A NOVEL AND HIGHLY SENSITIVE GAS-FLOW SENSOR USING A HOT-SPOT ON YBA2CU3O7-DELTA THIN-FILMS

A novel and highly sensitive hot-wire-type flow sensor constructed of a YBa2Cu3O7-delta thin film has been fabricated. When heating voltage was applied to the sensor, a hot spot appeared and the sensor had a hi gh sensitivity to air flow speeds of 0.04-4 m/s. Sensing characteristi cs have been examined for two different heating modes, constant-voltag e and constant-resistance. In the constant-voltage mode, the current w as proportional to the square root of the flow speed. In the constant- resistance mode, the output voltage was proportional to the fourth roo t of the flow speed, as is explained by the well-known King's law. In both cases, high sensitivity and good linearity were observed.