Annealing Effect on Temperature Coefficient of Resistance of Microflexible Thermal Shear Stress Sensor

Knowledge of wall shear stress is of primary importance in aerodynamic and hydrodynamic designs because it determines a major part of the skin friction drag. The sensitivity of microflexible thermal shear stress sensor is positively correlated with the temperature coefficient of resistance (TCR) of thermistor film, but the TCR of thermal sensor is extremely low due to the lattice defects of deposited films. A high-sensitivity microflexible thermal shear stress sensor with TCR of 5100 ppm/°C after annealing treatment is present in this letter. The annealing effect on TCR of magnetron sputtered thermistor films was investigated. The TCR increases with increasing annealing temperature and time until annealing time exceeds 6 h. The microstructural characterization indicates that of the TCR of thermistor films is dominated by electron grain boundary scattering. The TCR improvement after annealing is attributed to the growth of grain and reduction of the grain boundary reflection coefficient.