Time of flow sensor with a flow parallel wire

A flow parallel wire (FPW) with a center tap is used in a sensor for measuring the time of flow of a heat pulse generated upstream by a heater. The upstream and downstream parts of the FPW are combined to a half bridge resulting in a large output peak when a heat pulse passes the FPW. The time between generating the heat pulse and recording the peak maximum is only a weak function of the properties of the fluid.