Research On Tire Pressure Monitoring System Based On Nano Polysilicon Film Pressure Sensor

In this paper, a tire pressure sensor was designed and fabricated on SiO₂ layer of<100> orientation silicon substrates by MEMS technique and LPCVD method. The structure of the sensor is comprised of the Wheatstone bridge which contains a square silicon membrane and nano-polysilicon thin film. The four nano-polysilicon thin film resistances served as piezoresistors of tire pressure sensor were designed in the maximum stress area which were situated on the border of the square silicon membrane. When the tire pressure is applied to the silicon membrane, the silicon membrane presents elastic deformation, which gives rise to changes of sheet resistances and thus output voltage alters, and at last tire pressure could be detected.On this basis, combined with the test range retirement of the tire pressure, MEMS technique and LPCVD method could achieve the fabrication and package of the nano-polysilicon thin film tire pressure sensor. The dimension of the sensor chip is5×5mm². The results of static state characteristic test show that when the applied voltage was V_DD=5.0V, the sensitivity of the nano-polysilicon thin film tire pressure sensor was 0.117 m V/k Pa, the linearity was 0.239 %F.S., the repeatability was0.103 %F.S., the hysteresis was 0.115%F.S.. In the operation temperature range of-20?⁸0?, the temperature coefficient of sensitivity was about-0.106 %/?.According to the static characteristic test results, two modules were designed: tire monitoring module and the wireless receiving module. They composed the tire pressure monitoring system with a tire pressure sensor. By tire pressure sensor, tyre collect tire pressure monitoring module, combined with the temperature sensor data for temperature compensation of pressure data processing. Data information in wireless way is sent to the wireless receiving module, then to be managed and displayed. When the tire pressure is higher than or lower than the standard, system will warn. On this basis, thedesign, fabrication, test and debugging of the tire pressure monitoring system could be achieved favorably. The experiment results indicate that, the designed and fabricated nano-polysilicon thin film tire pressure monitor system, in this paper, not only could achieve the measure of pressure and wireless transmission function, but also increase of the stability and improve the temperature characteristic.