The invention relates to a sensor (102) and a control unit (702) for cooperation with the sensor. The sensor (102) serves for measuring a velocity of a fluid (308) flowing through a channel (306). The sensor (102) employs a thermal measuring principle, which measuring principle is robust regarding disturbances on the amount of power dissipated by the heating element (106). A sensor receiver (110) is arranged for receiving an electromagnetic radiation generated by a control transmitter (722) comprised in a control (702) unit for cooperation with the sensor (102). The electromagnetic radiation is employed for powering the heating element (106) which is arranged for heating the fluid. On the basis of a measurement signal generated by a transducer arrangement comprised in the sensor (102), a control actuator (724) controls the velocity of the fluid. For this purpose a sensor transmitter (116) is arranged for transmitting the measurement signal to a control receiver (734).