Multi-functional Combination Of Sensor Development,

The signal process and display circuits of multifunctional combined sensor are designed and researched by analyzing the sensitive mechanism of temperature sensor, humidity sensor and oxygen sensor. The structure of humidity sensor is designed through the deeply analysis of the polyimide capacitive humidity sensitive mechanism. The effect of fabricating process of humidity sensor on the polyimide sensitive membrane and the humidity sensitivity are explored and discussed. And the humidity sensor has been fabricated finally.The polyimide capacitive sensor, which is fabricated by the method similar to standard semiconductor process, has good linearity at low (6.1%RH) to high (97.1%RH) relative humidity range. The measured sensitivity for humidity sensor is 0.44Pf/%RH. The hysteresis and dielectric loss characters are measured and discussed. The sensitive mechanism of multifunctional combined sensor is measured and analyzed. The output voltage signals of temperature sensor, humidity sensor and oxygen sensor can be limited from 0 to 2V, and linearized to environmental change by multifunctional combined signal process circuits. Also the A/D converter and display circuits are designed and constructed to convert sensors' analog signals to digital signals.The multifunctional combined sensor has the features such as multiple function, small size and high precision. It can be used in environment detect, medicine, food and textile.