the substrate (1) from bottom to up. The humidity sensor also comprises a first capacitance electrode (5), a second capacitance electrode (6), passivation layers (7) and humidity sensitive mediums (8). The first capacitance electrode (5) and the second capacitance electrode (6) are arranged on the insulating layer (4) respectively and are equipped with a passivation layer (7) respectively; and the sensitive mediums (8) are arranged between the first capacitance electrode (5) and the second capacitance electrode (6), and also arranged above the first capacitance electrode (5) and the second capacitance electrode (6). According to the invention, sensor reliability is increased; technology steps are simple; and graphene oxide is employed as the humidity sensitive medium. Therefore, the sensor has advantages of high sensitivity, fast response speed and low hysteresis.

Description

technical field [0001] The invention relates to a relative humidity sensor based on standard CMOS (complementary metal oxide semiconductor) technology and MEMS (microelectromechanical system) post-processing technology, especially a capacitive relative humidity sensor using graphene oxide as a humidity sensitive medium . Background technique [0002] Humidity sensors are widely used in military, meteorological, agricultural, industrial control, medical equipment and many other fields. Over the past few decades, there have been many studies on capacitive, resistive, piezoresistive, optical, etc. types of humidity sensors. In the commercial field, the capacitive humidity sensor is the most widely used, because the capacitive humidity sensor has high sensitivity, low power consumption, and low manufacturing cost. Humidity sensors processed by standard CMOS technology have the advantages of small size, low price, and good product consistency. They are the hotspots of humidity ...

AI Technical Summary

Problems solved by technology

In 2004, Chinese Gu Lei proposed a capacitive relative humidity sensor made by CMOS technology. The sensitive unit of the humidity sensor is a flat comb-tooth capacitor structure, and the comb-shaped polysilicon heating resistor is placed under the comb-shaped electrode. The humidity sensitive medium is filled between adjacent electrodes, and polyimide is used as the humidity sensitive medium. The capacitance of this capacitive humidity sensor is mainly determined by the side wall area of ​​the comb-shaped electrode. When the sensor is processed by the CMOS process, the comb teeth It is difficult to make the thickness of the microsensor very large, so to achieve higher sensitivity, it is necessary to increase the number of comb-shaped electrodes, which will inevitably increase the chip area, so it is difficult to reflect the advantages of the small size of the microsensor, and the use of polyamide Imine as a sensitive material, the sensor responds slowly

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