Development Of An Auto Test System For Humidity Sensors Based On LabVIEW

Humidity plays an important role on the development of our societies and lives of human being. With the development of modernization, it's hard to find out any field which has no relation with humidity. Usually, it need to measure and control the environment humidity in the industrial, agricultural production, meteorology, environmental protection, national defense, scientific research, aerospace and other departments.People will feel depressive if the atmosphere is too wet, people will feel discomfort if the atmosphere is too dry. So, the air condition needs not only control the temperature, but also the humidity. During the industrial production, the control of humidity straightforward determines the quality of the production. The invalidation of integrate circuit has great relation with humidity. Therefore, humidity control is important at the manufacturing sites of precision instruments, semiconductor integrated circuits and components. At defense, firearms, ammunition, military equipment, armed devices can not be damp, so the military warehouses on the detection of humidity is essential. Humidity is the basic parameters of weather observation, and its measurement accuracy directly determines the accuracy of weather forecasts. In addition, it is necessary to detect and control the humidity for health care, building a greenhouse plant, eggs, food storage and mildew. For the above reasons, the detection and control of humidity is very important. It's an important subject to study the detection method of humidity and humidity detection sensors.Every characteristic parameter of humidity sensors must be tested at the beginning of its manufacture and before its leaving factory. The traditional test methods still take dominant place in all test methods. With the development of modern science technology and development of modern industrial production, and with the increasing testing quantity and the requests for higher testing speed and accuracy, the traditional testing style operated by human is no longer right for modern testing tasks. The virtual instrument technology as a perfect combination of the instrumental technology and computer technology makes a wonderful scheme for testing engineers.As a result of the combination of computer technology and instrument technology, Virtual Instrument technology has broken through old concept of instrument and will become artery of measuring system. The future of virtual instrument have to bond to related IT technology, just like the presence and development of the computer technology increases the invention and application of virtual technology, which exploded a technical revolution in the measuring technology area.In this paper, we study mainly on the resistance-type humidity sensor, the test system is illustrated at length, including the design of hardware and software structure, mainly the makeup of hardware, and at last supply a set test system composed with the simulation of signal processor, data acquisition, data analysis and control.The automated test system studied by this paper is based on the connection of a ZL-5 model LCR analyzer and a PCI-GPIB Interface using software LabVIEW to control, which is produced by NI. Several programs are designed in our system for the measurement of humidity sensing properties of sensors, such as response-recovery curves, capacitance characteristics, frequency properties, and complex impedance properties, which make our system a good candidate in sensor investigations. With this developing environment, all the hardware is integrated into a well functioning auto test system. The users just have to make a click with the mouse to send a testing command and the test results will be displayed on the screen very soon. And the signal data of humidity sensors is saved in text file to be processed. In addition, in order to satisfy user's requirement of processing data, the data text file can be changed into the EXCEL file in which the data processing and data plotting ability are sufficiently used.In order to fully verify the performance of automatic test system, we choose two different humidity sensors which are fabricated with different humidity sensitive materials to test using the automatic test system. The results show that the automatic test system met the testing requirements in the system function, job stability, the accuracy of data acquisition during the scientific research.