A flow sensor for liquids based on a single temperature sensor operated in pulsed mode

An anemometric flow sensor for liquids based on a single temperature sensor is presented. The sensor is based on a probe composed by a silicon chip glued to a copper cylinder acting as thermal feed-through. A precise temperature sensor and a resistive heater are integrated on the chip surface. The sensor is operated in pulsed mode to eliminate the interference of the fluid temperature, switching either the heater power or the probe temperature. The results of water flow tests in the range (1-30) l/b are presented. The problem of reducing the duration of the measurement cycle has been addressed with theoretical and experimental arguments.