Fabrication of flexible hot film sensor array and its optimization

To measure the flow field distribution parameters on the aerodynamic surfaces of airplanes and flow pipes, a hot film sensor array with the sensing material of nickel is fabricated on a polyimide substrate by the MEMS technology. The flexible and thin (whole thickness less than 100μm) sensor array can be attached upon a curved surface (such as airfoil) to measure the temperature distribution or flow parameters in a minimal invasion rapidly. The structure of sensor array is designed and the fabrication techniques are presented based on the magnetron sputtering and heat annealing. Then, the influences of the argon pressure, substrate temperature, sputtering power, and the annealing temperature on the temperature coefficient of resistance (TCR) for the sensor is studied. Finally, a high TCR of 4.64 × 10^-3/°C with good linearity is obtained.