TiO2 thin film temperature sensor monitored by smartphone

A novel TiO2 thin film temperature sensor monitored by smartphone is proposed and demonstrated. The sensing head is constructed by titanium dioxide thin film deposited on the polished quartz fiber tip. A smartphone and a diffraction grating are employed as interrogation system. Fiber with 45° polished tip connect the flashlight and the camera on the smartphone, and the diffraction grating spreads the transmission spectrum over the camera's pixels, allowing for repeatable measurements of shifts of the spectrum. Using this method, the reflection intensity of sensor can be measured by smartphone and then the surrounding temperature is monitored by the shift of the reflection spectrum. The experimental results show that the sensor exhibits a good linearity over a temperature range of −10 °C to 180 °C with the sensitivity of 0.4 6 pixel/°C. Consequently, the interrogation method can provide a low-cost, integrated and intelligent measurement platform for thin film fiber temperature sensor.