The core of a new generation of polymer humidity sensor - resistive thin film humidity sensor

7 New Generation Subsidiary Department, Kang Sensen, Xin Yang Mujie Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027 Today, mankind has stepped into the information age, and how to identify and process all kinds of information in a real and rapid manner has become an urgent need of society and people. .

As a device for capturing information, sensors are rapidly developing, occupying a very important position in modern highly-informed society and technological development. Humidity sensor is an important type of chemical sensor. It has a wide range of applications in the control of environmental monitoring of home appliances, meteorological and aerospace missiles, etc. in warehouses and agricultural production processes. Research at home and abroad has been very active. Japan and Finland have taken the lead in the world. In recent years, China has devoted considerable efforts to follow-up research, and has made odious progress in theory and development and application, and has developed practical products with advanced levels.

The history of humidity sensor development began in the 3rd. At present, in terms of moisture-sensitive materials, they can be broadly classified into large-scale electrolyte-based semiconductor ceramics and organic polymer-based polymers. Although the polymer humidity sensor started late, it has developed rapidly. It is currently the most widely used type of new-type humidity sensor. It can be divided into capacitive type resistive surface acoustic wave type and optical type, and the former two types are mainly. It has replaced the inorganic ceramic humidity sensor gradually with its advantages of fast response, high resistance to environmental interference, and other advantages. Among them, the polymer-resistance type humidity sensor is characterized by its good response characteristics, wide humidity measurement range, easy fabrication, and easy integration, miniaturization, and low price for mass production, which has become a focus of research and development trend. However, the humidity sensors used at present, whether they are inorganic type capacitive type or resistive type, have poor stability and reliability. Over the years, direct restrictions have hindered the practical application and progress of humidity sensors. Therefore, exploring new high-precision, high-reliability, stability, and long-life excellent humidity-sensitive materials, in-depth exploration of the mechanism of moisture sensing, and improving and improving the stability and reliability of the sensor response characteristics have attracted great attention and interest from scientists in various countries. Become the core of research in this field.

The progress of society and science has shown us a vast market for humidity sensors. In recent years, the field of application of humidity sensors has been continuously expanding. In addition to its application in the process control of meteorological household appliances, it is now more widely used for grain storage. Fruit and vegetable storage cultivation. China is a large agricultural country. The humidity sensors required for monitoring food moisture alone are very large. However, the current domestic production of humidity sensors is still far from meeting the market's demand for moisture-sensitive components. According to the survey, in terms of humidity sensors in China, there are still no fully industrialized products, even if there are small batches of housewares. The humidity sensor is suitable for low humidity use, the manufacturing process is complicated, the yield is low, the flexibility is poor, and the price is expensive. Resistive-type polymer humidity sensors are currently developing rapidly, but there is still a general lack of stability, poor water resistance, and poor anti-interference ability. So far, China's humidity sensor still needs a lot of imports.

In order to make our country's humidity instrument localized, and to make breakthroughs in the quality of its properties, we must quickly catch up with the world's advanced level. We must produce our own humidity sensors. Zhejiang University is aiming at current resistance-type polymer humidity sensors with better overall performance, focusing on its existing awful and weak points. After several years of research and selection of polymer-polymeric materials, it has been developed for industrialization. The new generation of polymer resistive film humidity sensor. It uses a composite polymer as a moisture sensing material and uses an interlayer composite technology and a microelectronics process. It has a wide range of testing sensitivity, high linearity, good response time, short service life, good compactness, small size, 5 excitations, 6,0.5, simple manufacturing process, low cost, easy integration, and miniaturized mass production, and can be applied to the development of precision electronic components. The storage of aerospace missile rockets, the detection of high-altitude aerial images, the prevention of mildew in food, the cultivation of greenhouses, the storage of poultry eggs, and the detection and control of humidity in various fields of environmentally-friendly air-conditioning households have potential economic and social benefits.

This column editor Yan Jianpei